Need help finding part for my '63 FI Unit

[Jack U.]

I'm just about finished with the mechanical restoration of my '63 coupe before it is taken to the painter over the winter.

I have one problem with the FI Unit and I need help tracking down businesses that supply parts. The person that is helping me with the restoration has some calls in to various people that he knows. They may or may not pan out.

The problem I'm having is with the choke staying open after the engine warms up. I think my father used the term "heat riser" but that may not be the correct term. The left side of the engine appears to be running "rich" which may or may not be an additional problem but I'll deal with that later if the choke correction doesn't fix it.

If you can provide me a few names that would be great.

[Alan Drake]

Re: Need help finding part for my '63 FI Unit

I think the part you are looking for is the Choke Valve Assembly. This is the same type part that is on a carb. Sits on the left side of air meter, is round, has a tube in the center that leads down to exhaust manifold which draws hot air. When air is hot enough the unit moves the Fast Idle Cam away from the fast idle screw thus letting the idle drop and opening the choke. The Choke Valve can be adjusted by lossing the 3 screws and adjusting the round cover a few notches to lean. The unit itself should be available from many suppliers.

If you do not have one yet, get a 1963 Shop Manual, it covers the FI operation for the novice.

[Dick W.]

Re: Need help finding part for my '63 FI Unit

Jerry Bramlett would be one source for FI parts and tech assistance. He is a frequent poster on this board

[Rick A.]

Re: Need help finding part for my '63 FI Unit

besides Jerry Bramlett at 251-478-4003, Jack Podell (has website) and John DeGregory (has website) are sources to check as they restore F/I units; also check with Frank Antonicelli at 717-566-5039

[Jack U.]

Thanks All

These are all good leads. Thanks.

[DANNY PANTUSO]

Re: Thanks All

If you want one of the best around he did my 63z06 TopFlight,his name is David Skiados out of North Carolina, 919-4604669.

[G B.]

You may not need parts, just repair.

The '63 -'65 Rochester FI choke design was flawed. Chevrolet tried to correct the design errors with two slightly different versions of a service "Choke Modification Kit", but those kits had design flaws too. Then when you add in the effects of carbon build-up, casting warpage, owner designed "improvements", and corrosion, it's a wonder that any of these chokes work at all.

Here's what I typically find when I repair '63 - '65 FI chokes. The diffuser cone casting has warped significantly causing the choke cross-shaft to bind. To overcome (rather than eliminate) this resistance, the owner has increased the initial cover setting in the rich direction. This will allow the choke to set itself when cold in spite of the shaft bind, but it makes the FI unit stay on choke too long. The correct fix is to eliminate the shaft bind by straightening the diffuser cone in a press or align boring the three holes for the cross-shaft. I prefer boring because it is less risky and more lasting.

You may also find that a past owner has installed a piston in the vacuum pull-off cylinder of the choke housing. Such a piston did come with the GM Choke Modification Kits, but no piston was used in the assembly line choke design. I don't use a piston either. I've found that they tend to stick over time because of choke housing warpage or carbon build-up.

The only modification I make to the factory choke design is to install a reproduction butterfly with a large open "window" in the upper half. This allows more air through the venturi cone while the choke is on and makes the butterfly plate significantly lighter (easier for the spring to actuate). I think a "windowed" butterfly plate is all GM need have furnished in their Choke Modification Kits.

Lastly, you should check to make certain the tube from the air meter to the choke housing and the tube within the exhaust manifold have not been restricted. Many Gyro Gearloose owners plug one of these tubes thinking it is a source of a vacuum leak. As a matter of fact, the whole system is a vacuum leak, but it's designed that way to suck heat through the exhaust manifold heat riser tube. Make sure the only restriction to air flow is the orifice in the center of the choke cover and the use of a baffle plate just behind the choke cover. You don't need to disassemble anything to check for good air flow through the choke housing. Just touch the chrome tube running from the choke cover to the exhaust manifold after the car has been running for 2 minutes. If you burn the crap out of your hand, good heat flow is happening.

[George J.]

Re: You may not need parts, just repair.

Jerry,

do you happen to have, or know of a source for, the choke housing itself for a '65 unit?
Thanks,

George

[Jerry G.]

Re: You may not need parts, just repair.

Your idea to open a window in the choke plate is very interesting. Can you describe the size and shape of window you put in the plate.
Also do you put bushing in the air meter choke shaft holes after you ream it out? Jerry

[G B.]

'63 - '65 FI choke housings

This choke housing (casting #7017271, GM part #7017270) was unique to the '63 - '65 Rochester FI system. It was not used on any carburetor and it has never been reproduced. I don't have any of these housings to sell you, nor do I know anyone who does. In fact, I've only seen a handful offered for sale separate from FI units during the last 30 years. Most rebuilders turn to relatively common choke housings from carburetors when they need a replacement to fit a '63-5 FI unit.

Rochester did use a choke housing on some 1962 - '63 carburetors that was identical to the 7017271 casting with two exceptions: the shaft hole was 13/32" diameter, and the casting number was 7016291. The larger shaft hole can be bushed down to the FI 5/16" size to make this housing an excellent substitute. Mounted on the unit it looks exactly like an original.

Rochester also used a similar, but not identical, choke housing on Chevy 6 carbs in the late fifties to early sixties. These housings will bolt up, but they have a "stepped" side wall that is quite noticeable. I sold one of these last week on eBay. It brought the princely sum of $10.50, and that included a brass reducer bushing for the shaft hole.

[G B.]

'63 - '65 choke butterfly window

I make the window the same general shape as the upper half of the butterfly plate, leaving about 1/8" of metal all around it (above the cross-shaft). It takes me about 30 minutes with a Dremel tool to make a neat window in a reproduction butterfly plate. I'm having a wholesaler price them in bulk quantities right now. I don't know how many I've made, but I know I'm tired of creating them one at a time.

When I align the cross-shaft holes, I primarily remove metal from the center hole to make it in line with the two end holes. It doesn't require much enlargement, usually less than .010". It never requires enlargement in more than one direction. I do not install a bushing.

[Jerry G.]

Re: '63 - '65 choke butterfly window

Thank you. Let me know when you have a butterfly you'd like to sell. Jerry

[George J.]

Thanks Jerry

Jerry,

you pretty much confirmed what I have found over the last 5 years. I have the housing but the threads that connect to the brass fitting on the tube that goes to the air meter are stripped. I have rigged it where it will work fine, but I would like one in better shape.
George

[Jack U.]

THANKS FOR THE REPAIR SUGGESTIONS!

Jerry, I can't thank you enough. The person helping me with the restoration only tried one of the suggestions you mentioned previously. He was totally out of ideas.

He told me to tell you that these are GREAT suggestions.

We're going to try them over the weekend and see what happens.

I'll owe you BIG TIME as we believe they will be right on target. As you can imagine, there is NOBODY in my neck of the woods that knows anything about these animals. You probably saved me a whole lot of money and time as a result.

[G B.]

You're welcome.

You'll notice that I didn't say "no problem". I'll leave that expression to the idiots who think it is an appropriate response to thanks.

I really don't mind giving free advice. That's good, because it's always been my best seller. I've cut back on my internet postings though because of a lack of feedback. It's frustrating to type out a lengthy response to someone only to have them disappear without comment.

The NCRS members who frequent this Board seldom leave me hanging. Other forums are not so polite, however. They allow posters to use a Secret Fairy Princess Name instead of identifying themselves. Then, after some jackass calling himself "427ratboy" begs for advice, the people who try to help are humped and dumped. This has cheesed me off so many times that I no longer even visit the other Corvette discussion websites.

Anyway, you are welcome to more of my free advice if you need it. Note to NCRS Webpolice: This is not a solicitation for business. I never charge for FI advice and I don't sell reproduction FI parts to Do-It-Ur-Selfers.