62 Fuelie Crash Tuning Course

[Stuart F.]

Good Morning;

This is about a 62 Fuelie that my son has, and is about to complete a sale. Prior to then, we want to address several issues - one being the FI unit. my last experience was with a 58 unit and that was over 50 years ago. Does anyone know of a good source for adjustment/ service information?

We took a ride with the car yesterday, which was probably the longest it had been run since it's restoration in the mid- 90's (yup, a real trailer queen). It starts good, but will not idle below 1200 rpm. Normal acceleration seems to be very flat. We know the plugs were changed just before my son bought it, and runs without any sign of misfire. It does seem to hesitate, however.

Any advice will be appreciated.

Stu Fox

[Loren L.]

Re: 62 Fuelie Crash Tuning Course

Drain the gasoline and start over.

[Stuart F.]

Re: 62 Fuelie Crash Tuning Course

Loren;

Similar thought that we had. We had run it down to near empty before we put in 8 gallons of new fuel before the drive yesterday. But what you're saying is we should have actually drained out the old fuel entirely. Probably so. We had a similar issue with the 69 L-89 my son has. He bought both cars from the same collector. We ran that one near dry and it too was near flat for performance, plus leaking Holley Tri-power carbs. We filled the tank with non-ethanol plus TEL additive and rebuilt the carbs. It's running real strong now.

The new owner of this 62 will drive it regularly. He has an identical red/red 62 with the base engine and drives it a lot. But with what you're saying, perhaps we should just let him take it and drive it as is with the caveat that we make him aware of the situation.

Thanks for the advice.

Stu Fox

[Tim S.]

Re: 62 Fuelie Crash Tuning Course

Stu,

I had the same problem with mine. The butterfly was not centered in the unit.


Here is the thread from it.

https://www.forums.ncrs.org/showthre...-F-I-high-idle

Hope this helps!

Tim

[Loren L.]

Re: 62 Fuelie Crash Tuning Course

One additional thing - "Sea Foam" fuel injection/carb cleaner is the only thing that I've ever had the "feeling" that it works in removing varnish (or whatever) from a system. Try an overdose (2 cans for your 8 gallons) and see if it brightens up. Good luck. Might also check the filter to see how much it has captured.

[Stuart F.]

Re: 62 Fuelie Crash Tuning Course

Tim and Loren;

Thanks for your postings. Believe I'm much further on understanding this than I was this morning. Very good information. I too dealt with misaligned throttle butterfly's on one of my AFB Carter's. My original carburetor was stolen and replaced by another incorrect model while my car was in a Corvette shop in Illinois for some serious repairs after I hit a deer. My first concerns were with issues I had with the work, and then later I realized I couldn't get the engine to idle down. Upon closer inspection, I found the carb change and the Bubba messed up butterfly's. Some one had started to disassemble the carb, broke the screws, then tried to epoxy them back in place. I of course went after the Corvette shop, but they pleaded innocent. Upon closer look at the car, I found they also took my master cylinder, starter, fan clutch, and other parts. They even had the gall to admit they coveted my glove compartment door (which is perfect).

Thanks again guys. Appreciate your help a lot.

Stu Fox

[John D.]

Re: 62 Fuelie Crash Tuning Course

Good Morning;

This is about a 62 Fuelie that my son has, and is about to complete a sale. Prior to then, we want to address several issues - one being the FI unit. my last experience was with a 58 unit and that was over 50 years ago. Does anyone know of a good source for adjustment/ service information?

We took a ride with the car yesterday, which was probably the longest it had been run since it's restoration in the mid- 90's (yup, a real trailer queen). It starts good, but will not idle below 1200 rpm. Normal acceleration seems to be very flat. We know the plugs were changed just before my son bought it, and runs without any sign of misfire. It does seem to hesitate, however.

Any advice will be appreciated.

Stu Fox

Stu, Do you have the shop manual? Corvette Servicing Guide is the worlds best. Actually features a 62 fuel injection but the info is great for '58 to 65.
Only fair for the '57's.
Qt: Did your son's son ever idle down below 1200? If so what RPM. How is engine timing. How much vacuum is the engine putting out.
Did you try adjust the idle screws? The big fat idle screw (horizontal) is for adjusting idle. The idle fuel screw is for smoothest operation, etc.
Cheater if all else fails. The '62 has an throttle plate adjusting screw screw. (has the best set up) Unloosen the jam nut with and turn the pan head screw out to decrease the clearance between the brass or steel (some 62's used a steel throttle plate). Yes I know you are supposed to adjust the idle with the venturi.
As Loren said you could be gummed up. If the 62 has Bill Thomas's favorite (not mine) spill valve than the piston could be hanging up because of good old ethanol.
I see so manyt '62's that appear to be having accelerator return spring issues. They have two maybe three acclerator return springs.
Maybe your accelerator rod clevis is out of adjustment if this car never idled down slower than now. If so that's an easy fix.
Disconnect the accelerator rod. Just hold the bellcrank with your hand and see if you can get the engine to idle slower.
Oops. Forgot something. Is the choke working. Is the choke butterfly all the way open? '
62 was the first year for a carbuetor choke. Wild contraption so it is. Choke rod almost a foot long. Could be binding. Linkage may be gummed up.
Use some good spray chemicals to loosend it (if you are lucky). Check the choke cover to see if it's hot when the key is on.
You should have called me. Hard typing all this stuff. John

[John D.]

Re: 62 Fuelie Crash Tuning Course

Spill valve piston must be hanging up. Accleration flat and idling fast. Listen to Loren. Once in a while he says something good. LOL

Meanwhile after 50 years or so here is what I have learned about 58 to 65 FI's. If you don't want comebacks then pitch the Bill Thomas favorite spill valve. Use the thumbtack style spill valve period. Now if your good guy spill valve works and you are happy that's great. JD

[Stuart F.]

Re: 62 Fuelie Crash Tuning Course

John;

Sorry, I should have called. Just know how busy you are now, etc. Thank you for the effort you made to type your thoughts. i would have gotten back to you sooner, but I've been waiting for my son to have enough free time so we can sit down and develop a plan. He flew up to JFK yesterday and would have been here this morning had his plane not broke. With the new FAA rules, the time he was waiting for the mechanics to do a fix is counted as flight time and he timed out and had to spend the night in a hotel. He was then supposed to start a three day trip today, but they dropped him from that too so he dead headed home this afternoon. So, we'll finally have a nice cool morning tomorrow to work on it together.

I'm making notes now to do an analysis of the 62's problems tomorrow. We looked at the unit yesterday briefly after our warm up ride and could not see any leakage at the high pressure pump mount. One point I want to note about the quality of the fuel; Prior to my son's purchase of this car, the previous owner/collector had dropped the fuel tank and cleaned it out. That's what he said, and we have no reason to doubt him. He's a straight shooter (NCRS member) and has a real nice well equipped garage to take care of his many cars.

Thanks again John.

Stu Fox

[Stuart F.]

Re: 62 Fuelie Crash Tuning Course

I spent practically the entire day working on my son's 62 Fuelie. Even with all the information I was able to glean from my research and the advice from my NCRS friends, I still ran into a number of issues I wasn't prepared for:
1) The choke on the 62 has the high idle cam to which the adjustment screw maintains contact with even when the choke is full off. This then provides one of three idle adjustments. The other two being the air screw and the fuel/mixture screw.
2) My son had put on a new choke cover on which the bi-metallic spring was assembled upside down. He installed it referring to the original for positioning with out the spring engaging the tang on the choke shaft. I corrected this and we did a startup. Nothing changed. The unit still wanted to idle at 1200 rpm. Any attempt to reset the choke high idle screw, or the air and fuel adjustment screw brought about almost immediate engine stall. With a vacuum gauge connected, and further attempts to balance out the adjustments by observing reactions to them, we were able to get the engine to idle at between 1000 to 1100 rpm with a vacuum reading at or above 17" hg. We were able to improve the engines response and eliminate the flat spot on acceleration. Then, after moving on to other issues for awhile, we returned to doing another startup and found that all our previous idle issues returned. Very frustrating! The engine runs rougher than any Fuelie I've ever seen.
3) Next, I went after the distributor fearing stuck weights. My first suprise was to see a two window cap. I believe it is correct, but dumb me, I never expected it. Unfortunately, my dwell tach meter chose this time to shoot craps (I haven't looked at this instrument for maybe 30 years, or since I last used points in my distributors). We did check the timing before and after I cleaned the weights and applied new springs. The advance restrictor bushing was laying on the distributor plate, so we cleaned it up and reapplied it. Not being able to get the idle speed down to spec, all we could do was look for a ball park reading for now.
4) We did a test for vacuum leaks and found none.

I believe we may still have a fuel problem and may try some sea foam in the tank.

The car runs good enough to have the new owner test drive it. Although we were unable to get the idle right, at least it won't die at a stop light, and it otherwise runs strong. We will have to make sure he understands he is buying a beautiful trailer queen, but if he drives it much he'll have to expect different problems will pop up. It is an older Top Flight car, and everything we checked it is exactly as it should be. All numbers and details are correct. We even pulled off the hardtop and found a beautiful like new white convertible top that fit perfectly, even with the expected wrinkles.

Stu Fox

[Stuart F.]

Re: 62 Fuelie Crash Tuning Course

OK, now that I have re-read your posts, it seems clear this unit has some internal problems - likely this so called "spill Valve". After (May be), if given the chance, I'll study this further and at least be able to explain to the new owner what is wrong and what needs to be done to fix it.

The thing that still makes my head spin is my #1 finding with the fast idle adjustment screw maintaining contact with the fast idle cam even after the engine is fully warmed up. It just don't seem to be right. Could someone have bent the linkage that much to bring this about?

Stu Fox

[Jim L.]

Re: 62 Fuelie Crash Tuning Course

The thing that still makes my head spin is my #1 finding with the fast idle adjustment screw maintaining contact with the fast idle cam even after the engine is fully warmed up. It just don't seem to be right. Could someone have bent the linkage that much to bring this about?

Couple of comments:

1. With the choke fully warmed up, the fast idle cam definitely should clear the fast idle screw. Bend the link rod which connects to the fast idle cam as needed to achieve this.

2. 17" vacuum is more than enough to allow setting idle speed and idle mixture with the two spring loaded screws on the rear of the air meter if everything else about the unit is "right".

3. If you can't get the idle speed down even with the large Idle Air screw fully seated, make a very small adjustment to the stop screw on the bottom of the air meter and try again (I suggest trying 1/4 turn at a time).

4. If the engine still won't idle down, you almost certainly have a leak at one or more of the plenum feet where they attach to the adapter plate. This is almost always due to the plenum not being completely flat. The right way to fix it is to have the bottom of the plenum lightly machined. Bubba gets good results, too, by just double gasketing the plenum.

Jim

[John D.]

Re: 62 Fuelie Crash Tuning Course

Stu, Corvette Servicin Guide 6M-23 Air meter and choke. One time at an NCRS regional I was called over to look at someones 62 that had choke/idle problems.
Stared at the drivers side a few seconds and found the problem.
Look at Fig 72. Positioning air meter ho se adapter. Notice the clearance between the hose (forward balance tube to air cleaner adapter) and the lower wildly bent choke rod. Make sure the hose is not touching the choke rod.
Doesn't take much to have a 62 choke hanging up See if the choke shaft/butterfly is not binding in the air meter cone.
As Jim mentioned you must bend the upper choke rod to suit. I use two pair of pointy pliers. Taped all over them so I don't gouge the rod.

I use an AC-DC converter to test the chokes. I set it on 13.25 or so Volts. Battery chargers are typically all over the board on voltage output so I gave up on them.
Test the choke assembly with the engine off using a 12 Volt source. Should take 4-1/2 to 6 minutes or so to go from Fast idle to off idle.
I would suspect you have choke shaft bind. Haven't seen a 62 come in the door yet that did not.
With 17" of vacuum (very good) you should be able to idle that baby down to 850-900 with no sweat.
If the rubber hoses are cracked that hurts the idle circuit but it would not effect the idle also. But not to the extend of the high RPM you are having.
I am going to guess all of your problems are in the air meter/choke assembly.

Make it easy for the moment Stu. Bottom of the verticle throttle shaft. Big adjustment screws. 1/4-28" long screw with a jam/lock nut. Unloosend the lock nut. Back out the screw. Try 1/4" turn at a time. Idle just has to come down. See Fig 70.
I assume your son has the shop manual for the car. Corvette Servicing Guide also known as the ST12 manual. Available from NCRS, etc.
It has the worlds best FI section.
See fig '69. Checking butterfly clearance. No set clearance for a 62 no matter what anyone tells you in writing or otherwise. Gail Parsons and I used to chat about this often. 62's are tough. Clearance can be anywhere from .002 and up. Whatever makes it work.
I usually will start off with a tight .004 clearance. But forget all that crap. JUST BACK OUT THE SCREW FOR NOW.

[Stuart F.]

Re: 62 Fuelie Crash Tuning Course

Thank you Jim and John for your expert advice. Being a carburetor man for well over 50+ years now, I realize I am in over my head. I left off with my 58 Fuelie unit when I sold it back in 1960 and never looked back. I had my fun whistling around with it in my 50 Chevy coupe.

All that asside, I hope to get my son's flight schedule for August soon so I can get some more time with this 62. One thing I am confident with is the choke shaft on this unit. I had the cover off and could easily move the tang from stop to stop freely. But, for some reason or other, someone bent the long link (nice job by the way) to make it idle off the fast idle cam. My guess is they were experiencing idle problems and couldn't take the time to troubleshoot it, rather they just did a quick plumber job to get it running in order to sell it. We can't do that.

Thanks again. I'll touch base with you either before Carlisle, at Carlisle, or after.

Stu Fox

[Barry H.]

Re: 62 Fuelie Crash Tuning Course

Stu, The boys are correct, I just checked my 62 & the fast idle screw does NOT contact the cam when fully warmed up. The idle speed then is controlled by the screw on the bottom of air meter & the large idle air bypass screw on the side of the air meter. Barry Holmes