Don Terrill’s Speed-Talk

Hi Guys,

I have a mild 383 sbc in a Chevelle street car (sees the occasional run down the strip) fitted with a set of Holley heads
part # cast on the head is 34r-11877a, but I cannot find info on that part #. but pretty sure they are 184 cc runners.

I know I would be better of with some AFR 195.s, but the budget is tight currently (maybe 195's later),
so are the holley heads worthy of some mild bowl and port work, would I get reasonable gains like maybe 40hp or so or am I wasting my time.

Has run 12.5 @ 108 with mild hyd cam, (dont no specs but it is mild) 10:1 hyper pistons, airgap, T350, 2800 stall, 3.5 gears I guess the engine makes around 400 currently.
Sees mostly street use only, so not really chasing any ET goals but would like to hop it up a little to maybe 450 or so if possible,
was planning on going maybe a bit more cam, mill a little of the heads and mild porting at this stage if worthwhile

Thanks

The holley heads I have have (34R 12111B cast number) have a good port design with a
20 degree valve angle. They need work in the bowl and around the valve guide boss. The
push rod pinch is also restricted as well as the exahust ports. There is plenty of material
there do do what needs to be done. With this done these heads will work nice with what
you have. I don't know anythnig about the diffrent cast numbers, what I have maybe
diffrent from yours.

Holley heads were made by Canfield they should have a freeze plug in the front. Decent heads, were great value, not sure if they are still in production today.

Try this link: http://www.competitionproducts.com/Canf ... 65-0-B-SP/

Sorry to inform you Brodix built Holley heads. They were originally built and designed by Brodix. I was in Dave Rodders Brodix design/R&D room almost 1 year before Holley marketed them. I was looking at them and he said he was going to have to kill me if word got out about them. I have also machined 2 engines for their employees that used the heads. They were near 190 CC and could be max ported to around 205 according to one of their head porters. They are a 20 deg head.
Great street head.
If you need any further info call Brodix. Ask for Mark. I don't think they will let you talk to Dave.

Hi Guys,
Thanks for the replies, I cc'd an intake port close to 185, chamber 66 ish, and the castings I have still have exhaust crossover.

Any thoughts as to what would give the best results for minimal work by hobby porting methods.

Because If need to pay to get them done at a shop, i maybe be better of off loading them now and putting the money towards some AFR 195's.

Thanks again

You can increase the flow by doing a high flow valve job on them.
You don't have to port a head to increase flow.
No head comes from the MFG with max flow. The MFG's all expect guys like us to fine tune their creations.
It has been my experience that all MFG's play numbers games and the numbers are inflated.
Probably not inteentionally.
Take your port Vol that you cc'ed. Say the spec. is listed at 189 cc. Then why are your heads at 185? Because the spec was for the mold/core box when it was new, brand new. No heads had been poured with it. As the mold is used (heads poured) the core wears away and the port gets smaller. The MFG uses design specs. Same thing happens with flow numbers. The MFG tests a few heads when they are first produced and the ones with the highest flow numbers get recorded on the data sheet.
What I'm telling you is: you can change heads, but you don't know how much if any you have improved your situation unless you test and compare each head on the same flow bench.
You might step up flow by 10% by the listed numbers, but in the real world they may be closer than that. Putting an inproved, flow tested, valve job might be worth the 10% on the heads you already have. Why would 2 employees of Brodix pick that head for their own street trucks and cars when they have the pick of the full line of heads Brodix offer. Could they know something? YES...But.... New heads would always increase the "Brag Factor" How much it is going to cost you?
Remember, bigger volume ports flow more air, but too big and you can loose port velocity.
A street engine needs port velocity to accelerate. (example: vortec heads) Don't chase, or get caught up in the flow numbers games. There are more factors to consider when matching a head to an application/use.

Thanks for the input Adger, dont plan to get caught up in big flow numbers, I understand the value of keeping the volume and cross section correct for the aplication
thats why I was asking what mods will give the best result for minimal work/cost on these particalur castings.

I just dont what to spend too much on these heads,
when the money I could end spending on them along with what I could sell the for, would pay for a new set of CNC AFR 195's.

Sounds like some valve and bowl work along with a general tidy would be a good plan then?

Thanks again

HP fan wrote:...Any thoughts as to what would give the best results for minimal work by hobby porting methods

These heads have a realy nice port design, as cast they don't come close to their potential.

The bigest gains will come from sizing the throat and valve pocket, cutting down the huge
guide boss in the intake port and a good valve job.