[John V.]

Posted this in the '64/'65 GTO forum. Looking for any additional help.

I set up the complete '64 tripower with what I think is an original vac secondary linkage. I hedged my bet and purchased the mechanical linkage kit from Dick Boneske, stored away for now.

I've been unable to experience the vac linkage because of what seems an impossibly simple thing.

Problem is, in order to connect the small link from the Vac Diaphragm Can arm to the rear carb, the end carbs have to be pulled open a tad. Not good.

Trying to figure out what part is wrong.

I made crude measurements of my stuff. Here is what I have, hoping somebody here has known properly fitting '64 vac linkage parts they can take measurements of to compare.

For the small link itself, I measure 27/32" center to center on the link "arms" and 1" from outside to outside of the arms, with the rod material being 5/32" dia.

I estimate it is short by approx. 5/32" which seems like a lot. It has a "hump" in it that I'm sure is factory. Either I have the wrong link, or the problem is elsewhere.

The diaphragm can assembly that I had seemed correct. I sent it out for rebuilding.

Essentially, the guy pried it open, replaced the diaphragm, replated it, and somewhat crudely crimped it back together.

When I received it back, the actuating arm that sticks out of the can seemed 180 deg rotated as it was not "centered" in the hole. I should have taken a pic of it before sending it out but didn't.

Seemed odd that a guy that "knew" what he was doing failed to get it right the first time. But I sent it back and he disassembled it again and rotated it for me so that the actuating arm is centered in the hole.

The diaphragm mounting bracket seems correct also. I acquired the can complete with the bracket years ago. The bracket looks just like the one in the factory illustration of the Tripower in the MPC.

It really only installs one way it seems. And I don't see that it is adjustable without butchering it.

I haven't been able to contact Dick Boneske for awhile but when I asked him for advice, he shared some pix showing how the parts should fit together.

The rear carb lever on mine is stamped RP 27767. The one in Dick's picture looked to have the same stamped no. so I think it is correct.

So that leaves the arm attached to the diaphragm.

Since I had it rebuilt, I can't be certain the correct arm is attached to the diaphragm.

As best I could, I measured the straight length of the arm at 1-13/16" from the base of the L shaped arm (where it is riveted to the diaphragm) to the peak of the rounded end just forward of the link hole. The center of the hole would be about 5/32" short of the peak.

Looking for somebody to measure the link arm on a good diaphragm can.

I suspect that is where my problem is.

Conceivably the bracket extends too far rearward but unless there were similar brackets with slightly different dimensions, that seems unlikely.

Crudely measuring the bracket, I got 3-3/16" from the face of the diaphragm can to the center of the forward mounting stud if somebody has a bracket and can check that dimension.

Hopeful that comparing my measurements with a known set of good parts will make it obvious where the problem is.

Some pix attached show what I've got.

[John V.]

Realized from my pix that I described the diaphragm rebuild mistake wrong.

The first attempt had the L shaped link arm arranged so that it was too close to the bracket.

Turning it around 180 degrees makes it come out of the can away from the bracket giving clearance for the link attachment.

It is not "centered" in the hole. You can see this in the 3rd pic. Doesn't really change anything.

The length of the link or the length of the arm coming out of the can seems to be the problem.

Need measurements to understand which one is causing the problem.

Thanks for any assistance.

[Kenth]

This is an original 1966 unit i repaired for spare.
L-shaped link #857 measures 1.725".
The rod measures 1.060".
Total length pulled measured from can to end of rod 2.490".

[60sstuff]

Curious to see what the 64-66 “OEM Vacuum Operated” Tri-Power experts say on this issue.

Mine works flawlessly, but “Scary as hell” just as it was designed.

Everything back at the RR of this unit is a fixed “nut and bolt” application, except for that small link arm held in place with cotter pins.
Although this link arm is heavy material, I wonder if it could be adjusted “bent” as you would a choke link arm?

I have several spare Vacuum components and all my link arms are the same length.

First photo is the one in question and the rest are my 66 unit.

Chris

[60sstuff]

MPC shows different numbers for the 64 verses the 65-66 link arm.

I pulled a spare arm to compare with the link on my 66. Same.

Last pic is the 8000 mile car.

[John V.]

Chris, does the '64 Diaphragm Vac can have the same p/n as '65/'66?

In your last post, pic 3 is very interesting. The end of the diaphragm arm extends all the way to the start of semi-circle on the lower edge of the bracket behind it.

Mine doesn't come close to extending out of the can that far.

Can you measure from the diaphragm surface out to the end of the arm? By end of the arm I mean to the very farthest peak point.

If you measure from the surface of the attaching rivet to the end of the arm instead, just let me know.

Your picture very much makes it look like that arm has to be longer than mine.

If so, strange because the dimensions Kenth provided are very, very close to the crude measurements I made of my pieces. However, he didn't indicate where he took his dimension for the L shaped arm from (can surface, rivet surface, diaphragm surface?) and out to what point.

I don't see any way the small link can be bent to make up the approx. 5/32" I need to make up.

[Kenth]

John V, i took the L-arm measurement from the end of arm to inside of the L arm itself, right next to the rivet holding the L-arm to diaphragm.

[John V.]

Kenth, thanks for confirming.

If anything, your arm comes up just short of mine but I'll chalk it up that your measurements are more accurate using a caliper perhaps?

I got 1-13/16" from the face of the diaphragm out to the longest point on the arm.

That translates to 1.8125" vs. your 1.725". So if anything, your shorter arm would make things worse for me.

But you got 2.49" from the diaphragm face out to the end of the link.

Using my estimations, I calculate 2-1/2" and then eyeballed with my ruler, I get the same 2-1/2" result.

carbking posted some charted info in a separate thread. But nothing jumps out at me that would help.

Chris, I'm still hoping you can measure the length of the arm in the pic I mentioned.

The visual evidence in that pic is the only thing that could suggest my arm is some sort of short version although that would make Kenth's spare short as well.

Anybody else have any thoughts about what my mismatch might be?

As it stands, I'm bummed that I can't figure this out.

[Kenth]

John V, the total measurment of the L out of the can i took from the end of arm pulled out, to the can mounting surface, not the diaphragm.
HTH

[carbking]

John - it would seem that you and Kenth have covered most of the bases.

If you have the spares, I would suggest trying your bracket, can, and arm on a different carb.

WHY?

Tripower is immensely popular, and there are lots of reproduction items available. I have seen throttle shafts where the indexing of the flats for the arm was wrong. This makes no difference if manual linkage is used, but could make a difference for factory vacuum linkage. Have also seen brackets with an incorrect angle.

But one test is worth 1000 opinions. If you have a spare to try, the test might tell us something.

And yes, this thread was the trigger for me posting the other thread, but the other thread is an attempt to help enthusiasts have an interchange to what might work if they found an inexpensive unit from a different year.

Jon.

[John V.]

Kenth, it all helps. Thanks.

Jon, I have no extra carb or vac actuator parts to experiment with.

I decided to pull the diaphragm out of the car. Removed the 2 carb mounting nuts that hold down the bracket.

Back of the vac can (hose nipple side) there is a small somewhat circular stamping. At top of circle it reads Delco and bottom of circle it reads Remy. Above Remy, pretty sure it reads USA.

Above USA and below Delco there is something else but pretty sure not a p/n. Possibly an R in a circle to indicate Registered Trademark. No other markings that I've noticed on the can. Nothing on the bracket.

I can loosen the other 6 carb nuts to see if I can push the end carbs rearward. I figure I gotta loosen both carbs otherwise the rear to front carb connecting link might inhibit movement.

But I'm guessing that won't help since tolerances being what they are, the likelihood that there is any significant "play" that will allow the rear carb to move rearward on its mounting studs is remote.

Measuring with a ruler from the face of the can to the furthest point on the rounded end of the diaphragm arm, I get 1-11/16" (1.6875").

The link is 5/32" dia. and I still measure it as 1" side to side, still by eyeball but using an engineering scale. The arms aren't precisely perpendicular to my eye, so it may be a hair wider at the ends than it is closer to the humped crossbar.

The hole in the diaphragm arm is 3/16" dia. and there is 1/16" of meat from the edge of the circle out to the end of the arm.

I calculate from the mounting surface of the diaphragm can out to the far end of the connecting link as:

1.6875" - 0.0625" + 1.0" - 0.15625" = 2.46875"

Just 21 thousandths short of Kenth's 2.49" measurement.

Wish I had an untouched end carb to compare the carb lever indexing. But the lower edge of the levers on mine appear to be parallel with the carb base plate (both front and rear carbs) and looking at pix that Chris posted, it looks like that's how the lever should be indexed.

My measurements seem to match the measurements that Kenth has made.

The only thing that appears to be different in all this is the pic that Chris provided that shows the diaphragm arm extended out much further relative to the bracket than the one I have.

Relaxed, my diaphragm arm extends 1-5/8" from the can surface to the peaked end of the arm.

Eyeballing the one in Chris' pic, I'd judge that arm to be at least 3/16" longer than mine.

[carbking]

John - the original diaphragm may be identified by the last 3 digits of the part number stamped on the diaphragm arm (see the other thread). From memory, 857.

There is another Delco vacuum motor that looks extremely similar to the tripower vacuum motor except that the can is thinner. I don't remember the exact application, but foggy memory says headlight actuator motor. The diaphragm is the same (different arm).

Maybe 40 years ago, to rebuild "dead" tripower diaphragms, I fabricated tooling to open the cannisters, remove the diaphragm from the oddball, affix the correct arm, place it in the tripower cannister, and recrimp the cannister.

Perhaps someone else looked at the oddball, and said "this will work", without doing the work.

Again, from memory, the oddball cannister, is maybe 3/16~1/4 inch thinner than the tripower cannister.

Jon.

[carbking]

Here is a picture of the arm:



Jon.

[John V.]

Jon, after reading your post, I'm thinking "repro" arm and I must have the shorter version.

Except, I look at my arm and on the side facing the bracket (so hidden with the bracket installed), I finally see the stamping and it is "857" just as your memory and chart says it should be.

Same as in the pic you posted. The '64 bracket obscures it, the bracket in your pic is for another application, right?

Hard to measure without calipers, but pretty accurately measured, my canister is 1-1/2" from rear flat surface to front flat surface. And even if it wasn't the correct canister, the arm can't extend out of it more than it does.

Attached is a pic of mine, see how the arm stops well short of the semi-circle on the lower edge of the bracket.

The other pic is the one Chris posted earlier, notice how it extends past the start of the semi-circle.

[John V.]

And to cover one more base, here is a pic of my bracket.

From the face of the can to the forward edge of the opening above the arm I measure 11/32" (just less than 3/8").

If it was bent in such away to move the can further forward, the 2 tabs that nut down at the rear-most carb stud would not align.

But in case somebody can compare brackets...

[John V.]

Got it hooked up. Haven't tested yet.

Thanks for all the help and advice guys.

Not sure if it would have worked if I just tried to reinstall the vac can after removing the carb hold down nuts.

But I decided to remove the carb also.

Then I connected the link to the carb lever arm and the vac can arm with the cotter pins installed but not bent (in case I had to pull them back out).

Eyeballing it, it looked like the holes in the vac can bracket lined up with the stud holes in the carb with the vac can arm completely relaxed.

I then put it back on the intake with the link still installed. In the end, to get around the lines and wires, I wound up installing the carb on the studs first followed by the still connected vac can assembly/bracket.

It went together fine without pulling on the vac can arm and the carb butterfly snaps shut when the lever arm is opened and released, so all is good now.

When tightening the carb back down, there did seem to be a little play in it on the studs. Probably could have made the link fit without removing the carb except my carb was stuck to the cheap paper gasket, so when I pulled the nuts off, the carb was stuck tight.

I replaced the gasket with a Fel-Pro 60113 gasket, much thicker, rigid gasket. Looks like the carb would more likely "slide" on this gasket even after the first install so probably could have "adjusted" the fit without removing the carb if this gasket had been used in the first place.

Never had to loosen the front carb.

Anyway, all's well that ends well.

Thanks again.

Next up, I'll be testing to see if the vac components all work. Anxiously anticipating that "scary" thrill that Chris mentioned if the vac system does pull the end carbs wide open!