Thread: tune a 350 thats modified?

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I just bought an 84 chevy 4x4 shortbed that the guys brother apperantly put a 350 bored 30 over with edlbrock carb,intakeand cam it runs ok but seems alittle under powered and occasionally pops out the carb at low rpms when driving , dont know what year it is . could any body tell me what to look fir for a year , type of heads and the tune up specs (altho Ill probably have to do that by ear ..ouch)

You can use the Internet to figure this out. On the passenger side of the block just above the water pump you should find the block serial number. Then check it against the Mortec list:

http://www.mortec.com/

The heads may not match the block so remove one of the valve covers and look for the casting number in between the valve springs to check against:

http://www.lpcinc.us/headcodes.htm

There are a lot of possible combinations of heads and blocks between 327 and 350s. Once you determine the casting numbers of the heads you can compare to the flow numbers for the more common performance heads.

http://chevyhiperformance.com/techarticles/41598/

There are many other Internet sites for Chevy engines, so many that you will be amazed. Check out Ryan's site for a way to estimate the performance of your engine.

http://www.ryanscarpage.50megs.com/combos1.html

Best Wishes,
Don Shillady
Retired Scientist/teen rodder

thanks for the tips Don, Ill pull all tyhe no`s this weekend while Im not using it for work ( at the moment my 90 ford 4x4 is down with a bad case of steering box blues so Im using my new /old play toy for work) work the ford , play with the chevy

Is it backfiring or is it just air coming back thru the carb. I had a problem with a rebuilt engine, it was weak running and it did not backfire, it blew air back out the carb. No one here could help. Followed their advice and wound up spending hundreds of dollars on parts. From rebuilding dist, carb, adjusting valves, replacing carb. I just could not get anyone to agree that the cam was either bad, or too retarded. Well the last is what it was the mach shop had the cam too retarded. Advanced the cam and walla has mucho nuts now. Need more info from you. The post before mine has excellent websites for ID purposes.

How much did you advance it? I am having the same problem with my 454 (same Edelbrock cam, manifold, and intake) where it spits out air and fuel on the take off. Right now I have it at 8 degrees BTCD as suggested by the MFR.

If you are talking cam timing, I think but I might be wrong, you can go +/- 4 deg. Techinspector or streets could prob tell you more. But if air and fuel are coming back thru carb with no fire you def have an intake valve open during comp stroke. Like with mine it was pretty close it didn't do it till about 1800rpm's. Heck you may have a valve sticking.

Darn, another edelbrock cam set up that pops through the carb. Check your valves with the engine running and covers off. Make sure your getting oil to each of your rockers. If not you might have the same problem as a friend of mine had. He had a bad lifter, his wasn't getting oil to #2 exhaust, figure the lifter was just collasping and not opening the valve properly. Take a look at that. IF that's your problem I will know that edelbrock sent out a bad batch of lifters.

This is becoming a common question isn't it? Like the other thread" tune a 350 with edelbrock carb". Hell jump back and forth between the two and you will probably find an answer.

Hey Whtmtndog, you and Graygoat should get together and help each other out. You both have the same problems and both live in Ossipee.

No matter how folks modify an engine and no matter what specs you think you need to follow, you simply can't fool a vacuum gauge.

Connect a vacuum gauge to manifold source and then prepare like you were going to use a timing light (vac. advance discon. and plugged). Advance distributor until you get highest vacuum and then back it off exactly 1" of mercury. This is on the money even if advertised specs differ. You also may have to adjust your fuel mixture and idle after this. Try it on a vehilce with known specs and you'll see it works.