ITS ALIVE...kinda (help with 1/2bp 12a holley 600)
 

ok...so as most of you know by now...ive rebuilt and done a 1/2bp to my 12a

i pull started it today...only it wouldnt stay running unless i had it above 3k rpms...im running small jets right now (.56s) for my primaries which i think are way too small and could cause the issue...how big should they be?

also...what else do i need for this setup?
is it supposed to be this hard to start up the first time? (it still wont fire on its own...needs to be pull started.)

Where are your idle mixtures screws set? They should each be 1.5 turns off the seat. Is your timing set properly? Plug wires in the right place?

Start with some 62's in the primaries. Are you running a power valve or is it plugged?

-Marques

66 in the primaries and 68 in rears,set your fuel pressure to 6 psi

my plug wires ARE in the right place...but i know my timing is off some (we havnt used a timing light yet)

should it run ok with 56s? by ok i mean will it not be as temperamental as ive stated it's being?

ill be ordering the 66s and 68s asap...but until then...ill see what i can do...

To get my 1/2 bridge started the first time, i had to squirt a little motor oil in each side of the carb to build enough compression. It started fine after, running at idle for an hour, after that, other than flooding and fouling the plugs the 3rd day.

Mine should be running lean with the mikuni on it that is set up for a stock port, but it fires right up each time and will idle at 800 rpm, and I have less than 3 hours run in time, at idle.

Congrats on firing it up. How does it sound compared to the vid I posted?

Keep us posted on your jetting. I still have a 600 to put on and have no idea how it is set up.

Ok...i havnt put any oil in the carb yet...so i might not have very much compression yet? is that why i cant get it to start on its own? also...it doesnt sounds as "mean" as yours does...but maybe that's cuz i havnt had it start below 2500rpms...

im kinda discouraged right now...so if anybody has any hints or advice...let me know...

man, do not just buy the two sets of jets you think might work. you are going to go thru a ton of jets tuning that bitch. step up and buy the holley jet kit. it gives you everything from 60 - 99 or whatever. it's only 50 bucks. completely worth it. any local speed shop should have this.

Don't give up, it's too much work to get to this point and quit. What many people don't realize, building an engine is often easier than the tuning and getting it to run right. That can be the most frustrating part of the project.

I couldn't tow start mine, the brakes need bled, again, so I tried the oil trick and it worked. The engine had sat since late Nov. so I figured a little extra lubrication wouldn't hurt.

In my vid, I don't have a full exhaust on the car, it stops at the rear axle. Just another little item to do. :rolleyes:

Did you port your exhaust ports, mine may be a bit big. :D That may account for some of the sound.

FBII, thanks for the tip on the jet kit. I'll be ordering one soon for my Holley. Now to figure out how to boost prep it properly and I may get another pants shifter. :rlaugh:

i tried the oil trick trochoid...and it workd...only it was still bein really temperamental...wouldnt go below 2500rpms without dying...i had it runnin for a good 20 mins...then it died when i tried to see if it'd idle...now it wont even TRY to start...just the same "whirrr whirr whirr"

WTF?!?!

somebody plz help me here...its really starting to get on my nerves...

From what I understand from time in this forum, a idle problem where the idle will not come down is usually related to a vacuum leak. Sorry to be so vague, but hopefully this will help you to look in the right direction. Good luck man, can't wait to hear that you got her running right. I'm hoping to find a blown motor to rebuild and do a 1/2 brigde port on..:)

I run 62s in my 12a non ported and they are just right. No dead spots. 50s are way to lean for your motor you will have major dead spots and trouble getting it to idle correctly. Regulate the fuel pressure to 6-8psi and probably use high 60s jets. Just my 2 cents.

Pull your plugs and check them. They may be fouled already, and check all 4 of them. Mine fouled early and I had to clean all 4 before I could get it to restart. If the idle won't come down, start looking for vac leaks.

yea, 50's are gonna be waayyyy to lean. which makes sense of the whirring sound and no combustion. no gas is getting to the motor.

if he's running his holley as minimal as i do theres no way he's got a vacuum leak lol, unless his carb has a hole in it haha... mines only got 1 line on it, and thats for OMP...

sorry for the confusion...its not that it idles high...i just have to keep it revved that high cuz it WONT idle...

also...i went out to start it this morning...and it started when i poured a little bit of oil into it again...then i ran it for another 15-20 minutes...then it died when i tried to let it idle...i then tried to start it up again...but it wouldnt start...even when i added fuel straight to the carb...so it seems the car wont start after it is warm???

ive got some mid-60s jets on the way...i hope that will fix a large portion of the problem...

sorry for the confusion...its not that it idles high...i just have to keep it revved that high cuz it WONT idle...

also...i went out to start it this morning...and it started when i poured a little bit of oil into it again...then i ran it for another 15-20 minutes...then it died when i tried to let it idle...i then tried to start it up again...but it wouldnt start...even when i added fuel straight to the carb...so it seems the car wont start after it is warm???

ive got some mid-60s jets on the way...i hope that will fix a large portion of the problem...

VAC LEAK!!! Make sure that you have all ports on the carb that you are not using, and if you still have the plate under the carb capped, because that will cause the problem every time

:confused:

now that kinda scares me, cuz im almost 100% sure EVERYTHING on the carb is capped that needs to be. could i be getting a vacuum leak anywhere else???