Milling and big block cylinder heads...

Milling and big block cylinder heads... - 06/08/09 03:17 AM

OK, here's the scenario...
I have a pair of heads off an engine and I want to cut them .030".... BUT the surface of the heads look odd to me, and I am wondering if they have ALREADY been cut....
They are 1974 440 heads, 3769902 heads. Can I measure from the base of where the lower head bolts go - down to the deck surface, or ...? How can I tell if they have been milled or not?
Anybody got any methods??

Posted By: landon1

Re: Milling and big block cylinder heads... - 06/08/09 03:31 AM

i heard 1" height were lower head bolts go....but when you're talking thousandths of an inch, idk how accurate that can be - best bet is to CC them

Posted By: CrAzYMoPaRGuY

Re: Milling and big block cylinder heads... - 06/08/09 03:35 AM

Quote:

i heard 1" height were lower head bolts go....but when you're talking thousandths of an inch, idk how accurate that can be - best bet is to CC them

I think they are SUPPOSED to be rated at 81.5 cc but most were 85-86cc that I have actually tested, so I'm not sure CCing them would be accurate either?!?

Posted By: JohnRR

Re: Milling and big block cylinder heads... - 06/08/09 03:39 AM

Quote:

i heard 1" height were lower head bolts go....but when you're talking thousandths of an inch, idk how accurate that can be - best bet is to CC them

this is correct very close , plus minus .005ish to 1.000 ..

902 is an open chamber head ??? , 81.5 cc ??

Posted By: landon1

Re: Milling and big block cylinder heads... - 06/08/09 03:42 AM

i think that the 906, 346, 452 heads are all about 86-88 CCs aren't they? i had never heard 81.5

Posted By: JohnRR

Re: Milling and big block cylinder heads... - 06/08/09 03:43 AM

Quote:

i think that the 906, 346, 452 heads are all about 86-88 CCs aren't they? i had never heard 81.5

90-92

Posted By: RapidRobert

Re: Milling and big block cylinder heads... - 06/08/09 03:44 AM

the factory milled head decks with a straight cutter & MOST machine shops use a circular milling machine so if the marks are circular you know for sure that it's been cut on.

Posted By: JohnRR

Re: Milling and big block cylinder heads... - 06/08/09 03:45 AM

Quote:

the factory milled head decks with a straight cutter & MOST machine shops use a circular milling machine so if the marks are circular you know for sure that it's been cut on.

A straight cutter ???

Posted By: landon1

Re: Milling and big block cylinder heads... - 06/08/09 03:45 AM

Quote:

Quote:

i think that the 906, 346, 452 heads are all about 86-88 CCs aren't they? i had never heard 81.5

90-92

maybe i got my numbers because that's what mine are supposed to be since they were milled

Posted By: RapidRobert

Re: Milling and big block cylinder heads... - 06/08/09 03:52 AM

Quote:

A straight cutter ???

Not sure about the exact name of the machine but it does leave straight milling marks on the deck surface

Posted By: CrAzYMoPaRGuY

Re: Milling and big block cylinder heads... - 06/08/09 03:57 AM

Quote:

i think that the 906, 346, 452 heads are all about 86-88 CCs aren't they? i had never heard 81.5

I went and checked a half dozen sites, all were 81.5 cc for the 902 heads....

3769902 1974 440 400 2.08" 1.74" 81.5cc

http://www.motortopia.com/forums/viewtop.../tp/1#post_3902

http://bionicdodge.com/bionic/index.php?action=printpage;topic=5657.0

Posted By: JohnRR

Re: Milling and big block cylinder heads... - 06/08/09 03:59 AM

Quote:

Quote:

i think that the 906, 346, 452 heads are all about 86-88 CCs aren't they? i had never heard 81.5

I went and checked a half dozen sites, all were 81.5 cc for the 902 heads....

3769902 1974 440 400 2.08" 1.74" 81.5cc

http://www.motortopia.com/forums/viewtop.../tp/1#post_3902

they list the 906 at 79.5cc

, thats the NHRA blueprint spec . measure what you ACTUALLY have , do not believe everything you read ...

Posted By: 1_WILD_RT

Re: Milling and big block cylinder heads... - 06/08/09 04:00 AM

FWIW whether they have been milled or not is less important than the final chamber volume, measure them now & cut them to obtain the volume you need to get the C/R you want...

BTW .0062 off the deck = 1cc & for every .010 off the deck cut the intake surface of the head .0123

And BTW John is absolutely right.. Blueprint spec isn't even close to what Mopar really supplied.. 88cc happened allot less than 91-92cc

Posted By: CrAzYMoPaRGuY

Re: Milling and big block cylinder heads... - 06/08/09 04:03 AM

Quote:

Quote:

Quote:

i think that the 906, 346, 452 heads are all about 86-88 CCs aren't they? i had never heard 81.5

I went and checked a half dozen sites, all were 81.5 cc for the 902 heads....

3769902 1974 440 400 2.08" 1.74" 81.5cc

http://www.motortopia.com/forums/viewtop.../tp/1#post_3902

they list the 906 at 79.5cc , thats the NHRA blueprint spec . measure what you ACTUALLY have , do not believe everything you read ...

Thanks for the great response!
I guess you missed where I said they were RATED at 81.5cc but most I have actually TESTED were 85-86cc....?

Is there anybody HELPFUL on MoParts left anymore?

Posted By: JohnRR

Re: Milling and big block cylinder heads... - 06/08/09 04:05 AM

Quote:

Quote:

Quote:

Quote:

i think that the 906, 346, 452 heads are all about 86-88 CCs aren't they? i had never heard 81.5

I went and checked a half dozen sites, all were 81.5 cc for the 902 heads....

3769902 1974 440 400 2.08" 1.74" 81.5cc

http://www.motortopia.com/forums/viewtop.../tp/1#post_3902

they list the 906 at 79.5cc , thats the NHRA blueprint spec . measure what you ACTUALLY have , do not believe everything you read ...

Thanks for the great response!
I guess you missed where I said they were RATED at 81.5cc but most I have actually TESTED were 85-86cc....?

Is there anybody HELPFUL on MoParts left anymore?

maybe you missed where i agreed they should be 1.000 , back away from the keyborad , put down the crackpipe and go measure them , they have probably been cut .

any more silly staements ?

Posted By: NachoRT74

Re: Milling and big block cylinder heads... - 06/08/09 04:05 AM

Quote:

i think that the 906, 346, 452 heads are all about 86-88 CCs aren't they? i had never heard 81.5

Quote:

Quote:

i think that the 906, 346, 452 heads are all about 86-88 CCs aren't they? i had never heard 81.5

90-92

Posted By: CrAzYMoPaRGuY

Re: Milling and big block cylinder heads... - 06/08/09 04:06 AM

Quote:

FWIW whether they have been milled or not is less important than the final chamber volume, measure them now & cut them to obtain the volume you need to get the C/R you want...

BTW .0062 off the deck = 1cc & for every .010 off the deck cut the intake surface of the head .0123

Therein lies a small problem and why I posted this....
Who knows if the heads have been shaved... they look like they have, but the intake surfaces look stock. If they were cut already the .0123 certainly hasn't been taken off. I just wonder if there is a way to determine what the factory height off some point on the head to the deck surface or something, so I have SOME kind of bearing...

Posted By: CrAzYMoPaRGuY

Re: Milling and big block cylinder heads... - 06/08/09 04:06 AM

Quote:

any more stupid questions ?

Yup.
Why are you here?

Now GET OUT!

Posted By: CrAzYMoPaRGuY

Re: Milling and big block cylinder heads... - 06/08/09 04:08 AM

Quote:

any more silly staements ?

You can't even EDIT meanly!

Posted By: JohnRR

Re: Milling and big block cylinder heads... - 06/08/09 04:08 AM

Quote:

Quote:

FWIW whether they have been milled or not is less important than the final chamber volume, measure them now & cut them to obtain the volume you need to get the C/R you want...

BTW .0062 off the deck = 1cc & for every .010 off the deck cut the intake surface of the head .0123

Therein lies a small problem and why I posted this....
Who knows if the heads have been shaved... they look like they have, but the intake surfaces look stock. If they were cut already the .0123 certainly hasn't been taken off. I just wonder if there is a way to determine what the factory height off some point on the head to the deck surface or something, so I have SOME kind of bearing...

It is not surprising to see the intake side not cut , that cost EXTRA over the deck mill .

Posted By: NachoRT74

Re: Milling and big block cylinder heads... - 06/08/09 04:08 AM

Quote:

Quote:

Quote:

i think that the 906, 346, 452 heads are all about 86-88 CCs aren't they? i had never heard 81.5

I went and checked a half dozen sites, all were 81.5 cc for the 902 heads....

3769902 1974 440 400 2.08" 1.74" 81.5cc

http://www.motortopia.com/forums/viewtop.../tp/1#post_3902

they list the 906 at 79.5cc , thats the NHRA blueprint spec . measure what you ACTUALLY have , do not believe everything you read ...

thats what made me choose some stuff "wrong"

Posted By: NachoRT74

Re: Milling and big block cylinder heads... - 06/08/09 04:10 AM

Quote:

FWIW whether they have been milled or not is less important than the final chamber volume, measure them now & cut them to obtain the volume you need to get the C/R you want...

BTW .0062 off the deck = 1cc & for every .010 off the deck cut the intake surface of the head .0123

and be sure about same block height on both sides!

Posted By: CrAzYMoPaRGuY

Re: Milling and big block cylinder heads... - 06/08/09 04:11 AM

Quote:

i heard 1" height were lower head bolts go....but when you're talking thousandths of an inch

Well, they are pretty well bang on at 1.00"
That being said, the TEXTURE of the head leaves me thinking somebody had a baddddd shift at Chrysler in the early 70's. It looks like the surface was prepped for a head gasket with 40 grit sandpaper!

Posted By: 1_WILD_RT

Re: Milling and big block cylinder heads... - 06/08/09 04:12 AM

Quote:

Quote:

Quote:

Quote:

i think that the 906, 346, 452 heads are all about 86-88 CCs aren't they? i had never heard 81.5

I went and checked a half dozen sites, all were 81.5 cc for the 902 heads....

3769902 1974 440 400 2.08" 1.74" 81.5cc

http://www.motortopia.com/forums/viewtop.../tp/1#post_3902

they list the 906 at 79.5cc , thats the NHRA blueprint spec . measure what you ACTUALLY have , do not believe everything you read ...

thats what made me choose some stuff "wrong"

Exactly, you believe what Chrysler put out not what some guy on Moparts with a negative outlook posts... Just cause he was right shouldn't have any bearing... Till you realise the reason he is so negative is he's BTDT & already paid those dues...

Posted By: CrAzYMoPaRGuY

Re: Milling and big block cylinder heads... - 06/08/09 04:15 AM

Quote:

It is not surprising to see the intake side not cut , that cost EXTRA over the deck mill .

So if the heads have NOT been cut and I will now be using .040" Felpro head gaskets, and I cut the heads .030" I shouldn't have much of an issue.

If the heads HAVE been cut and I run a Felpro head gasket with an additional .030" cut I will have an issue, I assume, if the intake face hasn't been cut as well.

Lots of guys will cut the head .030" and use a Felpro gasket and NOT do the intake surface, which is what I thought *might* have been the case, but if the head isn't cut and just had an atrocious surface I might not want to touch the intake surface either.....

Anybody confused yet?

Posted By: JG71B

Re: Milling and big block cylinder heads... - 06/08/09 04:20 AM

"Exactly, you believe what Chrysler put out not what some guy on Moparts with a negative outlook posts... Just cause he was right shouldn't have any bearing... Till you realise the reason he is so negative is he's BTDT & already paid those dues... "

well put!

Posted By: CrAzYMoPaRGuY

Re: Milling and big block cylinder heads... - 06/08/09 04:23 AM

Quote:

"Exactly, you believe what Chrysler put out not what some guy on Moparts with a negative outlook posts... Just cause he was right shouldn't have any bearing... Till you realise the reason he is so negative is he's BTDT & already paid those dues... "

well put!

It would be interesting to tear down a Mopar, Ford and GM engine from the late 60's and see just how far off EVERYTHING printed in literature was back then, heads ccs, compression ratios, rocker ratios, horsepower outputs etc etc....

Posted By: JG71B

Re: Milling and big block cylinder heads... - 06/08/09 04:23 AM

Quote:

Quote:

It is not surprising to see the intake side not cut , that cost EXTRA over the deck mill .

So if the heads have NOT been cut and I will now be using .040" Felpro head gaskets, and I cut the heads .030" I shouldn't have much of an issue.

If the heads HAVE been cut and I run a Felpro head gasket with an additional .030" cut I will have an issue, I assume, if the intake face hasn't been cut as well.

Lots of guys will cut the head .030" and use a Felpro gasket and NOT do the intake surface, which is what I thought *might* have been the case, but if the head isn't cut and just had an atrocious surface I might not want to touch the intake surface either.....

Anybody confused yet?

Sounds like you need a set of heads...

Posted By: CrAzYMoPaRGuY

Re: Milling and big block cylinder heads... - 06/08/09 04:24 AM

Quote:

Quote:

Quote:

It is not surprising to see the intake side not cut , that cost EXTRA over the deck mill .

So if the heads have NOT been cut and I will now be using .040" Felpro head gaskets, and I cut the heads .030" I shouldn't have much of an issue.

If the heads HAVE been cut and I run a Felpro head gasket with an additional .030" cut I will have an issue, I assume, if the intake face hasn't been cut as well.

Lots of guys will cut the head .030" and use a Felpro gasket and NOT do the intake surface, which is what I thought *might* have been the case, but if the head isn't cut and just had an atrocious surface I might not want to touch the intake surface either.....

Anybody confused yet?

Sounds like you need a set of heads...

NEXT rebuild...

This one is getting the car running and driving...
(I hope!)

Posted By: RapidRobert

Re: Milling and big block cylinder heads... - 06/08/09 04:31 AM

Quote:

Anybody confused yet?

not yet. I'd mock it up & put the heads/gaskets on the block & barely snug them down with several bolts & check your intake port to head port alignment which is the most important thing to want to get right with this(along w CR & quench) & when its right the bolt holes will easily be in alignment and head gaskets only compress a couple of thou from new to torqued.

Posted By: NachoRT74

Re: Milling and big block cylinder heads... - 06/08/09 04:51 AM

Quote:

Till you realise the reason he is so negative is he's BTDT & already paid those dues...

whats BTDT ?

I don't get every abreviation yet!!!

Posted By: JohnRR

Re: Milling and big block cylinder heads... - 06/08/09 04:53 AM

Quote:

Quote:

"Exactly, you believe what Chrysler put out not what some guy on Moparts with a negative outlook posts... Just cause he was right shouldn't have any bearing... Till you realise the reason he is so negative is he's BTDT & already paid those dues... "

well put!

It would be interesting to tear down a Mopar, Ford and GM engine from the late 60's and see just how far off EVERYTHING printed in literature was back then, heads ccs, compression ratios, rocker ratios, horsepower outputs etc etc....

I have , the 56K original mile 383 HP in my dart , it still has shim head gaskets with part number begining with 18 part number , the pistons are if i remember right .006 in the hole , should be .003 , I haven't cc'd a head yet ...

Posted By: 1_WILD_RT

Re: Milling and big block cylinder heads... - 06/08/09 05:00 AM

Quote:

Quote:

Till you realise the reason he is so negative is he's BTDT & already paid those dues...

whats BTDT ?

I don't get every abreviation yet!!!

Been There.. Done That...

Posted By: 1_WILD_RT

Re: Milling and big block cylinder heads... - 06/08/09 05:04 AM

Quote:

I have , the 56K original mile 383 HP in my dart , it still has shim head gaskets with part number begining with 18 part number , the pistons are if i remember right .006 in the hole , should be .003 , I haven't cc'd a head yet ...

So you'll telling me they only missed by .003... That would be exceptionally close to spec... Are you sure you didn't add a zero??? Cause .030 wouldn't really surprise me... .080 wouldn't eiither...

Posted By: MLR426

Re: Milling and big block cylinder heads... - 06/08/09 12:00 PM

Quote:

Quote:

i heard 1" height were lower head bolts go....but when you're talking thousandths of an inch

Well, they are pretty well bang on at 1.00"
That being said, the TEXTURE of the head leaves me thinking somebody had a baddddd shift at Chrysler in the early 70's. It looks like the surface was prepped for a head gasket with 40 grit sandpaper!

Sounds like heads were surfaced on a Platen Belt
surfacer. Many shops have platen surfacers for exhaust manifolds,oil pans, water pump housings etc. But many shops have platen surfacers and use them for surfacing heads. A good shop will have a CBN surfacing machine that uses a Cubic Boron Nitride 1/2" or 3/8" surfacing button for cast iron heads and blocks and PCD buttons Polycrystalite Diamond for all aluminum heads and blocks. These machines will give you the RMS surface finish you should have when using todays head gaskets especially with aluminum heads.

logan426

Posted By: JohnRR

Re: Milling and big block cylinder heads... - 06/08/09 01:00 PM

Quote:

Quote:

I have , the 56K original mile 383 HP in my dart , it still has shim head gaskets with part number begining with 18 part number , the pistons are if i remember right .006 in the hole , should be .003 , I haven't cc'd a head yet ...

So you'll telling me they only missed by .003... That would be exceptionally close to spec... Are you sure you didn't add a zero??? Cause .030 wouldn't really surprise me... .080 wouldn't eiither...

nope it's that close , I keep hearing of these MYTHICAL blocks that are .020 or MORE than factory spec but I haven't come across one yet , maybe I'm just lucky , I have another 69 383 HP I just picked up , rering/rebearing rebuild , original pistons , guess what ...

I put these TALLER than spec blocks right up their with UNICORNS ...