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  #31 (permalink)  
Old 07-20-2005, 08:56 PM
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Yeah, a higher stall converter would help things, just make sure it is lower than your cruize speed rpm or it'll be constantly slipping causing heat then transmission failure. There are calculators available for determining what rpms the engine will see at your highway speed but you must know what gear ratio is in the rearend and also the rear tire height-or maybe you already know how many rpms she turns at highway speed.
Can't get your machinist to put flattops in instead of those dished pistons? Tell your Dad it'll still run on 87 octane I guarantee. Have you recurved your distributor or is it stock?- there's a lot of extra throttle response if the spark advance curve is dialed in right. Bob

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  #32 (permalink)  
Old 07-20-2005, 09:36 PM
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Quote:
Originally Posted by baddbob
Yeah, a higher stall converter would help things, just make sure it is lower than your cruize speed rpm or it'll be constantly slipping causing heat then transmission failure. There are calculators available for determining what rpms the engine will see at your highway speed but you must know what gear ratio is in the rearend and also the rear tire height-or maybe you already know how many rpms she turns at highway speed.
Can't get your machinist to put flattops in instead of those dished pistons? Tell your Dad it'll still run on 87 octane I guarantee. Have you recurved your distributor or is it stock?- there's a lot of extra throttle response if the spark advance curve is dialed in right. Bob
Correct me if i'm wrong but I thought a 10:1 CR meant you had to run 110 octane gas? I've never heard of a 10:1 car on 87 octane, that'd ping like crazy and destroy our new engine...

We have NOT changed the rear end so whatever it came with stock is what's in there. I think they're 2.73's but I'm NOT sure. Maybe 3.08's.....???

Anyway, the engine came with points and condenser. My dad switched to GM HEI when he rebuilt the motor the first time, I'm not sure if it's 'recurved' or not. Heck I don't even know what 'recurved' means lol.

I seriously doubt i'm gonna get to swap the pistons, but we'll see. I'll do somemore talking.
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  #33 (permalink)  
Old 07-20-2005, 09:39 PM
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i saw a magazine, in a 350 they used 87 octane, and it had 11:1 compression with no detonation
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  #34 (permalink)  
Old 07-20-2005, 09:52 PM
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Any of you ever read the article about "The 350 GM should have built" I think it was published in Hot Rod. They built an 11:1, aluminum head engine that had rods from a Ford 300-6 (6.123" if I remember right) it was based on a 400 and had a 3.25" stroke. Made something like 415 hp and the difference between running regular and premium gas was like 3 hp and no detonation on the 87 octane. Displacement comes out to right around 352 ci.
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  #35 (permalink)  
Old 07-20-2005, 10:00 PM
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Quote:
Originally Posted by Blazin72
Any of you ever read the article about "The 350 GM should have built" I think it was published in Hot Rod. They built an 11:1, aluminum head engine that had rods from a Ford 300-6 (6.123" if I remember right) it was based on a 400 and had a 3.25" stroke. Made something like 415 hp and the difference between running regular and premium gas was like 3 hp and no detonation on the 87 octane. Displacement comes out to right around 352 ci.

There's really nothing special about that motor, the only reason it made 400 horse is because they had a full roller valve set in it and a 1200 dollar set of aluminum heads. ON ryan's combo page, a regular 350 with less compression, a cheap, flat tappet valve train and the same heads made more power at a lower RPM. I know which one I'd build!

K
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  #36 (permalink)  
Old 07-20-2005, 10:07 PM
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What's the Bore/Stroke on my 350?
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Old 07-20-2005, 10:10 PM
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BINGO on what Killer said and as for the comp. you won't need 110 for only 10:1 Heck most people around here run in the 9.5 -9.7 range on 87... I know for diffrent people it is diffrent but if you have a good ing. system and have to dailed in there will be no need for race fuel.

Chris
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  #38 (permalink)  
Old 07-20-2005, 10:10 PM
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Standard 350s have a 4.00 bore and a 3.48 stroke. The one Hot Rod built had a 4.155 bore and a 3.25 stroke
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  #39 (permalink)  
Old 07-20-2005, 10:11 PM
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Bore is is 4 and stroke is 3.48

a 30 over block is 4.030

Chris
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  #40 (permalink)  
Old 07-20-2005, 10:16 PM
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Quote:
Originally Posted by killerformula
There's really nothing special about that motor, the only reason it made 400 horse is because they had a full roller valve set in it and a 1200 dollar set of aluminum heads. ON ryan's combo page, a regular 350 with less compression, a cheap, flat tappet valve train and the same heads made more power at a lower RPM. I know which one I'd build!

K
I was just referring to the fact that they ran 11:1 compression on 87 octane
with no problems in response to the question about having to run 110 on 10:1. Thats all I was going for when I brought that up.
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  #41 (permalink)  
Old 07-20-2005, 10:24 PM
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Okay well I just calculated my CR and according to this It's 9.1:1 which is pretty good I think...
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  #42 (permalink)  
Old 07-20-2005, 10:25 PM
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I might have done it wrong, I don't know how to account for dished pistons, I know it's a negative number but I don't know what.....
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  #43 (permalink)  
Old 07-21-2005, 12:05 AM
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Can somebody tell me how to account for dished pistons?
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  #44 (permalink)  
Old 07-21-2005, 03:42 AM
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Sterling makes dished pistons with two types of dish: 10cc or 5cc. You should figure out which ones you have. Summit has them in their online catalogue.

With 10 cc dish I calculate your compression to be 8.4
With 5 cc dish it's 8.8
With flattops (valve reliefs) it'd be around 9.1

You could run flattops with 87 octane.

To calculate these I estimated 0.025 deck height, 0.038 gasket thickness, 75 cc chambers, and 4.030 stroke.
To use the calculator you linked to, just add the dish volume to the chamber volume. There are other calculators on the net which ask specifically for the dish volume; in which case it would be a negative value.

Whatever pistons your use, it might be worth it to use a thin steel shim head gasket to decrease the quench and increase the compresion ratio.
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  #45 (permalink)  
Old 07-21-2005, 05:48 AM
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Quote:
Originally Posted by Malibu73
Okay well I just calculated my CR and according to this It's 9.1:1 which is pretty good I think...
I came up with 8.01-1 using a 4.030bore, 3.48stroke, .025 deck height, .045 gasket thickness, 75cc for combustion chamber+10cc for piston dish+4cc's for valve notches.

Most of the cheaper composition head gaskets measure between .041-.050
thick.

If you were to have the block decked till the pistons were level with the top of the deck, then ran a .038 head gasket for the best piston to head clearance, and then switched the pistons out to flattops your compression would end up at 9.32-1.

This is a lot of work to go through but the engine will run soooo much better. The last engine I built was my Son's 327, it's running a Comp Xtreme energy solid lifter XE268S cam with is fairly healthy for a street 327, we ended up with 10.01-1 static compression with 2 valve relief flattops, zero decked block, .038 head gaskets and milled heads. The dynamic compression ratio came up at 8-1 which is perfect. The dynamic compression on his engine is as much as the static compression on your combo. The cranking compression on the 327 ended up being 180psi - it'll run on pump gas for sure. Check out my gallery for a video clip of the 327 running on our test stand. Bob
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