Inliners International Forums General Discussion Engines 250 intake/exhaust gasket leak

Gentlemen,
I have a rebuilt Chevy 250 (1974 head)with Offy intake and Langdon headers. It has been running well for about 4000 miles but has recently developed intake leaks.

What brand/type of gasket should I use for replacement?
Thank you.
Regards,
Ken

i used to use the fel-pro manifold gasket on my 292's, but im now a huge supporter of the remflex brand carbon crush gasket. google it!. instead of being a thin metal shim type, its a quarter inch or so thick puffy wafer of graphite carbon material. it crushes and seals just like the felpro but you get much better sealing around your ports, even if you have slightly warped or mis aligned sealing surfaces. i dont think you would need to re torque the fasteners on your manifold, but it never hurts to check.

the less appealing aspects of this gasket are that they are not something you can go to napa and get. speed shops and specialty stores *might* have one in stock but brace yourself... $60 american, give or take.they can be found on ebay for a little more $$, but be careful with them as they are brittle. its just held against some cardboard with cling wrap, and ups is...well..its ups, so if they guy packing your order half asses it or the guys shipping it play soccer with it, its probably going to break. oh, its really difficult to remove with the idea of re using it and just snugging it down a little more to seal again. most of the time it will self destruct if you try to remove it, so your mileage may vary in that aspect.

but if you put it on and leave it be, maybe check the torque every so often, youll be golden. just my experience and $.02

i,ve got the same leak right now. runs perfect at off idle but idling stinks and with me being crippled its a mojor job for me.

Gentlemen,
Thank you for your input. My concern is that if I run it at WOT or even cruising that it'll lean out too much and fry a valve. Any thoughts?
Also, has anyone found a clever way of getting a torque wrench to fit between the manifold and the head to properly torque the in/out manifolds?

Ken

USE A CROWS FOOT ON YOUR TORQUE WRENCH. ALSO THE CORRECT WAY TO REMEDY THIS PROBLEM IS TO REMOVE THE INT & EXH MANIFOLDS, BREAK THEM APART,SURFACE THE MATING AREAS UNDER THE CARB WHERE THE MANIFOLD BOLT TOGETHER "THEN" SURFACE GRIND BOTH THE EXHAUST AND INTAKE MANIFOLDS ASSEMBLED TOGETHER AT THE SAME TIME, SUPER CLEAN THE HEAD THEN REASEMBLE EVERYTHING WITH NEW DOUGHNUT GASKET.

bcowan has solid advice for a more permanent solution, if you were running a stock manifold setup like me. youve stated you have fentons and an offy for your setup. im curious about the flange thicknesses on both the fentons and the offy, and if you have to use a custom made "retainer" to make up for the differences.

ive heard that those fentons are sold in various "grades" of quality if you will. an A or AA casting will be near perfect as cast and it goes down hill from there. my point being that the sealing surfaces would also be in varying states of quality, either due to issues with the casting or it was a monday/friday batch. it wouldnt hurt to pull em off and have em cleaned up, along with the intake. im not sure how much it would cost to have them both cleaned up and matched tho.

i think swapping in that remflex gasket would be a more temporary solution, but when comparing swapping in a gasket to having to tear the manifolds off and send them out to be machined, the cost and down time involved, id just as soon start with the simple things.

let us know how things turn out!

i,d just use a true 292 3 bolt 2 1/2" outlet manifold if your performance minded

I pulled the intake and put it on a table flanges down. It rocked. It's at the machine shop now being surfaced. The Langdon cast iron headers do not contact the Offy intake howeveur the flanges on the headers are thicker than those on the intake. I initially secured them to the head with the stock cup washers and grade 5 cap scriews torqued to 24 ft lb. This go I am using grade 8 torqued to 35 lb as Leo Santucci suggests in his book. Any suggestions regarding the cup washers? Thank you.