1995 Vulcan 3.0L Rebuilt heads, plenum won't fit. Double stack head gaskets 🤨 ?

[Air Filter McWingnut]

The basic question, has anybody successfully doubled head gaskets before?
Basic problem: heads have been milled at the block surface by an amount unknown by me and are freshly torqued down now preventing me from taking accurate measurements to find out how much, although I might take them back off depending... The plenum won't quite fit between the "new" heads enough to thread the bolts and mount it.
A few things here, stacking gaskets doesn't sound like a great idea, don't get me wrong. I've heard of such "foolery" though, and I'm aware of the concept of head spacer shims to help preserve a combustion ratio. I'm still looking for some of those by the way.
More things: milling the plenum comes to mind, my local guy won't do it though. So fun. I do have access to a big enough belt sander I could sneak up on it with
Another idea floating around is making thinner gaskets to help compensate, but, I'm not convinced I have the technology to do that, and am slightly leary of going all out "permatex spooge doctor" with or without and additional carrier membrane. Plus, can't say I'd be all that confident in choosing a gasket material to do the three things. Four actually. Oil, gas, coolant and the thing I didn't think of, like thermal or movement characteristics.

To wrap it up for now, anybody have thoughts on the possible compression ratio change with the situation as I've tried to lay out, and before I do whatever the next dumb thing is like garble the plenum might I consider raising the heads to help make up for the loss due to milling? Making a plenum gasket? Belt sander? Therapy?

Thanks, I think that's pretty much it...

 

[Bgunner]

They do make different thickness head gaskets but with this you kinda need to know how much was removed from the block and heads to get the proper thickness.

 

[Air Filter McWingnut]

They do make different thickness head gaskets but with this you kinda need to know how much was removed from the block and heads to get the proper thickness.

True... Old H. Gaskets crushed are at around 0.045 and the new ones installed were around 0.050
I've yet to see thicker than somewhere around there...

 

[RonD]

So I assume you are taking over someone else's attempt to rebuild a 3.0l Vulcan engine

Block was resurfaced which is different than milled, so just makes it flat, doesn't remove material
I would replace the heads and head bolts instead of trying to make them work
Double heads gasket are a bad idea if you want any longevity from this engine

 

[Air Filter McWingnut]

It's mine actually, had her since 2016. Blown head gasket overheating issue, cracked an old head end of last year. Got the two new rebuilt ones to delete all the valve work but that has led to the complications above. Nothing happened to the block deck, except for that I cleaned it. All the variables that have snuck in so far have to do with the addition of the two rebuilt heads. As far as I can tell...

 

[RonD]

How did it get 2 head gaskets on each side?

Rebuilt heads are not milled just surfaced

If the lower intake doesn't fit then something else is at play here

 

[Air Filter McWingnut]

Correction in terminology accepted, thank you, and a correction offered to help clear things up. Currently there is only one head gasket under each cylinder head. I put them on. I'm considering adding one to shim the heads up.

 

[RonD]

There can be a fitment issue on some 3.0l lower intake castings

Read here: https://www.ranger-forums.com/2-9l-3-0l-v6-tech-32/3-0-intake-manifold-172018/

 

[Air Filter McWingnut]

There can be a fitment issue on some 3.0l lower intake castings

Thanks for sharing that, actually it's interesting I had already read that a few weeks ago before I started reassembly. I know exactly what that guy's talking about with the number three intake pushrod. The lower intake is for some reason cast around it.

 

[19Walt93]

Please don't double up the head gaskets. I've had heads and blocks machined before and rarely the intake manifold needs to be machined as well. Step one is to find out how much the heads were cut, then you can calculate how much to cut off the intake. Be careful though, 3.0's are 60 degree engines and most of the formulas to calculate what you're doing are based on 90 degree engines. A good machine shop will stamp the block or head with the amount they cut off. Rebuilt means different things to different people, I wish you luck.

 

[Air Filter McWingnut]

Please don't double up the head gaskets. I've had heads and blocks machined before and rarely the intake manifold needs to be machined as well. Step one is to find out how much the heads were cut, then you can calculate how much to cut off the intake. Be careful though, 3.0's are 60 degree engines and most of the formulas to calculate what you're doing are based on 90 degree engines. A good machine shop will stamp the block or head with the amount they cut off. Rebuilt means different things to different people, I wish you luck.

Great points, I appreciate that.

 

[Air Filter McWingnut]

Making thinner lower intake manifold gaskets (plenum) out of some Fel Pro Karropak, paper gasket roll. It's 0.030 thick and makes up or in this case, makes down the difference.
I don't want to try milling the plenum to fit, yet.... The Fel pro plenum gaskets that came with the upper end kit are 0.050 thick and are about 0.080 around the intake ports where there's a "crush bead" designed to presumably seal good after torque down. They just won't fit.
So, that's what I'm doing. Post more at some point assuming assembly goes well from here.
Am wondering if anybody thinks using some copper gasket spray also might be a good idea, or have any experience to share in situations like this. Permatex high tack? Copper spray? Something?

P.S. I certainly wil not be yanking the heads to stack two head gaskets in there I was mainly curious to see if anyone had any experience with head shims, or a funny story from somewhere. The answer is always no till you ask.