ah53

65 Fuelie. Injection unit rebuilt by Jack Ponwell in Sept. last year. It starts and idles fine but "chuges"/surges at cruising speed.
So what is the correct initial timing?
The distributor has points but not a TI is this correct?
The advance can say B29?

The story: I always wanted a fuelie and bought this car off eBay where I have bought a number of other cars and done well. This may be my Waterloo as it has correctable issues but still issues. I drove the car about 500 miles before the rear wheel bearing went just as an example. It is "numbers matching" and correctly date. I did not pay for the numbers. Right now I want to get it running right and then go on to getting the dash powered correctly and maybe a front end rebuild over the winter.

Geralds57

Your timing should be set at 12 degrees. It does not have to have TI. It was an option. Check the rear end ratio. As fas as the chugging, fuelies don't like 3:08, 3:36 ratios, at least that's been my experience. It makes be caused from something else but check that first before making any fuel adjustments. Podell bench test his units so it may be fuel related.

65hihp

It's a pretty car, and a desireable one if a real 65 FI coupe. That FI guru was probably Jack Podell. And initial timing is on the Tune Up page of the Corvette Shop manual, 10*-14* degrees, with 12* nominal.
Stamp pad date suffix HG was points ignition, and HN was TI ignition.
Good luck sorting it out.

Donald #31176

The surge @ cruise could be the VAC. The correct VAC is Delco 236-16 or the replacment B28.

jerrybramlett

I don't understand. How did Ponwell calibrate your FI on a bench? I thought they had to be running on an engine.

jim lockwood

You are implying (I think) that fuelie engines don't like to lug at low RPM and that's not true. If a fuelie chugs at low engine RPM, it isn't set up properly.

One of the final tests to which I put an FI unit I've rebuilt is to do a wide open throttle, 4th gear pull from just off idle. Any chugging or hesitation and the FI unit fails the test.
Hmmmm.... I didn't think he did any testing.

Jim

Geralds57

Ken Hanson did mine on my engine. I have two friends here locally that Podell rebuilt for their cars but neither tested on an engine. We ended up taking both cars to Ken for calibration and a little tweaking on each unit.

Geralds57

[QUOTE=jim lockwood;1592319654]You are implying (I think) that fuelie engines don't like to lug at low RPM and that's not true. If a fuelie chugs at low engine RPM, it isn't set up properly.

Mine did not like my 3:36 so I put the 4:11 back in it. It runs great with the 4:11.

Critter1

I agree. I've done the exact same thing with several units on my cars and other peoples cars that I've rebuilt/calibrated the FI.

jim lockwood

Nothing succeeds like success, Gerald, but I think you just covered up a problem by changing rear end ratios.

Jim

DZAUTO

My 56, with a SB400 and a somewhat modified FI unit, has been run with 4.88 gears and 3.08 gears (and several in between). Runs great with any gear. With the 3.08 (that is what is in it now), It seems to purr nicely at 3000rpm/76mph. Same with the T-bucket. It has a 327 and 65 FI unit. Runs great at any speed/rpm.

OC-1

original 3:36 posi, close ratio trans trans and 63 FI in 63 coupe, 327/ 350, ....happy combo.

the advantage of FI is no stumble

ah53

Thanks. the car is running a 3:70 rear. The stamp pads HG which indicated non TI but for some reason I thought the TI was standard.

ah53

Thanks and yes it was Jack Podell. I just never get the name right. The car has potential but it needs to be gone through. Here is the stamp pad, feel free to add your thoughts.

ah53

I've tried to find those numbers but no one has them. Delco lists the part as 1382 for a fuelie engine but does not give any specs. It might be my best option. Thank for your thoughts and advice

ah53

Jerry

I assume the "What" is meant for me. When I bought the car the "dealer" had Podell rebuild the unit. The dealer installed it on the car and the dealer shipped me the car indicating it was set to go. It did go just not very well. If it needs "tweeking" I would assume it would be more that adjusting the venturi screw. I would first like to rule out any other possibilities. The car surges/chugs primarily when cruising hence my concerns on a correct vacuum advance unit and a complete check of the timing. I have gone over your web page and appreciate the work you have put into. It will be extremely helpful.

jerrybramlett

The surging at cruising speeds may be due to a lean mixture or too much advance. I'd first make certain the gear pump has an A.C. stamp and part number. If it doesn't, it's probably one of those Chinese paperweights that can't be saved.

A correct-spec low vacuum canister can be bought on eBay for $15 - $50. Make sure it is stamped "B28" before paying for it. For example, here's a cheap one that might be right... but I can't see the B28 stamping in any photo: http://www.ebay.com/itm/Distributor-...9XBvu1&vxp=mtr

With a good spider and gear pump, the economy stop on a 7380 unit usually has only one or two threads sticking out of the lock nut after calibration. The tips of the stops are usually about 7/16" apart. The enrichment diaphragm rod length should then be adjusted so that only 6 - 7 inches of manifold vacuum will keep the lever on the economy stop.

Here are the other things I'd check if it was my car:

- use a piston stop to make sure the TDC mark on the balancer is properly coordinated with the engine timing scale.

- make sure the nozzles are flow-matched by buying a new set of size X from Sharon Parsons in Ohio.

- install a new spider from Paul Mazut in Massachusetts.

- install an anti-siphon solenoid from Gary Hodges in Oregon.

- have Rollin Jones in Ohio re-machine the gear pump and repair the chisel damage from the last seal removal. The chisel damage is why your pump seal is now glued in place with epoxy.

- make sure the mechanical advance limit bushing is in place inside the distributor.

- set the initial distributor advance so that the total advance at high rpm is 36 degrees. Always disconnect the vacuum advance while checking total advance.

- replace the unbalanced GM or Ruben axle link now in the fuel meter with a properly balanced reproduction link made by Frank Antonicelli. These are available from quality FI parts suppliers such as John DeGregory and Gary Hodges.

- find someone mechanically competent in your area who has owned a properly set-up FI system in the past. He doesn't have to be a professional mechanic, but offer to pay for his time to teach you how to do typical FI owner repairs and maintenance. Dennis Pacy in Massachusetts is reasonably close. So is Rich Thomas in New Jersey. These two know what a good FI system can do. They won't excuse a problem by saying "they all run like that".

All the above advice assumes you've got a stock cam with at least .030" valve lash, nothing but real racing gas in your tank, a main diaphragm with a noticeable "hump" around the magnesium wafer, no vacuum leaks from warpage at the base of the plenum, a properly matched coil/ballast resister combo, and half-turn lean sensitivity (to kill the engine) in the idle mixture screw adjustment.

Also, don't run platinum plugs, date-coded repro plug wires, anybody's gasoline additive, or a piston in the choke housing. Eventually, those things will give you problems.

There is much, much more to a good FI rebuild than cleaning everything and replacing seals. I can't imagine how any FI repairman can expect a unit to run right without calibrating it and then test driving it thoroughly. But maybe they're just that much smarter than I am.

Good luck.

Donald #31176

The following are B28 P/Ns

B28
> > > NAPA VC 1810
> > > AC D1312C
> > > STANDARD VC 177
> > > NIEHOFF DR 305
> > > BW V329

The B28 which is made by Standard Auto Products was discontinued about 3 years ago. About a year ago Rock Auto had Delco D1312C still available.

SWCDuke

Lars' listing does not show a B29. It may be a long discontinued VAC or maybe you are not reading the stamped data correctly, so double check. Also, check it with a Mity Vac. The OE 236 16 and contemporary B28 replacement should start to pull at about 4" and be to the limit at about 8".

If you do need a B28 do a Web search for Airtex 4V1053.

Duke

Powershift

If you have $$$, a new and accurate/correct reproduction of the GM 236 vacuum can is available from a guy in Chicago. I can provide info if needed, although it is in the archives if you check.

Larry