Pulled carbs and intake, need opinion.

[drooartz]

Pulled the carbs and intake last night in my quest to find what I think is an intake/exhaust/vacuum leak. The various carb bits seemed to be sealing okay, but I did notice something on the gasket between the header and the head.

The middle and rear branch seem to be discolored underneath where the header touches (you can see this in the pictures below). The front branch didn't have this discoloration. Is this normal or is this indicative of a leak?

Middle branch:

Rear branch:

 

[DrEntropy]

Without a real good inspection of the gasket, a qualified maybe. It kinda looks like a leak on the middle port.

I'd say clean all surfaces, new Payen I/O gasket, be certain all the studs are tight in the head. Check the face of the tubes to be certain they're all three in the same plane (properly finished concrete floor is good enuff for that).

Thickness of the flanges for both the exhaust and intake where the little "clamps" hold 'em against the head should be the same, too. If not the clamps will exert more force on the thicker of the two. Many a bent stud found here from that issue.

Hap's gonna box me earhole but: on reassembly I suggest you apply a thin film of grease on the gasket. Not like peanut butter, more like tanning oil. It'll smoke for a while on first running but it'll help allow the thing to seat/seal on torquing. Run to temp then check/retourque the nuts.

Hap: I'll be available for the whipping after five PM. :smirk:

 

[Hap Waldrop]

It would be neat to see the business end of the headers, but that may be more trouble than it's worth, sometime they machined perfectly flat, sometime they seal on welds, and if the welds are not belt sanded flat, then you could not be getting a good seal. Also there the old deal with flange thickness difference from the intake to the header flanges, if they are not equal, you may need to make up some special half washers if you will to get everything to pull down and tighten equally, if the washer you are using now are cocked when tightened, that could very well be your leak.

 

[DrEntropy]

It would be neat to see the business end of the headers, but that may be more trouble than it's worth, sometime they machined perfectly flat, sometime they seal on welds, and if the welds are not belt sanded flat, then you could not be getting a good seal.

We've even seen 'em where the weld at the tubing wasn't totally sealed and the resulting leak was between the tube end and the flange. That condition is usually apparent from the outside, tho.

 

[drooartz]

I've got some time this weekend, so I'll go ahead and pull the headers -- not that big a deal, just a little fiddling to get them out with the engine and steering column in place. I'm already in there, so might as well check everything.

I didn't do anything to the header surface when I installed it the first time, so worth checking now.

I'll check the flange thicknesses again -- they are close but not the same if I remember right.

 

[drooartz]

Thoughts on a good source for a Payen gasket?

-- never mind, found a set through British Parts NW, it's on the way.

 

[Guest]

(properly finished concrete floor is good enuff for that).

....also works as a good planing tool too.

 

[sim]

I installed some new headders that I bought from moss.
Could not get them to seal even with 2 gaskets. the head is Aluminum
the solution was copper silicon. Been more than 2 years no leaks