Id try a higher number powervalve

 

What carb?

 

Sorry, it's a 750 holly double pump with the choke horn removed.

I have heard of people blocking off the power valve, would this be wise in my situation? It seems like I have the jet spread for it.

 

Are you driving on the street often?

 

It is far from a daily driver, but I would say it is 50/50 track car street car now. It spends just as much time on the track as the street and when I do drive it on the street, it's for short trips to meets and stuff.

 

4779 usually comes with 70p & 80sec with power valve in the primary side. Most stock 750s I've tuned at the track wind up a couple numbers down from where your at.

 

What do the plugs look like? I would pull a couple before I did anything.

 

The plugs are fouled up and get that way rather quickly. Last year at the track the car got quicker when jetting down the secondaries. It picked up 3 tenths jetting down a few sizes, but was still stinkin rich. That's another reason I believe my lm2's afr reading. Reason why it still has the jets in it that it does is because I ran out of track time.

 

Unless you run in VERY GOOD air, I think that you will end up between 70 - 72 on primary and 78 - 80 on secondary. JMHO

 

This, you are jetted too high.

 

This is a great document to keep handy. It has the factory calibrations for most models. On a new combo, I always try to return any used or rebuilt carb to factory specs and then tune from there:

http://www.holley.com/data/TechService/Technical/Carb Numerical Listing.pdf

Assuming this is a 4779 Holley 750 mechanical secondary, it says the factory jetting is 70 front, 80 rear or 71 front, 80 rear depending on the year/model.

 

Alright, I swapped the main jets to 70 and the secondary's to 79, it seems to be alot crisper when you rev the engine. (It's raining so I can't drive it to find out)
However, I do believe the 2.5 powervalve is now opening at idle due to the rough idle, smell, and visible smoke in thr exhaust. Plus, the lm2 is reading anywhere between 8-10afr at idle. I'm not sure how to get the propper vaccum reading to find the propper powervalve for it with it idling this way.

Should I pull the 2.5powervalve and put a powervalve block off plate in just to get the propper vaccum reading to know which power valve I need? I think it would work just to get the propper reading, but you guys have alot more experience then I do for sure.

 

Alright, I swapped the main jets to 70 and the secondary's to 79, it seems to be alot crisper when you rev the engine. (It's raining so I can't drive it to find out)
However, I do believe the 2.5 powervalve is now opening at idle due to the rough idle, smell, and visible smoke in thr exhaust. Plus, the lm2 is reading anywhere between 8-10afr at idle. I'm not sure how to get the propper vaccum reading to find the propper powervalve for it with it idling this way.

Should I pull the 2.5powervalve and put a powervalve block off plate in just to get the propper vaccum reading to know which power valve I need? I think it would work just to get the propper reading, but you guys have alot more experience then I do for sure.

No, do not block off the powervalve if you do ANY street driving... try replacing it with a 6.5... get you primary jets set via light to medium acceleration(20-35% throttle) then set your secondaries via WOT...

 

So what plug and timing are you at? What is the camshaft and static timing? Base engine issues will have to do with things your listing as much as a carb issue

 

Chances are you will have a hard time getting your WOT AFR correct without being rich on cruise even with a higher power valve (which I agree with others you should try) unless you open up the PVCR's and and drop the primary main jets accordingly.

 

Get your self a vacuum gage and a holley tunning book ,don't always trust what you read on the TARD NET.Then you will be able to choose the right power valve,and read your plugs to find the right jets.

JT

 

You can trust anything about carburetors you hear from YETI or Mark here on the Bullet. By far the most knowledgeable guys that I have ever learned from.

 

Hey, a even a blind squirrel can pick the right power valve.