Arrowstorm

Very soon, I will replace the intake gasket in the Olds 307 for a 1985 Custom Cruiser.

I'm not ready to rebuild this engine yet.

Due to the engine running like crap and the fact that it sucks IN air at the valve cover breather grommets (enough to suck my thumb in slightly), I have come to suspect that I probably have a bad vacuum leak at the intake gasket, somewhere inside. I could find no leaks in the hoses or anywhere else. I have the gasket and I have VAST experience replacing the gasket on a 350, so that's not a problem.

My question is, without yanking this engine, can you guys think of anything else I might be able to do to clean this engine up while I have the intake off? I was thinking of pulling all the pushrods, rocker arms and lifters, carefully marking their placement, of course, and giving them a little paint thinner bath to clean them up of any gunk or deposits that may have accumulated over 30 years. I was also thinking about rebuilding the Q4 carb, since the last time was 10 years ago. It has a new O2 sensor, new EGR valve, and no discernible vacuum hose leaks of any kind.

It used to run beautifully and smooth, until I started to suspect this internal intake gasket leak when it all of a sudden started running like crap and I couldn't find any vacuum hose leaks.

This engine WILL be rebuilt in the future, but I must do this gasket replacement to get it back on the road for a year or two at the most.

This car starts right up, but like I said, just sort of runs like crap.

Any advice on helping this engine breathe a little easier without doing bottom end rebuild would be greatly appreciated.

Thanks,

Buz

joe_padavano

Unfortunately, your 85 307 has 7A heads and the matching A5 intake, so there won't be too much you can do to improve breathing short of jacking up the air cleaner and sliding a 350 in there instead. When you pull the intake, be SURE you get the correct gaskets for a roller cam motor. Olds made both styles of 307 that year and the non-roller gaskets won't seal properly on the peanut intake and exhaust ports (do NOT ask me how I know this...).

Arrowstorm

Well, I didn't know that about the gasket. I just ordered one a couple moths ago from Summit.

http://www.summitracing.com/parts/fe...ake/oldsmobile

It looks pretty much the same as the ones I've put in my 72 350 intake.

Is it safe and/maybe beneficial to clean out all the purshrods and lifters?

pavemobile

I too fought that 307 sealing monster. The gasket makers don't list a different part number for the swirl/square port intake gasket; but if you look up a 260 c.i. V8 from '79, '80, you will find - FEL-PRO MS96026, or VICTOR REINZ MS15944, or ROL GASKETS MS49020 - gasket sets. Fel-Pro always worked perfectly for me when the '86 was in stock emission trim.

joe_padavano

The correct intake gasket is FelPro MS96039. RockAuto shows this correctly, though with 7A heads (not to be confused with 7A heads) I always ask for a 1986 or 87 gasket just to be safe. The catalogs get unreliable when there were two configurations in a given year.

Arrowstorm

Ouch. So.... I better get that MS96039 gasket then, right? I won't even bother using the one I have. I'll just ditch it I guess.

....Unless anyone has any use for it! Lol

See? I'm glad I asked my questions. I could've ended up like Joe and had a story that I would have to remind others not to speak of!

joe_padavano

The correct gasket is only $8 from RockAuto (double ouch! )

By the way, the one you have will fit an earlier SBO, which is why it looks like the one for your 72 - it is the one for your 72.

Arrowstorm

$8 plus $2 for a carb mounting gasket. Already on it's way!

I'm just upset now because I was all ready and mentally prepared to tackle it tomorrow and now I can't.

Guess I'll just have to cruise in the Vista all day instead!