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View Full Version : Jets for Carb on 351 83' S&S 5000 feet


zhensley
06-18-2007, 01:30 PM
Anyone have a suggestion on jets for Holley 4160 carb on a ford 351 around 5000 feet? Currently running 69's but went up to 8000 feet and it was an absolute dog. Really bad, the only jets I could get my hands on were 60's put those in and it was running great but I think it was still a little lean. Now I am starting to think that the 69's were to rich at 5000 feet.. Any suggestions are appreciated...

Thanks,

Zach

TMCNo1
06-18-2007, 01:35 PM
Anyone have a suggestion on jets for Holley 4160 carb on a ford 351 around 5000 feet? Currently running 69's but went up to 8000 feet and it was an absolute dog. Really bad, the only jets I could get my hands on were 60's put those in and it was running great but I think it was still a little lean. Now I am starting to think that the 69's were to rich at 5000 feet.. Any suggestions are appreciated...

Thanks,

Zach

www.jegs.com and talk to their CS department

TRBenj
06-18-2007, 02:25 PM
69 is pretty darn big on a 351w, no matter what the elevation. Id say thats too big unless youre pushing a lot more power than stock. Stock size should be around 65-66.

Likewise, Id say 60 is too small for 5000', but thats just a guess. No one will be able to accurately predict what you'll need- not even Holley themselves- it varies too much based on your exact motor, use, elevation, etc. My best guess would be to start with a 64, but you'll need to do some plug chopping from there to dial it in.

Storm861triple
06-18-2007, 09:28 PM
I went down 3 sizes on the primary side from stock on my '92. The secondary side is not adjustable (no jets) so I changed the float level in that side to achieve the desired results.

zhensley
06-22-2007, 08:07 PM
So the 69 was running fairly decent, little slow out of the hole but not bad. I tried the 66 today and it was a huge dog and it couldn't even get me up to 32 mph.. Checked the plugs and they looked ok. What I don't understand is how I went from a 60 at 8500 feet to a 69 and 66 at 5000 feet and the 69 ran better than the 66. I don't get how it got worse going down to a 66. It may have been to lean but I would have tought that it still would have had good combustion, myabe just get hot or ping.

Storm861triple
06-22-2007, 09:20 PM
It won't get hot enough to ping, no matter what jet sizes you run. If itran better and faster w/the 69's, then that's what that engine likes. "Feed it what it wants." I'd say that it's running too lean w/66's if it ran better w/69's.