[racerboy]

I’m about to pull to pull the original WS 400 out of my ‘70 TA because it pings pretty bad on 93 octane. Engine has less than 6000 miles on it, but previous rebuild used the 8-eyebrow stock pistons. It has the original #12 heads. Everything else is original to motor (except alternator - different thread.

I’m trying to decide my best choice for an engine build, and I would really like yo run a stroker assembly. Here are my options, as I see them.

1. Simply get a stroker kit for my RA III engine. I’m not sure what kind of dish I would need to run the #12 heads, but this option is appealing to me because it keeps the car numbers-matching. One potential downside is that I think I would never feel 100% comfortable with beating on it too much because I’d be concerned about damaging the original 4-bolt WS block. Is that concern unreasonable?

If I pull the original engine out and tuck it away, then I have two other options:

2. I have a complete 1971 400 w/ #96 heads. I don’t know the history of this engine, but assuming everything passes magnaflux, I would build a stroker using this block. For originality, I’d prefer to have my #12 heads ported and run them on this block, unless running the #96 heads (which would need a complete rebuild) makes more sense on a stroker due to larger cc.

3. I also have access to a 1972 455 bare block. This block is already fluxed and bored .030 over. It is ready to be built. I don’t have any concerns other than reading some opinions they a stroker based on 3.00 inch mains might be a bit safer than using a 3.25 main block.

Plan is to run a SD Performance ‘Stump Puller’ hydraulic roller. I would also have Dave CNC machine a cast-iron intake. Car is a 4-speed (M-21) with a 3.73 12-bolt posi.

Other options I might consider (if I didn’t just build a stroker out of the original motor) would be to run a set of KRE d-ports they were ported by SD Performance. Biggest issue with this is that it’s not really clear when those heads might be available. Dave is still catching up on past work due to the flooding in his shop.

Asking for opinions here and also want to know if I could run #12 heads on a stroker or would the dish need to be so large they it would kill the quench area. Also, is a 400 that much safer to stroke than a 455, or is either equally fine. If I did go the SD Perf. aluminum head route, would a Street Dominator/Tomahawk intake be a better choice. This is going in a Trans Am so the aftermarket intake choices are limited due to the shaker.


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[25stevem]

The 96 heads on that 72 block sounds like the way I would start out!

Build that block nice and strong with most of the funds you have now and then down the road plop aftermarket heads on the motor.

In a buddy's car a bunch of years ago for two complete race seasons we ran a 72 455 two bolt main block in the high 10s in the 1/4 and when we pulled it down it was perfect and we would have had no issue with running it another two full race seasons!

For a street motor don't go nut's over running a 3" main Crank over the 3.250"!

[Mike Davis]

Nothing wrong with the 3.25 mains blocks. That is all I have ever run, and I run them hard shifting a 7200-7400 RPM. Just make sure the oil clearances are good. For a mostly street/ some strip car I would run a factory 103N Crank as well with a good set of forged rods. 96 heads with a Flat top will give you around 9.5 compression.

[racerboy]

Thanks guys. I was going to ask if I could run flat-top pistons with the 455/96 combo, or if I would need a dish. Sounds like flat-top would be the way to go.

The block is already machined at .030 over, but it has no crank/rods. I was thinking of just ordering a rotating assembly (Butler?) for the build. I’m assuming there’s no need to go with a stroker crank if I use the 455, and a cast crank should be fine, right? No need for a forged one? Definitely going with forged rods and pistons.

As far as the heads, would you just do a stock rebuild? I don’t know if any Pontiac specialists in NJ to do any porting anyway. Gessler (famous for Buicks) did the 670 heads on my 67 400 HO, but he’s retired now. I’d send them out if needed, but honestly, if I was going to run the 96 heads (not the 12s) then it would only be until I could get a set of KRE heads set up by Dave @SDPerformance, do don’t want to put too much $$ into the 96s.


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[HoneyHush]

What power level are you planning on? And what kind of exhaust etc are you running? I have a brother that has been running a stock block 2 bolt 455 and cast crank with a turbo for years with no issues so far.

[Jay S]

DSS has a 28 cc dish option, other brands have large dish options also. No reason you can’t use the 12s.

[25stevem]

True, he can build with the 12s and the dish Pistons, but that then locks him into a 72 CC head when / if he goes aftermarket.

[HoneyHush]

What would be the problem with a 72cc head? As you know the short turn is better and they flow like 12-15cfm better out of the box don’t they? As in an Edelbrock example. That would be a possible 20-25 free horsepower over an 87cc

[PunchT37]

I`m with Steve and Mike. 455 block. Save the RA3 400. Is the `71 400 a matching code for the 96 heads? I might be inclined to save that assy too for a non big car 400.

The 455 saves money on a stroker because it already is. If the 96 heads don`t belong on that `71 400, use em on the 455.

[PunchT37]

Originally Posted by Mike Davis

Nothing wrong with the 3.25 mains blocks. That is all I have ever run, and I run them hard shifting a 7200-7400 RPM. Just make sure the oil clearances are good. For a mostly street/ some strip car I would run a factory 103N Crank as well with a good set of forged rods. 96 heads with a Flat top will give you around 9.5 compression.

Funny how most lust over a 421 or 428 block but, the 455, not so much.

[jhein]

The problem you have is too many good options. Any of the combos you have would be good. With that cam it's gonna put you in the 500 hp range depending on heads, porting etc.

I was/am in a similar situation, use my current '70 WS block or something else, and 12 heads vs something else. I decided not to use the WS block but only because it's already 60 over and it's never been sonic tested. I decided against the 12 heads due to losing compression with dish pistons, need for porting etc. For my needs, the stock E heads will flow plenty good and I get a little higher compression and better chambers.

What is the bore on your WS block? If that block is GTG, I'd probably use it. You get 4 bolt mains., which most people say you don't need but why not have the extra strength?

BTW, are you gonna use 1.5 or 1.65 rockers?

As for the crank, it's kinda like the 4 bolt mains. Almost everyone told me I didn't need a forged crank for my build, but since it was within my budget, I did it.

So, I think the Aluminum heads and forged rotating assembly are the way to go but it is the most expensive setup. But, you could use the iron heads and a cast crank and still have a fantastic motor and enough money to get a TKX, which would be an awesome combo with your 3.73 rear.

Like I said, too many good options.

[wbnapier]

I have a 455, with #48 heads that have 70cc chambers. My piston dish is 35.8cc to get approximately 9.25:1cr for California 91.

I have the SD Performance Stump Puller. No issues on 91 octane, and it has 15"+ idle vacuum for brakes.

The engine is really stout and comfortable to drive at all RPM ranges. It does everything. It will tear the tires off, my wife can drive it, and I am going to teach my 15 year old daughter to drive on it.

It's a great engine combo.

Good luck!

[Jay S]

If it was my car going back with the original engine would be the only option. I’d consider a temporary engine while the original was being built if it was projected to take too long, but that is the only exception for me. I’d do the stroker in the original engine with the 12 heads or fix the issue with the original engine, get rid of the 8vr pistons, and put a proper cam in it.

I know people mean well taking out the original engine to save it. I use to think that was the thing too do also, then I watched what happened to my friends RA 4 car. A while back that friend bought a running 70 GTO RA IV four speed car with non original d port 400. By complete chance, nearly 2 years later he found and bought the original RA4 engine. Shortly later he got married and sold off some of his cars. The guy that bought that RA4 car turned around sold the numbers matching RAIV engine to one person and the car to another. The original engine got separated from the car again. That did not set well with my friend or me, but obviously there was nothing we could do, they guy claimed it made more money do it that way. I think it is well intentioned to try saving the engine, but in reality it doesn’t always go down like we think it will. Just my 2 cents. I know it is just my opinion, and respect the other views on that topic. I haven’t seen many original engines go back in cars after they are pulled and swapped.

[tom s]

If you decide to do the 455 drop me a PM,have a friend with a set of 40 over brand new forged pistons for pretty cheap.Tom

[64gp4spd]

Racerboy, Reach out to Larry Hanson at Hanson Racing in Middlesex NJ 732-748-9770
He has been building Pontiacs for over 40 years.
Built a few different engines for me. He speaks Pontiac.
Tell him I, Rich Smith said to call him.

[racerboy]

Appreciate all the feedback. I’m pretty sure the 400/96 combo is all original from intake to pan (no carb). It is being given to me as payment for something. To be honest, I never thought that that combo meant anything to anyone, but I guess it might be worth something to someone looking for a complete motor.

I haven’t actually seen the 455 block yet, was only told it was available by the shop that has always done any machine work for me.

I guess I was a bit nervous about stroking the WS block, but that nervousness doesn’t come from anything concrete. Just a ‘what if’ moment regarding blowing the original engine.

Funny thinks is I have a built 428 sitting in my garage right now. I went through this same situation back in 2000 with the 400 HO in my ‘67 GTO. Like the TA, that car is all-original, number matching, but it had a real bad rear main seal leak. I pulled that engine to go through it, but instead I stick it under the bench and ran a 428 w/ 670 heads so that it looked like the original. In 2011, I sent the car for a full frame-off resto down to Steve (4004spd here) and finally rebuilt that engine (another WS block lol). I didn’t stroke it, but did go w/ a SP-like hydraulic roller cam. As I mentioned, Gessler had done the original 670 heads for me back in 2004 or so. That engine is back in the car, and the 428 sits on a stand.

Someone asked about exhaust. I am planning on running the RA manifolds no matter what engine combo I build.


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[racerboy]

Originally Posted by Jay S

DSS has a 28 cc dish option, other brands have large dish options also. No reason you can’t use the 12s.

I’m a complete novice, but I thought I read somewhere that too big a dish did more harm than good because it killed the quench. Did I misread that, or are they just better at matching the dish to the combustion chamber these days?


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[racerboy]

Originally Posted by 64gp4spd

Racerboy, Reach out to Larry Hanson at Hanson Racing in Middlesex NJ 732-748-9770
He has been building Pontiacs for over 40 years.
Built a few different engines for me. He speaks Pontiac.
Tell him I, Rich Smith said to call him.

Thanks Rich! Good to know there is a Pontiac guy in the ‘area’ (about 1.5 hr south of me)


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[racerboy]

Originally Posted by wbnapier

I have a 455, with #48 heads that have 70cc chambers. My piston dish is 35.8cc to get approximately 9.25:1cr for California 91.

I have the SD Performance Stump Puller. No issues on 91 octane, and it has 15"+ idle vacuum for brakes.

The engine is really stout and comfortable to drive at all RPM ranges. It does everything. It will tear the tires off, my wife can drive it, and I am going to teach my 15 year old daughter to drive on it.

It's a great engine combo.

Good luck!

This is good info. Did you have your 48 heads ported in any way? My 12 heads are bone stock. They did get a valve job when the engine was rebuilt back in 2009, but that rebuild was 100% bone-stock rebuild, other than hardened seats (I have to check paperwork previous owner supplied). It was also not done by a Pontiac specialist, unless Los Gatos is a well-respected Pontiac builder on west coast.

BTW - I’m not a superstitious guy or into numerology, but you were the #12 post in this thread. Is that the universe telling me to run the 12 heads? Hmmm…. lol


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[77 TRASHCAN]

What cam in in your 400 now??? 6000 miles is not many...even with those crazy pistons, you might have a chance to make it drive worthy...