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Old 11-18-2003, 01:27 AM
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sugestions for building a blown BBC

I have a 77 454 chev, and a 425 B&M blower to build for my 48 anglia panel, I havn't really ever built a engine like this before and would like some suggestions from some of you engine experts, I don't really plan on racing this monster, its mostly for advertisement for my shop, but who knows, I might just get the guts to take it down the 1/4 sometime.
The motor has 68K miles on , I think the heads are 118cc ??. Just need some Ideas guys, I will be driving it on the street , so it will have to be bad and streetable , The blower is a B and M 425 Mega charger, Ideas for the cam grind head work, crank, pistons, etc,etc, thanks BILL P.S this might belong in the engine section,

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Old 11-18-2003, 01:03 PM
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Is this a stupid Question or what?? come on guys somebody must have some Ideas, I don't want to take it to a engine builder and just say DUH, just build the damn thing, I would at least have an idea of what would work good, sound bad and kick a little butt once in a while , thanks Bill
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Old 11-18-2003, 02:06 PM
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Hey Bill.....................Not much action on this thread, I would think that the guys here would have been all over this.

I don't pretend to know anything about blower motors. I do know that the compression ratio needs to be kept low, maybe 8:1 or even 7.5:1.

That is about the extent of my knowledge on this subject.
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Old 11-18-2003, 02:15 PM
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First the idea of iron heads is scarey. If it burps
or anything and you torch a head then it is scrap.
If I was doing this I would look at a set of aluminum
heads. 2 reasons: you can fix them if something happens
and these rats on boost tend to run warm and with
the alum. head it will help in cooling.
The charger you got is mild so a stock GM crank is fine
and I would get a set of aftermarket I-beam rods.
Pistons are key, spend the money and get a set of custom
built blower pistons with the ring lands moved and with
coated top and skirts. This is expensive but the piston will
get the abuse. Shoot for around 7.5 to 1. This way you can
more boost if you choose to go racing.
Oil pan. I hate to see a stock oil pan on a blower engine.
You need a good 8 to 10 qt pan for both windage room and
for cooling of oil. Just very good insurance.

Camshaft needs to be around 230is and on a 112 with no
advance. Lift around 570ish.

Cstraub
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Old 11-18-2003, 02:19 PM
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I would build the motor to be around 7.5:1-8:1 compression without the blower, that way with the blower on , you would be able to run pump gas. The compression with the blower would be around 9.5:1 depending on how much boost you run. I would talk to the people at JE or B&M for the piston that would match your combo exactly; I am no expert when it comes to blower compression ratios. As far as the heads go, you might want to think about just having them cleaned up, mainly unshrouding the valves, and bowl blending. As far as which pistions to go with, I have always liked JE. Eagle makes high quality and reasonably priced rotating assemblies, so they may be someone to look at as far as crank/rods go. I am not sure what you are using for heads, but if you are using ovals, I would use something like a Comp Cams 280 AH hyd flat tappet cam. It is a blower cam that has a power range of 2500-6500. That would give you streetability, and still give you the power and good sound that you want. If you wanted a hyd roller, I would look at the NX279HR. That is labeled as a nitrous cam, but a nitrous cam and a blower cam are pretty much the same thing. Calling Comp Cams and talking to them about which cam is the best may also help.


Adam
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Old 11-18-2003, 11:36 PM
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Hey Thanks guys, this is what I wanted to hear, some different Ideas, I like the Idea of the alum heads, they are a little spendy but what in hotroddin isn't, I have had this blower on a small block,that was just Mildly built, with a stock cast crank, and I was always worried about putting it through the pan, I did have the heating problem too, but solved that with a little bigger rad,
this is the first big block I have played with , and being in a small car it shouldn't take to much to give it some Ba!!5,
thanks again guys Bill
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