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Old 11-30-2012, 06:42 PM
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Pontiac 350 zero decking?

I don't want to buy a 400. I want to reach 400 pounds of torque with a street cam(5200 rpm) in a 1969 Pontiac 350. Do I really need to zero deck the block to help get to 400 pound of torque? I mean just how important is zero decking and how much does it cost roughly? thanks

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Old 11-30-2012, 07:02 PM
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Zero decking wont help you much there. Put a 4.25 stroker kit in it from butler, you'll get there. Port your heads -decent cam -dual exhaust w/ H or X pipe 4barrel and dual plane intake....
Butler also sells a 4.00 inch stroke assembly, with a .030 bore, it takes the 350 to 383
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Old 11-30-2012, 07:07 PM
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Stroker kit is too expensive. Mildly ported heads(210 cfm or so), headers, ebrock intake, 600 cfm carb, points with pertronix, taylor wires, this cam maybe COMP Cams Xtreme Energy Cam and Lifter Kits K51-221-4 - SummitRacing.com. How much machine work, balancing, blueprinting, decking, C.R. ratio, would I have to do to get to 400 pounds of torque out of a small valve pontiac 350?
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Old 11-30-2012, 07:15 PM
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Quote:
Originally Posted by LATECH View Post
Zero decking wont help you much there. Put a 4.25 stroker kit in it from butler, you'll get there. Port your heads -decent cam -dual exhaust w/ H or X pipe 4barrel and dual plane intake....
Depends on the heads and current deck hight and type of pistons. If you go zero deck you may be able to raise the compression. Higher copression will surely rasie the tq you can make but is of course not the only thing to have done.

Usally cost is not extreme if you take the block in to the shop bare. But it is not always cheap some machine shops will find some extra work to do.

But latech is surely right butler performance. They usally have the cheapest soultion for pontiac. Machine work is very costly in my area. So getting the kit that just works is always best. Not sure how hard it is to get 400 ft bls from 350 poncho. With bad heads and low compression you may be pretty far away.

As i always tell the pontiac guys go chevy or 455+ cubes. If you want cheap get a chevy motor if you want big tq get the 455 punched out to meet your needs. Butler can set you up cheaper than you may think. Once i was done building my 455 i could of had an 800 hp pump gas motor from butler. Or same hp in chevy combo.

Hopes this help.
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Old 11-30-2012, 07:21 PM
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Small valve poncho heads , even ported well , wont pull 210 CFM even at .500 lift.
Torque can be increased easily by lengthening the stroke, and keeping port volumes smaller and more uniform to increase velocity of airflow.
I would suggest a pro charger or a blower to get there.
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Old 11-30-2012, 07:22 PM
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Quote:
Originally Posted by Nuck Chorris View Post
I don't want to buy a 400. I want to reach 400 pounds of torque with a street cam(5200 rpm) in a 1969 Pontiac 350. Do I really need to zero deck the block to help get to 400 pound of torque? I mean just how important is zero decking and how much does it cost roughly? thanks
This would net a simple increase in compression, without the attentitive changes to increased cam timing i.e. getting to a later closing intake valve, this would have a very minimal effect on power and may make a very detonation prone motor. On top of that the 69 Poncho uses a cast rod, it's not healthy to lean on 'em very hard.

Bogie
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Old 11-30-2012, 07:25 PM
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X2 What bogie said. You will want a set of forged pistons and rods. I used sealed power forged (NOS) and some 5140 rpm rods in my build.
The cranks are way strong enough to handle the power increase, and the 350 block is a 3 inch main diameter block which is plenty strong.
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Old 11-30-2012, 07:29 PM
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Zero decking allows you to control the quench distance by simply using a head gasket with the correct compressed thickness.
It is beneficial when raisng the compression ratio on a street motor that runs pump gas.
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Old 12-01-2012, 04:59 AM
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Try to achieve .040" to .060" deck clearance. That includes .041" gasket thickness and .010" minimum piston to deck height. I cut my 421/455 engine blocks to .010" deck clearance and used .039" gasket thickness.

The main advantage of having a minimum deck clearance is your engine will run much cooler and will be less prone to pre-ignition, which is often confused with detonation.

The 350 CI block cannot be bored large enough (0.245") to make more than 350 lb. torque using a 350/400 crank. The 3.875" bore is too small in relation to the 3.75" stroke. Historically, all the best running NA engines are "over-square" meaning the bore is larger than the stroke.

Get a 400 CI block while they are still a "dime a dozen" , bore it .030", install Speed Pro forged pistons, use your 350 CI crank and tell everyone it is a 350 CI engine. Most Pontiyackers would never know the difference.
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Old 12-01-2012, 06:54 PM
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Sometimes I am very impressed with this forum. This is not one of those times. First of all the engine in my motor was rated at 355 lbs of torque from the factory. So your statement is demonstrably false. Second, here is an example of a well built Pontiac 350 getting 385 pound of torque and 353 horsepower.
Third, in Rocky Rotella's book on rebuilding pontiacs there is a build by Ken Brewer which claims 425 lbs of torque out of a 360 cubic inch pontiac 350. The valves in that motor are 2.08 and 1.66. Which is something that I found to be very interesting. I don't want to start a flame war, but what you said is false.
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Old 12-01-2012, 07:28 PM
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I don't know what everyone has against the Pontiac 326/350 small bore moderately long stroke engine. The last year that GMC used a Pontiac engine in thier pick-ups, they used a small bore 389, for a total of 316 cu in, for economy and torque. Years ago, a friend asked me to drive his '66 Tempest with a 2bbl 326 automatic to the paint shop. When I got there, I opened the hood to check the codes to make sure he hadn't been fibbing to me. I could have sworn that it was a well tuned 389, but it was just a good running 326. A 350 may have 50 less cubic inches than a 400 (actually only 46 less), but they can be made to perform!
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Old 12-01-2012, 07:39 PM
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Butler Performance - Pontiac Short Block Kits

Problem solved... The upgraded butler rotating assembly for the 350 is very expensive and oddly long stroked.

Your going to spend a lot of cash to make a true 400 ft tq with a 350 in the end it would be cheaper to get the right motor and go. 461 cubes will solve all the problems you are having for less than 3500 bucks.
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Old 12-02-2012, 12:17 PM
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Quote:
Originally Posted by Nuck Chorris View Post
I don't want to buy a 400. I want to reach 400 pounds of torque with a street cam(5200 rpm) in a 1969 Pontiac 350. Do I really need to zero deck the block to help get to 400 pound of torque? I mean just how important is zero decking and how much does it cost roughly? thanks
400 ft/lbs is doable w/the stock crank and the heads you already have, if you clean them up and get a good valve job on them. Talk to Butler for a cam. Better yet, ask Butler about the 3.75" stroke 350 and whether it'll make 400 ft/lbs instead of listening to me- or anyone else here.
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