how much gap can be taken up by gasket?

Hi,

got a question regarding my intake manifold/vacuum leaks... About a year ago I traded a vintage Offenhauser manifold for a reproduction of a later factory manifold cast in aluminum. Big mistake. The repro does not fit. When I set it on the engine there's huge gaps although the manifold will fit if I force it to. If I install the bolts and just snug them with a speed wrench there's about .011" gap at one corner, .009" at another, .005"-ish at the third, and the fourth fits well.

Should I worry about this or just go ahead and install it? I have access to both steel and composition gaskets. The composition gaskets mic out at about .065" before install. How much do they typically crush?

nate

Reply to
Nate Nagel
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Reply to
Shep

yes, I'm fairly sure that the intake was milled inaccurately and that is the source of the whole problem. Issue is finding someone with a milling machine that is willing to work on it, and has the specs for a Studebaker V-8 intake (or is willing to take the time to "copy" a cast iron one)

nate

Shep wrote:

Reply to
N8N

Reply to
Shep

Depends at least partly on how much "oomph" goes into tightening the nuts/bolts and the exact composition of the gasket, but about .015 is what I've always been told. Dunno if that's just anecdotal, or if there's some "science" behind it, but, as I say, it's what I've always been told.

My dad used to do a lot of heavy-equipment wrneching for the outfit he worked with (a rather large contractor doing a *LOT* of government work), and if there was a need to get a certain pieceof machinery back in action ASAP without taking parts in for machining, and there was enough bolt/stud available for it to fit, he'd slap down one gasket, coat the "top" side of it with hi-temp permatex or similar, then slap a second gasket on and torque things down. Never heard any mention from him of problems with that method, but he did tend to want the gear back in the shop to be torn down and done "proper" (Send out the not-quite-right parts for machining, etc) once the "we *GOTTA* have this! Contract said we'd be done yesterday, and the penalties are piling up!" type situation passed and there was time to do it right.

For an intake manifold, I can't see it being a big problem, but for something like a head gasket or similar "high pressure" situation, I don't have a difficult time thinking that the too-thick gasketing might be too weak to contain the pressure.

Reply to
Don Bruder

The real problem is that it appears that the ports are "core shifted" WRT the manifold casting, and that the milled surface is true to the outside of the casting not the ports. The bolt holes are drilled to match the ports so I don't want to just slot the bolt holes to let the manifold "twist" as then I'd end up with a port mismatch. Therefore the cut would have to be made at an angle on each side. @#$%$%^& repro parts.

Yes I know that I can run a cast iron manifold; I just don't want to. I like my shiny stuff, and cast iron is heavy.

An aside: does anyone have an e-contact for Offenhauser? They claim that every manifold they've ever made is still available, but just try to buy a Stude V-8 manifold from them. (the manifold for the Champion six is still readily available, but I'm not about to put a six in my car... just ain't happening.) I do have a high-res scan of a 1954 Offenhauser flyer with the part number of the Stude V-8 manifold kit, which apparently includes a carb hat for an early Rochester carb to allow it to mate up to the stock rear-inlet Stromberg WW 2bbl air cleaner. I doubt that sending it to them would accomplish anything other than proving a point; but if it prompted someone to go clean out the back room and find the cores for this manifold I would be one happy camper.

nate

Shep wrote:

Reply to
N8N

IMO that's not a big deal i.e. Once (forced) tighten down your aluminum manifold will perhaps conform to your needs once the engine has run for about 20 - 60 mins at operating temp.

Reply to
Backbone

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