Just put the alcohol carb. on my Camaro. 355 with 11.5 compression nothing special, Rupert 750 144 jets square. Picked up nicely to 6.60's from 6.80's and runs consistent and builds heat. On decel past the stripe it makes an odd sound like the fuel burning in the headers. Not a popping like you get from sucking air at a header gasket but more of a one loud thump like in the collector. First time I looked in the rearview for the smoke and crankshaft.
Posts: 1585 | Location: E TN | Registered: February 13, 2009
Make sure you don't have any exhaust leaks. It will suck air and burn raw fuel in the header.... Can be from slip on collectors and or from blown/leaking header flange.
Posts: 431 | Location: Pride, La | Registered: April 18, 2006
I had a few little backfires in the pipes after the stripe, thought my tune was off....turned out to be 1 slip pipe leaked enuff to cause sucking in air on decel. & causing the backfires - couldn't notice the leak standing next to it but.....
I'll check but I don't think it's got any leaks. Was fine on gas last week. I don't use header gaskets as I've had leaks always use high temp sealer. Does have slip tubes but headers have been on for years nothing touched in a while. It's not a pop more of a whoomp.
Posts: 1585 | Location: E TN | Registered: February 13, 2009
It sounds to me like it's getting a rich shot when you close the throttle and igniting in the headers. His carbs have always been notoriously rich on the idle circuit and if you are rich on the mains it could be even more likely. Just a possible guess from your description.
____________________________ 2017 and 2018 Osage Casinos Tulsa Raceway Park No-Box Champion
2018 Div4 Goodguys Hammer award winner
Posts: 3189 | Location: KIEFER, OK. | Registered: August 17, 2007
Posts: 1135 | Location: The problem is not the problem. The problem is your attitude about the problem. Savvy?” ~~ Captain Jack Sparrow ~~ | Registered: August 21, 2000
Originally posted by CURTIS REED: It sounds to me like it's getting a rich shot when you close the throttle and igniting in the headers. His carbs have always been notoriously rich on the idle circuit and if you are rich on the mains it could be even more likely. Just a possible guess from your description.
That's what I was thinking. I didn't think I was rich at 144's and I keep turning the idle adjustment screws a little leaner at a time, started at 1 1/2 out and keep inching them down as I heard Rupert's are rich at idle.
Posts: 1585 | Location: E TN | Registered: February 13, 2009
Rich fuel mix or not, gases won't burn in the header unless there's enough oxygen for it to burn. Seal the headers up real good and the problem goes away. Had this trouble on a set of borla up swept headers that the inlet flange on the muffler was corroded away, no matter what i did with the fuel mix i never got it to stop. The fix was to weld in an overlay on the inlet side of the mufflers to seal it up and cover all the rust holes, problem went away.
Posts: 431 | Location: Pride, La | Registered: April 18, 2006
Eman, As stated abouve make sure no leaks in exhaust. Do not know the rest of your fuel systen but after the run if the float gets over run and excess fuel is running in to the carb, when the throttle plates closed it will pop a little in the headers.
Posts: 321 | Location: ohio | Registered: June 06, 2006
Originally posted by Triple Nickel: Rich fuel mix or not, gases won't burn in the header unless there's enough oxygen for it to burn. Seal the headers up real good and the problem goes away. Had this trouble on a set of borla up swept headers that the inlet flange on the muffler was corroded away, no matter what i did with the fuel mix i never got it to stop. The fix was to weld in an overlay on the inlet side of the mufflers to seal it up and cover all the rust holes, problem went away.
