opinions on this carb set up?

kmarccoco · #1 (**permalink**) 07-16-2006, 05:35 PM

after replacing my speed demon 850 for a race demon 750, i seemed to get more power. when the swap was complete, we had jeted the new 750 #73 in primary and secondary. a power valve also in primary and secondary. it had way more power than the 850( jets #85 #93). but, with the new carb and smaller jets it seemed to run a bit hotter. i could really feel it in the foot box. the pipes were hotter too. seemed to be running great otherwise, but the heat concerned me.

so, i put new jets in the primary #75, and #76 in secondarys. i left both power valves. i havnt been able to really test it today because it is over 100 degrees here. i'll try it tonight. i did take it for a short drive, and i think the engine cooled off a bit. the power seemed to be there too, but didn't drive it long enough to decide.

anyone else have the same set up as mine?

428 ci big block, edlebrock performer heads, 10.5-1, roller cam/roller hippo lifter, duration at .050 = 248...

jmarsey · #2 (**permalink**) 07-16-2006, 06:13 PM

Duane's 428 is very similar and I think he's running an 830HP with #84's square. I'm not sure. He is pretty savvy with FE carb jetting. My gut feeling is you need to jet up and get this right asap. You can find him here at CC as "decooney".

Good luck, John

kmarccoco · #3 (**permalink**) 07-16-2006, 07:37 PM

thanks john. i'll see if he is available.. it seems to be pretty close though.. i know with the 850, it was a bit rich. the leaner mix seemed to give it a much better idle, and noticabley more power.. i dont think it was that hot with #73's, but i'm not sure and want to be cautious. the water temp was still 180-190, oil temp 160-180.

jmarsey · #4 (**permalink**) 07-17-2006, 12:08 AM

Just to give you an idea, my fairly radical 331 runs a 750hp with 73's squared in the summer on the street. When the air temp cools or on the track, I'll jet up. It's good you are checking and making sure you're jetting is right.

John

kmarccoco · #5 (**permalink**) 07-17-2006, 07:29 PM

you engine looked really clean when i saw it at toms. pistons looked new.....i just want to make sure my temps are good.. might buy egt gauge. its a learning experience thats for sure.

Zoom This · #6 (**permalink**) 07-18-2006, 12:05 PM

Pull your plug(s) and read them too. They'll have a good story to tell you on how the motor is running.

kmarccoco · #7 (**permalink**) 07-18-2006, 10:27 PM

plugs looked pretty good, one cylinder looked a little rich. but the rest were really clean. i read that with the h.o ignition its hard to read the plugs, they always look clean unless way rich or lean... dont know how tru that is, makes sence though..