James B

I am running a 4160 (750 CFM) carb on my mild 355. It stumbles when I give it gas and I believe that is because it is trying to dump too much fuel into the car. The carb is probably too big.

I was wondering if anyone had changed there carb from having a metering block to having changeable jets?

Thanks

larrywalk

Generally stumbles when slamming the throttle open are caused by going suddenly lean. Try a larger squirter. You may have to go to into the low 30s. The 4160 should work fine.

tonyv123

vetteguy75

I had the same problem....stumbling & hesitating when starting...changed the accelerator cam (from orange to green #1 setting) and no more problems!!! I got the cams from Summit Racing...

You may want to try that first....

Good luck!

James B

Sweet deal I will keep this in mind when I do further tuning!

Fscott

I would grab a few squirters (up to 35) and a bunch of jets and start changing and testing. Keep notes when you're doing this cause you will not remember each setup....

James B

This is if I decide to convert my carb to have jets? I guess im not that familior with my carb.

lars

Your stumble has nothing to do with the secondary metering plate - tune the primary side (it has a metering block with jets) and the carb will run fine.

Jims66

Agree totally. I switched from the 600cfm to the 750cfm on my L79 15 (or so) years ago. That carb came stock with size 72 primary jets and a metering plate w/vac secondaries. It stumbled too until I switched to 70s. When the real hot and humid weather hits here in Maryland I'll go to 68s. I've always written the jet size on all my cars right on the carb's fuel bowl with a permanent black marker so I know what's in there. A little gas on your finger will take it right off when you change jets again.

tonyv123

James.

Tuning info for your carb, jetting at bottom of page:

http://holley.com/data/Products/Tech...199R9934-3.pdf

Jims66

That's interesting......., my 3310 came with size 72 Jets out of the box. The Holley "paper" says 70s. I wonder if they've since changed the size as I bought my carb back in 1989-1990 timeframe. Even more interesting is that I've ended up actually running the car most of the time (9-10 months of the year) with the 70s !!

tonyv123

Jims66

That link was for a 4160. If ya go to the holley site you'll find the same kinda info for yer 3310.

Her ya go, I looked it up for ya. Good luck.

http://holley.com/data/Products/Tech...199R9934-3.pdf

Jims66

That appears to be the same document you sent the link for in your earlier post which is where I saw the the 70 jet size (bottom of the doc,). I thought 4150 and 4160 was the carb's series (double pumper, vacume secondary) and that the 3310 number was the actual carb part number..., in my case, a 750cfm. Am I missing something ??