Rebuilt 350 sbc engine, XE262 cam, seems to need more gas.

[81 LeMans]

Stock engine ran ok on this carb. #17085584. Now with the XE262 cam, and vortec heads, engine seems to be running very lean. It can hardly run after the choke comes off, without help from the acc pump, until its really warm, before it will idle. I assume it needs bigger jets and metering rods. Am I correct? What size would it need? Its pulling 14" of vacuum at 700 rpm. Much less than stock. Its affecting my brakes, so I plan on adding a cannister. Timing is set at 10 degrees. Any help would be greatly appreciated.

[Shark Racer]

218/224 110LSA right? That's not a hell of a lot of cam.

Have you tried setting the idle mixtures? You really need to run through calibration stuff.

Start by picking up Cliff's book.

The idle & off-idle are controlled by the idle down channel, idle tubes, idle mixture passage sizing and the idle mixture screws.

[81 LeMans]

Hi Shark. Thanks for your input. I'll start there, with the idle mixture screws. I have picked up Cliffs book and plan to follow one of his recipies on a second carb. You're right about that cam. Its not radical by any means but its as big as I thought I should go, seeing as how I intend to stick with stock stall and stock gearing. I'll let you know the results of setting the idle mixture screws. I assume the engine has to be fully warmed up before I do that. Thanks again.

[Shark Racer]

If it seems like it's having trouble staying alive, cup your hand over the primaries a bit and see if that smooths it out. If that does, then turn the mixture screws out. If it's really not wanting to stay alive, take them out at least a full turn to help it out. (assuming that the cupping trick worked)

I the cupping trick made it worse, you're actually too rich but I expect you're running on the lean side.

If the carb is completely stock, I expect you'll need about 5 turns from gently seated to get the thing to behave.

[73 Z28]

Can you post a picture looking down at the primaries. I'm thinking that this is a single main air bleed carb and that will affect the jet/rod combo to use.  Opening up the idle mixture screw holes to about .095 and adding .090 of idle bypass air will improve idle quality. To get the most performance out of your new camshaft, though, the whole carb should be gone through.

Paul

[81 LeMans]

Thanks Paul. I'll take a picture this weekend and post it. I have several other carbs to chose from, as well. I'll post those numbers too, in case one of them might be a better choice, to rebuild.  Al

[77cruiser]

Try about 5-6 deg. more timing & see if it's better, may have to adjust your total after that though.