Timing or fuel?
Thread Starter
3rd Gear Member
Joined: Mar 2007
Posts: 574
From: Houston, TX
Timing or fuel?
I have a 302 with a Holley 600 CFM carb. I just had the carb rebuilt and I think it's adjusted correctly - I put a vacuum gauge on it and turned the two screws until I got the maximum reading; about 18. Turns out, both screws were almost completely screwed in to get that reading.
When I'm at idle or low rpm, then stomp on it, the motor spits once before kicking in. Is this a timing issue? Or is this still a fuel issue?
I haven't checked the timing yet - going to buy a timing light this weekend. But since the car doesn't have a stock cam in it, I don't know what the timing should be anyway.
When I'm at idle or low rpm, then stomp on it, the motor spits once before kicking in. Is this a timing issue? Or is this still a fuel issue?
I haven't checked the timing yet - going to buy a timing light this weekend. But since the car doesn't have a stock cam in it, I don't know what the timing should be anyway.
6th Gear Member
Joined: Dec 2005
Posts: 5,212
From: Hills of California
before you do all that stuff (which you should indeed do) Start by adjusting the accelerator pump injection duration.
I forget how it looked but there should be a way to adjust the amount of fuel that gets pissed into the carb from the accelerator pump.
IT could be starving for fuel so check the linkage. If there is some kind of lever with an adjustment move the actuator rod further Inwards on the level this will make it pee in more fuel when you stomp on it.
As for timing it should sit around 12 static just because its not pinging does not mean you should advance it any.
-Gun
I forget how it looked but there should be a way to adjust the amount of fuel that gets pissed into the carb from the accelerator pump.
IT could be starving for fuel so check the linkage. If there is some kind of lever with an adjustment move the actuator rod further Inwards on the level this will make it pee in more fuel when you stomp on it.
As for timing it should sit around 12 static just because its not pinging does not mean you should advance it any.
-Gun
Last edited by Gun Jam; Mar 25, 2010 at 03:44 PM.
6th Gear Member
Joined: Apr 2007
Posts: 10,468
From: California
Ugh....time to start over.
Set the timing first, start with around 14 at idle and 36 total, good starting point. Pull the carb and adjust the idle position until about .020 of the transfer slot is showing, put it back on and start it. THEN adjust the idle mixture to get as close as you can, then play with the idle speed a bit moving it up or down as necessary, reset the idle mixture again. THEN get the jetting correct at WOT, then adjust the accelerator pump.
Also pick a power valve rated at around 4" less than idle vacuum(once you have idle properly set) or about half the idle vacuum...somewhere in there.
Set the timing first, start with around 14 at idle and 36 total, good starting point. Pull the carb and adjust the idle position until about .020 of the transfer slot is showing, put it back on and start it. THEN adjust the idle mixture to get as close as you can, then play with the idle speed a bit moving it up or down as necessary, reset the idle mixture again. THEN get the jetting correct at WOT, then adjust the accelerator pump.
Also pick a power valve rated at around 4" less than idle vacuum(once you have idle properly set) or about half the idle vacuum...somewhere in there.
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