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Who Knows About Chevy 348s

11/07/2011 3:25 PM

I have a 57 Chevy 3100 with a 348 in it. It is not the original engine I know, it came with the 235. But I wanted to know if any one can tell me some cool stuff about mods for this engine and what I would have to do to bore it to a 409.

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#1

Re: who knows about chevy 348s

11/07/2011 4:07 PM

I don't think you can bore a 348 out to 409 dimensions. There isn't enough metal left after you are finished boring. You'll regret it. You can install stroker crank to get to 377 cu. in. but I would'nt open up the bore.

409's used a casting with thicker cylinder walls to achieve the larger bore.

That's about the sum total of my knowledge about the old school bus motor.

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#2

Re: Who Knows About Chevy 348s

11/07/2011 5:53 PM

Find a machine shop with some old school gear heads around. They will be able to tell you the max you can bore it out, as well as have sources for matching pistons and rings.

Unless you have the equipment to rebore it, you're going to end up at one of these places anyway.

If it was mine, I'd go with the bore of a 350. Parts are readily available. If you just like to burn gas, I've got a 454 I'll sell you.

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#3

Re: Who Knows About Chevy 348s

11/07/2011 10:20 PM

You can go to a 437 w/650 hp...

" Sherman started with a more available 348, boring it 0.045 over and installing a Scat 4.00-inch stroker crank to build a 437 that makes 650 hp on pump gas. That's about 150 hp more than a good-running, old-school, full-race 409 used to make back in its days of legend. Read on to find out what it takes to reanimate your own W-series mill."

How to article...

http://www.hotrod.com/techarticles/engine/hrdp_0911_chevy_w_series_engine_build/viewall.html

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#4
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Re: Who Knows About Chevy 348s

11/08/2011 6:50 AM

Nice job!

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#5
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Re: Who Knows About Chevy 348s

11/08/2011 7:33 AM

Thanks for not making me dig that issue out again. Good answer.

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#9
In reply to #3

Re: Who Knows About Chevy 348s

11/09/2011 3:53 PM

thanks, i was under the impression that if i went to a 409 then i would have toilet paper thin cylinder walls. but now that i know this i know i can go bigger if i want to fork out money at the pumps.

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#6

Re: Who Knows About Chevy 348s

11/08/2011 7:37 AM

While building your 348 to the same performance level as Sherman did would not be as cheap as rebuilding a 350, the eye appeal of the W series engines when the hood is opened will yield a better return than the stock market. good luck. Send pictures.

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#7

Re: Who Knows About Chevy 348s

11/08/2011 8:31 AM

This engine is capable of lots of HP,but it also carries a lot of weight.The long connecting rods and long stroke make this a very high torque engine, which is why it was used in a lots of trucks, buses,etc.

They also enjoyed some success at the 1/4 mile strip, with a 3 duces or 2 4's setup.

The most popular use in the south was bootleggers, who loved the high torque which allowed them to run tall gears, increasing top end speed, but still having good "git" from a stop.Not much downshifting required, just stomp it.(So I've heard ).

I once raced one in 1/4 mile and did very well. If I remember right, it had a Crane R322 Roller cam, triple valve springs,1.2 ratio rocker arms,11.5 pistons,high volume oil pump,ported polished heads,copper o-ring head gaskets,and 2 Holly 780 Carbs.,with the double pumper kit,and Sodium filled exhaust valves.The rest of the details elude me right now.

If your motor is in good shape, it should be easy to add lots of bling, with chrome valve covers,alternator, etc.If you run it on the strip, you will spend tons of money trying to get all that power to the ground, because of uneven weight distribution.

For racing 1/4 mile, I would go with a 350 or, if you can find one, a 67 or 68 302 from a Z28 Camaro.A real high revving 1/4 mile scorcher!

Well, that's my 2cents worth (1967 cents, that is)

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#8
In reply to #7

Re: Who Knows About Chevy 348s

11/09/2011 3:51 PM

thanks man. that helps out, because if i can just put taller gears in it because of the torque, and it does have alot of torque, then i can get more speed and wont have to spend quite so much money. i know that the bugatti veyron has a 7 speed trannie, do you know if there is anything i can do to more gears than 7 so i get a low end for towing too besides spliceing gears like truckers did to get so many gears?

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#10
In reply to #8

Re: Who Knows About Chevy 348s

11/14/2011 12:03 PM

What transmission do you have now? There are 4 speed transmissions that were used in passenger cars that should be strong enough for normal driving. The Saginaw transmission was made with 2:52 first gear, and also with 3:08 first gear. The 308s were in older big Pontiacs, Oldsmobiles and Vegas. The Muncie came with 2:20, and 2:52 gear sets. The T5 would offer the best of both worlds with low first gear ratios, and an overdrive fifth. There are quite a few gear combinations to the T5 transmissions. The T5 vendors are on the internet if you look, and they can help you find a good combination of strength and ratios. Good luck.

She's real fine, my................

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#11
In reply to #10

Re: Who Knows About Chevy 348s

11/14/2011 3:47 PM

im not quite sure what transmission i have in it, i do not think it is stock, but i may be wrong. i havent got there yet though, i havent even started tearing the block apart yet. rite now i have the carb off and i am trying to get the money for a gasket kit i need 4 more bucks. i found a napa kit that will fit my carb and any other gaskets i need i can get at the kragens near shasta lake. they sell individual gaskets. i was actually just looking at a muncie for sale in my neibor hood. but i like the T5's.

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