[ponchjoe]

Hey guys,

I have a set of stock 670 heads that have been rebuilt with Manley SS valves, new exhaust seats etc, the paperwork says milled .007 to clean up only.
I am trying to cc them but I’m coming up close to 80 ccs on the two I did, is this possible?
Thanks

[Formulas]

Valves sink a little on a seat grind, +cc .. original valves were nail heads not concave +ccs ... .007 cut is about -1cc ... most data charts on chamber sizes are deeply flawed by evidence on how many are reported 72-75 cc when some are a little less and some are closer to 80cc

Thats why you have to check actual numbers planning a build

[ponchjoe]

Originally Posted by Formulas

Valves sink a little on a seat grind, +cc .. original valves were nail heads not concave +ccs ... .007 cut is about -1cc ... most data charts on chamber sizes are deeply flawed by evidence on how many are reported 72-75 cc when some are a little less and some are closer to 80cc

Thats why you have to check actual numbers planning a build

Was wondering about the shape of the valves adding a little. These heads were sitting on a shelf for quite awhile and I’ll almost bet they are low mile heads to begin with. The castings are really nice.
Should I check more them all or just a couple on each head?

[b-man]

I would check them all so you know how consistent they are.

Then afterwards touch them up to equalize them as close as you can.

[P@blo]

The 670 heads I have are 83cc after going in for new guides, valves, and springs. The chambers have also been altered by butler and were 81cc at the time. Hopefully the pictures come through

[ponchjoe]

Originally Posted by P@blo

The 670 heads I have are 83cc after going in for new guides, valves, and springs. The chambers have also been altered by butler and were 81cc at the time. Hopefully the pictures come through

Wow 83? No pics came thru but I’d like to see them . Can you send them to chiefponcho@gmail.com?
Thanks

[steve25]

Those dish faced valves and the valve, job at least in terms of the intake valve are like adding 3 to 4 CCs to the chamber siize.

I like that the shop used a big OD exh valve seat incert because then hopefully the seats ID did not intrude on the valve bowl as much as I have seen with work like that done on some heads.

I have seen when flow testing 15 or more CFM knocked off by a seat incert!

I would CC two chambers in each head to see how they check out, if there is no more then a 3 cc difference between them I would call it a day and bolt them on.

[steve25]

Joe. At a chamber volume of 80 CCs and with the 5 CC valve notch volume of those race tech pistons I come up with a 9.95 to 1 compression for your 435 motor..

[ponchjoe]

Originally Posted by steve25

Joe. At a chamber volume of 80 CCs and with the 5 CC valve notch volume of those race tech pistons I come up with a 9.95 to 1 compression for your 435 motor..

Thanks Steve. I assume this is based on zero decking? If not how many ccs do you gain for stock deck height?
Thanks again

[steve25]

Joe I used a deck height of .012” because I did not know what you had for a deck height.

That .012” works out to a added 3.33 CCs.

Here’s a list of what I used.
Cylinder. 891 CCs

Valve notch volume. 5 CCs

Deck height 3.33 CCs

I don’t know if your block has any valve chamfers in the deck.
Head gasket. 9.7 CCs

Ring land volume. 1.5 CCs.

[chiphead]

Mine came back at 80cc after new valves and slight laying back of chamber on plug side. Glad to hear this is typical. I thought I had mis measured or valves were really sunk. Before work, they measured 76cc by a machine shop.

[ponchjoe]

Originally Posted by steve25

Joe I used a deck height of .012” because I did not know what you had for a deck height.

That .012” works out to a added 3.33 CCs.

Here’s a list of what I used.
Cylinder. 891 CCs

Valve notch volume. 5 CCs

Deck height 3.33 CCs

I don’t know if your block has any valve chamfers in the deck.
Head gasket. 9.7 CCs

Ring land volume. 1.5 CCs.

It’s a 69 400 block and has the two chamfers at 3 & 9.

[ponchjoe]

Originally Posted by chiphead

Mine came back at 80cc after new valves and slight laying back of chamber on plug side. Glad to hear this is typical. I thought I had mis measured or valves were really sunk. Before work, they measured 76cc by a machine shop.

Thanks Chiphead. That is why I posted as well, cc’ing is not hard but also not something I do often lol

[steve25]

Get some clay and form it into those valve chamfers and then dunk them in your Cc tube to see how much they displace.

My moneys on about 3.5 CCs.

Your compression would then be 9.65 to 1.

[P@blo]

Here you go ponchjoe.

[ponchjoe]

Originally Posted by P@blo

Here you go ponchjoe.

Thanks. Kind of validates my number, my valves seem a bit more proud than yours .

[P@blo]

That picture was as bought but the valves sit the same. The heads have since went in for new solid bronze guides, valve job, and springs. My shop does not like to use the seat inserts on Pontiac heads so I add a bit of two-stroke fuel oil to my gas and have never had issues.

Also, I checked my invoice and heads are 82cc not sure why I was remembering 83cc. Not that 1 cc is a big difference. Basically added 1cc over when they were done 15 years ago with the new valve job. Butler removes 3-4 ccs on the chamber modification so im not sure where you would be, volume wise, if you modified yours. Figure mine were 76-77 cc before the chambers were unshrouded. These 670s were also ported to 240-250cfm and they did not install the seat inserts then either.

[ponchjoe]

[QUOTE=P@blo;6548707]That picture was as bought but the valves sit the same. The heads have since went in for new solid bronze guides, valve job, and springs. My shop does not like to use the seat inserts on Pontiac heads so I add a bit of two-stroke fuel oil to my gas and have never had issues.

Also, I checked my invoice and heads are 82cc not sure why I was remembering 83cc. Not that 1 cc is a big difference. Basically added 1cc over when they were done 15 years ago with the new valve job. Butler removes 3-4 ccs on the chamber modification so im not sure where you would be, volume wise, if you modified yours. Figure mine were 76-77 cc before the chambers were unshrouded. These 670s were also ported to 240-250cfm and they did not install the seat inserts

I can definitely see where they opened them up

[ponchjoe]

All are between 78 and 80 ccs.

The deck appears to be untouched but there are some random numbers lightly stamped in places, some illegible. Did the factory do that?

[johnta1]

Factory usually used letters (if used). Like 'M'