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intake sludge buildup Pages: 12Last

mhamilton on Sat February 23, 2008 6:08 PM User is offlineView users profile

Spent this afternoon resealing my Malibu 229 intake, I was shocked to find every intake valve had a very heavy buildup of sludge. You can't even see the valves any more, looks like 1/4" or more has built up. The intake runners and manifold are also oily inside, manifold has a lot of oil burnt on the surfaces.

I looked at my PCV hoses, the inside of those are clean, as is the PCV valve. I don't loose any oil between changes, so I don't think valve guides are shot--unless it's burning oil on startup. It would be hard to tell if it was burning a little oil--between the air injector an cat converter. This engine has only 40k miles on it with 3,000 mile oil changes. Yet the valves look like they have 150k... where in the world did this junk come from? Glad to know that Seafoam treatment didn't fix anything...



The only consolation is that my cam is surviving nicely. And you have to love the extra 1/4" of material not removed from the intake ports

CorvairGeek on Sat February 23, 2008 8:11 PM User is offline

1. EGR
2. Normally would be valve stem seals on a Chevy, but you said you don't have oil loss.
3. Fuel deposits, I recall various carburetor issues in the past too.

I thought Seafoam was magic from everything I'd heard and read too!

I'm sure some of the GM Top cylinder cleaner would do the trick. I think it will eat up anything.

-------------------------
Jerry

mhamilton on Sat February 23, 2008 9:10 PM User is offlineView users profile

I believe the EGR could gum things up, I see all the black deposits in its passages. But, this stuff in the intake is all oily. The entire interior of the manifold is oily, with burned on deposits. I had thought it could be from crankcase vapors after shutting off the engine, but how would all of that be getting into the manifold? I do get oily condensation in the crankcase breather pipe, but that's doing its job.

Still, after 40k miles my valves look like this? The carb never ran that rich, I don't think (I always got 20 mpg).

Was also thinking possibly a cracked manifold? It's the cast aluminum type. But that would surly suck in oil very quickly. And, no cracks that I could see.

I will have to get some top end cleaner next time I'm at the dealer. The Seafoam apparently did nothing. And the BP gas ain't making anything better!

NickD on Sat February 23, 2008 9:37 PM User is offline

Seafoam and other combustion chamber decarbonizers do a fair job on cleaning such things as carboned up rings, but do very little for the intake part of the intake valves.

Buy three bottles of Chevon Techron or equivalent, back of the box or bottle always shows a gummed up intake valve before and after, stuff does work and add a bottle to three consecutive fillups. Heck follow the directions on the bottle.

PVC and EGR contribute to that and does build up over time, try and remember to add that stuff every 30K miles or so, and you do notice a difference if you are in touch with your engine. Think it has something to do with burning hydrocarbon based fuels, even BP has carbon in their fuels. I can see that buildup on the bottom of your valve stem head casting, it's a lot of work to take your engine apart and clean all that stuff off, I don't do that anymore since some of this snake oil actually works, and it does. Pulled an intake off just to check it because I am somewhat skeptical about claims.

Edited: Sat February 23, 2008 at 9:40 PM by NickD

mhamilton on Sun February 24, 2008 9:47 AM User is offlineView users profile

Thanks, I'll get some Techron along with the GM cleaner.

I would also be very interested to find out if the stuff really works and cleans up the junk I'm seeing. Though, there's no way I'm pulling that intake again to find out. 5 hours bent over that engine compartment, I should have known better... can hardly move this morning!

NickD on Sun February 24, 2008 1:56 PM User is offline

Gunk choke and carb cleaner with a wire brush works fairly well to clean up the inside of the intake manifold. I am dead tired, wife is on call this weekend, lot's of sick people this weekend.

HerkyJim on Sun February 24, 2008 7:35 PM User is offline

Hmmm,

my '72 Plymouth 318 intake manifold is waiting for me install it; I'll have to take a peek into the intake/exhaust ports and see if I can see any of that nasty build up on my valves. The one and only valve job was at 118,000 miles and its got 230,000 on it now. Was running good, but I got an urge to pull the manifold to see if the EGR jets needed cleaning. Got the manifold home from the machine shop all nice and clean and shiny aluminum painted.

So I had it hanging from the hoist with a piece of clothesline after I trial fitted it, and the knot slipped on one end. It didn't bounce. Cast iron is brittle. Glad I didn't have finger or toe in the way. Teach me a lesson (again) about shortcuts. Got another manifold at the junkyard...hundred bucks plus another forty to clean and NDI. Expensive lesson too!

I was watching TV last week, and saw that Shell is touting their gas as superior to the "discount gas" and showing a clean valve and one that looks like yours. Meaningless comparison, but people buy the advertising bs. Surely the Royal Dutch Shell company wouldn't mislead us consumers: right? If I remember they were in the news about their oil platform and also about bogus reserves claims a while back.

I used to use Marvel Mystery Oil in the gas. I'm just another sucker. Snake oil? I also ran a couple of Chevron Techron treatments a few years back. I'd like to see a chemical analysis of Chevron's Techron and WallyWorld's SuperTech gas treatments compared. Probably be surprised.

HaHa, be surprised if the presence--or not--of those deposits has any significant effect on anything except enriching the oil and chemical companies.

Your exhaust crossover passage looks pretty good, like its not running rich or burning much oil.

Edited: Sun February 24, 2008 at 7:37 PM by HerkyJim

bohica2xo on Sun February 24, 2008 8:53 PM User is offline

What you have there is simply a byproduct of burning hydrocarbon fuel, aggravated by the retarded cam timing so popular with that decade's emissions systems.

The valves run hot, and the fuel that flows past them boils off the light fractions if the droplets hit the valve. The heavy hydrocarbons stay behind, and buildup happens over time. Fuel additives can help by adding different hydrocarbons to the mix that have higher boiling points. They recombine with the gunk on the valve and loosen it enough to fall off & be consumed in the combustion process. The trick is to make it happen in managable sized chunks over a long enough time span to be acceptable to the spark plugs...

The retarded cam timing provides passive EGR by opening the exhaust valve late - then closing it late, and sucking some exhaust gas back into the cylinder. Then on the intake stroke the intake opens late, mixes the intake charge with this & closes late. The late closing pukes some of this now hot crap back up the intake tract - and the coanda effect insures plenty of it hits the valve behind the seat. This does lower efffective cylinder pressure, & reduces nox somewhat.

Advancing the camshaft about 6 degrees would help, but you would need to recalibrate the ignition advance curve & mixture accordingly. Be nice to have the horsepower back however...


B.

-------------------------
"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

mhamilton on Sun February 24, 2008 9:40 PM User is offlineView users profile

Jim, I also have seen that Shell commercial lately. Mine look like the "before" valves, only 10x worse. I am honestly shocked that much buildup can occur. I've got a 283 with inches of gummed oil in the block, an exhaust crossover clogged solid, and the valves still don't look as bad as this 229. I will also have to ask around, see if the 305s of the era have the same buildup problem.

Was browsing online, offered under GM Vehicle Care is a "Fuel System Treatment Plus" 88861011 @ $23.13 for 20 oz... has an identical bottle and word-for-word description as the Techron--which costs $10.88 at Advance Auto.

Bohica, that does certainly explain the heavy and rapid buildup on this engine. I will have to look into the OE cam specs, see if I can make sense of them. Not sure I want to start recalibrating this engine after I just got it right... but if I did want to advance the cam, what would that require, an adjustable cam sprocket? Or just advancing one tooth on the gear?

Oh, BTW, that SuperLube has been working flawlessly in my HEI advance. Even in freezing weather it's had no trouble. Thanks again for pointing me to that.


CorvairGeek on Sun February 24, 2008 11:33 PM User is offline

I didn't see the buildup on my '84 305 when I had the intake off around 150K when the gasket blew out at the corner of a coolant passage. It had a steady diet of premium fuel up until that point, and I only ran it with EGR for less than 3K miles total during new break-in (now at 214K).
I concur with the retarded cam timing, it seems quite profound on the 229/305 engines. My 305 would get so "lazy" acting after 100K on a single roller chain, even with a steel cam gear at 200K with the second chain replacement. I went to a double roller the last time it was apart. I've assisted/changed enough worn chains on engines people thought were "tired" that it is a common issue with '70s and later engines.

-------------------------
Jerry

NickD on Mon February 25, 2008 12:28 AM User is offline

$10.88 at Advance Auto for Chevron Techron? In a 12 oz. bottle that treats 12 gallons of gas? My Fleetfarm sells that for $4.89 that has the identical ingredients listed as Slick and one other brand they also carry, but that sells for twice the price.

The lower part of your engine sure looks clean, wouldn't see that in a 283 in a 57 Chevy with a breather tube rather than the PCV, would need a putty knife to scrape off at least a 1/2" of sludge in those, a lot more under the valve covers. Those weren't the good old days, slow down on a dusty road, and that breather would suck in tons of dirt. It was actually better to slip the gear into neutral and rev the engine while coming to a stop.

bohica2xo on Mon February 25, 2008 3:04 AM User is offline

I find that using a degree wheel & indicator on an engine of that vintage usually leads to vomiting...

One of the good things about the 229 is the fact that it shares so many parts with the SBC. In this case, the timing set is one of those parts. You will need an "adjustable" timing set - a whole tooth is way too much. I have a bad habbit of checking the stock part, then broaching a new keyway in 186 degrees from the first keyway. I suspect the next guy wonders what happened to the crank sprocket.

Several companies make adjustable (or fixed multiple choice) timing sets for the 229 / SBC. Comp Cams #2100 has 3 keyways +4, 0, & -4 degrees. Units like THIS offer infinite adjustment across +6 to -6 degrees. Look around, there are probably 25 makers of adjustable SBC parts. I would have looked it up on GM's site for ya - but without the latest flash/shockwave/java/jackoff software loaded up, the site just hangs up...

Glad the SuperLube worked out for you.

B.

-------------------------
"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

NickD on Mon February 25, 2008 9:39 AM User is offline

Think I still have my degree wheel around here, someplace, haven't used it in years when it was legal to modify an engine, now, just put a wrench on the crank with the spark plugs removed, you can feel the slop in the chain. Last time I did that was on my 454, but not sure what I would have done if it was sloppy, a real PITA to change that thing in a motorhome. Even hate to think about a water pump failure, must be getting old.

Got a kick out of reading HerkyJim's post, same thing happened to me awhile back with a heavy object falling off my line, well a dog runners line, I don't hang my socks. I instinctively kicked my right foot forward to break the fall to save the part, but got a crack in my big toe bone. Well, that grew back, at least I saved the part. Hanging that super heavy plate steel motorhome gas tank from that line was testy, put that on a stool and made sure it was secure before removing the stool so I could paint it. Still learning, the slower and more carefully I move, the faster I will get the job done. I didn't drop my AT.

mhamilton on Mon February 25, 2008 12:34 PM User is offlineView users profile

I'm sure there's a tradeoff. I know after I replaced my broken EGR I started getting better economy, but I run 87, not premium. Aside from that, "technically" I'm supposed to have all emission equipment present and operating for inspection, even though I have no more sniffer test. However, that rule seems moot as they just check off "okay" for everything, including the O2 sensor my car doesn't have (the same people that thought my Impala was too hard to steer).

I do know that my old timing chain was extremely loose. Looked like it could skip a tooth. And I doubt it was the original chain, since the timing cover had 2 gaskets on it. The 229 got a standard timing set, while the 305 got one of those nylon covered setups. Anyway, when I installed the new timing set, I just aligned the marks and that was it. I really should have known better--had I checked tolerances and specs back then, I would not be having problems with this engine now.

I do wonder if the cam is retarded even more than stock? It would explain the exacerbated gunk buildup and other problems. Thanks for the link Bohica, I think a good timing set will be in order when I rebuild this again. If not to advance it more, at least to get it to spec.

Nick, the $10 bottle is 20 oz. for 20 gallons, they also sell a smaller bottle for $6. I will have to stop in the store one day this week to look.

CorvairGeek on Mon February 25, 2008 6:22 PM User is offline

It's funny how GM (and others) knew the nylon/potmetal wonder gears wouldn't last long enough in the 90 degree V6s, but would last just long enough (at a minimum) in light duty V8s.

-------------------------
Jerry

mhamilton on Mon February 25, 2008 8:26 PM User is offlineView users profile

I found the valve timing specs. The V6 has considerably more overlap than the 305. It also has more valve lift, about 0.03" more.

The intake opens 42* BTC, closes 78* ABC, 300* duration. The exhaust opens 78* BTC, closes 52* ATC, 310* duration. 94* overlap. Those values are excluding ramps.

So how do these figures compare with a "normal" engine? Again comparing with the 305 (and 267), those valves open later, close sooner, and have less duration. The Buick 231 is the same way.


After driving the car today, something is wrong. Suddenly and unexplainably it is running quietly, and almost smoothly. How does a new bead of silicon at the front of a manifold do that?

Edited: Mon February 25, 2008 at 8:33 PM by mhamilton

NickD on Mon February 25, 2008 10:22 PM User is offline

Carbed engines are extremely sensitive to any vacuum leaks, leans out the mixture that causes the engine to run much hotter, internally.

Never ceases to amaze me how easy it is to hand turn an engine (spark plugs removed) with the timing chain/belt off, and how strenuous it is with the chain/belt back on. Some engineers were aware of this valve train loading problem and no wonder why the chain/belts are short lived, GM always liked their 150 pounds plus valve springs. Supra turbo with a DOHC uses 35 pound springs. Recall an old MB design that was valve spring free using a special cam that both opened and closed the valves. Some talk about solenoid operated valves, not sure if that ever was put into production or not, but certainly don't want a glitch with an interference engine.

CorvairGeek on Tue February 26, 2008 1:27 AM User is offline

I'm surprised to hear there is a difference between the 229/305. The limited specs from the '84 shop manual didn't suggest it. The 231 engine had no camshaft specs at all.



-------------------------
Jerry

NickD on Tue February 26, 2008 9:09 AM User is offline

Valve timing must not be important, in all 31 pages in my GM shop manual, not even mentioned on my 454, but does say the valve springs have a 230 pound force that explains why my arm got sore trying to verify where TDC was on this engine.

Also not important in my 2.2 L four banger with over 431 pages of manual that is larger than the engine itself. Does give the dwell period of how long the intake or exhaust valve is opened, but does not state when either of these valve open or close in relationship to the TDC for each cylinder.

Suppose a guy could mount a degree wheel and measure the opening and closing of each valve to see if the numbers are even close, valve lift seems to be important, as that is given. But what good is valve lift if you have more than a 1/4" of sludge under the valves. Intake is always worse, but the exhaust valve also has lots of buildup, and that crap is really hard to manually remove. Before my lath days, used a pocket knife and a SOS pad, worse yet was trying to remove carboned up piston rings without wrecking the piston, bu the real PITA was trying to take hydraulic lifters apart for cleaning. But wow, did that make a difference in engine performance, even hated to start up the engine after all that work, because you knew it would get filthy again.

The theory of various cam cuts was to keep the doors opened longer so you can dump in more air/fuel and get it out, but a price was paid in idle. But what the heck, with dual exhaust and glass packs, that sounded cool. Hot Rod Magazine was relied on heavily back then as use to be a highly technical magazine if you had limited resources, but you had to choose your speed range and pay the price for the other ranges, variable valve timing was already recognized as a need. Easy to get that today, buy a Honda. Ha, happened to see a recent copy of HRM at the local library, today, it's all crap.

Keeping an engine clean always was a problem and still is today, somethings never change. While the electrodes on spark plugs stay sharper longer, they still carbon up eating away at that spark. Still pull out my old spark plug cleaner and blast them with walnut shells, regap, but don't have to file the electrodes, still good yet, so that job is a little easier. If I can find the spark plugs and don't have to remove half the engine to get at them.

bohica2xo on Tue February 26, 2008 2:07 PM User is offline

Wow, where to start...

"The intake opens 42* BTC, closes 78* ABC, 300* duration. The exhaust opens 78* BTC, closes 52* ATC, 310* duration. 94* overlap. Those values are excluding ramps. "

After cleaning the vomit from my keyboard, I am going to guess that those specs are some more GM fantasy specs - where the duration is figured at the point where .000025 inch lifter movment would occur in a perfect system. "excluding ramps" Uh Huh. Timing is best measured @ .050 inch lift, since effective valve flow starts there. All aftermarket cam manufacturers list an "advertised duration" to compare with factory fantasy numbers - as well as an effective (usually @ .050) duration.

The biggest thing wrong with that profile is the huge overlap. Even accounting for the reduction at a real world .050 lift, it is very large. By comparison, some cams have less than 2 degrees of overlap, and 20 to 35 is very common.

You asked how it compares to other engines. I have not done much serious GM work since 1980, so I had to dig a bit. The older GM stuff & Ford specs are close at hand however, so I will start there since they were all carbureted engines. From my notes, established with a degree wheel:

-----------
EXH lift at lifter : 0.257" = 0.400" lift at valve
INT lift at lifter : 0.258" = 0.402" lift at valve
(Note: lift at valve assumes a rocker ratio of 1.56)
IO: 3 ATDC
IC: 220 ATDC=40 ABDC
INT Duration: 217 degrees
EO: 220 BTDC=40 BBDC
EC: 3 BTDC
EXH Duration: 217 degrees
6 degrees of overlap

This was the stock camshaft in a 110 hp, 2.7L Corvair An economy engine like your V6

----------

FE Ford
68-70 428CJ 270/290 cam

IO 18 BTDC
IC 72 ABDC
EO 82 BBDC
EC 28 ATDC

46 degrees of overlap

This was a street cam in a heavy car, with a single 4bbl. New factory cam on install.

-----------

63-67 427 med riser 8V 306 / 306

IO 40.5
IC 85.5
EO 88.5
EC 37.5

78 degrees of overlap

NOS OEM camshaft checked on install, 5/16/2001. P/N unknown, marked with inverted V

This was a "nasty" cam, with .025 lash mechanical lifters. Fouled plugs, idled poorly - but took full advantage of the two four barrel carbs.
----------

Mk IV Chevrolet 454 CID

Duration at 0.006" Lift: Intake: 300° Exhaust: 306°
Duration at 0.050" Lift: Intake: 240° Exhaust: 246°
Lift at Cam: Intake: 0.330" Exhaust: 0.337"
Lift at Valve: Intake: 0.560" Exhaust: 0.573"
Timing at 0.050" lift:
IO 10° BTDC
IC 50° ABDC
EO 59° BBDC
EC 9° ATDC
Centerlines: Lobe Separation - 112° Intake Centerline - 110°
19 degrees of overlap

Crower cam, checked in install. 454 installed in jet boat. Great midrange & throttle response.

----------

Small Chevy

Duration at 0.006" Lift: Intake: 308° Exhaust: 318°
Duration at 0.050" Lift: Intake: 234° Exhaust: 244°
Lift at Cam: Intake: 0.325" Exhaust: 0.340"
Lift at Valve: Intake: 0.488" Exhaust: 0.510"
Timing at 0.050" lift:
IO 10° BTDC
IC 44° ABDC
EO 59° BBDC
EC 5° ATDC
Centerlines: Lobe Separation - 112° Intake Centerline - 107°
Overlap 15 degrees

Checked on install. Light street car (T bucket) with single Predator. Cam make unknown, assembled from customer basket case. Ran good to 6500 straight up. Advanced 2 degrees, midrange better but top end about 5500. Went back to straight up, because improved midrange made the car hard to manage.

-------

Pay special attention to the SBC cam above, since it's "advertised" duration is similar to your V6 cam. Look where the exhaust closes, compared to your cam. I recall hearing the dealer BS about the "hot cam" in that engine. An advertised 310 degrees is great if it happens at the right time. All of that overlap means the EGR is unecessary. That late exhaust duration would be good with a well tuned set of headers about 7500 rpm - but with the backpressure of a stock exhaust it just fills the cylinder with exhaust gas.

The overlap you show compared to the SBC performance cam is about 80 degrees different. Again, dilution of the intake charge, and a bunch of crud back up the intake tract.


Now, for comparison to more modern emissions engines:


Northstar
1993 - 1999 Cadillac (L37 (VIN 9)
• Valve Timing (With Ramp at 0.100 mm Lift)
• Intake Opens 13 degrees BTDC
• Intake Closes 73 degrees ABDC
• Exhaust Opens 51 degrees BBDC
• Exhaust Closes 13 degrees ATDC

• Valve Lift
• Intake 9.4 mm 0.370 in
• Exhaust 8.6 mm 0.339 in

• Duration (@ 0.100 mm Lift)
• Intake 266 degrees
• Exhaust 244 degrees

• Valve Overlap (@ 0.100 mm Lift) 26 degrees

For the metric challenged, 0.1mm is .00397 - or about .004 inch lift for comparison.

-----------------

It is no wonder the engine seems rough, and is hard to calibrate. It would be very interesting to see the actual (.050 inch lift) timing events on the camshaft you have in it.


B.

-------------------------
"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

mhamilton on Tue February 26, 2008 6:19 PM User is offlineView users profile

Bohica, thank you very much for taking the time to type that all out! That's a great help to me, just what I was looking for to compare.

You're very right about the GM specs. Both GM's own specs and the MVMA specs are identical, with no notation on where those values were measured from. Since they are way out there, I looked on NAPA's page for their stock replacement cam (I have a stock replacement cam from CarQuest, don't remember who made it). These are definitely more conservative:


NAPA Part CEP2291703

Cam Lift (Intake): 0.234"
Cam Lift (Exhaust): 0.257"

Degrees Overlap: 54 Deg

Advertised Duration (Intake): 260 Deg
Advertised Duration (Exhaust): 280 Deg

Duration at .050" Lobe Lift (Intake): 176 Deg
Duration at .050" Lobe Lift (Exhaust): 194 Deg

Cam Timing at .050" Lobe Lift (Intake Open): 20 Deg After Top Center
Cam Timing at .050" Lobe Lift (Intake Close): 16 Deg After Bottom Center

Cam Timing at .050" Lobe Lift (Exhaust Open): 28 Deg Before Bottom Center
Cam Timing at .050" Lobe Lift (Exhaust Close): 14 Deg Before Top Center

Lobe Centerline (Intake): 108 Deg
Lobe Centerline (Exhaust): 112 Deg


You're right about the GM specs being *a little* exaggerated. Perhaps those values are true at a few Angstroms of lift

Hmmm... compared with your SBC specs, now it's a more realistic duration at 0.05" lift. Still claim 54* overlap, but at the 0.05" specs, they have 0 overlap with the exhaust closing 14* BTC intake opening 20* ATC. Intake still has 16* during compression to blow out junk.


Jerry, I think I have a similar chart in my FSM, but the cam specs I got from the GM info. I was surprised that the specs were not identical to the 305, unless GM was trying to make the V6 smoother, or bring its performance up to the level of the Buick V6.


Nick, actually my exhaust valves are clean. I had done the gaskets not long ago. I guess everything in the exhuast is thoroughly burned by the air injector. That may or may not be a good thing, those valves probably don't last as long with all that heat.

Poppet valves do seem to be PIA. I read about one company in the 'teens that made an engine with sleeve valves. The piston went up and down inside a rotating sleeve, which uncovered the valve openings in the cylinder bore.


Edited: Tue February 26, 2008 at 6:23 PM by mhamilton

bohica2xo on Tue February 26, 2008 7:14 PM User is offline

Hmmm...

That NAPA cam info looks a bit more in line with reality. Ir only remotely resembles the "factory" specs.

You can sure see where they reduced the BMEP of that engine for emissions. They trimmed the duration, but retarded the cam so that the intake closes closer to the normal place - and open the intake late. This is retarded timing with short duration.

Personally I probably would have looked for more camshaft for that engine during rebuild, but you have what you have. It appears that that cam was a smog part from the beginning, which makes sense for when it was first produced. The retarded cam timing began with the 1968 to 1970 years, where it was a quick fix with an existing camshaft - just move a keyway in the crank gear & instant NOx reduction... No new camshaft issues, old stock still works etc.

The short duration certainly reduces gross horsepower, but brings fuel economy with it - if it happens in a timely manner. Since I doubt you rev the hell out of it you would probably not notice the reduction in power above 4500 that would happen with an advance. You would notice the improved off-idle & midrange.

Advancing smog profiles can work out well. I had a 1986 Ford 2.3L 4 banger that I advanced the cam 6 degrees on @ about 5,000 miles. Based on the before & after it got better mileage - and still passed smog testing. It would run away from the 2.8L V6 trucks of the same model year, leaving them to guess what happened. The "smooth" factory power curve dissappeared. It was a bit snappier off idle, and the midrange pulled like an I6. It would fall flat on it's face about 4500rpm - the power curve died in a vertical line on the graph. 6 degrees was the limit, anymore & it would have been a JD tractor. 4 degrees was ok, and had more of a stock feel. I put 300,000 miles on it advanced 6 degrees - never had it apart to look at a valve.

B.

-------------------------
"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

mhamilton on Tue February 26, 2008 7:51 PM User is offlineView users profile

Had I known what trouble this engine was going to be after rebuilding, it would have been tossed in a dumpster. But hindsight...

Quote
The short duration certainly reduces gross horsepower, but brings fuel economy with it - if it happens in a timely manner. Since I doubt you rev the hell out of it you would probably not notice the reduction in power above 4500 that would happen with an advance. You would notice the improved off-idle & midrange.

So the short duration does improve economy? But advancing it would improve low end, not top end?

You're right about not reving. With the 2.41 axle and 2.7 1st gear, plus a small carb, I do not think this engine could even get up to 4500 rpm. And like all the GM engines of the day has more low end torque than hp. Like your 2.3, this 229 seems to take a nosedive over 3500 rpm. The few times I've tried passing gear around 55 mph, it makes a lot of noise that sounds like power, but the speedometer doesn't move. The best acceleration is holding 2nd out to 45 mph, can feel the torque peak at 2500.

Hmm, I'm not sure. Since I this isn't a performance engine, not sure if I should start messing with new cam profiles. If I had time and access to a dyno, might be interesting to see what happened with cam changes. Still would like to see if it's retarded from spec. And I would like to clean up these stock heads with mild porting, possibly a valve job, so it at least flows better with what it has.

NickD on Wed February 27, 2008 6:56 AM User is offline

"Mk IV Chevrolet 454 CID

Duration at 0.006" Lift: Intake: 300° Exhaust: 306°
Duration at 0.050" Lift: Intake: 240° Exhaust: 246°
Lift at Cam: Intake: 0.330" Exhaust: 0.337"
Lift at Valve: Intake: 0.560" Exhaust: 0.573"
Timing at 0.050" lift:
IO 10° BTDC
IC 50° ABDC
EO 59° BBDC
EC 9° ATDC
Centerlines: Lobe Separation - 112° Intake Centerline - 110°
19 degrees of overlap

Crower cam, checked in install. 454 installed in jet boat. Great midrange & throttle response."

Wow, I haven't played with valve timing for years, are we talking crankshaft or camshaft degrees here, seem to recall that one of them was twice as much as the other. Also recall graphing these numbers out so you have a pictorial view of when the valve opens or closes in relationship to the position of the piston.

Have read in EGRless engines, the exhaust valve closes earlier to leave some spent combustion deposits in the engine that effectively does the same thing as the EGR, but never verified that with the numbers. And finding the numbers is another problem, what was your source?

bohica2xo on Wed February 27, 2008 2:26 PM User is offline

Well, you have it apart right now. This would be the time to correct things...

I would drop a Schneider 256H in that thing before I put the intake back on. I almost never put a stock cam back in an engine. It would certainly make kickdownd more fun.

Schneider cams for 229 chebby


Nick:
You ask where the numbers come from. Any good cam supplier will include the basics in advertising & on the cam sheet. I always check a cam on install with a degree wheel & dial indicator. You need to do this to correct any mfg errors in the 5 parts (from five vendors!) that affect timing. I always start with establishing actual TDC, and correcting the damper markings - they are usually close, but rarely right on. I also add a mark at my maximum expected advance, usually 30+ degrees - makes a quick rev check simple with a plain old light.

The specs I posted are all collected data from a degree wheel & indicator by me. The corvair cam was used, but in good shape. The 8V FE ford cam was one I installed in a side oiler I sold someone - I actually removed a bigger cam to put that one in...

The Northstar specs I grabbed from the internet, hence the metric numbers. They look to be inline with other current designs, but I did not collect them myself.

I always degree a cam. Ever get a bad LM78xx regulator? If there is a LM7812 that is actually a mismarked LM7808, I am the guy that will get it. Or worse, the other way around. The only cam supplier I have never had an out of spec camshaft from is Schneider. I still check his stuff anyway.

B.

Edited to add:

Did you mean this camshaft plot?



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"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

Edited: Wed February 27, 2008 at 2:29 PM by bohica2xo

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