RAMBOW

Trying to understand when milling & decking affects the intake seat angle enough that it has to be modified... (i want ot avoid that)

I have TRW LF2323-30 pistons going into my new motor. They are dished and according to their website give ~ 9.6:1 w/ an 80cc head (this is from memory so maybe not exactly the right numbers)

I have stock uncut E heads (most likely 80+ CCs), and a virgin block.

If i have the block squared and zero decked (or close to it, leave just enough meat to be cut again for a future rebuild) does that change the head angles enough that the intake needs to be cut- or is that only if the head is ALSO milled a significant ammount?

I want to maximize the compression I can get with these pistons, so would like to deck the block & mill the heads as much as i can w/o requiring intake mods.

is there any sort of guideline for how much you can cut before there are fitment problems?

Thanks-
Ben

cutlassefi

Again you're going about this *** backwards, maybe you should've used the KB IC886 instead, smaller dish (14.5) and .015 taller. May have allowed you not to have to deck anything.

But with that said if you're trying to "maximize" (not sure how high you want to go) your compression then you really need to cc the heads, then check to see how far down in the hole your pistons are. Figure your true compression from there.
Then install the intake with the gaskets on, scribe around the top of the gasket, then remove it and lay it along the manifold lining up the scribe marks with the intake. See where the gasket lays vs port alignment, then decide whether or not it needs milling. If the intake seems to sit higher on the heads then remove the gasket and check it again, the gasket is about .065, figure from there how much you may or may not have to remove.

67Olds442X2

On my build using basically the same parts, I didn't have to modify my intake. My block was cut .040, heads .060 and the same pistons were roughly .003 in the hole. I couldn't use the rubber seals at the ends because the intake sat too high. Basically mine was cut to the max and intake worked, still definitely follow Marks advice, I didn't verify my ports. I will the second go around.

ah64pilot

I agree...even if you don't deck anything, it's still an easy couple of horsepower that you can save by port matching the intake. It's a fairly simple process if you know what you're doing. If not, take the intake to the machine shop that's doing the block and heads and let them do it for you, about $100-$150.

I had my block decked .006" and didn't NEED to do it, but I had my heads ported and wanted my intake to be opened up to match the heads. I matched the intake to the heads and scribed the lines on the intake. Then I had Nicken's Racing do the actual porting on it. There is a smooth transition from the intake into the head because of this procedure...worth the money for me

MDchanic

I'll be confronting this question at some point as I make progress on my motor (on hold while I work on the rest of the car...), and now seems as good a time as any to ask a possibly dumb question (yes, I know: "There are no dumb questions, only dumb people").

It seems to me that with the heads fitting square to the block and the intake manifold fitting at a 45° angle to the heads, reducing the components to a series of symbolic 45/45/90 triangles shows that I need to machine the same amount off of the intake manifold gasket flange that I want the manifold to move along the gasket surface.

In other words, if the holes miss lining up by 0.007", then if I machine 0.007" off of each intake gasket flange, the holes should line up again

If I need to know how far down the front and rear valley sealing flanges are moving toward the block (and whether they'll need to be machined), I can determine that by using the Pythagorean Theorem (a²+b²=c²) and solving for the hypotenuse (in other words, 0.007²+0.007²=0.0001, and √0.0001=0.010), which would tell me that the manifold will drop 0.010" closer to the block after the gasket flanges are machined 0.007".

Am I right on this, or do I need to rethink it?

Thanks,

- Eric

ah64pilot

Also, even if you CAN use the rubber end seals...DON'T! You're better off using a bead of Ultra Copper along the end rails. You can use an old Mondello trick to help it seal even better by taking a center punch and dotting the block and manifold mating surfaces before assembly.

RAMBOW

I fully realize I'm doing this in a funny way- half thats my ignorance, and half is just the way its working out trying to do it on a budget- trying to resolve at least the first part of that...

I got the matched, balanced set of pistons & rods used, and I'm going to use them... So that puts me in the position of building the block and heads to suit them.

Block machining is coming up quick, but at this point i have not done anything other than have the crank ground & drilled, so like i said, i'm just trying to wrap my head around it so I ask for the right things.

67Olds442X2

I totally forgot that my heads were cut on the intake side as well as the exhaust side. Cutting the intake side of the heads may have answered your question.

69442C

This is supposed to be a friendly site...and I don't like to see talk like this. It brings back bad memories.

MDchanic

Hey, my brain STILL hurts from having to pull that stuff out of there.
It's been 30 years since high school .

- Eric

ah64pilot

Just stop already! It hurts my eyes to see that! You can keep talking, just don't quote it anymore...

Not to mention you make me feel really dumb After reading it, it comes back...but there is no way my brain would have an original thought about the Pythagorean theorem.

TripDeuces

I found this chart to answer your question.

Where 'A' is the amount removed from the head and 'B' is the amount removed from the intake.

MDchanic

Are you sure that A and B represent the intake gasket milling and the intake base milling, and not the head gasket milling and the intake gasket milling?

- Eric

TripDeuces

I couldn't get the picture to download but 'A' was the head to block surface and 'B' was the intake to head surface.

Here's the website: http://www.goodson.com/technical_sup...le_milling.php

MDchanic

Right. That's what I thought.

The head is at 45° to the intake manifold, and has the intake flange surface at 90° to that, so that flange is at 45° to the head and to the intake, so the numbers equal out.

But if you want to know how much to mill the bottom surface of the manifold where it seals against the block in the front and back, you've got to use that thing I mentioned above which must not be named .

- Eric

TripDeuces

Yes that's also listed at the bottom of that page. It's 'A' x 1.4 for the bottom cut. Since a gasket isn't being used here and just RTV I don't think that is as critical.

MDchanic

Makes sense.

I'm just threadjacking because I may have to do this at some point and want to have an idea of what I need to look out for.

- Eric

J-(Chicago)

Just mill the heads. Not the intake manifold.
If you mill the intake, it would only be good for that engine and combo. Then, most likely someone will sell the intake somewhere down the road and screw over the next guy.

There is at least a 1/8" gap between the bottom of the intake, and the front block rail. Plenty of room to work with.