I did a favor for my brother in law by rebuilding the engine in his 67 Camaro. I was about ready to give the car back to him but I decided to test run the car to make sure the car performed as it should.

The problem I am having is at idle I can feel an irregular exhaust pulse in both exhaust pipes. It appears that it is maybe one cylinder because one pulse is stronger then the others. This is a dual exhaust without any cross over.

If I rev the engine to around 2200 to 3000 RPM I can hear it starting to break up slightly. When I road tested the car at part throttle it begins to break up and has no power. Sometimes this condition is worse then others, and on occasion it will pull hard with an occasional hiccup.


Everything is either new or reconditioned in the engine except Valve Springs. All parts are brand name ... no generic parts were used.

Here's what I have done so far:

-Tried a different distributor (new points, vacuum advance, condenser, cap, rotor and coil)

-Tired new different spark plugs

-Replaced plug wires with Accel 8mm solid core wires

-Checked timing numerous times

-Readjusted the hydraulic valve lifters to 1/3 turn preload (Engine running method)

-Cranking compression test around 170 psi all cylinders.


Engine components:
Comp Cam 268H-10 (Close to stock)
Comp Cams Lifters
Original Springs
Stock Q-Jet Carb (Rebuilt)
Stock Intake
Headers w/header mufflers
Power Glide
Stock type flat top pistons
Heads reconditioned with 3-angle valve job and valves hand lapped

I'm beginning to think the valves are not sealing properly and this is causing the poor performance.

ANY HELP or advice would be greatly appreciated!

Thanks
Brian





[Modified by RED92LT1, 9:48 AM 9/2/2002]

 

How many times are you gonna post this????


Did you degree the cam?

 

Sorry About the additional posts ... they weren't showing when I checked. I thought something was screwy so I changed the title.

Yes I degreed the cam and installed it straight up.

 

Plug wires crossed????

 

Nope ... Trippled checked the plug wires.

 

Head gasket problem?

 

If it was a head gasket I would think I would see traces of oil in water or water in the oil.

Thanks
Brian

 

Had a bad valve spring on a mustang...did the exact same thing.

But, usually an intermittant break up at rpm is ignition related, I can see you were thinking the same thing.

 

Thanks all for your help!!


Brian

 

Cam installed properly?

My car ran like a dog and had no power because I had accidentally installed the cam about a tooth off.

The car seemed to run worse when warm than it did cold.

 

Nathan,

I initially thought it was a cam problem so I degreed the cam and made sure it was installed straight up ... and it was.

The problem with this whole project was that I worked on this over the past 14 years ... but over the last 2 years spent more time trying to get it done and out of my driveway.

Thanks for the response!
Brian

 

Hmm. It sounds ignition related but you've checked all of that seems like.
I don't know man, maybe it's just mad at you for working on it for 14 years!