3x2 tuning

[Timothy B.]

Re: 3x2 tuning

I've never heard of this method, why would you want to do this when the secondary carbs are not functioning at idle?
Easy to check for leaks internally-just look down the throats at idle.

Can you look down the end carburetor throats and see a vacuum leak. If Stu reports a high idle speed after the fast idle cam is down how would you troubleshoot. Sounds like a vacuum leak to me.

[Ken A.]

Re: 3x2 tuning

Tim,
No disrespect, but you've never worked on a 3x2 setup. You can't remove he end carbs without removing the center carb and what about the fuel lines- no simple way plug them up.

[Stuart F.]

Re: 3x2 tuning

Thank you all for responding. Actually, the end carbs do idle some. What I have read, there is a small full time idle port in each one. I intend to use the starting spray to rule out any base gasket and throttle shaft vacuum leaks. I have a good parts breakdown from an old Holley Carburetors manual by H.P. Books dated 1972 edition. The information with the kits was worthless. I'm hoping for something as simple as the safety linkage that ties the end carbs to the center for WOT closure. I had no information how to adjust the positioning in the center carb slotted link. Also, I intend to check the torque on the mounting bolts and nuts as my son has a tendency to over tighten everything, and I have read that these bases tend to distort causing a binding condition with the throttle shafts. I real would hate to take the carbs off, but will if I have to.

Thanks again for the responses.

Stu Fox

[Domenic T.]

Re: 3x2 tuning

Actually, I did what Tim suggested many times with the 3/2 set ups back in the 60's. I found the end carbs leaking air MANY times. Most were linkage and some were worn butterfly & or shafts.
I had aluminum plates 1/4 thick that I used to block the end carbs.
They were Rochester not Holley but that doesn't matter in this situation. Also it was common to remove the end carbs and put the 336 rear end back during the harsh winters and give things a rest.

DOM

[Domenic T.]

Re: 3x2 tuning

I did forget to say that if you suspect a butterfly leak, you can squirt oil in the end carbs and see if the idle changes. You can also see how long it takes to suck the oil in.
I stopped looking down carbs years ago ( whith a running engine) after a suppress hair cut and my eye lid hairs burnt together.

DOM

[Stuart F.]

Re: 3x2 tuning

Thanks for your input Dom. I think in the course of troubleshooting, to remove the end carbs is a bit drastic until and if one can exhaust all other possibilities associated with a correctly rebuilt set of carbs (I can attest to them being correct cause I did them, Ha!). I believe the wise thing to do is look at the installation first because the carbs were working well before, except for a leak at the center float adjuster indicating too high of a float level.

I never got singed from looking down the throat of a running carb, but I had my share of headaches from exhaust and burning oil fumes.

StuFox

[Domenic T.]

Re: 3x2 tuning

Stu,
When I was young, I looked down the carb with the engine at idle to see if the accelerator pump was working properly.
I grabbed the linkage to goose it and, well, you know!!

DOM

[Stuart F.]

Re: 3x2 tuning

It appears that I have taken over this thread with my own efforts to set up the 3 x 2's on my son's L-89 (69). If I did then I guess I have to say I'm sorry.

As noted in my previous posts, I did a final adjustment on the carbs this morning (while it is cool out)' and all went well. I started by using starting spray and I found no leaks. I re-adjusted the linkage that ties the end carbs to the center carb to insure their closing from WOT. I found that the rear carb may have been a little tight and possibly held slightly open at idle so made what amounted to just a one turn correction. With the engine fully warm and idling, I re-checked the float levels, the idle speed, and the mixture adjustment. I arrived at a perfect 900 rpm idle at a steady 16" of vacuum. The engine responds smoothly.

All my fears were laid to rest. I still have the touch. My son is very pleased with the outcome. This is one sweet running L-89.

Thanks for all your advice and suggestions.

Stu Fox