[gavin]

First of all before I get told there are better heads this what the guy wants to use. I am presently trying to modify a pair of 1960 heads. I have sourced new valves at standard size. These are about 5.25” so I could not adapt sbc valves of a bigger size. I was looking at using crowder 26906 sbc springs but these have a 1.8” height and I’m not sure if the deck is thick enough to go the extra .260” depth. Any suggestions on a better spring? We want to use a cam with some lift. Second I want to use spotts rocker stud kit so has anyone used them on 60 or earlier heads? And third rocker arms . Do the 61-66 rockers work on these heads? Many conflicting opinions so who has actually done it? I am going to port them a little the intake is not that bad just under 64 ho heads. Exhaust is horrible. Any and all advice taken on board. I will post my results when finished so the next poor sod knows what’s needed. Thanks.

[b-man]

Thread copied to ‘60 & Older Pontiac Tech forum for more exposure.

[gavin]

Thank you b- man much appreciated.

[25stevem]

Gavin next week I will be getting a set of 1962 heads to port up from a fellow, I will post up info and we can port along/ by number if you will, lol!

Yes, the Exh side flow wise on these heads suck and I believe is that main reason that Pontiac got a rep early on for poor Exh flow.
With the change in 67 to the 14 degree valve inclination angle things got much better!

So you have checked and the installed height with these 5.250" valves will need to be 1.800" for sure?

I see a potential problem in terms of running the stock height valve covers once the needed rockers are on the motor with this installed height.

Also in terms of the rockers once your using the correct lenght push Rods for a 1.800" installed height, I don't think the stock rockers would work right for the motor anyway!

I think roller rockers will be needed.

Also it's best that you convert the motor to oil thru the push Rods and tap those old oil feed holes in each head deck to block them off with a recessed Allen pipe plug.

[tom s]

I assume you will be doing screwin studs,if so you dont need to plug anything.Tom

[MarkS57]

Originally Posted by 25stevem

Gavin next week I will be getting a set of 1962 heads to port up from a fellow, I will post up info and we can port along/ by number if you will, lol!

Look forward to the 1962 head results. 1st engine I rebuilt, always wondered what could be done with them.

[25stevem]

Years ago I took a set of 77 castings fitted with a 1.96" valve and a chamber shape akin to a 670 casting up to 250 cfm from a stock 183.
When I get these next week I am guessing 230 cfm can be done, we'll see!

[tom s]

Steve,years ago when I built the factory experiment all alu Pontiac engine it was a 1958 castings but had 1960 pattern heads.1.88 intake and 1.60 exhaust.Dave at SD did some port work and screwin studs on them.They floed 220 on the intake at 500 lift.We used a 2801 cam with a set of Comp 1.5 roller tip rockers,also used a set of factory NOS 1956 HFT lifters.Because we had to sleeve the block we ended up with 366 CI.The engine made like 318 HP with a single 4 AFB.10-1 CR.Tom

[25stevem]

Thanks for the info Tom!

[peters23]

I am currently rebuilding a set of 1960 heads, but note that I am not an expert, learning as I go.
Stock valve spring installed height is 1.530 on these, so not much room for tall springs.
I happened to acquire some NORS springs and am planning on going with stock lift cam (probable 066).
If you use +0.050 keepers and 1.600 high springs (like Crower 68404 or Comp Cams 988) then you only need to deepen the spring pockets by 0.020 or so which should be fine.
There is a water jacket below the springs, but I don't know how thick the casting is there (probably close to .25", maybe less).
You will need to cut down the valve guide tops, especially if you want to run seals.
I was able to machine stock sized valves from 2012 BBC exhaust valves, and you could probably make oversize valves too, although not much room in the bathtubs.
I am also looking at expanding the bathtubs out a bit on the non-quench side to decrease the CR, curious as to how much meat there is in that area...

The SBC rockers seem like a close fit on these heads, and I am going that route, with screw in adjustable studs.

[25stevem]

In terms of chamber wall thickness without cutting or drilling a mule head to confirm I guide yourself with what the average port wall thickness is which is .180”

With this in mind removing .050” is safe.

Here’s what I can offer up picture wise from board member.
This is the exh port and chamber of a 6X head.
Chamber thickness looks to be pretty good and maybe the earlier heads have even more since those where times before the factory became stingy with cast iron.

[gavin]

Thanks for the interest guys the 1960 and earlier heads present a few challenges. Peters23 I would really appreciate if you would put up your progress on these heads. I will be using stock size valves as we have a new set. I was wondering about rockers and would appreciate seeing how yours work out. Tom s were they chev rockers and did you leave the bigger studs on the same centres ? 25stevem I will enjoy following your work I have a flow bench ( home made) so I will try and copy your results although with smaller valve I won’t quite as successful. With all this info I am feeling more confident. Thanks.

[peters23]

I bought a single Howard Cams 90007 long slot SBC rocker arm and did a rub test at the valve stem and the pattern looked pretty good near the stock height setting.
I did not check the pushrod side (really need to assemble the rest of the engine for that) but comparing side by side they look very close to the OEM rockers to me.
I expect that custom length push rods will be needed to dial things in.

To get close to stock size valves you can machine both intakes and exhaust from Ferrea F5146 BBC stainless exhaust valves, which measure 1.880 x 11/32 x 5.350. Thats what I used

EDIT: below is cross section of 1955 head from Pontiac literature, likely very similar to 1960.

[gavin]

Thank you Peter it’s what I to know.

[tom s]

Dave left the stock valves,put in screwin studs and we used Comp cams 1.50 roller tip rockers.Not sure if he used longer valves.We oiled thru the rockers.Tom

[25stevem]

For you guys who can do a check , I thought I had heard ages ago that the latter steel rockers will work once a certain amount of lift is used and the stud slot is lengthened .
The part I don’t recall is if this was with ,
1) longer valves?
2) a reduced base circle cam, maybe part of the more lift thing?
3) which way the stud slot was lengthened?

[tom s]

I have always used the 65-66 rockers in 61-64 applications that had stud oiling with no issues.I only had one time to use a pre 61 head and just used the Comp roller tips.Tom

[gavin]

I am hoping peter23s efforts will answer these questions. I know a few hotroders that would like to use the early engines but the heads put them off. Pre 60 Pontiac engines are not that uncommon and are generally cheap as no one wants to use them as the heads mods are problematic for most. The more easy mods with cheap stock style parts the better. Adapter plates that Bruce and I designed make it cheap to adapt a early engine to late trans. I stopped work on them due to lack of interest. Just need a modification to pin position on the drawing. On the subject of early blocks they are a very robust thing. I think you just need to add bigger diameter 455 studs and use the very big stock early main caps and bottom end is going to work to a high horsepower level. With with cheap adapter plates you have a very good block.

[25stevem]

Gavin, I dug out a 1961 389 #345 casting that I forgot I had.
It has the 1.88"/1.60" valve sizes so we can reference each other's porting work as it should be.
I should have this head knocked a part tonight and do a flow test tomorrow to get some base line numbers to post up.

[25stevem]

Gavin what intake manifold will be run on top of these heads ?
If it will be a factory iron one you should make up a wood plate adapter to flow test a few of the runners on the shallow plenum side that have the tightest turns in them ( most restrictive) if you can.

There’s nothing more counter productive to good drivability and increased top end power then having reworked the heads to flow more then the intake manifold can pass!