Ultra Street Avenger 670cfm jetting

BruceSnyder · #1 (**permalink**) 07-01-2012, 08:45 PM

I rejetted my carb today to 68 primary and 73 secondary. What I thought was suppose to be stock jets of 65 primary and 68 secondary turned out to be 63 primary and 73 secondary. What's up with this?

Gaz64 · #2 (**permalink**) 07-24-2012, 12:10 AM

Quote:

Originally Posted by BruceSnyder

I rejetted my carb today to 68 primary and 73 secondary. What I thought was suppose to be stock jets of 65 primary and 68 secondary turned out to be 63 primary and 73 secondary. What's up with this?

Bruce,

Since nobody else has answered your post, I thought I would chime in.

Did you buy the carb from Holley or another distributor, who may have jetted it leaner primary richer secondary?

Some more info would help, is the carb a vacuum secondary?
Does it not have a power valve in the secondary metering block?
Quite normal to have richer jets on the secondary side without a power valve.

BruceSnyder · #3 (**permalink**) 07-24-2012, 06:27 PM

I bought the carb from Summit Racing. I contacted Holley. They told me the 63 primary and 73 secondary jets is stock for the Ultra Street Avenger 670cfm. No sure why they do that. Although, my engine is running great with the 68 primary.

brandx · #4 (**permalink**) 07-25-2012, 06:33 AM

Your engine looks to be close to what I am running. I have the same carb. What altitude are you at. I am at about 4000'. My carb came with 65 from new. I am at 62. Just picked up an lm-1 and will get the readings but 65 was getting black coating on plugs. Have not done any changes on sec jets. Have you looked at the plugs since changing the jetting?

BruceSnyder · #5 (**permalink**) 07-25-2012, 07:32 PM

I'm in Tacoma WA. So very close to sea level. I haven't looked at the plugs but it is running very well.

lovehamr · #6 (**permalink**) 07-26-2012, 05:30 AM

Quote:

Originally Posted by BruceSnyder

I contacted Holley. They told me the 63 primary and 73 secondary jets is stock for the Ultra Street Avenger 670cfm. No sure why they do that.

It's Holley. If you called back today and spoke to a different person you'd likely get a different answer.

Texasdoc · #7 (**permalink**) 10-19-2012, 09:01 PM

I have the 670 Street Avenger. I also bought mine from Summit. However, it was really messed up. Definately someone had bought it and returned it. The secondaries were opened significantly and the primaries closed. Before I figured out how to tune the carb, I couldn't get the idle below 1500.

Mine came with 65 primaries and 68 secondaries. I switched the primaries to 68 and the secondaries to 78. It runs much better now. Before, when it was hot, it would stumble at approx 2500-3k rpm. I don't have an Air-Fuel meter, so not sure exactly where it was.

Edit: Oops, sorry, I have the Steet Avenger, not the Ultra. Not sure was the differences in jetting between the SA and the Ultra is supposed to be.

70mach123 · #8 (**permalink**) 04-23-2013, 03:27 PM

I just had an issue with my 670 Ultra where the factory incorrectly put the 63's in the secondary's and the 73's in the primary's!!! It was bogging when my 351C hit 3rd and 4th. Holley gratiously gave me a new set of bowl gaskets. I then opted for a pair of 68's in the front and stayed with the 73's in the back. All is now good, what a pain though. worth double checking if your new one is acting up. Be sure to have new gaskets, these bowl gaskets are good once. Part # 108-83-2