FM73project

My 79 is hard to start after sitting overnight. Ive rebuilt the carb and tuned, filled the bowl overnight with no leakdown but still have to crank for 15-20 seconds before starting in the morning. Any advice?

69Vett

checked your choke for proper operation ?

FM73project

I will check the adjustment. I've been so focused on the bowl leaking, maybe I've overlooked the obvious. Thanks

vbgod1

Take the air cleaner off and look at the choke plate as you give the throttle a full pump as if you were flooring it. This should close the choke. Then hold the choke plate open and look down the carb throat and pump the throttle again and see if you see a jet of gas squirt into the carb and into the intake manifold. This verifies gas. Then, as someone is cranking it, the choke pull off should open the choke about the gap you could get a dumdum sucker stick into. Without any tools, this would be a quick check for carb related starting.

Kirk H

I'm not sure what you mean by no "leakdown". Are you pulling off the airhorn and checking to see if the fuel has emptied out of the bowl overnight? If it has, then you have one of three problems that I am aware of...
1) porous carb bowl which fuel is seeping from (not uncommon)
2) leaking well plugs which need to be epoxied
3) bad fuel pump check valve that can siphon fuel back out of the bowl

If you know there is gas in the bowl and it still is a hard start, check obvious items such as timing, fouled plugs, cracked cap, choke pull-off adjustment (1/4" is close), vacuum leaks, etc.
Please let us know what you find!

FM73project

I've rebuilt two Rochester carbs using " Lars Grimsrud's" instructions, with good success. One, the primary plugs were leaking and emptying the bowl overnight. I just assumed that was what was happening here. Like I said earlier, every morning it takes 15-20 seconds to start, then afterwards it starts immediately all day. I've got the carb off and will recheck all the settings. Next I will check timing, etc.
I appreciate the Forums help and the wealth of knowledge from its members.