Lapping was one of " old JD's specialty's .

 

I'm gonna go out later this morning and remove the diaphragm I installed. Both the one I removed, and the one I use to replace it, had the nice "roll" around the perimeter, like your photo. The one I had in my collection of FI parts was new, still in the cardboard pouch, stapled together.

But, I could have been old... and stiff.

I will take photos when I get it out later this morning.

The only thing I changed was the diaphragm. I didn't change any "settings". I pushed the axle link "shaft" back in and remounted the axle link. Didn't mess with the ratio lever or the power/economy stop settings.

I'll report back. I want to try to get the car driving for my Corvette Club show on Sunday.

 

Here are some photos.

The first two are the new diaphragm in the car now, right after I removed the "lid". Not much of a "roll" like Jim's photo. I did not pull it taut. I simply lined up the screw holes

The second two are the old diaphragm. Seems to have more of a "roll" to it.

The new diaphragm that I used could be very old.....20 years or more. Doesn't feel stiff, but............

The axle link is freely moving up down, about 1/8" plus. The surfaces look flat using a metal rule.

 

Chuck,

The new diaphragm looks fine to my eye. The less pronounced "hump" compared to the older diaphragm won't cause any issues. (Fun fact: In operation, the up/down movement of the diaphragm disc is only a few thousandths of an inch.) If it were mine, I'd probably try to get the slots in the diaphragm to line up a little better with the holes in the fuel meter lid, but that's just me.

The slight wrinkles visible in the last picture of your older diaphragm *might* cause some operational issues. It's impossible to say for sure. In extreme cases of diaphragm wrinkles, the diaphragm becomes so stiff that the engine won't start. If that diaphragm is otherwise still extremely soft and flexible, I'd be tempted to try using it.

Keep in mind, tho, that's I've got equipment which allows me to measure how well the diaphragm is working or not working. Absent such equipment, the safe approach would be to not use it.

 

Thanks for your advice, Jim.

Using the old principal of "repairing the thing you did last, before the problem began", I have nothing to lose by putting the old diaphragm in. It feels very flexible.

It barely runs with the new diaphragm I installed, and as I have mentioned, that is the only thing I changed. I did push the "axle" back in the axle link. Never touched any adjustments except the idle/air screw.

I can have it back together in about 45 minutes and give it a try. I'm trying to get the car running for my Corvette Club annual show on Sunday.

Ironically, the car has been running like a scalded dog for 10+ years..... until this axle link "incident".

I think I'll use a slight film of Permatex or Indian Head Gasket Shellac to hold the old diaphragm in alignment on the fuel meter.

Wish me luck. If it doesn't work, I'll order a new diaphragm, and try it again.

 

I reinstalled the old diaphragm. If you look at the photo, it has much more of a "jellyroll" around the circumference.

I painted a layer of Permatex on the top of the fuel meter, then put the diaphragm on, aligning the holes. Then, I painted a layer of Permatex on the underside of the gasket and lined it up. Finally, I painted a layer of Permatex on the underside of the "lid". Screwed it all back together.

The car was a bit cantankerous starting, but smoothed out, and ran better as it warmed up. I drove about 2-3 miles around my development. Then Vettefred stopped by. Took him for a ride, and when I got home, David V was there, so he got a ride too. Car is running very well.

Must have been the diaphragm? That's the only thing I can think of. I'll be ordering a new one to keep as a spare.

 

Hi Jerry,

If I'm more or less forced to send-out a '62 Rochester for rebuild, how many reputable folks would be open to the project?

Thank you, Sir!

Jay

 

Thought I'd post a follow-up on this thread.

Finally today, got the car running like the "old days". It's running great, like a "scalded dog" as they say.

I replaced diaphragms. I took the unit off the car and took it to an old friend in Dunedin, FL. He's been fooling with FI units for 50+ years. Original owner of a 62 FI car.

We spent 2.5 hours examining the unit. We couldn't find anything wrong. Tested the squirt pattern, tested things with a Miti-Vac, etc.

When driving the car, it has what I'll describe as a "lean surge". Won't run smoothly. Won't accelerate smoothly. Still difficult to start.

SO.....................

Today, I took the shield off of the fuel meter, the shield that covers the economy stop, the power stop, and the ratio lever.

What did I see? The ratio lever had slipped outside the economy stop screw, and was locked back in the most "economy" position. Wish I had taken a photo, but I took a screwdriver and pushed it forward, now placing the ratio lever between the power stop and economy stop. Nothing seemed bent...

Fired up the car.............and VOILA... it was back to normal. Don't know how that happened. Don't know how many of us missed it.

Attached is a photo of the ratio lever now between the economy stop and power stop. I'm gonna keep the shield off so I can observe this area. Don't want it happening again.

As a bonus, I did install 8 new spark plugs and a new set of points/condenser. Drained the gas tank and put in 10 gallons of fresh 93 octane no ethanol fuel. Ohm'ed my plug wires too. None of that helped.

 

Chuck, what that tells me is that the Ratio Roller inside the Fuel Meter has lost it's grip on the shaft of the Ratio Lever. There can be two reasons for that: First, the clamp screw has worked loose or, second, that the Ratio Roller itself has fractured (it happens). Either way, the Ratio Lever will walk out again and the lean surge will happen again.

You seem comfortable dealing with the Main Diaphragm, etc. So my suggestion is that you open up the top of the Fuel Meter and inspect the Ratio Roller for the root cause of the problem.

 

Thanks for responding, Jim. I was thinking the same thing, but for now, I'm exhausted working on this car. It's been 6 weeks.

My back aches, my forearms and hands are bruised and cut from replacing spark plugs, and on and on.

I'm gonna walk away for a bit and drive the car and see what shakes out. I'm wondering if somehow that lever got "man handled" and was forced over the adjustment screw? It seemed to snap back in place. I will keep an eye on it. I want to drive the car.

 

well now Chuck if it acts up again you know where to look and what replace.

 

Before you go for a drive consider this: When you pushed the Ratio Lever back into position, there could have been enough grip on the Ratio Lever shaft by the Ratio Roller that it got pushed close to the edge of the curved Axle/Link lever. It's also possible that engine vibration could cause the Ratio Roller to "walk" and clear the curved lever entirely. If that happens, the engine will stop instantly. You'll need a tow.

 

I'll take my chances. In the meantime, I'm gonna buy a new ratio roller to have on hand. I don't want to tear things apart, and not have the parts to put things back together..

 

Normally I am a subscriber to FI posts. Dont understand how I missed this one. Extremely interesting and enlightening for myself. The wealth of knowledge and experience and sharing is incredible. Thank everyone who contributes. Looking forward to the follow ups.

Drive em safe
Leo

 

I went out this morning, and measured (to the best of my ability) the in/out movement of the ratio lever

It will move in/out about 1/8". Obviously, when I push it "in" toward the fuel meter body, the body stops the lever. When I pull it out, it stops about 1/8" out.

Never paid attention to how much is normal "play" in this lever.

I started yesterday looking for a replacement "ratio roller" just in case I need one. No luck yet.

 

There should be no perceptible in/out movement. None. Zip-point-zero.

Frank Antonicelli has had Ratio Rollers in the past. Have you checked with him?

 

Thanks again, Jim.

No, I haven't contacted Frank. I will do so.

 

Frank is the only source I've known about. AFAIK he makes the Ratio Rollers. And, like his Axle/Link assemblies, they are little pieces of jewelry.