I need alot of help with my chevy 350...long post

I will start by telling eveyone my combo. I have an 87 s10 with a 350. The engine has a comp cam XE274 cam, 1.94 ported heads, 1.5 roller rockers, Hurricane single plane intake, edelbrock 750 carb, Super Comp headers, Mallory magnetic breakerless distributor and MSD6A ignition. The trans is a TH350 with 2500 stall and rear has 3.42 posi.

The best my engine has run was after it left the mechanics with fresh plugs and the timing set. Ran high 12s. The timing started jumping so we pulled the distributor and put it back with new springs and bushings. I dont have a timing light or the dollars to send it to the mechanic again so we set it by ear. The truck now runs high 13s. The truck blows some serious black smoke when racing now and doesnt seem to rev freely to 6000, almost surging.

Heres the questions

1) Could the timing be off that much to kill my 1/4?
2) Could my 750 carb be fouling my plugs?
3)What plugs and gapping would you recommend?
4) Would putting on my spare Holley 600 solve the richness problem and still give plenty of gas/power?

Any other advice would be greatly appreciate

1. yes 2.yes 3 . 0.035 to0.045 4 .650 would be nice but try it .holley do not like dirt it may some junk in it like in the air bleeds. if it has a power valve it my be bad and will make it hard to start run rich if it out, it will let the fuel out of the bowl check the needles and seats . the floats .look at fuel psi 7.5 will work and time it with a light .what size spring did you put in the dist?

The holley 600 came off of my previous engine and didnt have one problem the 2 years it was on...It has sat up for a little while so I am going to freshen it up with a rebuild kit. Its hard for me to imagine dirt getting to my carb. I have filter on the pickup in the tank, one pre fuel pump and a clear one post fuel pump. I put in the smallest springs that came with the kit. I was told that will make the advance come in quicker. Would putting heavier springs in keep it from peeling out so much early in the rpms? Stupid question I know but I'm new. Any other advice would be greatly appreciated.

UPDATE...I bought a timing light and have been playing with it for a couple weeks now. I set the timing at 14, 16, 18, and 21 degrees advanced. It seems to run better with 21 degrees as far as low end. I jetted the carb down as well and theres no more smoke when flooring it. I didnt change the plugs because they looked fine. I changed the alternator because it was only showing 11 volts and the new one shows over 13. The truck runs pretty good but I would think a 350 in an s10 would be faster. I am thinking of dropping the single plane intake for a high rise dual plane and changing the rear gears to 4.10 from 3.42...any thoughts on that?

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Originally posted by joewee350
UPDATE...I bought a timing light and have been playing with it for a couple weeks now. I set the timing at 14, 16, 18, and 21 degrees advanced. It seems to run better with 21 degrees as far as low end. I jetted the carb down as well and theres no more smoke when flooring it. I didnt change the plugs because they looked fine. I changed the alternator because it was only showing 11 volts and the new one shows over 13. The truck runs pretty good but I would think a 350 in an s10 would be faster. I am thinking of dropping the single plane intake for a high rise dual plane and changing the rear gears to 4.10 from 3.42...any thoughts on that?

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AT 2,500 I WOULD TRY TO HAVE MOST OF THE ADVANCE OUT.I WOULD TRY TO FOCUS MORE ON TOTAL TIMING.I WOULD START AROUND 36 MAKE A PASS AND SEE WHAT IT DOES.DID YOU GO FASTER?OR DID IT GO SLOWER?REMEMBER TO ONLY MAKE ONE CHANGE AT A TIME AND WRITE IT DOWN.YOU NEVER SAID HOW MANY R.P.M.'S. YOU LEAVE AT.ARE YOU TRYING TO (FOOT BRAKE) THE CAR TO 2,500 IF YOU ARE THEN MOST OF YOUR INITIAL TIMING WILL BE OUT.DON'T FORGET YOU ALSO HAVE THE WEIGHT'S AND SPRINGS YOU CAN PLAY WITH.3.42 TO A 4.11 IS A BIG JUMP.IF YOU CAN'T HOOK IT UP NOW IT IS ONLY GOING TO GET WORSE WITH THE GEAR CHANGE.

Quote:

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Originally posted by joewee350
UPDATE...I bought a timing light and have been playing with it for a couple weeks now. I set the timing at 14, 16, 18, and 21 degrees advanced. It seems to run better with 21 degrees as far as low end. I jetted the carb down as well and theres no more smoke when flooring it. I didnt change the plugs because they looked fine. I changed the alternator because it was only showing 11 volts and the new one shows over 13. The truck runs pretty good but I would think a 350 in an s10 would be faster. I am thinking of dropping the single plane intake for a high rise dual plane and changing the rear gears to 4.10 from 3.42...any thoughts on that?

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Before changing gears, definitly drop that single plane for a good dual plane like a Performer RPM. Seems also that the springs are now too tight in you advance curve Your having to set base so high because of how long its taking for the curve to come in and then by the time it does your way too high killing top speed.