Thread: engine has no power/torqe part 2

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Hi

im posting this to let you guys know that i did figure out what the problem whas

heres what i did i started looking at the carburator again
so my first test whas to rev the enginge up to the piont where it starts to die
at that point i did take a spray bottle with gas and sprayed in to the throuth of the carb instead of dying it picked up as long as i feed it with gas

long story short after looking through the carb again not really noticing anything obvious
i did decide to try something i took the smallest drill i could find and drilled the main jets
but the carb back together and now it runs ok it revs up like it should and drives ok

the main jets in the carb had the number 49 on them dose anybody know what size i should have for a 307 chevy or a 350 for that matter

If my memory serves... I had 64's or 66's in my Mustang w\ 302... I'd like to suggest an inspection of the power valve circuit also.. It should be supplementing the fuel supply upon vaccum lowering..

Thanks for getting back to us..

I'd expect something up in the 60's, but also the jets and metering rods work together and are paired up. I would think that hogging out the 49's would help, but you need the metering rods to go with the new ID of the jets, too. Do you have the book on the carb? Most can be downloaded these days.

While somewhat “un-scientific” you’ve done something that a lot of hot rodders have done over the years, i.e., “open-things-up-a-bit!” While not recommended by Holley, it sounds like it helped you identify the issue and perhaps point toward a resolution.

The stock main metering jets for a 650 Holley (4150) are typically number(s) 67 on the front and 73 or 76 on the rear. Where a 49 came from is beyond me - - the smallest factory jets from Holley on any of their four barrels (that I’m aware of) is a 60. A 49 is pretty small!

Bear in mind that the number doesn’t always equal the hole size, e.g., a 49 is actually a .048” jet. The 72 is .075” and so on.

Part numbers for Holley jets are easy – they’re 122-xx, where xx = the Jet Number. You could buy a bunch of individual sets to try ($7.00 a pair), i.e., 122-66, 122-67 (front) and 122-71, 122-72, 122-73 and do some experimenting. I’d start with 66 in the front and 72 in the rear for a 307. For time sake, I’d recommend that you buy the Holley Jet Kit (36-181, $53 from Summit). It contains two each from 64 – 99. You’ll never use the bigger ones – but by the time you futz around with a bunch of individual jets, it’s easy to surpass the cost of the kit. Price them local as well – there’s got to be several shops in Bellingham that carry Holley parts.

Hope this helps!
Glenn

good place to start is buy some 65 and start there

Originally Posted by pat mccarthy

good place to start is buy some 65 and start there

Great minds do think alike

Originally Posted by glennsexton

Great minds do think alike

i lost my mind along time ago. most stuff is things that float to the surface. not sure if it is more of a reaction