#21  
Old 02-12-2020, 02:48 PM
pontiacjeff pontiacjeff is offline
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Quote:
Originally Posted by dmac View Post
Because the 350 will be drawing less air, for your purpose you may not need or want larger valves. to keep it simpler without worries about the valve notches.
Agreed

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  #22  
Old 02-12-2020, 04:31 PM
LostHighway LostHighway is offline
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Small valve heads would certainly make the job easier, but I doubt its worth the extra cost and hassle of finding/paying for them vs just notching the bore at the machine shop and using the heads that are already on the car that I know are good. I dunno... Seems fine to me.

I called RaceTek (AutoTek) and the pistons are over $700. (whatever, this is how it is right now, unfortunately)

YEAH I get the 400 would be better. Let me explain this ONE MORE time in a nice way. This car is matching numbers are CHERRY! I want the original motor in the car, painted the factory color, with the factory castings. Its "all original" right?? 380hp @ the crank will be fun.

I'm not even going to entertain the "400 swap" idea right now...

So what kind of cam do you think a 4.25 stroke 3.915 bore engine needs?

What kind of headflow do you think should be needed for cylinder filling?

  #23  
Old 02-12-2020, 05:00 PM
pontiacjeff pontiacjeff is offline
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Since you are still running the stock 75 350 and 5C heads, they are 94cc and already have the 2.11 intake valve. The block also already has a chamfer at the top of the cylinders on the intake side. The increase in stroke and displacement will only raise your compression to about 8.5:1. You are going to have to mill the heads a lot (and the intake side, too) to get 9.5:1. Using a custom piston with only 2 valve reliefs will help a little. A thin Cometic head gasket will help, too.

You can get by with a roller cam, but the lower compression will limit your duration to under 230deg. A RA3 style, 212/224-ish will work good in a 9:1 "400". A 5C head with minor bowl work and a RA4 gasket match blended into the port will give enough airflow to make good power.

I built a 8.5:1 428, stock 6x heads with no port work at all, only 1.77 ex added. Hyd roller cam, 224/224, 114lsa .500 lift, made 400hp and 428tq on 89 octane

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Last edited by pontiacjeff; 02-12-2020 at 05:14 PM. Reason: Correction
  #24  
Old 02-12-2020, 05:02 PM
grandam1979 grandam1979 is offline
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https://butlerperformance.com/i-2459...-4-250str.html

  #25  
Old 02-12-2020, 05:21 PM
Will Will is offline
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with approximately 8.7:1 compression you can run 87 octane gas, no problem. That Butler rotating assembly seems like the way to go. You can get them with domed pistons for more compression if you want to run premium.

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  #26  
Old 02-12-2020, 05:21 PM
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'grandam' you beat me to it!!
I was gong to mention the Butler kit too.

I am glad to read of more people building the P350, it's been too long overlooked for it's larger bore brethren...

Considering that a '69 350HO, which is not wild by any standards, outpowers the much more acclaimed Oldsmobile 'Ram Rod' W31 engine with less compression, and no "select fit" shortblock components, is something that has left me scratching my head for a long time...

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  #27  
Old 02-12-2020, 07:44 PM
LostHighway LostHighway is offline
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I doubt my machinist is going to buy a butler kit. He's gonna measure and get what he needs directly.

I still dont have any answers for my questions... How much cylinder head flow is needed to feed a 409 to 6000rpm?

What range of roller cam do you suggest for cylinder filling such a small bore with a long stroke? What compliments such an undersquare engine as far as camshaft selection goes?

What do you think it'll make hp wise?

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Old 02-12-2020, 08:35 PM
Steve C. Steve C. is offline
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Knowing the larger 4.5 stroke engine will be sensitive to under-flowing cylinder heads. Take it with a grain of salt but this might be of interest....

http://www.wallaceracing.com/calc-cfm-head.php



.

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  #29  
Old 02-12-2020, 08:42 PM
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Quote:
Originally Posted by Steve C. View Post
Knowing the larger 4.5 stroke engine will be sensitive to under-flowing cylinder heads. Take it with a grain of salt but this might be of interest....

http://www.wallaceracing.com/calc-cfm-head.php



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Killer TA Steve!

  #30  
Old 02-12-2020, 08:47 PM
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Quote:
Originally Posted by 'ol Pinion head View Post
Compare the performance of stock '65-67 Olds 442 400 engine to one from a '68-69 Olds 442...
I am with OPH here - I used to do Olds for a couple decades - the earlier square 400's would rip up the later very undersquare units.

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  #31  
Old 02-12-2020, 08:50 PM
Steve C. Steve C. is offline
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LostHighway.... thank you.

Minimum required airflow for performance

http://members.cisdi.com/~anesthes/projects/airflow/

Search and you will find other similar material for interest.


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http://www.hotrod.com/articles/0712p...tiac-trans-am/

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5.14 at 140 mph (1/8 mile) , true 10.5 tire, stock type suspension
https://www.youtube.com/watch?v=qDoJnIP3HgE
  #32  
Old 02-12-2020, 09:02 PM
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Quote:
Originally Posted by LostHighway View Post
I doubt my machinist is going to buy a butler kit. He's gonna measure and get what he needs directly.

I still dont have any answers for my questions... How much cylinder head flow is needed to feed a 409 to 6000rpm?

What range of roller cam do you suggest for cylinder filling such a small bore with a long stroke? What compliments such an undersquare engine as far as camshaft selection goes?

What do you think it'll make hp wise?
With all due respect to everyone here, you're asking guys for their opinion. MOST have never built an engine similar to what you want.

Paul K. posted that he recently built, not one but 2, 4.25 stroke 350's. If it were me, he's the guy I'd be trying to get info from.

http://forums.maxperformanceinc.com/...8&postcount=13

As for cyl filling, the smaller Voodoo cams are said to do that. Obviously, the smaller cam will produce more low end torque. The lager one will produce more hp, above 5000 rpm.

https://www.lunatipower.com/voodoo-r...8-262-270.html

https://www.lunatipower.com/voodoo-r...8-270-278.html

"...I called RaceTek (AutoTek) and the pistons are over $700..."

As I mentioned, the guy at Auto Tec told me that you can buy pistons cheaper from one of their hi volume dealers. Here's an actual quote from their Email.

" Don a volume dealer with good prices would be Shannon’s Engineering."

Shannon also told me that the shelf blank 350 pistons would have 3.8cc valve reliefs, just like their larger bore Pontiac pistons. He said that any valve reliefs different from this would require an extra cost, full custom piston. I suppose that's because they have computer programs for the 3.8cc Pontiac reliefs.

" They have 3.8cc valve reliefs which are deep enough for most cams except all out race. Changing the valve reliefs will turn it into a "full custom" bring the price up. "

So, since you're still in the planning stages, why not price your pistons thru Shannon's Engineering. I suppose it's possible that the pistons have gone up that much. But, since he still sells the larger bore pistons for just over $500, + shipping, I doubt the pistons you want would be $700. But, as usual, I could be wrong. Won't coast you a penny to get his price. All my contact with him was thru Email.

https://shanonsengineering.com/

Now, as mentioned, I was not asking about a fully custom piston, but rather one that can be made, using existing "shelf blanks". I think some of the other engines that can use some of these same shelf blanks are: some LS engines, 318 Mopar engines, 283 sbc engines. As always, I could be wrong.


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  #33  
Old 02-12-2020, 09:06 PM
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Quote:
Originally Posted by ponyakr View Post
With all due respect to everyone here, you're asking guys for their opinion. MOST have never built an engine similar to what you want.

Paul K. posted that he recently built, not one but 2, 4.25 stroke 350's. If it were me, he's the guy I'd be trying to get info from.

http://forums.maxperformanceinc.com/...8&postcount=13
I am indeed interested in his advise.

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Old 02-12-2020, 09:13 PM
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2X for Paul K!Tom

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Old 02-12-2020, 10:15 PM
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Paul K. also sells parts at very good prices.


.

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Old information here:
http://www.hotrod.com/articles/0712p...tiac-trans-am/

Sponsor of the world's fastest Pontiac powered Ford Fairmont (engine)
5.14 at 140 mph (1/8 mile) , true 10.5 tire, stock type suspension
https://www.youtube.com/watch?v=qDoJnIP3HgE
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Old 02-12-2020, 10:16 PM
Navy Horn 16 Navy Horn 16 is offline
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Quote:
Originally Posted by LostHighway View Post
I doubt my machinist is going to buy a butler kit. He's gonna measure and get what he needs directly.

I still dont have any answers for my questions... How much cylinder head flow is needed to feed a 409 to 6000rpm?

What range of roller cam do you suggest for cylinder filling such a small bore with a long stroke? What compliments such an undersquare engine as far as camshaft selection goes?
Brother, I was right where you were in 2014. I had a worn out 350 that I wanted to rebuild, and a stubborn machinist and mechanic that insisted on doing it "his" way.

After thousands of dollars and a lot of headaches (and an engine that wouldn't pull a greased string out of a goat's ass), I found Butler Performance. More importantly, I found their customer service. You are asking these questions because your machinist doesn't know dick, and he's never built what you want to build before. Butler has done it 1000X, that's why they have the kit ready to sell you. If your machinist won't buy it, it's because he's ripping you off by "getting it directly" and marking it up 30%+.

You wanna know what roller cam works with that setup? Ask Jim Butler or one of his sons. They will ask what kind of driving you are going to do, what trans and rear end you have, a few other questions and get you set up with what you need.

Don't fool around trying to re-invent this thing. Go ask the folks that have the riddle already solved.

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  #37  
Old 02-12-2020, 11:14 PM
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I bought my Autotec piston from Paul K right here on the forum.

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Old 02-12-2020, 11:33 PM
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Half-Inch Stud Half-Inch Stud is offline
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455 with EGR will do better in hp, tq, mpg.

455 crank with 350 block overbore is lower in all 3. if you have the Slugs then it would be a fun deal.

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Old 02-12-2020, 11:52 PM
LostHighway LostHighway is offline
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Quote:
Originally Posted by Navy Horn 16 View Post
Brother, I was right where you were in 2014. I had a worn out 350 that I wanted to rebuild, and a stubborn machinist and mechanic that insisted on doing it "his" way.

After thousands of dollars and a lot of headaches (and an engine that wouldn't pull a greased string out of a goat's ass), I found Butler Performance. More importantly, I found their customer service. You are asking these questions because your machinist doesn't know dick, and he's never built what you want to build before. Butler has done it 1000X, that's why they have the kit ready to sell you. If your machinist won't buy it, it's because he's ripping you off by "getting it directly" and marking it up 30%+.

You wanna know what roller cam works with that setup? Ask Jim Butler or one of his sons. They will ask what kind of driving you are going to do, what trans and rear end you have, a few other questions and get you set up with what you need.

Don't fool around trying to re-invent this thing. Go ask the folks that have the riddle already solved.
Actually, my machinist built a 383 Pontiac last year that did 430hp with a mild cam that went in a LeMans. He’s also done HUNDREDS of other BOP stuff, from classic Jags to Pre War stuff like Duesenbergs, Auburns etc. to full on race deals for lots of guys who are well known around Texas.

I’m not even sure if he’s the machinist I’ll use, I like a few of the Pontiac machinists I’ve met. Since I’ve bought my car, I’ve been impressed with the Pontiac crowd. I’m asking these questions because I would like to know. It’s part of making this decision. I’m not the type to throw money at a machinist and not know what’s going on. Funny enough, Butler might be my last choice. I don’t even see them around helping others or giving out advise like the other guys do. That’s a big deal to me.

  #40  
Old 02-13-2020, 03:29 AM
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"...Butler has done it 1000X, that's why they have the kit ready to sell you..."

Just curious. What makes you think Butler has built thousands of 4.25 stroke 350's ? Would be curious to know exactly how many they've built, if any.

It has been posted that they have a several month back log of engines to build. Wonder how many of those builds involves a 350 block ?

Here's a list of their common crate motor builds. Doubt they do many 350 block builds, at all. The total number, in recent years would be interesting.

https://butlerperformance.com/c-1267...-complete.html

"...If your machinist won't buy it, it's because he's ripping you off by "getting it directly" and marking it up 30%+..."

That's a pretty presumptuous thing to say, not knowing that particular machinist.

MAYBE, he wants to do the measuring & see exactly what pin height he'll need to order, on the pistons, so that after a square-up deck cut, he won't have to machine lots more material off the deck.

As for the profit involved, he will make more, buying the individual pieces, than a Butler assembly, even if you buy all the pieces & take them to him, because he'll get paid for balancing the assembly. If he buys a Butler assembly, Butler gets paid for the balancing.

Here's a list of Butler ready-to-assemble short block kits. No 350 blocks mentioned. Leads me to believe they don't stock any 350 core blocks, because of lack of demand.

https://butlerperformance.com/c-1234...-assemble.html

They can list the 350 stroker rotating assemblies, without ever actually building a 350 stroker, since the 4.25 crank is the same crank used in 400 block stroker assemblies. Since the rods are also the same, the only thing different is the Pistons & rings. And they probably don't stock any 350 pistons. So, they wouldn't even order the pistons, til the customer ordered 'em. Then, after the pistons arrived, they'd get all the parts together & balance the assembly.

Would be interesting to know how many 4.25" 350 block stroker assemblies they've sold. Because of the reputation they have & the high volume of engines they build, their base price for a basic 400 block stroker is around $10,000. Higher with any upgrades.

I dare say there are lots of no-name engine builders out there who can build a good 4.25" 350 block Stroker, for much less than $10k.

Len Williams still sells 455 long blocks for around $5500.

http://lenwilliamsautomachine.com/455_Long_Block.html

He also shows an alum head 400 for $7900.

http://lenwilliamsautomachine.com/40...ock_Heads.html

So, you don't have to pay $10k for a Pontiac street engine. But, you can if you want to.

Don't know what Paul K. would charge to build a 4.25" 350 block stroker. But since he recently built a couple, he can give you a real close estimate.

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