Intake port alignment milling question

[no green]

I’m building a 496 mopar RB for my dad’s bracket racer, and right now I’m fitting our existing victor 440 (pn 2954) intake to our new ported performer rpm heads (pn 60919), and I have a bit of a challenge.

When I mock the intake into place with .065" shims (the thickness of the valley pan and gaskets), the top of the intake port is .100" higher than the top of the head port. I measured with a scale. The bottom of the intake port is the same .100" higher than the head.

By my math... to lower the ports .100 to line up right, .120" needs to be milled off the intake face (or head face), but that seems like a lot of material to me. Did I do my math right?

I don’t know what "a lot" would be in this situation. Is milling that much off common, or at least probable?

I have not checked the deck height, yet, but I know it, and the heads, were only decked to clean. I have it mocked up with .027” cometic head gaskets, but might end up with .040” (need to check piston to deck and valve clearance).

When I mock up the intake with no shims or gaskets, it lines up almost perfectly.

I re-did my mock ups about a dozen times, and kept getting the same results.

Advice?

[GOSFAST]

With that unit and others, Ford 545" we have here now for one, you have to remember these used "tin" intake gaskets.

Olds/Buick is another case, tin valley pans, so when you substitute a more standard .060" thick type gasket you will need to mill at least the difference between the tin (.022" nominal and the .060" replacements) from the intake sides just to get back to original. You need to start at a .040" pass minimally on the intake. The end rails should fall right into place.

(Add) The heads could be milled same amount on the intake sides to accomplish the job but you (or someone else) won't be able to use the original setup with those castings anymore. We have some iron SCJ heads here that may be slightly more valuable in the futrure on a resto, this led us to "chop" it off the alum intake instead?

Thanks, Gary in N.Y.

P.S. The 460" Ford stroker here took exactly .040" off the intake side-rails to be right, fell right into position! End rails fit perfect.

[wyrmrider]

I forget the formula but are you also using the additional paper gaskets?

[no green]

I forget the formula but are you also using the additional paper gaskets?

Yes. what I remember measuring was gasket+gasket+valley pan .025+.025+.015=.065.

now I see they advertise this as .075" thick, so I'm going to measure it again.

this is what I'm using:

http://www.jegs.com/i/Fel-Pro/375/1215/10002/-1

I don't remember the exact formula, but according to my research (I don't have tools to measure), the intake face on the RB is 10* from the deck surface, the factor on my milling chart for 10* says 1.2.

amount to move x 1.2 = amount to remove from intake surface

.100 x 1.2 = .120

Edit:

This is the source I used:

http://www.crankshaftcoalition.com/wiki ... nder_heads

.707 ÷ (SIN (45 - intake face angle)) = factor

.707 ÷ (SIN (45 -10 )) = 1.23

my reference book has a chart that said 1.2... so that's what I rolled with.

[PackardV8]

.707 ÷ (SIN (45 -10 )) = 1.23

my reference book has a chart that said 1.2... so that's what I rolled with.

Your math was more exact than the reference book, but holding those tenths are difficult in any case.

OT, but Mopar has always used odd intake face angles on every one of their OHV8s, as did early Cad, Olds, Studebaker and SBC, while most later V8 engine designs, SBF, FE, BBF, late Olds, Pontiac, Packard all used right angles.

[67satellite]

I always heard for every .010"off the head gasket surface, take .0123" off of the intake gasket surface or manifold. Sounds like your .012" will work fine.

[cgarb]

Sounds like if you assemble with no shims or gaskets it lines up perfect? If thats the case you may end up removing more like .065 off the intake not .012". My advice is don't take all the material in one cut, cut half thn reassemble, check and recheck. Its easier to take 2 or 3 cuts than to fire up the welder. Good luck.

[wyrmrider]

think through which edges you want no smaller than the manifold
you definitely do not want a lip at the top
are the heads a teensey bit bigger than the manifold?
then you can work with is too much or too little better

[pamotorman]

if removing the .065 thick gaskets makes it line up I would say you need to remove that amount from the intake flange.

[Cubic_Cleveland]

if removing the .065 thick gaskets makes it line up I would say you need to remove that amount from the intake flange.

Ding ding ding!!!!

[no green]

if removing the .065 thick gaskets makes it line up I would say you need to remove that amount from the intake flange.

That's where my confusion is coming. I agree with you, but why is my math not confirming this? Am I using the wrong formula or method?

I'm all for removing a little at a time and test fitting it, but my machinist is 1.5 hours away... and packing up the whole motor to take over there, and loose a week waiting for it to come back, would suck.

Besides that, I'd like to understand what's going on here.

[panic]

Read my article: http://victorylibrary.com/mopar/intake-mill.htm

[wyrmrider]

good for you
and
we'll all learn something
measure twice-cut once
I'll see what the Direct connection and Mopar performance books say a little later tody

[Dave Koehler]

Something else to consider. If you don't want to wind up with an oddball manifold you can't sell later you may want to mill the intake side of the heads.

[jsgarage]

Another thing to consider before cutting (I'm not familiar with that block)- lowering the ports also lowers the base. Will you need to also clip the bottom of the manifold to get it to seal on the valley?