69 Holley Tri-Power Carb Follow-up

[Stuart F.]

As I posted in my thread about questions on the subject, we have the L-89 up and running now.with the new carbs after a battle with the usual Holley leak gremlins. On subsequent test drives we've noticed a habit of the rear carb wanting to hang open just a bit. By a bit I mean an additional 500 RPM at idle. One can pop it back to normal by pushing on the safety linkage on the driver's side by hand, or goose it a few times which sometimes does the same thing. We noticed a sticking condition before installing the rear carb and tore down the vacuum diaphragm linkage. By re-positioning the diaphragm and return spring it seemed we had corrected the problem, but I guess not completely.

Has anyone else had a similar problem with a rear carb, as on the tri-power, or even with a 4 barrel Holley equipped with a vacuum operated secondary throttle??

Stu Fox

[Wayne M.]

Re: 69 Holley Tri-Power Carb Follow-up

As I posted in my thread about questions on the subject, we have the L-89 up and running now.with the new carbs after a battle with the usual Holley leak gremlins. On subsequent test drives we've noticed a habit of the rear carb wanting to hang open just a bit. By a bit I mean an additional 500 RPM at idle. One can pop it back to normal by pushing on the safety linkage on the driver's side by hand, or goose it a few times which sometimes does the same thing. We noticed a sticking condition before installing the rear carb and tore down the vacuum diaphragm linkage. By re-positioning the diaphragm and return spring it seemed we had corrected the problem, but I guess not completely.

Has anyone else had a similar problem with a rear carb, as on the tri-power, or even with a 4 barrel Holley equipped with a vacuum operated secondary throttle??

Stu Fox

Stu -- have you followed the adjust procedures below ? Read the 4th pic before the third .

]'67 Carb brochure (Custom).jpglate 69 L68 setup (Custom).jpgTripower adjust-2 (Custom).jpgTripower adjust-1 (Custom).jpg

[Stuart F.]

Re: 69 Holley Tri-Power Carb Follow-up

Wayne;

Thanks, but yes we did go by the instructions as I believe I got a set probably from you when I rebuilt the previous set of carbs my son had on the car (they were a replacement set). His new carbs are supposed to be brand new factory built pieces with the correct P/No's and date stamped in them. As I understand the instruction, it is to ensure there is a small amount of play or clearance between the clevis pin (screw) and the slot in the linkage arm. That was the first thing I re-checked and it was correct Our suspicions lie more with the diaphragm being as how the thing stuck sometimes when operated by hand before installation. We're thinking it either will cure itself with use (break in) or he will have sold the car before then. He is good about disclosing any issues with any car he sells or trades (to a fault).

Stu Fox

[John M.]

Re: 69 Holley Tri-Power Carb Follow-up

Stu I recently dealt with exactly the same problem. It turned out to be a slightly warped baseplate which, by the way, can be caused by a non flat manifold contact. So, when off the car everything worked nicely, popped open and shut no problem; on the car it stuck now and then. If you remove the linkage and it still does it, try loosening the carb to manifold bolts a bit which will confirm or eliminate this possibility. These things do run well when you get all these bugs out as you know. Of course they'll still leak a bit....
John

[Stuart F.]

Re: 69 Holley Tri-Power Carb Follow-up

Thanks John. We'll give it a try.

AMEN to the "leak a bit"

Stu Fox