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Discussion Starter · #1 ·
Looking for some help on what heads to run with my new build. :confused:

Was running a stock L98 350 with aluminum 113 chevy heads and small cam (no specs) with weiand 142 blower, msd locked out distributor at 32* advanced with 6btm ignition box. This will be goin back in my 89 c1500 (single cab short bed) 2wd that weighs about 4000 lbs has 5 speed manual tranny and 3.73 gears, also just a street truck that i want to go like hell and will prolly take to the track every now and again.

Looking to build 355 with forged eagle rotating assembly, new comp blower cam (228/238 @.50 duration with .540/.545 lift with 1.5 rockers and 114 LSA)
weiand 142 blower with stock pulleys still 6" lower and 3.05" upper
holley 750 dp blower carb

I have looked at the AFR 195 with 75cc combustion chambers
If i use 75cc combustion chambers my C.R will be 7.46 & 7.73 depending on which rotating assembly is chosen.

Want the engine to be reliable, strong and not worry about breaking pistons, rings or anything else for that matter, but i dont wanna kill the low end power and torque by dropping c.r too much and be dependent on boost.
 

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. Hello... welcome... where are you located? ( ours off to right --> )


. Might as well make it a 383" while replacing the rotating assembly... see how your compression ratio works out then... always good to have more cubes/torque for a truck...
.
 

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Discussion Starter · #3 ·
Thanks and im in the tampa fl area. yeah i thought about that as well just not sure how well the little 142 will work with 383?
 

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Discussion Starter · #5 ·
Nothing has been bought yet just trying to get all my ducks in a row. I've been told by some people u want that low compression and others say you can get away with higher? I know it's not a big blower but it's what I got and it ran good how it was just didn't hold up to long.
 

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With a -22 piston, .030 350 with 75cc and .041 gasket I come up with 7.89:1.

Didn't mean to degrade your 142, just that it's not able to make any big boost you'd expect from a 6 or 8-71, I think you know that when you seem to steer away from a 383. I run an 8-71 on my 383 Nova. If you plan to stick with the 142 for a while consider bumping the c.r. some, check to see what boost you will see before you buy parts, I'm not tuned into the 142's to know.

Keep in mind what your effective c.r. will be when shopping, that would be your static computed with the amount of boost, it can get out of hand quickly for guys throwing big boost at an already strong NA motor.
 

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Discussion Starter · #8 ·
No it's all good, I know the 142 is nothing great but I got the motor and blower on a good deal and was a huge upgrade over the 305 the truck had. I would love to build a 383 with a big blower if I had the money but I don't so I'll have to stick with the little blower for now.
 

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Discussion Starter · #9 ·
If I run my 350 .030 over JE forged -22.0 cc pistons, forged crank 3.480 stroke with forged 5.700" rod with afr 180cc heads with 65cc combustion chambers the compresson ratio I got from the eagle website was 8.23:1. Then add the 6psi of boost and get around 12.0 effective compression ratio.

Not sure if im missing anything?
 

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If I run my 350 .030 over JE forged -22.0 cc pistons, forged crank 3.480 stroke with forged 5.700" rod with afr 180cc heads with 65cc combustion chambers the compresson ratio I got from the eagle website was 8.23:1. Then add the 6psi of boost and get around 12.0 effective compression ratio. Not sure if im missing anything?
That's what I'm seein', 12.0:1 Effective Compression Ratio, which should be pump gas compatible. I'm not sure that I would use those heads though. They are the best flowing heads for a naturally-aspirated motor, but I might be interested in using less expensive heads with more intake runner volume because with a blower, the heads do not need to be efficient in a naturally-aspirated atmosphere, they only need to be big enough to pass air in an artificially-aspirated environment, which most any head will do if the runners are big enough to begin with. I might be thinkin' something like Dart SHP 200cc, or even Pro-Filer 210's. Although the blower will homogenize the air/fuel mixture pretty well, I'd engineer a 0.035" squish into the motor. Add up your stack of parts and report back.

For you fellows who don't know any better, there is no such thing as "normally-aspirated". There is only naturally-aspirated and artificially-aspirated.
 

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If I run my 350 .030 over JE forged -22.0 cc pistons, forged crank 3.480 stroke with forged 5.700" rod with afr 180cc heads with 65cc combustion chambers the compresson ratio I got from the eagle website was 8.23:1. Not sure if im missing anything?
What are you using for gasket thickness in that computation? With a .041" I see 8.61:1. The stroke, rods and runner cc's don't factor into the c.r., I see the same ecr as you guys with 6#'s boost.
 
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