Engine problem - Team Camaro Tech
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post #1 of 23 (permalink) Old Nov 17th, 12, 11:28 AM Thread Starter
Sigve
 
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Engine problem

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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post #2 of 23 (permalink) Old Nov 17th, 12, 11:52 AM
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Michael Gekko
 
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Re: Engine problem

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.

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post #3 of 23 (permalink) Old Nov 17th, 12, 12:05 PM
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Re: Engine problem

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.

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Last edited by Everett#2390; Nov 17th, 12 at 12:21 PM.
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post #4 of 23 (permalink) Old Nov 17th, 12, 01:18 PM
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alex
 
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Re: Engine problem

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
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post #5 of 23 (permalink) Old Nov 17th, 12, 02:47 PM Thread Starter
Sigve
 
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Re: Engine problem

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.
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post #6 of 23 (permalink) Old Nov 17th, 12, 02:51 PM
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Re: Engine problem

Quote:
Originally Posted by CamaroNorway View Post
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.

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post #7 of 23 (permalink) Old Nov 17th, 12, 03:15 PM Thread Starter
Sigve
 
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Re: Engine problem

Quote:
Originally Posted by Eleanor's Nemesis View Post

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.
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post #8 of 23 (permalink) Old Nov 17th, 12, 03:40 PM
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Re: Engine problem

Quote:
Originally Posted by CamaroNorway View Post
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.
Yep, you want the float level so that you have to nudge the fender with your hip to get gas to dribble out of the sight hole. The fuel has to be pressurized though-if you have a mechanical fuel pump the engine has to be running (keep several soaking wet rags around) or if it has an electric pump just turn it on with the engine 'off'.

You should do as Everett suggested and pull the needle and seat out of the carb and inspect for trash. Even the smallest bit of trash will cause too much gasoline to rush into the carb.

Iirc that cam is pretty big, Extreme Energy by Comp....that would explain the low vacuum when idling.

Where is your vacuum advance plugged in at the carb? Is it ported vacuum (above the throttle blades in the carb) or manifold vacuum (below the throttle blades)?

1968 Camaro NHRA/IHRA SS/C 'Super Stocker' 396/Jerico
1968 Street/Strip Camaro 350 w/PG
1968 Caprice NHRA/IHRA Stock ELiminator O/SA 327-250 HP



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post #9 of 23 (permalink) Old Nov 17th, 12, 03:57 PM Thread Starter
Sigve
 
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Re: Engine problem

i will look into the carb tomorrow.

i don't have a vacuum advance connected. i'm running a mechanical advance dizzy.
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post #10 of 23 (permalink) Old Nov 17th, 12, 04:13 PM
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Michael Gekko
 
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Re: Engine problem

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.

1968 Camaro NHRA/IHRA SS/C 'Super Stocker' 396/Jerico
1968 Street/Strip Camaro 350 w/PG
1968 Caprice NHRA/IHRA Stock ELiminator O/SA 327-250 HP



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post #11 of 23 (permalink) Old Nov 18th, 12, 05:45 AM Thread Starter
Sigve
 
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Re: Engine problem

i've checked the carb, and could not find anything wrong.

if i want to change the heads, what would you recommend? up to 1500$
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post #12 of 23 (permalink) Old Nov 18th, 12, 06:16 AM
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Re: Engine problem

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.

1968 Camaro NHRA/IHRA SS/C 'Super Stocker' 396/Jerico
1968 Street/Strip Camaro 350 w/PG
1968 Caprice NHRA/IHRA Stock ELiminator O/SA 327-250 HP



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post #13 of 23 (permalink) Old Nov 18th, 12, 07:14 AM
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Re: Engine problem

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.

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post #14 of 23 (permalink) Old Nov 18th, 12, 01:13 PM
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Re: Engine problem

Quote:
Originally Posted by Eleanor's Nemesis View Post
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.
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.

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post #15 of 23 (permalink) Old Nov 18th, 12, 01:56 PM Thread Starter
Sigve
 
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Re: Engine problem

it's a manual choke, and it's lock in open position.

i just remembered that it was a valve lash on all valves when dismounting the engine. but this cam/lifter should have a preload, right?
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