Technical tri power jet size??? sbc

running a sbc,offy 3x2 manifold,rochester carbs
stock crate engine,8.5 compression,hei dist.
what size should the jets be in the carbs???

 

If I remember right I have 52's in the outer carbs and 56 in the middle.

 

Depends on the size of the motor and RPM's.
^ very close to what I have used, 55 center and 51 in the ends

 

Gee, small block Chevy......265 to well over 400 cu. in. how about a better description!
KK

 

treefiddy?

 

It's all about the compression. 8.5 was pretty standard in 57-70's when those were used so stock jetting will be close. My 65 -283 Chevelle had 52's and it had 9-1 comp. Cubic inches doesn't have as much to do with is as most think.
The biggest thing is you need to get on it pretty often because the outers vibrate and fill higher than the float level and cause rough running. I ran them on a 350 and loved them. They were off a 335 hp 348.

 

brand new crate 350 ci

 

ill try 55's and see what happens!!!
i can drill them my self

 

If you go to big, solder them up and do it again. Remember drill numbers aren't jet sizes...

 

yep, I just kept drilling until I got good color on the plugs and called it good.

 

After drilling them, tie a piece of good cotton twine to the vise (or the front bumper if it's not a 'g***er' )
about 2 feet long.
P*** the free end of the string through the newly drilled bores, and polish them one-at-a-time, running the jet up and down the tightly held string. Works wonders:
When I was at the Sunnyvale BMW agency, I had a number of BMW Coupe customers, inline 3.3 liter 6 cyl. with dual two-bbl carbs, sometimes came in running roughly even after carb service.
I'd go into carbs, inspecting everything...always culminating in jet polishing (really) followed by precise linkage adjustment! 'Zooooom!'

 

I run 57's in the primary carb and 53's in the two outboard carbs. This is on a 377 sbc.

 

'65 327 10.5:1, elevation is 4500'. 55's in the primary w/51's in the dumpers. Been fighting a slight bog off idle, thinkin' accelerator pump then tryin 56's in the primary carb. Likes a little rpm before mashin' the pedal.