Ok, some of you may know that I've been chasing a running issue for two years now. Symptoms are low vacuum, surging, stumbling, O2's showing extremely rich, poor gas mileage, fouling plugs in a matter of a couple of minutes, ect.

We found the problem, but that opened another can of worms. The following pics were taken after somewhere between 5 and 10 minutes of run time:

http://community.webshots.com/photo/...94571579KpUXgL
http://community.webshots.com/photo/...94571655YCxCWF

The intake manifold isn't sealing to the heads. Joe Prince orignally did my heads two years ago, and I have no idea who he farmed out the machine work to. What we do know is that my combustion chambers CC'd at 52, indicating a cut of approximately .015". The above pics were taken after the manifold had been cut by the same recently.

What I'm wondering is if there is ANY way to take a proper angle measurement of the head to manifold surface vs. the front and back edge of the block (where the manifold sits) to figure out what angle the intake manifold surface needs to have??? Or if there is a way of measuring from head surface to head surface to figure it out??

I know the deck height of the block comes in to play somewhat, but sadly, my motor was done by AP Engineering and of couse, I have no specific specs on the motor (go figure). I am trying to avoid pulling the heads at this point but it seems like that may be my only option at this point.

BTW I've been working with Golen Engine Service on this and they've been nothing but outstanding to work with. Extremely knowledgable guys, and if it wasn't for Chad (who's seen this before) I'd probably still be chasing my tail on this.

 

I would look for a thick gasket (1/8") if there is such a thing for an LT1. Your other course of action would be to double up the gaskets, glue them together with weatherstrip adhesive. It does not appear that the manifold really seals anywhere, which might not be that bad after all.

 

Looks like the heads were angle milled, that can screw up the mounting surfaces if the intake isn't milled to match the new resultant angle. Check the angle between the flat front and rear block area where the intake sits with the heads, and then check the intake portion. Or you could set the intake on with no gaskets and use feeler gauges to check gap between the lower and upper part of the head between itself and the intake.

Easy fix would be a thick gasket or even 2 gaskets together (ghetto). Best option would to match the intake by milling or pull the heads and check.


P

 

DITTO!

 

Well, maybe the picture isn't clear but gasket is wet on the lower section without a distinct line so if they were angle milled, even acidentally its was backwards. IE more taken off the manifold side of the head than the spark plug side. Poor guy.

 

Ok guys, thanks for the replies. Looks to me like you're confirming what I've NOT wanted to do, which is that I'm going to need to pull the heads and send them up to Golen also, so that they have the heads and intake on hand. I sent the manifold up there today so Chad should be looking at it early next week, at which point the decision will be made to pull the heads or not.

I am NOT looking forward to going through the hassle of undoing my ASM headers. Those are the absolute worst when it comes to bolt clearances.

 

Your machine shop should have the right protractor to get the angles off the block and heads and then be able to cut the manifold to match.

Like is said above compare the angle of the china wall/intake surface to that on the manifold. a paperclip bent to match the angle will work.

 

I was thinking that something like that would work, but I'm sick of screwing with it. I'm done playing around and am fed up with trying to get this thing running after two years. I'm pulling the heads and sending those to golen also.

 

Well, after mulling it over last night, I made the decision to just pull the heads and have it done right. So, they're coming off starting today (just have to find a valvetrain tray!!) and should be getting shipped out on Monday.

Thanks for the words of wisdom and guidance everyone. I appreciate the help.

 

Maybe I'm missing something, but it looks like the problem is not an angle match between the intake and heads, but that the intake is bottoming out on the block rails before it rests on the head faces. Why not just machine 3/32 off of the intake manifold where it rests on the block rails? That way it will now sit on the head/intake faces. The gap between the block rails and intake will have silicone sealer so it does not have to be a precise dimension.
This area on the intake has to be machined no matter what you do. You can't get the head's intake faces inboard from where they are now without machining the combustion chamber side-which now changes the cc's. Don't want that! Why take off the heads?

 

I'm taking the heads off so that Golen Engine Service has both the intake AND heads on hand to do what they need/want I.E. mock them up on a short block themselves.

The intake isn't bottoming out on the block, I checked that with a feeler gauge, and there was plenty of room there.

 

Just curious.... do you know if Joe PRince is still around? Haven't heard much about him or Jay Fisher in many years.

 

I know Joe is still around, I drive right by his place every now and then and there's always some sort of F-Body other than his there. I personally haven't talked to him in several months though. He's got to still be tinkering around with the performance stuff, but on what scale I wouldn't have a clue.

Jay Fisher, if you're speaking of the same from the dealership name, as far as I know they're still going about business as usual.

 

Chad @ Golen has my heads and manifold and has mocked everything up on a block (decked, as mine has been). He said that it wasn't sealing perfect, but wasn't leaking to the point where I should be barely running. He thinks that I've got something else going on because all of the residue in the combustion chambers and inside of the heads/manifold is all dry, not wet like oil would be. Which just irks me to no end because I'm still chasing my tail with this.

Burning oil........what would leave the same approximate residue/carbon deposits as running rich, right?? I AM running rich to a point, because of the low vacuum I'm pulling from the supposed internal leak at the manifold (I'm pulling 6-8 In/Hg @ 1000 RPM idle and running 43 PSI @ same idle with a WOT pressure setting of 44 PSI). When I pulled my plugs several of those were wet with oil but have subsequently dried. Could the same thing have happened to my heads/manifold, it simply dried out to the point of looking like it's not oil being burned?

Double-stacking Intake Manifold Gaskets -- I've heard of this being done by a couple of people. How effective is it?? It may be my last resort. My plan is to put everything back together with a single Fel-Pro 1284 and give the car a chance. If that doesn't work out, then I'm going to double stack a pair of 1284's and see what happens.

I'm pretty sure this is the fix because of how the car ran the first time I pulled the manifold and put it back on, I overtorqued the manifold, and the car ran great for a couple of days, but then degraded. I've checked everything else and everything is good. Cam timing, opti, plug wires, coil, ICM, ect. ect. ect. I've done a lot of hot-swapping parts from my other 93.

Thoughts??

 

I guess the obvious question, to me at least, is.....if Golen already has the heads and intake, why not have the match the components so they ARE perfect fit? Since they have the heads, have them check them over to see if there are any problems like valve seals, spring rates, cracks, warping, etc. Better to have them inspect all the stuff now than to reinstall and second guess yourself later.