jets

[john910]

i have a jetting question, sbc with a holley 750 79 jets primary and 80 secondarys, plugs are black? it has a comp cam. 292 501 lift, 202 intake just a mild motor, autolite #26 plugs . any help i am a dummy!!!!

[BEAST477]

What size sbc and what kind of rpm's are you turning it? Be honest is this a street or race engine?

[john910]

sbc 355 drag race 7000 max

[BEAST477]

Are you running power valves? Could be one is blown. Is it possible your primaries are open too far exposing the transfer slots?

[john910]

no power valve are out

[BEAST477]

Have you set your idle mixture screws on your metering blocks? If not check them. Start at 1 1/4 to 1 1/2 turns out. Is it loading up at idle or does im seem rich at all rpm's?

[john910]

all 4 are set at 1 1/2

[TS1955]

Check your float level too.

TS1955

[john910]

yes floats are ok. all 4 corners are 1 1/2 turns. . just don't know were to start with jets. they were new and after warming up engine i pulled the #1 plug and it was real black. funny thing is when i went in house. my white socks were black. went right thru my work pants and turned them black. i have zoomie headers. don't know if i should wait and make a pass then check them at the end of track. thanks for the help, john

[TopspeedLowet]

Take the Zoomies off the heads and use a conventional manifold or header and you will get some engine vaccum signal back that the zoomies are killing at idle. Beast was correct about the power valve issue, accept that you do not have enough vaccum signal at idle to keep fuel atomised at low engine speeds like a blown valve would act like.
If you love them zoomies more than performance, then you are right where you should be with that set up. Gasoline carb set ups with zoomies net no idle power or tuneability in most all cases. When you get your blower you will be all set with them zoomies.
Bruce

[john910]

makes sence. i put them on for nostalgia looks on my 32 austin. to run in nostalgia races.

[john910]

also , what about going to e-85 or alcohol

[TopspeedLowet]

makes sence. i put them on for nostalgia looks on my 32 austin. to run in nostalgia races.

That is usually the logic for running a zoomie set up on a gasoline carb engine.
Sorry if you did not know that would likely be the net of the use of them. You most likely have a very happy engine once you check all the usual carb adjustments to be sure they are correct with any other exhaust system but the one you have.
Bruce

[john910]

last year i ran headers , just wanted to change the look. maybe i'll use the headers when i run weekly, then use zoomies for the nostalgia races and just pust up with a little black smoke.