Engine miss and low power rebuilt 350 Chevy

[HAFROD]

I built a flat top 350. I had some 882 heads that I got from craigslist that were supposed to be fresh from machine shop. They had sat for several years by my garage door and got rusty. I removed the valves and put in an organized tray and marked the heads with a die grinder so the correct valves went in their guides. I took them to a machine shop for vatting and he had to surface them because of pitting. I lapped the valves and reinstalled with new seals and Z28 valve springs. I got the car running and it has a miss. I drove it to work all week and it has gotten worse. I pulled the intake and the side runner gaskets were oil soaked. Oil was in the heads intake runners but dry in the intake manifolds runners. I suspected it was my miss. I swapped intake manifold with one I had on the old motor and fired it up again yesterday. Still has the same miss and low power. I had swapped out distributors and a coil in the HEI thinking it was the problem. No luck. I have assembled many small chevys and freshened up many heads. I've always messed with small blocks and they're all I know. I consider myself pretty good on them but this issue has me lost. I would say that I have probably assembled about 25-30 small chevys and drag raced many. Any ideas?

 

[pontiacgp]

have you checked the plugs, I've had the ceramic on a plug cracked new out of the box and that will cause a miss...

 

[81msw79]

Like pontiacgp said pull the plugs check they are not cracked or fouled from the oil bath. A quick compression test on all cylinders will be a good idea too before going full tilt into tearing it down.

 

[81msw79]

You msy also want to check the resistance on your plug wires may also be weak spark issue

 

[lilbowtie]

Great advice above, how low on power and does it feel like a dead cylinder, and what did the plugs look like? - I hope you have checked out the simple things like wire routing - I have messed that up more than once. Are you running both valve guide seals? and it wouldn't hurt to check the compression.

 

[HAFROD]

I called in one of my mentors from when I was a teenager. This guy is old school to the bone and knows his stuff. He messed with it for about an hour. He says its sucking air from somewhere. When I changed the intake, the side runner gaskets were oil soaked and oil was present in the intake runners on the heads. We noticed the new intake gasket area that's visible between intake and heads were showing signs of oil soak again. By the time he was done checking things, the side gaskets oil soak was spread. He also adjusted the lifters with it running but when you bring the rpm up you can hear a couple clacking. He's suspecting warped or bad machined intake surface of heads, cam going flat, weak valve springs, or bad lifters. So now I'm at a cross roads. I have a set of brand new in box Edelbrock E Street heads (64cc). I don't know if I should pull the heads and check the surface of every lifter for excessive wear. If no wear, should I replace all lifters and install E Streets? OOOOR should I put in the old stock Goodwrench 350 and call the midnight drags season over? I'm pretty tired of tearing the top off this motor but at least I'm well practiced.

 

[pontiacgp]

I would drop in the Goodwrench 350 and put your engine on a stand. It's alot easier working on an engine attached to a stand and you can figure out the problem(s) . If the oil is seeping past the intake gasket then there is a problem with the face of the intake or the head or both

 

[Ribbedroof]

How much were the heads surfaced, and was the intake machined as well? Had a buddy with a L79 Chevy II that had a similar issue after surfacing heads and intake. Wound up starting over with a different intake.

 

[lilbowtie]

Sounds like you have narrowed it down to the intake - the gaskets shouldn't be getting oil soaked. I guess it would be worth taking the intake back off, cleaning everything up and set the intake on it w/o gaskets. It should sit tight against the heads and have clearance at the block. As far as the lifter noise my fathers 79 did the same thing since new, took it back a couple of times and they said it was nothing. Traded it in @86,000 and they said they could hear some lifter noise - conversation got heated after that but all I'm saying it lived 86,000 mi that way. Don't give up on it yet my little throw together 350 surprises everyone and I'd be happy to tell you what is has.

 

[HAFROD]

I already changed intake manifolds and its doing the same thing. The heads were a craigslist buy and seller only knew they were fresh from machine shop. I was told nothing about any milling or surfacing which obviously has been done