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Engine problem

5K views 22 replies 11 participants last post by  CamaroNorway 
#1 ·
Hi


I've got a 68' Camaro with a 383 motor in it. It ran quite bad. When it got hot, it would stop. I had to stop the car, put it in park and give it some gas to keep it alive. But then it came a lot of black smoke out the tailpipes. I took out and teared the engine down. This is what I've figured out of the engine:


-Comp Cams xe294h 12-254-3 cam
-Keith Black 9932 - .030 icon fhr piston
-PEP 4340 DG3 – 185QD crankshaft
-Edelbrock 2925 intake manifold
-Procomp heads
-Holley 650cfm vac.sec
-MSD dizzy mech.advance
-MSD coil
-MSD 6al2


My initial timing is 14-16* and advance is 34*.
Vacuum is measured to about 6-8hg at about 800rpm.


Could it be the Procomp heads that's causing the problem.
I've read on the internet that they are not good.
 
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#2 ·
its got a 4340 crank in it, that should be a good piece.

Reads to me like you had/have a carburetor problem as evidence by the black smoke.

How do the cylinders look? Any scarring on the walss or on the pistons?

Some people like the ProComps, others don't. Maybe the castings have improved, I don't know for sure as I would use DART or RHS or GM myself.
 
#7 ·
How do the cylinders look? Any scarring on the walss or on the pistons?
the cylinders, pistons, piston rings looks fine to me.


no, i do not have experience with carbs, but i checked the float level, and the fuel was just below the inspection hole. that's ok??

and is it normal to with so low vacuum in the engine while idling?? 6-8"hg. not stable. when revving it's about 15"hg.
 
#3 · (Edited)
Along with Michael's suggestions, the black smoke from the tailpipe is a symptom of too much fuel.
I suspect either the choke plate closed or a piece of foreign material got stuck in the needle and seat and flooded the engine with fuel.
Engine oil would smell of fuel if a great abundance of fuel leaked past the rings into the crankcase.

Sigve, welcome to the Club, enjoy the cruise.
 
#4 ·
I agree with all of the above check all the fuel issues powervalve etc. if it,s a Holley . Are the cyl walls and pistons gas washed and scuffed? I don,t care for the Pro comp stuff or those K/B pistons with that funny ring land in the middle but you gotta work with what you have . First off you need to take care of the fuel issue maybe a carb rebuild is in order . if it,s an old holley make sure you get an anti back fire valve kit and install it during the rebuild. give us more info and we can help you better . Alex
 
#5 ·
i've tried with a brand new holley 650 DP, but then it would not run at all.

I could drive it around, and it ran fairly good (maybe not as much power as I hoped for) until the temperature reached about 176 F(80 C), then it started to "cough, chocking" and the black smoke when i put it park and gave it gas.
if i had not put it i park the engine would have stopped.

if i let the engine cool down for a couple of hours, it ran fine until it got hot again.

if i got it to the same temp just by idling and revving it(no driving around), the problem would not occur.

i've got a Th400 tranny.
 
#6 ·
i've tried with a brand new holley 650 DP, but then it would not run at all.

I could drive it around, and it ran fairly good (maybe not as much power as I hoped for) until the temperature reached about 176 F(80 C), then it started to "cough, chocking" and the black smoke when i put it park and gave it gas.
if i had not put it i park the engine would have stopped.

if i let the engine cool down for a couple of hours, it ran fine until it got hot again.

if i got it to the same temp just by idling and revving it(no driving around), the problem would not occur.

i've got a Th400 tranny.
If you put a brand new carb on it and it wouldn't run then you need to make some adjustments to it-most notably setting the float level.

Do you have any experience with carburetors? If not don't be intimidated....they are easy to work on and adjust, especially Holleys imo.
 
#10 ·
Street cars really need a vacuum advance to run properly-I suspect that is partly responsible for your car not running very well when driving around.
 
#12 ·
I would try to find the problem first. Just simply changing stuff out can be like a dog chasing its tail.

As for the head choices I would look into the RHS offerings, or the GM Vortecs, or an Edelbrock head. Some DART Iron Eagles would be a good choice,too. Those companies produce good quality castings, imo.
 
#14 ·
I would try to find the problem first. Just simply changing stuff out can be like a dog chasing its tail.

As for the head choices I would look into the RHS offerings, or the GM Vortecs, or an Edelbrock head. Some DART Iron Eagles would be a good choice,too. Those companies produce good quality castings, imo.
:yes: Absolutely! Sigve, as Michael says, throwing parts at the problem costs more, in most cases, than hiring a good mechanic to fix it correctly. And throwing a set of heads at it is about as costly of a shotgun blast that you can shoot.
Psssst,,,, check your choke.
 
#13 ·
I ran Procomps on my SBC 406. The castings are good and I was extremely happy with the quality. It depends on who assembled the heads and the parts used. Mine were built by Walker Racing in California.
 
#16 ·
If it is a hydraulic lifter cam (and I'm almost certain it is) then there shouldn't be any valve lash...it should be zero. The hydraulic lifters do usually need some preload, typically when you reach zero lash turn the nut another 1/3 of a turn to 1/2 turn.

I think a lot of your problem is having no vacuum advance. I would try a VA distributor before I spent money elsewhere.
 
#17 ·
As already said, don't throw a huge amount of money at it just yet.

Try tuning the carb first.

Then check distributor. I run a similar distributor setup (but Mallory). Not ideal for street driving but you can make it work.

Is this just a street car? No strip? If it is just a cruiser, you might want to try a smaller cam. Just an idea.

I think these are the specs on your cam.

http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=89&sb=2
 
#20 ·
As already said, don't throw a huge amount of money at it just yet.

Try tuning the carb first.

Then check distributor. I run a similar distributor setup (but Mallory). Not ideal for street driving but you can make it work.

Is this just a street car? No strip? If it is just a cruiser, you might want to try a smaller cam. Just an idea.

I think these are the specs on your cam.

http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=89&sb=2
this is just a car for street driving.

What about a vacuum leak somewhere? It would have to be a pretty big one.
I know that cam is huge and those Hg levels are in line with a cam of those specs, but don't assume 6 or 8" of vacuum is correct until you eliminate any vacuum leaks.
i tried checking for leaks with "starter gas". sprayed around the intake, front and back of heads. not on the underside of the heads, because of heat from headers and "starter gas". afraid of fire.
the vacuum didn't chance, and no chance in rpms.

Once you get the carb sorted then maybe look into the ignition since it's only when hot and only under load.
If the distributor is the type that does not require an ignition box I'd try removing it and rewiring as appropriate. Or try an MSD 8360.
If it does require the box, check the voltage on the small red wire for the control power of the 6AL and make sure it is at least 13.5V when running. Control power should come from the IGN spade on the fuse block inside the car, not from the cloth covered resistor wire that may still be coming from the bulkhead connector on the firewall. This is also the case if you get rid of the box and run just the coil and distributor. Heavy red cable should go straight to battery positve and heavy black cable should go straight to battery negative.
i've got a MSD 85551 dist. the small red wire is connected to IGN, and heavy red and black to the battery.
i haven't measured the voltage, and now the engine is teared down.
 
#19 ·
Once you get the carb sorted then maybe look into the ignition since it's only when hot and only under load.
If the distributor is the type that does not require an ignition box I'd try removing it and rewiring as appropriate. Or try an MSD 8360.
If it does require the box, check the voltage on the small red wire for the control power of the 6AL and make sure it is at least 13.5V when running. Control power should come from the IGN spade on the fuse block inside the car, not from the cloth covered resistor wire that may still be coming from the bulkhead connector on the firewall. This is also the case if you get rid of the box and run just the coil and distributor. Heavy red cable should go straight to battery positve and heavy black cable should go straight to battery negative.
 
#21 ·
As stated before I think your problem is in the carb. It is a shame that the engine got torn down before you started the post. It is hard to tell the problem with just a pile of parts. Procomp heads are a knock off of the Edelbrock heads. Changing to Edelbrock prob would not change much if any. As far as having the timing locked down it shouldnt be a problem if you have a sthall converter. Black smoke like stated before most of the time is too much fuel. Needle and seat, fuel logged float, blown powervalve, or float adjustment. With that cam I think I would use a double pumper and ditch the vacume secondary. Many people on 5this site have alot of skill and information , I'm sure they can help get you back on track, just got to get it running again first.
 
#22 · (Edited)
Just wondering, is it actually "black" smoke you are seeing or is it more of a bluish haze?

Pull one of the spark plugs and describe the conditions of the electrodes.

Are they black, oily, sooty or tan/brown?

Might help diagnose the problem.

On a different train of thought...are you running an electric fuel pump?

Vic
 
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