Hey guys, I got a weird problem. I think I might know what it is, but I wanna see what you think before I go digging around.

I was looking at my spark plugs today, since I am still tinkering with the carb (Holley 3310) trying to get it right, and I noticed something weird.

All the plugs on the drivers side looked ok, a little lean, but not bad. Ok, not too bad, right?

Then I went and looked at the plugs on the pass side, and they are all black! It looks like carbon, and its a pretty thin layer of it (ie. hasn't been building up).

I think it might be the intake manifold gasket on that side is leaking oil in, but I'm really not sure. I did change out the intake gaskets about 2 months ago when I did the intake swap. Maybe one is leaking?

 

i am assuming that your running a carb with factory or aftermarket dual plane intake, one bank of the carb could be running to rich, to lean etc...

 

He's got a single plane intake, so the 360° firing.

 

Yes, like Mike said, I do have a single plane intake. Thats why I didn't think it could be one side running richer than the other. The carb tune is identical between left an right as well (ie. idle mixture, jetting, etc.)

 

Anyone else have any suggestions?

 

AA,

You might have an oil leak on the right bank, or an air leak on the left bank.

This is all presuming that the heads are the same on both sides. Don't laugh - I've seen that. Even heads with the same casting number can have different ports and valve sizes. Those late '70s and early '80s head castings can be tricky that way. If everything is stock, you shouldn't have that issue, but things happen in rebuilds.

Another possibility is a sticking heat riser valve, which would restrict exhaust flow on the right bank. I'm not even sure if the '83 used a heat riser, or if you still have stock exhaust manifolds, but it's a possibility. Most of the later heat risers were vacuum actuated, so if you have one and changed your intake (and didn't reinstall the stock TVS to control the valve) you may have that problem.

 

I never thought of the heads... they are two different casting numbers, but basically the same crappy heads (882 and 624 IIRC). Far as I can tell, the heads have never been off the engine, but I can't say for sure. They have never been off while Ive owned it.

The heat riser valve under the exhaust manifold isn't a problem. The plate itelf was knocked out before it was reintalled.

Stock manifolds will give way to headers and a whole new system back to the street come spring, but for now its basically stock exhaust and cast manifolds.

 

Different heads, eh? Even though they are supposed to be similar, there are differences. Ever looked into the valve sizes? Chances are, this engine was apart at some time and was reassembled with odd parts. Perhaps it cracked or damaged a head at some point in a previous life, which might explain the odd one.

 

The only info I could find says the 624s are the same as 882s, but there are 3 possible valve sets it (the 624) could have... 1.72/1.5 , 1.94/1.5, or 2.02/1.6

I couldn't say which I have though. I've never had the heads off. They are otherwise the same though, with 76cc chambers. I got all this from www.mortec.com

I got a new intake gasket set today, and will be redoing them probably next weekend. If nothing else, it couldn't hurt, right?

 

Ok, I got it fixed today.

Turns out, it was actually a combination of a few problems. I was right, the intake gaskets were bad - 3 of the ports on the pass side had a leak. Not sure why, but they did. So that got fixed with new, higher quality gaskets.

The short stumble it had when you get on the gas hard is now fixed too. All I had to do to remedy this was change the position of the accelerator pump cam. Works great now! I also did some tweaking to the carb and timing, and the engine runs like a top now, almost feels as good as EFI!!

Thanks for your help guys!