Correct fuel pressure for dual carbs? Options

[terrymason]

I'm having alittle trouble getting my dual carbs dialed in, the 1st is rich, and the second is lean. My fuel pump was putting out 3.5psi, but the guy I bought my carbs from said I should run 2.6psi instead. What do you guys think?

I've got 60 idle jets and 180 mains, which I thought was overkill, until he told me that I should run 2.6 instead of 3.5 psi.

[rhodyguy]

sometimes a bit more info is helpful. no mention of the type of pump, type of fuel presure regulator (stand alone or incorperated in the pump itself) and whether you're using a good fp gauge. how does the engine run when you're off the idle circuit? how the carbs behave at certain engine speeds is important. are the plugs for one carb drastically dif colors? are you measuring the flow at idle 850-900rpm?

k

[terrymason]

sometimes a bit more info is helpful. no mention of the type of pump, type of fuel presure regulator (stand alone or incorperated in the pump itself) and whether you're using a good fp gauge. how does the engine run when you're off the idle circuit? how the carbs behave at certain engine speeds is important. are the plugs for one carb drastically dif colors? are you measuring the flow at idle 850-900rpm?

k

I don't know what brand pump, but the regulator and 2 inline fuel gauges are sceptre brand that I got from pep boys. I've stopped using the fuel regulator (cranked it up to 5, it's max), and both pressure gauges (one before each carb) read a steady 3.5 out of the pump.

Having said that, I'm getting a new pump and jets (may not need the jets) from CB performance as soon as the west coast wakes up.

I have only measured fuel pressure at idle, something for me to do when I go home.

Car seems to idle fine, but when I goose the gas, I get a backfire out of the 2nd carb.

I've only pulled the plugs on the 2nd carb (backfiring one), and they look ok. I'll pull all the plugs tonight.


Thanks everyone, it sounds like I've got a good list of things to try when I get home. specifically:

1. measure the flow around 2K rpm - verify that it's 3.5
2. lengthen the linkage on my lean carb to verify that their isn't a situation where one is leading the other.
3. pull and compare all plugs

Once I get my new pump in the mail, I'll throw that it. If that doesn't fix things, I'll open my carb up and adjust the float level.