[bayside_norm]

My 1966 Goat is going to be a weekend warrior... with the wife, of course...

I just aquired a clean set of 670 heads to replace my incorrect 9773345 heads. The early 389 heads were mounted so the previous owner could use an (also incorrect) 62 tripower. I can also mount a set of 7K3 heads.

With headers, HO cam, stock rear and TH350, is either of these heads worth machining? I've been warned that the 670 heads can create an interference with the valves and pistons if a comp cam is used. Also the cr is an issue, might need dished pistons to bring it down to pump gas levels.

I'm thinking new seats, bronze guides, Ferrera stainless valves, and maybe roller rockers..unless I can stay with adjustable studs and make it work.

So, which heads... 670? or 7K3? Or, start over!? heheh

[Mr. P-Body]

Norm,

670s are hard to beat. Good heads. The valve-to-block thing is only an issue with 350s or 326s. The valve-to-piston thing is an issue with ALL heads. A small amount of material removed from the chambers around the spark plugs will give the 389 a tolerable static compression ratio. About 5 CCs should do the trick.

If it's a street car, to run on 93, you don't want TOO MUCH cam in there. 230-240 (@.050) intake duration and .520 lift will be plenty! An 041 cam would be okay with the events advanced 4 degrees. Comp XE274H would be better...

Jim

[bayside_norm]

Originally Posted by Mr. P-Body

Norm,

670s are hard to beat. Good heads. The valve-to-block thing is only an issue with 350s or 326s. The valve-to-piston thing is an issue with ALL heads. A small amount of material removed from the chambers around the spark plugs will give the 389 a tolerable static compression ratio. About 5 CCs should do the trick.

If it's a street car, to run on 93, you don't want TOO MUCH cam in there. 230-240 (@.050) intake duration and .520 lift will be plenty! An 041 cam would be okay with the events advanced 4 degrees. Comp XE274H would be better...

Jim

Jim, thanks for the additional info on the cam. I really wanted to use the 670 heads! If I did my math right, taking 5cc out of the chamber whould bring the cr down into the mid 9's? I've been unable to find any posts from guys running these heads on a 389... only the 400/428. Thanks!

[Keith Seymore]

I have the 670 heads on my '65 389...but that's about where the similarity stops. It's a 12.5:1 race motor from back in the day (heads were installed in 1967) so I can't help much more than that.

K

[bayside_norm]

Originally Posted by Keith Seymore

I have the 670 heads on my '65 389...but that's about where the similarity stops. It's a 12.5:1 race motor from back in the day (heads were installed in 1967) so I can't help much more than that.

K

Keith,
thanks, that's what scares me.. 12.5:1! I like the potential but hate the gas issue.
I can't find a reliable way to tell what my cr will be if I just bolt these babies on, other than I know I will need to do something along the lines of what Jim mentioned above. Still lookin'!

[BVR421]

Using these assumptions,

bore= 4.06
stroke= 3.75
670cc= 72
gasket= .041
deck= .020
reliefs= 7-8cc

static compression ratio about 9.7

hard too say how many valve jobs and surface cleanups a 1967 head may have had in its life, the chambers may be milled down to ???
SD Performance has a CNC program to reshape and open up the chambers for a more efficient shape as well as lowered compression.
I think mrPbody has that capability as well in his excellent machine shop
check with them on that.

[Jerry H.]

Bayside, welcome to PY. I saw your post over on the HAMB. You've come to the right place. You won't get anyone flaming you over here.

[steve25]

The 670s chambers can be inlarged by 5 to 8 CCs (depending on how much you need) changing them in to a simi open chamber in about 3 hours, I have done it many times and have made up templates for a 5,6 and 8 CC inlargement.
The straight wall of the intake runners are a good amount straighter than any of the latter D-ports, as such with just bowl porting and going up a tad into the window area, 240 CFM@28" can be had in less work time than the other D-ports.
All so on the exhaust side of the 670s their is no casting nub on the crown of the short turn like all othe D-ports that upsets the out bound flow.
These heads, like the latter #16s and the latter 5C castings and such with the air injection casting ledge on the out side of the head do weigh more than the other D-ports by almost 5 lbs if I recall.
In rebuilding these heads you should in the least.
1) replace all the guides with 1/2" guides, no thin .030" walled P/B sleves please!
2) all new valves.
3) Drill and tap the air injection bosses in each exh port for a allen set screw to block off all the exh ports from each other.
4) install no lead exh seats with a minor bowl blend job.
5) and in reguareds to the INTAKE valve job, do not add a 15 degree top cut, as that only uses up chamber floor meat, does not do much for the flow, and on the next valve job will really sink the intake valve and you WIll loose a bunch of flow.
6) Do not use RA4 type tuliped intake valves!

[Keith Seymore]

Originally Posted by Jerry H.

Bayside, welcome to PY. I saw your post over on the HAMB. You've come to the right place. You won't get anyone flaming you over here.

What's going on over at HAMB? Are they getting flame happy?

This is the second time in two days someone mentioned getting "reamed out" over there (the other one was Deadhead, I think, on his control arm mods).

[bayside_norm]

Originally Posted by Jerry H.

Bayside, welcome to PY. I saw your post over on the HAMB. You've come to the right place. You won't get anyone flaming you over here.

thanks Jerry! Actually the guys at H.A.M.B. were pretty cool about it, absolutely no harm done. (I should have said it was a '65 Goat... !!)

[bayside_norm]

Originally Posted by steve25

The 670s chambers can be inlarged by 5 to 8 CCs (depending on how much you need) changing them in to a simi open chamber in about 3 hours, I have done it many times and have made up templates for a 5,6 and 8 CC inlargement.
The straight wall of the intake runners are a good amount straighter than any of the latter D-ports, as such with just bowl porting and going up a tad into the window area, 240 CFM@28" can be had in less work time than the other D-ports.
All so on the exhaust side of the 670s their is no casting nub on the crown of the short turn like all othe D-ports that upsets the out bound flow.
These heads, like the latter #16s and the latter 5C castings and such with the air injection casting ledge on the out side of the head do weigh more than the other D-ports by almost 5 lbs if I recall.
In rebuilding these heads you should in the least.
1) replace all the guides with 1/2" guides, no thin .030" walled P/B sleves please!
2) all new valves.
3) Drill and tap the air injection bosses in each exh port for a allen set screw to block off all the exh ports from each other.
4) install no lead exh seats with a minor bowl blend job.
5) and in reguareds to the INTAKE valve job, do not add a 15 degree top cut, as that only uses up chamber floor meat, does not do much for the flow, and on the next valve job will really sink the intake valve and you WIll loose a bunch of flow.
6) Do not use RA4 type tuliped intake valves!

Steve, thanks a lot for that info, I'll know more about what needs to be done when the heads arrive by mule team. I didn't see any air injection bosses... was that a West Coast requirement? Not sure where these heads came from originally. I've also been advised not to waste time getting any porting done, seems these heads flow pretty good in stock form and I like the fact that there's enough meat in the chamber to let me mill them for a tight fit and still lower the compression a bit!

[bayside_norm]

Originally Posted by BVR421

Using these assumptions,

bore= 4.06
stroke= 3.75
670cc= 72
gasket= .041
deck= .020
reliefs= 7-8cc

static compression ratio about 9.7

hard too say how many valve jobs and surface cleanups a 1967 head may have had in its life, the chambers may be milled down to ???
SD Performance has a CNC program to reshape and open up the chambers for a more efficient shape as well as lowered compression.
I think mrPbody has that capability as well in his excellent machine shop
check with them on that.

Wow, thank you, that's pretty much exactly where I want to be. If I had to do some milling to get a good mating surface I might relieve a tad more. I already contacted SD about this project, and I'll be talking to some shops about maybe getting the whole block massaged... last build was in 1974, just bearings, HO cam and ring job... time to call Nunzi in Brooklyn I think!

[steve25]

All 670 heads have the air injection bosses.In stock form they flow enough with a hot cam and the motor in a high state to tune to make about 430 HP, but if you are not looking for a monster street motor I would shot to make abot 380 to 390 HP as the difference in its fuel usage with the price of gas now is alot just with that HP difference!

[bayside_norm]

Originally Posted by steve25

All 670 heads have the air injection bosses.In stock form they flow enough with a hot cam and the motor in a high state to tune to make about 430 HP, but if you are not looking for a monster street motor I would shot to make abot 380 to 390 HP as the difference in its fuel usage with the price of gas now is alot just with that HP difference!

Steven thanks... I will do that. Just to make my day, I checked out my parts shelf today and found a nice set of complete 093 heads I must have picked up in my travels. So now I really have to sit down and figure out what I want to run on the '66!