I am building my 67 Valiant project with my kids. It is intended to be a budget street and strip car.

Engine is a 76 440
Holley SD intake
Holley 750-3310
Fenderwell Headers

Engine is essentially stock. I have a MP .474 Cam that I am going to run, even though it may not be ideal. Windage tray, double roller chain etc. Nothing special other than intake, exhaust and cam.

Eventually I would like to up the compression and run better heads.

My question is, what actual HP benefits am I likely to gain by home porting the heads which are 452 castings? I have done a set or two before. Fairly good at it, but not perfect of course.

Is it worth the effort? Based on my combo, what HP increase is likely assuming I do a good job?

Thank you for your time.

I think you can pick-up 20+hp doing the pocket port thing. a good valve job with back cuts would be a plus.

On 452 heads, a proper valve job and bowl blend will easily pick up 20-25cfm.

Definitely worth it IMO.

head milling will get some compression increase; especially if you don't use a .039" head gasket. be sure to mill the intake side of the head to compensate for what you take off the block side.

Interesting question. Personally I wouldn't spend the time to tear down a set of cast iron heads and port them but time vs. money is something that everyone has to sort out for themselves. A big block A body car is nose heavy anyway so why not find a used set of aluminum heads to go on there? You might find some used Stealth heads for roughly the same cost that it would take to rebuild and port a set of cast iron heads.

Of course, if you're doing the heads as a shop class project then time vs. money doesn't really matter. In that case it is just an education project so go after it. If you need another set of 452 heads in case those get messed up they are easy to find. I have a few cores sitting in my shop that I'll never use and I'm sure others do as well.

I don't think it would be worth the effort for the results with the current set up of cam/carb. I would drop that carb and go for a DP Holley, that alone will give you better results with virtually no effort. Ported heads are the way to make hp but you need enough cam/carb/comp to take advantage of the better breathing, none of which you have currently in my opinion.

Take a look at what the 68 & 69 BB darts are doing in stock eliminator. A cast iron head that has some tricks but very close to stock. A relatively stock profile camshaft(ramp and duration are adjustable) that puts these cars into mid 10's. That head and motor are working with lift below .500. As mentioned, a Stealth head with a cam under .525 and the right converter and gear will bring you down to 11.0 and easily into the 10's. Nothing exotic, just parts working together.

Lol...fast stocker heads are nowhere close to stock, other than the valve size. Stocker cams are wild duration and overlap profiles. Roller cam profiles with stock lift basically. Plus, $2500 carbs, $6000 transmissions all equate the the 1 second under ETS.

That said to not mislead the OP, your closing comments are spot on. A 440 that seals well and the right cam/converter/gear should get in the 10’s if it hooks with entry level aluminum heads.

Do you have an idea on chamber volume? Hopefully less than 90 cc.

I was thinking the same thing. Friend of mine has $8k in a set of "stock" iron Pontiac 400 heads for an NHRA class car.

A-stock low use 452 head, oe valve job and valve
B-valve job, back cut, blend bowl, open pinch

Lift———A/B
.100—— 61.4/69.6
.200——123.6/148.8
.300——184.8/207.8
.400——205.7/235.0
.500——222.5/258.8

I don’t see why you’d need a big cam to take advantage of that.



I sure hope those are SS heads!!

I've got a 9.5 - 1 cr 440 with 452 heads, 214/182 valves pocket ported and port matched. Motor has motor 557 mec. cam , it dynos at 520hp and 545 ftlb torque.
He's going to need to cut the heads down to 80cc and use a steel gasket.

SS/GT to be exact. Factored as a 1974 model Pontiac 400, 8.5:1 compression, "stock" heads, q-jet carb, etc. Ran 10.20s in a 3rd gen Camaro. Rules say no porting though. I know YOU know Dwayne, I was just pointing out how much goes into a pair of heads that are supposed to be "stock".

SS heads are allowed to have a lot of work done to them......... so they’re expensive if you want “good” ones that flow well and will pass tech.
Porting has been allowed in SS for many years now.

Ok, I stand corrected. I was under the impression they could not be ported and were severely limited to what could and could not be done. This was 15 years ago also, not sure if they've changed rules now or not.
I do know he took them to another shop to be freshened up and they cut the combustion chamber to unshroud the valves...which rendered them illegal and are now doorstops.

Chamber mods are also allowed now.

As mentioned earlier, if its an educational journey, than go for it, and if your hand is as steady as Dr Dwaynes (fast68plymouth), than there is definitely good hp to be had with port work. Personally, I would go the route of finding a set of already worked heads, preferably a closed chamber and aluminum if within the budget, because your compression is going to be really low (like 8-1 at best) with the 90cc 452. Or consider having them milled, and definitely use a shim gasket to help bump up the compression.

Tell you what
In the spirit of the season. If you can provide me with simple proof that this is a true vocational project where some kids might learn something. Brand new Sidewinders with valves delivered to your doorstep for 650.
I will discuss the bits to assemble them with your kids if you want/
Todd

WOW !!! AWESOME !!!!!

Mr. Marsh steps up to the plate!