SU issues

[Tri-Star]

Ive spent too many hours with limited success. It has been running rough the last few weeks with extreme loss of power. I tore the carbs apart cleaned them and put them back on and tuned them. Most power has returned but still running rough. The air flow is ballanced, im at 1 and 7/8 turns mixture, both float bowls appear to be working the same. Heres where the issue lies im sure: When i press on the piston lift button on the back carb (making it only run on the front carb) it lowers slighly in rpm and runs a little rough. That means the front carb is tuned correcly from my understanding. BUT when i do the same on the front ( making it run only on the back carb) it stalls out right away. From what i have read this means its lean. Currenly both carbs are at the same mixture but i have taken it all the way to 3.5 turns and it does the same thing. Any ideas?

[ChrisZ]

I just had the same issue, first i sealed all the mounting flanges with non hardning gasket, it helped a little but i also adjusted the float high at the same time, so it could also be it.

Then i got the car 6 new plugs and problem solved.

Look a few lines down in the "help me" forum and you will find the thread.

Chris

[Carl Beck]

Also - you always want to check the little rubber hose that runs from the float bowl to the bottom of the carb. This hose needs to be a very high quality formed vinyl construction - and over the years many have been replaced with less expensive, even cheap rubber fuel line. These rubber lines easily kink with age/heat - and restrict fuel flow..

FWIW,

Carl B.

[biddljj]

The Z-Therapy DVD really hits the idea that the supply tube between the float chamber and the supply jet is not a Checker Auto Store item.

Jay

Not just a Z - zdisease

[Tri-Star]

all wires are on correctly

all sparkplugs are pretty nasty (cleaned/sanded them same problems tho)

The jet hoses are good (expensive ones)

If i squeeze the front jet hose the car stalls out

If i squeeze the back hose the car runs at lower rpm a a little rough

Im gonna go borrow a timing light now and buy new plugs

[Arne]

All indications point to the rear carb. Sounds like it's not delivering much fuel at all. You are aware that both carbs should not necessarily be adjusted the same number of turns, aren't you? I'd try leaving the front as is, and richening the rear carb only, pehaps as mus as a full turn richer to start.

[Tri-Star]

new sparkplugs same thing

cant get ahold of timing light atm

After running i pulled the piston off the carbs and compared fuel level in the nozzle. The rear one is much lower then the front, even after i adjusted the rear float bowl again. Although i think i saw a increase with the last adjustment.

Yes, i know they dont have to be the same i have had them at 2.5 and 3.5 at the same time before and didnt notice a difference. Maybe now with the float bowl a little better maybe ill have some luck with the mix nut.

[ChrisZ]

i remember readinig some place that the float hight isn't the same on the rear as on the front on one of the round top carbs, i just can't find it again, what type do you have 3 or 4 screws?

Chris

[Tri-Star]

3 screw

was able to get the right mix after adjusting the float even more. Runs smooth at 90-95% power now. yay! thx for all the help.

[geezer]

i remember readinig some place that the float hight isn't the same on the rear as on the front on one of the round top carbs, i just can't find it again, what type do you have 3 or 4 screws?

Chris

This should help identify the carbs and get the float heights adjusted properly.

Edited April 19, 2009 by geezer
added a title to aid in searches

[ChrisZ]

That's what i was referring to Ron, in all FSM it states 13 to 15 millimeter, this chart is what's needed to have it done correct.

Can't these scans be some kind of sticky to download ?

Chris

[biddljj]

Geezer,

Thanks for the SU jpegs !

Jay

Not just a Z - zdisease