Visit The Dirt Forum for More Information

Author Topic:   2 barrel 500 holley?
nailngoracing
Dirt Maniac

Total posts: 170
posted July 08, 2005 10:52 PM  
what is a good jet starting point with and without a power valve on a 350.

streetstock82
Dirt Forum Racer

Total posts: 81
posted July 09, 2005 10:04 PM  
depending on motor and cam specs, i'd say 78-80
to start. they have 73s at first and you need to up jet 6-8 sizes to maintain proper enrichment.

nailngoracing
Dirt Maniac

Total posts: 170
posted July 10, 2005 10:19 PM  
is that with a power valve or without?

streetstock82
Dirt Forum Racer

Total posts: 81
posted July 10, 2005 10:42 PM  
that would be without the power valve. what are your engine specs, cam, compression, rpm range.
let me know what they are. I personally would not use a 4412 without the power valve but thats just me. I've built many engines and carbs with the 4412 and ive never had one cause
a problem. you can have more trouble without it actually. they come stock with a 4.5hg and thats what we use in most engines. unless its like a limited late model with a seriously radical motor, a 4.5 works pretty well

streetstock82
Dirt Forum Racer

Total posts: 81
posted July 10, 2005 10:49 PM  
i misread your first post and generally when with a mild cam and mild compression, start with either a 73h or a 74. with a little more cam (mechanical) and more compression a 75-76 is adequate. on the last 383 i had, it made 615 horse on the dyno and it had 78 jets and a 4.5 pv in it and it was an amazing performing engine. it ran in a late model and beat alot of 30-40,000$ motors. it also was a stock holley casting without a tricked out body or block. they are an excellent choice for drivability and performance when built right.

sc1 racing
Dirt Freak

Total posts: 419
posted July 11, 2005 01:40 AM  
id start with an 80 jet and reset idle mixture screws. get a good run on it and shut it down and check the plugs. better to be rich than lean and 73 or 74 is definatly lean. on power valve im not 100% sure but was told to start car and run engine up to racing rpm and take a vacum reading. that vacum reading is the sixe power valve you will want.

i may have been misinformed so if someone with actual knowledge knows about this please let me know...im already smelling something here..

streetstock82
Dirt Forum Racer

Total posts: 81
posted July 13, 2005 01:51 PM  
on a motor that isn't highly radical, a 73-74 jet with a 4,5 power valve isnt bad. On a b-mod
i build motors for it has a 4412 with 73h in it and its a 9;1 comp hydralic cam motor that sees 6000 rpm regularly and its perfect with 73s. it depends alot more on the combination of engine.

sc1 racing
Dirt Freak

Total posts: 419
posted July 13, 2005 08:34 PM  
we almost change jets nightly..depending on temps. if it gets cooler we up the jets if it gets hotter we lower..

a stock 2 barrel is set up for a stock street engine, so i dont see how the same jetting will be ideal for a race engine staying 5 grand and up..i sure wouldnt try it

streetstock82
Dirt Forum Racer

Total posts: 81
posted July 14, 2005 11:08 PM  
we started with 75s and motor would not rev properly and sometimes loaded up in corners. jetted down an plugs look beautiful engine is crisp and runs great, temp is perfect. dont need huge jets to feed a motor that cant eat it.

nailngoracing
Dirt Maniac

Total posts: 170
posted July 17, 2005 10:29 PM  
I am running size 90's right now...

It is a little hard to start but runs really good on the track.

We run another car with 80's and a 25 power valve...it seems ok...new car...new driver...need a little more time to tune!

jay116
Dirt Freak

Total posts: 428
posted July 18, 2005 05:33 PM  
Cool air will lean the motor out thats why you should run a little rich when its cold.


Back to the Archives