Cylinder head questions

[69greenleaf]

I have a 68 model 440 block and rotating assembly (Not the 6-pack setup) with a set of “untouched” 452 heads. From what I have been reading online measure out to 88-90cc,putting my motor between 8.6:1 and 9.0:1 (don’t know exactly how far the piston are in the hole). I’m wanting to get my compression ratio around 10:1 maybe even 10:25:1. I am wanting to get the head cc down to 75-80cc. Would I be able to mill the 452’s down that much and still have my intake manifold fit properly? Would it be better to spend the money on some close chamber 915’s? Or maybe just fork up the cash for some close chamber aluminum heads. Just wanting some professional advice before I make my next move. Thanks.

 

[68Moparmaniac]

Can't go wrong with a set of 915's if you can find some good castings, they have gotten pricey as of late though. You may have to look at plan B for your heads, lots of choices out there.

 

[727]

If I remember correctly. I put a set of 452's on my surface grinder and took them down quite a bit. It throws the valve gear out of spec and because the oil hole through the head is angled, it was offset where it lined up with the block.
You can enlarge the oil hole to make it work and you can get adjustable rockers or change your push rod length.
My advice would be to get some aluminum heads and make my tire company stocks go up.

 

[Brandy]

There was someone on here that was selling a set of 915's yesterday....

https://www.forbbodiesonly.com/moparforum/threads/915-heads.170184/

 

[PRHeads]

I vote for “C”....... new aluminum heads.

 

[MoparLeo]

The question that evry one should ask before making recommendations is, "what are you trying to do, and what are your expectations?" Just because? building a strip car? Don't know, just sounded like a good idea ? What about the rest of the engine ? Aluminum heads on a stocker with oe intake, cam and exhaust manifolds ? Or....

 

[69greenleaf]

The question that evry one should ask before making recommendations is, "what are you trying to do, and what are your expectations?" Just because? building a strip car? Don't know, just sounded like a good idea ? What about the rest of the engine ? Aluminum heads on a stocker with oe intake, cam and exhaust manifolds ? Or....

I’m really wanting to make it a strip car. 1/8” mile because that’s all there is for local tracks. Still want to be able to take it down the road for car shows and what not, but I’m pretty dead set on racing the car. The rotating assembly will remain stock. Heads, cam, intake, headers, and a little bit of nitrous (150 shot) is the plan for now. I Have a early model 383 block I’m wanting to “build build” possibly big stroker kit. but wanting to get the car to a decent spot before spending all my money on building a new motor.

 

[beanhead]

....Just wanting some professional advice before I make my next move. Thanks.

Here ya go..doesn't get any more professional than this!

I vote for “C”....... new aluminum heads.

Thanks PRH!

 

[69greenleaf]

Just got off the phone with my local machine shop. It’s looking that the cheapest route will be to mill the 452’s I have down. Does anyone have an idea how much I can safely take out to not have to do any major modifications? The machinist I talked to say it would probably be around .040 to get them down to 80cc. Does that seem right/safe to do?

 

[68Moparmaniac]

Just got off the phone with my local machine shop. It’s looking that the cheapest route will be to mill the 452’s I have down. Does anyone have an idea how much I can safely take out to not have to do any major modifications? The machinist I talked to say it would probably be around .040 to get them down to 80cc. Does that seem right/safe to do?

May run into issues with your intake seating to the heads properly. A competent machinist can fix the angle issue on your intake but as stated in post #3 I would be concerned about valve train geometry among other things. The only other way to raise CR would be with piston's which can get deep into your pockets. Since your mainly looking to race with minimal street duty seems logical to go with a set of aluminum heads, you may just come out ahead going this route.

 

[33 IMP]

You really need to know how far down in the hole your current stuff is. Are you sure they are 68 pistons and not some generic replacement thats .110 in the hole? You cant get to where you want without knowing where you are. A quick and easy compression improvement would be some .015 steel shim head gaskets, in place of .043 generic composite gaskets, can mean a half point increase.

 

[33 IMP]

If you are really planning on making a 383 stroker, 496 maybe, i would put together what you have, run it, dial in chassis, launch techniques, have some fun, solve problems, and put the effort and money into the engine you really want.

 

[MoparLeo]

Push rod length, intake port alignment, rocker angle...... Remember that once you machine it off..you can't put it back. Mistake$ co$t money. Get your "recipe" compatible combination of parts sorted out before you buy. At least we got to get a lot more info about what you want to do other than a simple head question. Info helps.

 

[Cranky]

Yup....will probably take a tad more than .040 to take out 10cc. Also wouldn't hurt to check all the chambers. Had a set of heads that one cylinder on the ends were about 3cc smaller than the others. And like mentioned, you need to check fit and port alignment etc. So, the untouched 452's need nothing else done to them?? How bout doing a bowl job ie valve pockets? Mopar heads suck in that area and just doing that alone will really make an improvement. I also vote 'C'

 

[beanhead]

I guess I missed it before, I just read your post number 7. I see you're wanting to race it...in my opinion bumping up the compression a bit and not doing anything else to those heads is going to leave you very disappointed. That alone is not going to increase your power output much. If you're after performance, you need airflow a lot more than you need 10-1 compression...and to get factory heads moving air you're talking bigger valves and porting which is going to end up costing as much, probably more, than aluminum heads. Don't forget about machining for better springs and seals, which is also already done on the aftermarket pieces. Then factor in the amount of weight you save off the front of your car, chamber efficiency etc...it gets expensive to run fast so you might as well do it right the first time..

 

[69Bee]

Rule of thumb for BB Mopar heads (79/81/83cc heads), remove 0.0042" per 1cc of volume. Therefore, 10cc would equate roughly to 0.042". I agree with uneven chamber volumes, and that they are actually where they say they should be. Measure to verify your numbers and do the math. The main thing to remember here is that IF you decide to work the 452 heads, they WILL need guides/ex seats/ valves/ springs, and deck milling (obviously), but do NOT cut the intake, mill the intake side of the head instead. If you mill the intake, it is now married to that engine. Mill the heads, and the intake can be used on any engine. The intake side of the head should be milled 0.0123" for each 0.010" milled from the head/block. This means that if you mill only the head (not block deck) 0.042", you would need to remove 0.0492" from each intake side of the head. Since the manifold doesn't seal to the block, it isn't necessary to mill the valley rails, but I do to clean them up and for head/valley alignment. I usually cut about 0.012" to 0.015" for a general head/block cleanup, but you would need to cut a little more for 0.042" head cut.

 

[fratzog lover]

How bout doing a bowl job ie valve pockets? Mopar heads suck in that area and just doing that alone will really make an improvement.

Oh yeah. Muy importantisimo.

 

[PRHeads]

“Best” vs “cheapest”

Almost never the same thing....... or result.

 

[PurpleBeeper]

I have a 68 model 440 block and rotating assembly (Not the 6-pack setup) with a set of “untouched” 452 heads. From what I have been reading online measure out to 88-90cc,putting my motor between 8.6:1 and 9.0:1 (don’t know exactly how far the piston are in the hole). I’m wanting to get my compression ratio around 10:1 maybe even 10:25:1. I am wanting to get the head cc down to 75-80cc. Would I be able to mill the 452’s down that much and still have my intake manifold fit properly? Would it be better to spend the money on some close chamber 915’s? Or maybe just fork up the cash for some close chamber aluminum heads. Just wanting some professional advice before I make my next move. Thanks.

a) double check those numbers....I think your static compression ratio is a little higher than you think. I believe the 452 heads have the same combustion chamber size as the 68's original 906's. Minus anything you'd lose running a thicker Felpro head gasket vs. a factory style shim head gasket, the static compression ratio should be the same as stock.
b) closed chambered heads is definitely the way to go. 915's or aluminum closed chambers if you have more money.
c) To me, the big problem with milling down the 452's a whole bunch is the intake manifold-to-head mating surfaces start to get off & the intake gets hard to seal. I know you can mill off the intake face of the heads or the intake itself....but it's just a pain in the butt (ask me how I know)

 

[1968rt]

Milled these over .070 to 67 ccs. Been over 7 years no problems