Hot Rod Forum : Hotrodders Bulletin Board - View Single Post - Confused about carbs, need help!
View Single Post
  #35 (permalink)  
Old 01-19-2013, 12:32 PM
CHEVILLAC's Avatar
CHEVILLAC CHEVILLAC is offline
HEATHENS AUTO CLUB
 
Last photo:
Join Date: May 2011
Location: PDX Oregon
Age: 37
Posts: 32
Wiki Edits: 0

Thanks: 7
Thanked 0 Times in 0 Posts
Quote:
Originally Posted by cobalt327 View Post
CHEVILLAC, in case I wasn't clear on my recommending you use the small Edelbrock carb, this is to get the engine up and running. If the carb is in good shape, you can basically bolt it on and w/a possible/probable change to the step up springs, you'll be able to at least drive it to see what else is needed.

I always advise guys to first set the distributor up w/a performance timing curve, before tuning the carb beyond adjusting the idle mixture screws and the curb idle speed.

A performance timing curve for a stock GM HEI consists of lighter mechanical advance weight springs (the weights are usually OK as-is) and limiting the mechanical advance to about 10-15 degrees. The rest of the timing (about 20-25 degrees) will come from the initial timing. Details are at the link I added several posts ago.

I seldom recommend locking the mechanical advance out so it doesn't work, but in this case- w/the cam as big as it is- you can do this to get it up and running. Then later on you can go back and set it up w/a curve if you want to. This is easy to do but it may require an ignition interrupter switch be installed so the engine doesn't kick back against the starter when you start the engine (locking the mechanical advance and the interrupter switch are also covered in the link). I'd use about 32 degrees timing to begin with- not optimal, but enough to see what you have. This isn't what you want w/a high rear gear, but as long as you don't mat the throttle from a too-low rpm you should be OK. If you hear detonation though, you'll need to back off the timing, back off the throttle/load on the engine, or add the curve I talked about above.
The previous owner says it's setup to be all in (initial + centrifugal) with 36 or 38 at 3500rpm and no vac adv. The motor was setup and tuned on the dyno and the only thing he did since was pull the motor from the car and remove the fuel injection. I know it ran like a scalded dog at that point so I just want to leave it as is, get it carb'd with the proper stall and go from there. I read the link on performance dizzy setup and bookmarked it for later in case I decide to go that route. I'm just reluctant to try to fix something that isn't broke, I just want to adapt it to carb.
Reply With Quote