452 heads cc's
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It completely depends on how much material is machined off.
I measured several sets of BB heads and found they were as much as 90 ccs and as little as 86 ccs. The 86 cc heads had been rebuilt at least twice.
I measured several sets of BB heads and found they were as much as 90 ccs and as little as 86 ccs. The 86 cc heads had been rebuilt at least twice.
I thought the only difference between stock uncut 906 and 452 heads were the valve seats in the 452 were for unleaded fuel
.0055 is roughly 1 cc.
It might be faster on a broach but I surface iron and aluminum heads daily and it's quite a bit of time to get .022 off of a head and that only will decrease your chamber size by 4cc's
In reality the heads are likely to clean up at less than .010 so you'd be looking flat heads but not much less volume of a chamber.
Also for every .0055 your intake should be cut .011 to keep you bolt holes aligned.
I recently did my trickflow heads, I milled off .080 and to get my intake to sit down I had to mill .140 to get it close. I have adjustable rockers so I didn't need new pushrods.
To bad you don't live closer
It might be faster on a broach but I surface iron and aluminum heads daily and it's quite a bit of time to get .022 off of a head and that only will decrease your chamber size by 4cc's
In reality the heads are likely to clean up at less than .010 so you'd be looking flat heads but not much less volume of a chamber.
Also for every .0055 your intake should be cut .011 to keep you bolt holes aligned.
I recently did my trickflow heads, I milled off .080 and to get my intake to sit down I had to mill .140 to get it close. I have adjustable rockers so I didn't need new pushrods.
To bad you don't live closer
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If you're asking because you want to raise the compression on a late model 440 that has the pistons .155" in the hole don't bother to mill them. You won't gain enough to make it worthwhile even at a .060" cut. Plus you'll need new pushrods too.
Tom
Tom
This ^^^^^^
That's assuming alot
The op is asking about the chamber size after his heads are milled & yes, there's no difference between the two except for the cheesy induction hardened seats, which after a good valve job are no longer hardened lol
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No, I agreed with something VERY specific!
Actually, Jim Laroy and his son Cody found there are some differences. In fact, I've seen Jim say the ports on the 452s are a smidge better than the 906s. "I guess" if you're gettin down to the nitty gritty you would want the 452s, but for the vast majority, they only real difference is the "hardened" seats. I use quotation marks, because induction hardening is good for the original valve job.....sorta. lol
Is it the 452 or 346 [ or both ] that have the Huber bump in the intake ports?
According to the MP notes, 72-78 400s & 440s. Milling the heads 060 increases CR from 8.5 to almost 10:1; 440s go to approx 9.8:1
According to the MP notes, 72-78 400s & 440s. Milling the heads 060 increases CR from 8.5 to almost 10:1; 440s go to approx 9.8:1
That's probably accurate, considering that the general shape of the circumference of the chamber is round. You're removing a lot of real estate at one time. BUT, with the piston down in the bore .100" plus, all you may be doing is setting yourself up for detonation, so I would be careful.
I'm putting together a 400 with KB240 pistons, stock rods, 383 steel crank and when I cc'd the heads on the 4 corners and they came in at 87.6 and 88 on one head and 87.6 and 89 on the other. I need to cut them to make them straight but wanted to know what amount of cut will equal cc volume. I thank you very much for your explanation it's awesome. Basically it will be a 9.25 comp 400 for fun driving in my 79 Magnum, I use my 73 Blue Duster for track use
Rusty I've also heard exactly that. On the other hand I was over helping Nick @ Nick's garage and he found 906 to be a bit better, tried 346 and they were identical. Goes to show that aside from the hardened seats which we all know go away after 1st valve job they are very close to one another. Thanks
Those chamber volumes vary not because the head is cut wrong. They vary because of the slight differences when the sand cores were put together at the foundry.
If you want them all the same you're going to need to do some grinding in the chambers to equal them out.
Tom
If you want them all the same you're going to need to do some grinding in the chambers to equal them out.
Tom
I had some port slices at work and there's no physical difference. If he is getting numbers from a flow bench that are better I can understand that as 452 castings tend to be better in appearance.
Thanks Tom, I'm unshrouding the valves and whatever more it needs i guess i'll cut off 5 thou more on the side that has 89cc. Since i'm there I'll try to equalize it as much as I can. It's mostly cruising and maybe mild brackets Opened up the bowls with Serdi and looks great
I'll have to go check that, I have several sets a of both . I don't recall any bumps in the ports and the little shop turd put the cut aways in the recycling load last summer.
That's going to be awesome, have fun.
He was comparing flow numbers. There's a thread on it around here somewhere, since it's been years ago so it's probably buried, but he said the 452s were better. But as I said, It'd be splittin hairs for sure for most of us and besides, with all the aluminum heads available today, it's kinda a moot point anyway.
And you know, IMO, people make WAY more hooplah over hardened seats than they're worth. On most applications like we do, they simply are not needed. People will argue that till the end of time, but it's true. With these street cars, they are pretty light, especially A bodies. Normally, they have lower gears than stock that help make the job easier on the engine to move the car. Anything that keeps exhaust temp down. Vehicle weight, gear ratio, big cooling systems that cool RIGHT. All that. Now on a truck, especially a tow vehicle, or one that's used to haul stuff, you'll want hardened seats. But by and large, on our cars, it's just a myth that won't go away. Just because all the forums and magazines say it, doesn't make it true.
Yeah I think I've seen that thread. 100% agree with the heads available today
Stainless valves also will help if the seats aren't hardened.
I agree, but those aren't even necessary if the car is light enough....and we all know A bodies are. But you're right. They sure won't hurt anything.
Exactly. I simply cannot figure out other than rules limitations why anyone would go iron nowadays......unless it's a situation like the slant 6, where nothing is available.
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