283 6 two barrel idle problem.

Just got my 283 running but i cant get the idle to come down. I'm running a offenhauser 6 2 barrel manifold but have blocked off the front and back two carbs and am running only off the center two. They are rochester 2 g's. I've got all 4 of the idle screws backed all the way off. We've messed with the timing,but now have it set at 28 degrees, which is where it seems to run the best. I can say without a doubt that there are no vacume leaks, yet it still wants to idle at around 1500 rpm's. It sounds and runs great, but the bitch just wants to go. Need help from people more knowledgable then ourselves.

 

First thing I would check for is a vaccuum leak somewhere.
Taker WD-40 and spray it around the intake and carb bases while it's running. If it speeds up, then you have a leak.
r

 

Look down in the carbs with a flashlight, are the throttle blades closed all the way?

And you said you backed off all 4 idle screws...you mean idle speed screws right? I thought there was only one per carb? the one on the linkage, with the spring around it, in this picture



The idle mixture screws should be screwed in gently till they bottom out, then unscrewed two turns each.

 

CZ, By setting the timing at 28 you are just masking your problem,put the timing back to 8deg.or so and then find whats causing your no idle.You say you have the idle screws back out ? They should be only about 1 1/2 turns out. If you still have an idle problem you might have an air leak around the manifold or one of the unused carbs are causing the the air leak. Have you hooked up a vaccum gauge to it? A normal reading at idle should be around 18in. or so. If you have much less then you do have a leak. Good luck, N.N.

 

If he's checking the timing at 1500 rpm, then 28 degrees isn't so unreasonable...

 

Did the idle change any when you backed the idle screws off or does it idle pretty much that high no matter what?

 

later 2g's that came on engines that had an EGR valve have holes in the throttle plates, they were a front fuel inlet.

 

don't the front inlet carbs have the larger bases and won't fit on the 3x2 or 6x2 intakes?

 

Thanks for the quick responses. I've used carb cleaner istead of WD 40, as well as hooked an air hose to my vacume advance line and sprayed soapy water everywhere searching for bubbles, I did find one minor leak and have fixed it but it made no difference. on the back of my carbs there are 2 screws, I'm assuming they are both venturi controlls, but am not certain, and at this point i have gone frome 1 turn out to all the way in. This helped some, but i know thats not how they should be. I've checked and the blades are all the way closed. At any less advance she starts to back fire out the carbs when I give it fuel as it starts to die. Is 8 degrees advance the ideal timing that i should shoot for? the engine makes right under 300hp

 

8 degrees is a reasonable number for idle. 34 degrees is a reasonable number for full advance at a couple thousand rpm.

Pictures are gonna help a lot....

 

I've got three hole to four hole adapter plates, but they are very close together now and it is a royal pain in the ass to do anything to them. I wouldnt do it again thats for sure, I'de save my money for some strombergs.

 

No expert here, but shoudn't the idle circuits on the end carbs be sealed with epoxy?

 

Thanks for the help, i'll go take some pictures and screw with the timing some more and post the update this afternoon.
Thanks again,
Brady

 

If it's backfiring through the carb, doesn't that indicate a lean mixture?
Is you timing acurate?
r