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  #16 (permalink)  
Old 11-05-2012, 10:09 AM
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Quote:
Originally Posted by MouseFink View Post
An engine is a air-pump:
How much torque an engine can make is based on its cubic inches.
How much horsepower an engine can make is based on its total valve area.

A Pontiac 350 CI engine is deficient in both areas.

The maximum oversize bore for a Pontiac engine is .060" regardless of the original bore size. The maximum OS bore for a 350 CI Pontiac engine is 3.935" for a total displacement of 365 CI. A Pontiac engine needs at least a 4.00" bore to unshroud 2.11"/ 1.77" valves. That is exactly why Pontiac engineers went to a 400 CI engine (4.12" bore) in 1967 (2.11" / 1.77" valves) to be competitive with the Chevrolet 396 Rat motor.
Like I said, I agree with you in so many areas, but torque is not just dependent on cubic inches, it'd also dependent on stroke, air flow, compression etc.. If cubic inches where the only factor then all 350's would have the same torque, Chevy, Pontiac, Olds, Buick and Ford, no wait a minute Ford would have more because they had a 351 and the older 352 would make even more right?

As far as horsepower there are many more factors that determine this. If it's only valve area, again it's air flow, (which isn't only achieved by valve size. air flow can be achieved by porting and polishing), fuel delivery, compression etc.

I'm not disagreeing with you about cubic inch and bore size and all that, I'm saying that he has a 350 Pontiac and wants to know if it can be made to make power, the answer is still yes. You don't need a 2.11 intake/1.77 exhaust valve to make an engine produce power...Lots of small block Chevy's used a 194 head and they go really fast too. How many small block Chevy's had a 2.11/1.77 head?

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Old 11-05-2012, 10:13 AM
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350 CI Pontiac block. + .060" OS
Probe SRS custom forged pistons, 3.935" bore
CAT H-beam steel rods, 6.800" C-C
New stroker crankshaft, 4.00" stroke, 2.200" BB Chevy rod journals, 3.00" main journals
1967 - 1970 small valve heads (no need for large valves due to bore size)
Edelbrock intake for 750 CFM Q-jet.
Total displacement: 389 CI

Option #2:
Buy a used 455 Pontiac engine. Do a ring and valve job. Tell everyone it is a 350 CI engine....

Last edited by MouseFink; 11-05-2012 at 10:20 AM.
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  #18 (permalink)  
Old 11-05-2012, 10:43 AM
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Quote:
Originally Posted by MouseFink View Post
350 CI Pontiac block. + .060" OS
Probe SRS custom forged pistons, 3.935" bore
CAT H-beam steel rods, 6.800" C-C
New stroker crankshaft, 4.00" stroke, 2.200" BB Chevy rod journals, 3.00" main journals
1967 - 1970 small valve heads (no need for large valves due to bore size)
Edelbrock intake for 750 CFM Q-jet.
Total displacement: 389 CI

Option #2:
Buy a used 455 Pontiac engine. Do a ring and valve job. Tell everyone it is a 350 CI engine....
Point taken, and I DO AGREE WITH YOU...The fellow said he had a 350 Pontiac and could it be made to make power and he wanted to build it himself. The question was not "I have a 350 Pontiac but would a 455 be a better choice". It's the old adage, "there is no replacement for displacement so, Again, I AGREE WITH YOU. I'm only trying to answer the questions as they are presented. Early in this post I asked if he wanted to spend the money and that building a 350 Pontiac would be expensive. He has come back several times with a resounding YES. If a Pontiac 350 is what he wants that is his choice and all these cubic inch scenarios have been asked and suggestions made.

So in conclusion I AGREE WITH YOU, I don't try and put down any manufacturers engine, they can all be made to perform if enough money is put into them, some choices are better than others and there are many choices not as apt to accept performance increases as a Pontiac 350, that's why I say I agree with you.
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Old 11-05-2012, 11:53 AM
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Regardless of the make of the engine:

The only substitute for CUBIC INCHES is RECTANGULAR MONEY.
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Old 11-05-2012, 12:05 PM
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Quote:
Originally Posted by MouseFink View Post
Regardless of the make of the engine:

The only substitute for CUBIC INCHES is RECTANGULAR MONEY.
There ya go my friend, same book, same page.

Ray
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Old 11-05-2012, 12:30 PM
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The real issue is with what else can be done with the same money. Yes 350 can be built but its all wrong for power. Bore is too small and stroke is too long. I didnt think those 2.11 valves would fit in the 350 bore sized head. You can't use the 455 64 or 15 heads on a 350.

With 2 grand you could have a used LT1 with big cam and exhuast. That will make more hp than most 455 HO's. Stock they make 300hp.

Not a poncho hater at all. I love to see all the GP's on this site. My poncho had 455 ho from factory with 64 heads. i built a new engine and went with aftermarket everything. It was mad power but still not as fast as a chevy with the same money thown at it. But it would make my 71 GP SJ jump and run. It was a major suprise to most ppl to see the big yellow GP squat and jump away from them like they were standing still on the highway. Even funnier to see them try to keep up in long corners. My 4000 pound gp would go around an exit ramp faster than a porche. I know seen the porche sliding around trying to keep up. LOL

So I love pontiacs but if i ever get another one it will have a chevy motor or something from Butler performance in the 600 cube range. Bulter is money well spent. His stuff last and runs strong.

With all that said sorry to say I have no advice that relates to your post. I can't really help but to say buy a 400 and dont take any wooden oldsmobile motors. But I may have a 455 crank in my secret stash...
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Old 11-05-2012, 12:37 PM
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My brother built a 350 Poncho I forgot if it has 4X or 6X heads and I tell you his Firebird could get it in fact compare to my 70 GTO I had im sure it has more power now the heads were worked on and so on.

Thinking his Firebird has a pos with 373 gears and it's standard my Goat had 323 gears with no posi and all stock.
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  #23 (permalink)  
Old 11-05-2012, 12:51 PM
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Agreed with what you posted, especially the Butler Performance products (they even have packages now for the 326 and 350, stroker kits and all).

Chevy products are cheaper and more of them out there, that's why so many people go Chevy. I've seen many threads about horsepower per cubic inch, if we did a dollar invested per cubic versus horsepower thread, Chevy would win hands down. Performance parts supply places make more "make your Chevy go fast kits" than any other manufacturer. The question never was is this the best choice to make the most power for the least money, the question was can I make my 350 Pontiac produce respectable horsepower and I want to build it myself. All the questions and suggestions where made in early posts and the fellow still wants to go 350 Pontiac. Well, my hats off to him and will try to give him the most sound advice to the best of my ability and would welcome all kinds of positive, well thought out, experienced advice from the users of this forum. I love Pontiacs, Chevy, Olds, Buick, Ford, Mopar...special place in my heart for AMC...they can all be made to go faster than when they rolled off the assembly line and if it wasn't for people daring and attempting new and improved parts and methods we wouldn't have anything to discuss.
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Old 11-05-2012, 03:02 PM
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Quote:
Originally Posted by 69 widetrack View Post
OK, if your committed to building a Pontiac 350, buy it for the fifty bucks...Take it home...Take it apart and don't throw everything into a box and hope your going to remember it...you won't by the time it comes to putting it all back together. Mark each piston as to which cylinder it came out of the block, mark each rod and cap as to how they came off. Label everything that doesn't go to the machine shop Take your block, heads, crank, pistons and Rods to your machine shop...Get the block checked for cracks (magnaflexing), check to see if the engine needs to be bored...Chances are it does, have them check the crank to see if it needs to be ground. Get a price for all the machining including cam bearing installation as well as new freeze plugs. I left the heads out of this because I don't know what kind you have, let me know about your heads and we can discuss it.

First steps, we can try and walk you through it and I think one step at a time is probably the best way. That way you don't spend a bunch of money on parts and pieces only to find that your block is cracked.
x2
I built a 350 poncho.. on my way to a 400.. it was a down and dirty rebuild...
honed the cyl./new wear parts/polished the cast rods../and a little better cam.. and bolted it in place of the 301 that was under the turbo..
that wrong rod %, small bore, elcrapo heads poncho. ran mighty well even with the HUGE turbo lag.. ran very low 13's with it.. not bad in a 3800lb t/a and a turbo and carb engine set up for 301cid..
the 400 was faster.. but that was after tons of work on the turbo end of things..
good luck..
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Old 11-05-2012, 03:12 PM
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Quote:
Originally Posted by E.Furgal View Post
x2
I built a 350 poncho.. on my way to a 400.. it was a down and dirty rebuild...
honed the cyl./new wear parts/polished the cast rods../and a little better cam.. and bolted it in place of the 301 that was under the turbo..
that wrong rod %, small bore, elcrapo heads poncho. ran mighty well even with the HUGE turbo lag.. ran very low 13's with it.. not bad in a 3800lb t/a and a turbo and carb engine set up for 301cid..
the 400 was faster.. but that was after tons of work on the turbo end of things..
good luck..
Thanks, It's good to hear reinforcing comments on Pontiacs. Sometimes people like to take a road less traveled and in turn make believers out of avid non supporters.

Thanks again.
Ray
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Old 11-05-2012, 05:03 PM
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YeaI'm going to give the Pontiac 350 a go at it just to say I built one. hell for $50 bucks I can at least pull it apart. The guy that built my 455 say's he's willing to coach me.
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Old 11-05-2012, 05:12 PM
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Thanks for all the comments guys. I love this forum. My 455 is a monster. My dad had a 72 GP with a 400 in it and when I took him for a ride he was asking for the seat belts! lol... I've had guys out here tell me I cant build the Pontiac 350...well I'm going to try. Going to post pics...may be a few year process lol
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Old 11-05-2012, 05:25 PM
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Excellent and I'm sure he can give you pointers as well...just run everything by people that have done it before and you'll be OK...don't take any one person's opinion as gospel...get confirmation on any opinions.
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Old 11-06-2012, 09:49 AM
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After reading through these remarks, I gotta say a couple things.

First, the bore/stroke ratio is of very little importance in building a performance engine today. We used to think it was paramount... it's not. Rod/stroke ratio is far more important for longervity, and as long as the bore is big enough for the intake valve to "work", it WILL make power. The Quad-4 is a good example. The 2.3 version is a larger bore/shorter stroke. The 2.4 is the opposite. The 2.4 will run away and HIDE from the 2.3 (to a much greater "degree" than the slight increase in displacement).

Pontiac installed "48" cylinder heads on MANY '69 350HO engines. Those are 2.11/177 valves. They also used "17" and "47", both "small valve". IMO, these "work" a little better. The shrouding issue is not without some truth.

Making HP and making torque sometimes go "hand in hand". Not always. A 350 Chevy has no trouble at all making 500 HP. A 350 Pontiac (standard bore, it's really 354 CID) will have trouble getting there because the heads don't "work" as well. Can it be "done"? Of course. By the same token, a 350 Chevy has trouble making 450 lb. ft. This is due to the large bore and relatively short stroke. The heads aren't quite as "good" in the low-flow ranges either. The longer stroke and "long" rod in the Pontiac allow it to easily make that kind of torque, and more, usually at lower revs. Camming has a great impact on this, as well.

FWIW

Jim
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  #30 (permalink)  
Old 11-06-2012, 10:07 AM
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Quote:
Originally Posted by Mr. P-Body View Post
After reading through these remarks, I gotta say a couple things.

First, the bore/stroke ratio is of very little importance in building a performance engine today. We used to think it was paramount... it's not. Rod/stroke ratio is far more important for longervity, and as long as the bore is big enough for the intake valve to "work", it WILL make power. The Quad-4 is a good example. The 2.3 version is a larger bore/shorter stroke. The 2.4 is the opposite. The 2.4 will run away and HIDE from the 2.3 (to a much greater "degree" than the slight increase in displacement).

Pontiac installed "48" cylinder heads on MANY '69 350HO engines. Those are 2.11/177 valves. They also used "17" and "47", both "small valve". IMO, these "work" a little better. The shrouding issue is not without some truth.

Making HP and making torque sometimes go "hand in hand". Not always. A 350 Chevy has no trouble at all making 500 HP. A 350 Pontiac (standard bore, it's really 354 CID) will have trouble getting there because the heads don't "work" as well. Can it be "done"? Of course. By the same token, a 350 Chevy has trouble making 450 lb. ft. This is due to the large bore and relatively short stroke. The heads aren't quite as "good" in the low-flow ranges either. The longer stroke and "long" rod in the Pontiac allow it to easily make that kind of torque, and more, usually at lower revs. Camming has a great impact on this, as well.

FWIW

Jim
So true Jim and you said it very eloquently. So many people focus on horsepower when torque is another element very often ignored. Excellent post.

Ray
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