[ponyakr]

This thread is for anything connected to using a Pontiac 350 block, with a 4" or larger stroke crank.

It can include recipes & ideas for all types of 350 stroker builds, be it low budget performance, street/strip, or race only. Can include anything about the block & block machining, cranks, rods, pistons, cams, heads & anything else that goes inside or bolts to the outside of a Pontiac 350 STROKER.

Might need the help & expertise of some of you machinist/engine builders with this subject, since there doesn't seem to be a lot of readily available info. The only article I'm aware of is about the Ace Brewer 383 build. He had 350 stroker parts available. But he's no longer in business. So, the only stroker assemblies I am aware of is what Butler offers, with the high dollar Ross pistons.

So, lets try to come up with all the possible 350 stroker ideas we can, in order to save some of those 350 blocks.

http://www.hotrod.com/articles/hppp-...-engine-build/

[694.1]

Would there be any advantage to a stroked 350? I am thinking high piston speeds in proportion to the bore & difficulty filling the cylinders with A/F.
Studes used long strokes which is great for torque but hard on fast moving parts.

[ho428]

The simplest scenario I came up with was to just punch it .060 over for a 365. Made for a pretty screaming little injun with some 2.06 int and 1.66 exh valve 295 cfm KRE D port heads on it, a T2 intake and Holly 750. Made 400 hp on pump gas, probably more in it with some tweaking.
Ended up busting the ring land on a cast piston after a few seasons of racing, but any 350 forging will be custom.

I'd like to try a 4" bore with a 3" stroke in a 350 block. Same as a 302 chevy but with a longer rod. The custom billet crank cost is the killer.

[72LuxuryLeMansLa.]

Originally Posted by 694.1

Would there be any advantage to a stroked 350? I am thinking high piston speeds in proportion to the bore & difficulty filling the cylinders with A/F.
Studes used long strokes which is great for torque but hard on fast moving parts.

Read this and ask yourself if there is an advantage.......

http://www.hotrod.com/articles/hppp-...-engine-build/

[1968GTO421]

^^ That's a great article. The engine uses only a 4" stroke same as a 421/428. Much less stroke than the 4.210 of the 4555/462 that are very popular. The heads have big valves than the majority of aftermarket heads sitting on a 383 Chevy SBC and there is the longer rod of the Pontiac for less cylinder side loadng. If my 429 blows like Paul's (GTOFREEK) 428 did, this stroker 383 Pontiac has a lot going for it, especially w/ low cost blocks.
http://butlerperformance.com/c-12348...413-cu-in.html

[ponyakr]

Originally Posted by 694.1

Would there be any advantage to a stroked 350? I am thinking high piston speeds in proportion to the bore & difficulty filling the cylinders with A/F.
Studes used long strokes which is great for torque but hard on fast moving parts.

" Read this and ask yourself if there is an advantage......."

Yep, a stroked 350 has a few advantages over a stock stroke 350,

Here are a few I can think of:

(1) More torque.

(2) Easier to make more hp @ a lower rpm.

(3) It will have lighter pistons & stronger rods. So, it'll rev much quicker, and will probably be safe to at least 7500 rpm, with a forged crank, should anybody wanna build one with enuff top end flow & cam.

(4) 500 + hp & 500ft lbs of torque is possible.

(5) And, as many others have said, the 350 blocks are either real cheap or free. So, that makes the cost of a 350 stroker in the same ball park as a stock stroke 400, with equal quality parts. Also, about the same as a 400 block stroker. For those who feel they need both hp & torque numbers in the 600's, the 350 stroker is not for them. But, for those who can live with less, the 350 stroker is a viable option.

Check out the numbers on that Ace Brewer 383 again. You can see upgrades that would put it up near that 500hp mark. . High compression alum heads, are the 1st thing that pop into my mind.

Or, if you're on a smaller budget, and/or don't need 500hp, there are all sorts of iron head/intake & HFT cam options. So, you can still make up near 400hp, with a very streetable and pump gas safe 350 stroker. That's more power than most of the average Musclecars had, back in the day. And it should be slightly easier on rear tires, than the 455 + engines are.

[TCSGTO]

Originally Posted by 72LuxuryLeMansLa.

Read this and ask yourself if there is an advantage.......

http://www.hotrod.com/articles/hppp-...-engine-build/

Did anyone ever notice on that build how it gained 50HP from 5900 to 6100 RPM and made 30 some numbers less on peak torque. Pretty unusual for an undersquare motor. It looks more like a true 430 ft/lb 430 hp. Still stout though for a sub 400" motor though.

[ponyakr]

I don't have a clue how accurate the dyno was. But I bought an older built '69 Tempest X-Stocker 350HO. The dyno sheet read 434hp. That was with legal #48 heads, factory crank, cast rods, TRW l2339f.030 pistons, iron intake & 750 Q-jet. And it didn't have one of the super radical Stocker cams like they run nowadays.

So, to me, it's easily believable that a lite piston 383 with a roller cam could make 450 + hp.

[694.1]

"The dyno sheet read 434hp."
With little more than a cam this motor was pulling 70+ HP over a stock 400? I would LOVE to hear more. What cam? Was the Dyno sheet from anybody reputable?
Don't take this the wrong way, I would love that guy to build my next engine!

[ponyakr]

"...I would love that guy to build my next engine! "

I'm not sure, but I think a local guy probably did the machine work. He did most of the Pontiac stuff in our area. He now works in the engine department at Joe Gibbs Racing.

https://www.facebook.com/ernie.holde...ef=friends.all


The car was built by a family of long time class racers, who lived in Ruston, Lousiana. Their last name is Cardwell. If you look at the control panel, in the last pic below, you can make out the words Cardwell Motorsports. A Pontiac friend helped them find the body. They had quite a few competitive Chevy class cars.

Ronnie Cardwell was still driving a competitive Chevy powered '90 Bird Stocker, as of 2003. I talked to Doug a few months back. He said they have been out of racing for several years now.

http://sportsman.nhra.com/2003/sport...BelleRose.html

Not real sure why they built this Pontiac powered car. They just happened to pick a combo that was not competitive, with the NHRA hp factors, that were in place. It ran mid 12's, so they didn't even try to wring any more out of it.

They sold it to a bracket racer, & I bought it from him. Was gonna run it at our local 1/8 mile track, but our track didn't open that year, so I sold the heads, & the roller. Some Pontiac friends are rebuilding it as a street/strip car. The owner is gonna let me use it as long as I want to. They'll haul it to the track for me occasionally, IF our local track opens this year. The owners are having a management dispute.

[gtofreek]

Probe pistons were garbage, so it's just as well they went out of business.

A couple years ago, I had CP talked into making a nice Forged stroker piston with a great set of rings for the 350. I just needed to get 5 orders. Couldn't get one person to commit to a set, so that deal went away. For a set of forged pistons, with Steel gas nitride rings, for $675, IIRC. They also had a super stout piston pin.

[ponyakr]

Depends on who you ask. Ace thought they were OK. I didn't know Ace, & have no idea if the Probe pistons were any good or not.

Here's a thread Ace did on a 383 build. He also talks about 350 head gaskets, which are no longer available. I assume the Cometic 350 gaskets, with cut-outs for the cylinder chamfers, are the best 350 gaskets available today. If anybody knows different, please post your info.

Anyhow, thought some might enjoy this thread.

http://www.pontiaczone.com/forum/showthread.php?t=15973


"...Couldn't get one person to commit to a set, so that deal went away..."

Yeah, I can think of a lot of Pontiac parts that are no longer available. But, for this thread, we need to come up with parts that ARE available. So, what is your selling price for 350 stroker pistons NOW ?

Are those you can order any better or cheaper than the Auto-Tec modified shelf pistons ? Do you consider Auto-Tec pistons "garbage" ? Or are they at least slightly better than the Probes ? Any experience with them ?

[gtofreek]

Ace didn't machine engines. I have seen several sets of Probe pistons, and seen as much as .002" difference in size in 1 set of pistons. These are the only pistons in the last 15 years that I had to bore 8 different sized holes to keep piston to wall clearance the same. The skirts, and head thickness is very thin, etc., etc. They looked nice at a glance, but when you really start looking them over, they are not that good.

Autotec are good pistons but lack a couple design features that are nice to have, like positive oiled piston pins, rather than splash oiled. The CP pistons that we we trying to get done, had all the cool features that you would normally pay $800 or more for a custom set of them. That's just for pistons too. These we could sell the pistons with a set of rings that had a steel gas nitride top ring that would be good for N/A, boosted, nitrous applications, for under $700. Autotec with rings cost a more than that, and is not as nice of a piston. I could probably still get that deal going again if there was more interest in it. We only need to get an order for 5 sets, and they will give us that deal.

[Transporter]

Just curious, are all 350 blocks pretty much the same or is there a "557" version of the 350 to be avoided? Also, of course it would take a sonic test to know for each block, but in general could a 350 go .100 over?

Just asking.

[ponyakr]

"...under $700. Autotec with rings cost a more than that..."


I am in no way trying to start an argument. And I obviously don't have anywhere close to your level of knowledge or experience.

I'm just passing on info I was given. Here's a copy of the Auto-Tec price I was given, I suppose it's been about 2 years ago, now.

" Shelf part pistons with a bore 3.905, and compression height change with wire locks (easier, better, cheaper), and pins are 445.00. Hastings ductile plasma moly 3.908 bore (not much filing) ductile plasma moly rings in 1.5,1.5, and 3MM are 104.98. Shipping for pistons and rings is 33.00. These prices are for a check. Debit cards cost 1.6%, PayPal costs 2.6, and credit cards cost 3%. We could have the pistons made for cast moly 5/64, 5/64, 3/16 OEM type rings for 64.07 and you would not need to file the gaps. If you can verify a price a dollar less, we can make it 2 dollars less. 507 445 3235 Thanks Shanon "

I assume the price would be slightly higher now. Haven't inquired. I remember reading, here on PY, that somebody bought a set of Auto-Tec pistons for around $500 shipped. Don't remember what size engine they were for.

This guy advertises the larger bore Auto-Tec Pontiac pistons for $485.30 + shipping.

https://shanonsengineering.com/colle...at-top-pistons

And they'll move the pin location for free. I'm not advertising for this guy. It's just the only Auto-Tec prices I know of. If somebody knows of better prices, or a Pontiac vendor with similar prices, by all means, please post your info. Auto-Tec gave me this guys name, back when I inquired about the 350 pistons. They said I could get a much better price, buying from one of their dealers. I suppose they gave me that guys name because he is a high volume Auto-Tec dealer.

This thread is meant to provide info for building a Pontiac 350 stroker. For those with plenty of $$ to spend, just go with a Butler Ross piston assembly. For those who wanna save a few bucks, the Auto-Tec pistons are one option. The cranks & rods can be bought from a lot of places.

[ponyakr]

Originally Posted by Transporter

Just curious, are all 350 blocks pretty much the same or is there a "557" version of the 350 to be avoided? Also, of course it would take a sonic test to know for each block, but in general could a 350 go .100 over?

Just asking.

Not likely you'll find a 350 that'll safely go .100 over. But, that brings up a question. I know a guy who had a 350 with 8 sleeves, I think it was supposed to be used for a dirt track build, or a high perf build of some kind. My dummy question is: Would using sleeves allow you to run a larger bore size ?

Somebody on this site once said that he thought the 500810 blocks had the thin main webs, like the 557 blocks had. I've asked several times, here, and on other sites. But I haven't been able to find anybody who can come up with any close-up pics of one of these blocks, which proves it, one way or the other. That might be cause those blocks are extremely rare.

The Wallace site says they were only used in late '76.

http://www.wallaceracing.com/enginesearch4.htm

Makes more sense to think they were used in late '76 & in the '77 models, til they were all used.

Other sites say they came in late '75.

http://www.teufert.net/pontiac/bloccast.htm

Also, it's been confirmed by many that some 350 blocks, especially in the earlier years, had cylinder chamfers on both sides, for the intake & exhaust valves. But, most of the later blocks had chamfers on only one side. Only way to know for sure is to check it out. It has been said that it is not a big problem to add the chamfers, by somebody who knows what they're doing.

And, the '68-'69 350 blocks will have only 2 motor mount bolt holes on each side. Beginning with the '70 models, I assume they all have 5 holes on each side.

Here are the only 2 pics I have found which are supposedly 500810 blocks. Can't tell if they have all 5 motor mount holes or not, And can't tell about the main webs either. Maybe some of you guys can blow these pics up so we can tell more about the blocks.

[gtofreek]

I'm here to tell you that we pay a lot more than $445 for a set of Autotec pistons, A lot more. The only way I can see someone getting them for that cheap is if they bought a whole bunch of sets at once. There are a lot of internet whores that sell stuff to only make a few bucks off of each part, and make their money in volume. I bet those pistons can't be had for that price anymore. When Autotec first started, they were offering a lot of deals to get going, and get their name out there. Then we saw they had a big jump in pricing. Don't get me wrong, they are still reasonably priced for a custom forged piston. It's just that with the CP pistons I spoke of, we can sell them with rings for less money than we could sell the Autotecs without rings.

Originally Posted by ponyakr

"...under $700. Autotec with rings cost a more than that..."


I am in no way trying to start an argument. And I obviously don't have anywhere close to your level of knowledge or experience.

I'm just passing on info I was given. Here's a copy of the Auto-Tec price I was given, I suppose it's been about 2 years ago, now.

" Shelf part pistons with a bore 3.905, and compression height change with wire locks (easier, better, cheaper), and pins are 445.00. Hastings ductile plasma moly 3.908 bore (not much filing) ductile plasma moly rings in 1.5,1.5, and 3MM are 104.98. Shipping for pistons and rings is 33.00. These prices are for a check. Debit cards cost 1.6%, PayPal costs 2.6, and credit cards cost 3%. We could have the pistons made for cast moly 5/64, 5/64, 3/16 OEM type rings for 64.07 and you would not need to file the gaps. If you can verify a price a dollar less, we can make it 2 dollars less. 507 445 3235 Thanks Shanon "

I assume the price would be slightly higher now. Haven't inquired. I remember reading, here on PY, that somebody bought a set of Auto-Tec pistons for around $500 shipped. Don't remember what size engine they were for.

This guy advertises the larger bore Auto-Tec Pontiac pistons for $485.30 + shipping.

https://shanonsengineering.com/colle...at-top-pistons

And they'll move the pin location for free. I'm not advertising for this guy. It's just the only Auto-Tec prices I know of. If somebody knows of better prices, or a Pontiac vendor with similar prices, by all means, please post your info. Auto-Tec gave me this guys name, back when I inquired about the 350 pistons. They said I could get a much better price, buying from one of their dealers. I suppose they gave me that guys name because he is a high volume Auto-Tec dealer.

This thread is meant to provide info for building a Pontiac 350 stroker. For those with plenty of $$ to spend, just go with a Butler Ross piston assembly. For those who wanna save a few bucks, the Auto-Tec pistons are one option. The cranks & rods can be bought from a lot of places.

[A.W.Dille]

I've been following this post for a couple of days now. I have a 72 350 block in the garage that I ran in my Grand Prix for 5 years. Been contemplating the stroker build myself. But mine would be primarily used for racing only with very limited street use. Butler seems to be the only company listing the parts for that particular build that I've found so far. The 388 would fall into the perimeter of what I would like for a nostalgia build for a 63-65 Tempest., if I can find one I could afford.
Since aluminum heads would exceed the budget some, I'd likely use some heads I have on the shelf. I think it would be a fun engine with plenty of torque and good rev-ability..
But I could be wrong, I have been before.

[HWYSTR455]

Originally Posted by gtofreek

... These are the only pistons in the last 15 years that I had to bore 8 different sized holes to keep piston to wall clearance the same. ...

The pistons in the Olds 350 I built are Probe, and they are junk. I did have variance in the piston/wall clearance, but the killer for me was the pin bosses, they varied too, and I think that was from the factory, there was no sign of abuse, overheating, etc after very low run time (EDIT: and they were sloppy).

The last machine shop did the best they can, but they make noise when running, and it drives me nuts. It's just time I build a 455 for that thing.

I need to go back and look, but in the 80s, I built a 350P, and pretty sure I went like .090 or .100 over with it.

.

[ponyakr]

Hey Paul, since you can buy the CP pistons cheaper, please inquire about the NHRA legal 350 Stocker pistons, they sell. They have the wider ring grooves & stock pin location, but might be a good stock stroke piston, IF the price is decent.

The NHRA specs show 2 different part numbers for 'em: P2-CP & P6CP

http://www.classracerinfo.com/Engine...3&MAKE=Pontiac

These pistons have no valve reliefs, but will work with some small cam builds. And reliefs can be cut. But, price might be ridiculous.

I also priced some Venolia 350 pistons, back when I got the Auto-Tec price. Their price was $74 each, without rings, + shipping. That's better than Ross, but not cheap, for anybody who just needs a good forged piston, for a decent street build. Seems I remember that Ken Keefer had a decent price on BRC pistons back when he was in business.

It appears to me that any of the piston makers could just use a 5.7 LS or 318 Mopar blank(or whatever you call an unmachined piston), and machine it to 350 Pontiac specs, for a reasonable price. But, maybe there's not enuff profit for them, doing it that way. I have no idea.