Ok im running a Holley 600 (Vac Sec) and i knew it was lean coz my plugs were white but i never knew how lean it was.
Well i had 55 main jets i took it to a carb place and the guy told me it should have 65s in it (around 63 is the smallest he would advise to run) so yeah no wonder my car felt gutless.
well im getting my new jets this friday and ill report back on how it runs then.


The main reason i posted this is because i have asked on here before what jets i sould run and no one was able to give me a jet size, SO for anyone running a Holley 600 on a 305 you should be using a set of 65s for youre main jets.
(I forgot to ask about the power valve so ill add that size when I get it).

EDITED: sry put the . in the wrong spots.

 

This isn't making sense. Power valves come in 5.5, 6.5, 4.5, 7.5, etc., which are the inches of vacuum that they start opening. If you have a big dead spot off-idle, then you need a power valve with a higher number. You want as low a number as you can get without that dead spot to keep the PV closed under cruise.

Jets are numbered 64, 65, 66,...88, 89, 90, etc. You should have around 66 jets in the primary as a starting place.

 

I edited my first post i had 6.5 i ment 65 (i was not shure if there was ment to be a . there or not, sry about that)

there is no 6 on either of my primary jets, i can take a photo when i take them out if you want?

 

Sometimes the numbers on the jets aren't stamped right next to each other. A bit sloppy, in my opinion, for something that is supposed to be a precision part.

 

yeah you would think with a part that is ment to be exact to the 0.01mm that they would stamp the numbers clearly and straight.

 

I picked up a set of 65's and 67's just to test how it will run, I ran both sets with no difference then just to findout why im running so **** i went around the carb with carby cleaner (to find any leaks) and BINGO! masive RPM spike when i sprayed the secondary throttle shaft.
Ok so now i know why it runs like **** at idle so i used some Heat resistant silicone (RED 360*) real rubery stuff and filled around the ends of the secondary throttle shaft (I don't use the secondarys, I have blocked the vac passage off for them) just as a temp fix for now coz im getting a new Holley 650DP when i get my new engine setup.
I let it sit over night and when i restarted the enging my idle picked up to 1,200RPM from 800RPM the night before, now i lowerd the idle and it is staying nice and smooth at 650RPM in [D] with the 65's.
now going 30kmph then going to WOT it drops back a gear hits 3,500RPM gets wheel spin then shifts at 4,300RPM
it is running heaps better and im going to try the 67's next weekend to see how it runs then.