HELP major carb issues

[78mali350]

Just had a friend of mine come over to help time the enigne. we got that done and done right. now the car runs so rich it backfires and is excessivly slow on acceleration. how do i adjust the carb to tune the motor to run good again. before the motor was timed the car would run okay but still lagged in the acceleration department. i need help on this as fast as possible PLEASE!

Engine is a Crate Motor GM 350
Carb is a 500cfm edelbrock carb

thanks
vince

 

[82355supreme]

Backfiring is usually a lean condition. Bogging is rich. My question is, unless it's all you could afford, why on earth did you put a POS Edelbrock 500 on a 350 CI engine?? A Holley 650 would be way better suited.

If anyone has a 650 Holley you could borrow just to try it, I would. I am not familiar with the Edelbrocks, but I believe you adjust with meter rod height?? If this is correct, raise the metering rod(s) to let more fuel in.

Also, make sure your total timing is 36-38*.

 

[78mali350]

timing is correct edelbrock we have always had on our cars and never had a single problem with them. tomorrow we are getting a 600 cfm carb to see if that will do anything for the problem

 

[pontiacgp]

what did you friend use to set the timing?. To set the timing I advance the timing till it pings and then turn it back just a bit or I'll use a vacuum gage to set it...

 

[78mali350]

he used a timing light......

 

[82355supreme]

Was it a dial-back light?? If not, you have no idea what the total advance is. Are you using the vaccum advance?? If you are, then between the mechanical & vaccum it should be advancing enough, but again, without a dial-back light you don't know.

Like I stated above, you need 36-38* total, all in by 2800-3000 RPM.

 

[betcha618]

To set the timing I advance the timing till it pings and then turn it back just a bit..

Thats a real backyard way of doing it.

 

[85 Cutlass Brougham]

It sounds more like a problem with timing than the carb. The 500cfm size will not be a problem with anything other than top end acceleration where it becomes a restriction. Other than that, the 500 should provide crisp acceleration off the line, better than any larger carb except for a Q-Jet. Have a look at the advance mechanism and be sure it is not binding, the advance weight bushings are good and you do not have too light a set of advance weight springs. If that all checks out, reset the base timing at 10 degrees BTDC. If all of that does not help, try setting the timing by turning the distributor to improve idle quality while it is running. It may be that the timing light's calibration is off as this has happened to me with my Craftsman light. Now, you should also reset your carb to base settings too by turning both of the idle mixture screws full lean and turning them out 1.5 turns. Once that is done, set your idle mixture using a vacuum gauge by going for the highest idle vacuum reading. If it is still too rich under acceleration, you will need to go to a weaker step up spring in the power piston. This will lean out the part throttle circuit. Oh, I almost forgot, if your power brake booster is bad, you will have a massive vacuum leak that will make all of your tuning attempts futile.

 

[pontiacgp]

Thats a real backyard way of doing it.

timing the engine using the ping may be backyard to you but it'll beat a timing lite any day.....if I run premium gas I can advance my timing a little bit and so if I had it timed with a timing lite you think it'd still be on the mark??...

 

[betcha618]

Thats a real backyard way of doing it.

timing the engine using the ping may be backyard to you but it'll beat a timing lite any day.....if I run premium gas I can advance my timing a little bit and so if I had it timed with a timing lite you think it'd still be on the mark??...

its just a backyard way of doing it. and Any one that does any kind of performance mods to their car runs at least premium all the time anyway.