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SBC Questions

5K views 37 replies 8 participants last post by  Custom10 
#1 ·
I have an 82 GMC Sierra with a built 350 and 350 turbo trans. Street driven.

Here are the specs on my motor:

350 4 Bolt Main .040 Over
Scat forged I beam rods
Keith Black flat top pistons 4v reliefs
Moly rings
World Sportsman II heads 2.02 valves and 64cc chambers
Edelbrock performer rpm intake
Edelbrock 650 carb
1 7/8 longtube headers
Lunati Bracket Master II Cam 300 duration
Crane Valve springs
Crane roller rockers
Comp Cams double roller timing set


Trans:
350 turbo
b&m rebuild kit
stage 2 shift kit
Hughes Performance 3000 stall

I haven't dynoed it, but the truck runs very well!

My questions are... what would I need to add/change out to make my motor a 383 stroker? How much more horsepower would I be looking at?

Also, would a tunnel ram intake make very much more horsepower or torque?

Thanks guys.
 
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#6 ·
Without knowing compression thickness of head gasket ?41 mabe,tulip valves or flat,tapered top on pistpns or flat all the way to edge ,how thick are top ring lands,rod length,has block ben decked ,does it have 3.48 stroke or stroker notice bore .040 will raise slightly ,if all fairly close to standard approx 9.75
 
#10 ·
I bought the truck with them on there. They are suppose to be hooker super comp long tubes. I'm kinda looking around for some headers on the used market right now, that I want to paint black, so I'll keep in mind the 1 3/4 recommendation.

Also, I'm not sure on whether the heads are ported or not. I'm guessing the sportsman heads don't come from the factory ported, right?
 
#11 ·
The sportsman heads can be nicely ported. Local here used those heads for quite a few years before upgrading to vic jrs. The car (67 Camaro) dipped into the 10s a few years ago with a 355.He then build a replacement 383 with victor heads.
The sportmans when ported flowed 265 CFM.
The headers you have should have a 7 bolt flange if they are 1 7/8 tubes. Those are big tubes...If they are hooker headers,make sure you buy the hooker pattern for the inside gasket if you replace gaskets
 
#12 ·
Opinnions are like ? well everone has one ,Heres mine if i were going to do the majorty street driving ,I would used 1 5/8 for low & mediun rpm range 1000-5200 with a 355 leave big tube headers for high rpm and 406 -and 434 guys and light weight vehicles ,more tpurque where you will be operating, I run 1-3/4 on my big block 496 in picture above it is in a 1953 chevy p/u Very happy with results
 
#15 ·
Yeah, the headers were on the truck when I bought it, but If i ever change them out I'll keep these suggestions in mind. Do different tube diameters on long tube headers make big differences in the sound of the truck?

Do you guys think I would gain much on the street by going up to a 750 carb?
 
#18 ·
Maybe you guys can help me figure this out... It seems like my truck should have a bit more power when I just punch it to the floor from a dead stop. So, I was hoping maybe a little bigger carb would help that?

I was thinking maybe when I floor it and those rpms go up, it's just not getting enough gas.
 
#20 ·
Maybe you guys can help me figure this out... It seems like my truck should have a bit more power when I just punch it to the floor from a dead stop. So, I was hoping maybe a little bigger carb would help that? I was thinking maybe when I floor it and those rpms go up, it's just not getting enough gas.
Am I correct in assuming that the motor doesn't have enough poop to spool the converter up and get up on the cam? What does your ignition timing look like. How much initial at the crank? How much in the weights? What rpm at full advance?
Suggest 20 degrees advance at the crank, 16 in the weights, all in by 2800.

I tried to find something wrong with the SCR/cam/DCR, but everything looks good as far as matching up. I see 10.2:1 SCR, DCR should be right at 8.3:1 with the intake valve closing at 47 degrees ABDC @0.050" tappet lift.
 
#38 ·
I think what he is trying to say is that more stroke & cubes will tend to tame out the ruff idle and low rpm "slug" effect of a higher duration cam.

300 adversized duration in a 283 will be allot harder to deal with on the street than 300 in a 383 kinda thing, just thinking out loud
 
#32 ·
Yeah, the truck runs great, though like was suggested earlier a little bigger carb could help out I think.

As I mentioned I'm looking for a 750 cfm carb. Do you guys recommend something with vacuum secondaries? Also, should I go for single or double pumper?
 
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