Ok- checked the obvious hoses on carb(Holley 750) for good tightness, single plane intake, not sure of make, will smell oil in the am.. Already had to have the builder replace floats with carb once(can't believe this for a supposedly brand new carb), and now a still leaking carb?? .. Will keep you posted- thanks again
Electric fuel pumps w return lines?
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The tried and true method for checking vacuum leaks is spraying carb cleaner around areas that could leak. If the idle raises, that's where your leak is. Visual inspection really doesn't tell you much.
I recently experienced similar problems. I run manual brakes, so I had a cap in the port at the base of the carb, not visible from above. When I pulled the carb, I found that cap had dry-rotted= huge vacuum leak. I yanked the nipple out, tapped the hole, and installed a pipe plug. Beeeotch ain't gonna leak no mo'!!!!
I recently experienced similar problems. I run manual brakes, so I had a cap in the port at the base of the carb, not visible from above. When I pulled the carb, I found that cap had dry-rotted= huge vacuum leak. I yanked the nipple out, tapped the hole, and installed a pipe plug. Beeeotch ain't gonna leak no mo'!!!!
Also, do you have that square bore carb on a spreadbore intake? Could be not sealing at the base. They make plates to fix such problems....
Ok- IT WAS the "new" carb!!! My guy threw a new 770 Holley he had on it and it ran great!!- damn, disappointed a bit re- engine builder, but at least we have an answer.. Now, hope this solves what we thought were fuel boil or vapor lock issues, so we'll see after running it hard for some time.. I also couldn't get engine temps below 200 either, even though plenty of radiator, twin fans etc...
The 770 is a vacuum secondary and since this is a 4 speed manual with a somewhat lopey cam, next will be a mechanical secondary carb.. Anyone like the AED carbs?
The 770 is a vacuum secondary and since this is a 4 speed manual with a somewhat lopey cam, next will be a mechanical secondary carb.. Anyone like the AED carbs?
Custom built carbs are about a G. Download a manual for your carb and get a rebuild kit. You'll surprise yourself once you understand what you're working with.
Glad you found your problem - sound like the problem with the new carb is nothing more than a float adjustment. Even with the floats adjusted to the sight glass hole I have had several carbs still dribbling out of the mains and needing more adjustment. Problem happens when people think they know they are doing and start adjusting. Worst mistake is playing with the blade adjustment once it is set to the idle port - people think it's an rpm adjustment.
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