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Mike,
I own a 63 fi coupe. crank time for me is reletively low. i would say that she fires up in 2-3 seconds on 50 degree cold starts regardless of sitting for a day or week. The only time i have to "deal" with starting it is after it sits all winter (4-6 months of sitting). Hot starts require me to press gas pedal to floor - then it fire right up
I had a 62, which is basically the same unit mechanically. It started in 3-5 seconds cold, and instantly hot, with the throttle about half open. Are you depressing the throttle once before start to set the choke? If not, depress the throttle once before cold start to set the choke. Then leave the gas pedal alone. No need to pump it, there is no accelerator pump. If it's properly set up, it should start pretty easily.
I have (2) 63 FI coupes, both with fresh engine and FI rebuilds and neither will start without being primed. We have found it is better to prime compared with cranking on and off for 3-5 minutes. All the best parts were used in the FI rebuilds and still need to prime. If one started immediately it would indicate our error on the other. Both injection units were rebuilt by known specialists. Both have tested cranking valves. Maybe we need electric fuel pumps. In 1963 my father had the same starting problem. Must run in the family.
1) CSV effectiveness. There is a big difference in CSV's. Some "work", but seal off too quickly. The best CSV's are rebuilt originals. Even those don't test perfect forever. Every now and then one will go bad very early in service.
The NOS Cranking Signal Valves are all no damn good by now. Well, that's not exactly true. They're just fine as cores for rebuilding. The all-new reproduction CSV's are...uh...not nearly as good as properly rebuilt originals.
2) Engine vacuum during cranking. Measure your intake vacuum while cranking. Three inches is great, two inches will work, and one inch or less means you better keep the can of starting ether handy.
Cranking vacuum varies with more than ring and valve sealing. It also changes with cam event overlap, compression ratio, starter motor speed, and position of the throttle butterfly.
The choke setting doesn't come into play much on a '62 - '65 unit until the engine fires. It does set the fast idle cam which affects the throttle butterfly position, however. If your '62-5 FI engine takes more than 5 seconds to light off cold, try cranking before you set the choke. Then stab the pedal once after you hear the engine hit.
Bottom line if you're having trouble starting a '62-5 FI engine: contact the known (or unknown) specialist who provided the CSV in your unit and find out exactly where it came from and how it was tested. If your engine pulls 2 -3 inches of cranking vacuum, then the CSV needs an instrumented test to see if it's sealing too quickly. And no, I don't mean a mouth suck test unless you can read a vacuum gauge plumbed to both nostrils while you're doing it.
In 1992, I decided to take the 63 FI roadster to Palm Springs for the vintage race and the 40th Anniversary celebration. After sitting for 2 years in Dick Daleiden's barn and a 45 minute battery charge, the car lit fired and ran after 15 seconds of turning over. You should NOT have to prime the unit every time you want to start the car.
In the last two paragraphs of my post above, I should have said "7360 - 7375 series units" rather than "62-5" units. Of course most 64 and all 65 injected Corvettes had 7380 series units which didn't use a Cranking Signal Valve.
I also should have mentioned a rare internal fuel meter problem that I've only encountered once. This 7375 unit owner claimed his FI engine was impossible to start cold without priming. The FI unit had been rebuilt by a known FI butcher many years before. This rebuilder had used a chisel to remove the gear pump seal. Among other damage, the chisel broke the outer carbon bushing around the pump shaft. The outer bushing wasn't replaced. That let the gear wobble a bit and chew into the pump end plate. The excessive clearance on the gear caused the pump output at cranking speeds to be so low that it wouldn't effectively seat the anti-siphon pill valve ball. I believe that during cranking much of the pump output was then spilling back into the fuel bowl through the partially open anti-siphon valve. The rebuilder didn't catch this problem because he didn't calibrate the unit or even test start it on an engine.
Bottom line if you're having trouble starting a '62-5 FI engine: contact the known (or unknown) specialist who provided the CSV in your unit and find out exactly where it came from and how it was tested. If your engine pulls 2 -3 inches of cranking vacuum, then the CSV needs an instrumented test to see if it's sealing too quickly. And no, I don't mean a mouth suck test unless you can read a vacuum gauge plumbed to both nostrils while you're doing it.
Jerry:
I would love to contact Rochester and chew their rear end for putting out a faulty product. I have two 7375 units and have had them for years. One of them, I rebuilt maybe thirty years ago and the other hasn't been touched since it was new. I ran both of these on an L-79 stock engine as recently as two years ago. However, in my memory, neither of them would start quickly after not being used for a week or so and if they set for a month, would take extended cranking to get them to start even when the units were almost new. Restarts after the initial are instantaneous.
Per your suggestion, I get 1" of cranking vacuum. I know the rings are stuck in this engine from dis-use so that is probably causing the low vacuum. However, when the engine was near new, I think I still had extended cranking after periods of non-use and that was what prompted the "survey".
I also did some checking on the cranking signal valves. I applied vacuum to pump 15" on the threaded side with my finger over the nipple side. Released the finger and:
One of them took thirty seconds to drop from 15" to 0.
One of them dropped to 0 in seven seconds
The third one took 120 seconds. Interestingly, two days ago, the same test on the same valve only took 15 seconds.
All three of these valves are either original or near original. I think I replaced one of them because of flooding. Interesting to note that you said even NOS would not be any good now, let alone used ones.
Any comment?
PS. I did get two off-line e-mails. Both of them reported less than instant firing after sitting for a week or so.
Mike, I don't disagree with your slow start scenario. Watch a clock with a second hand for 5 seconds and think about cranking an engine that long. It's quite a grind.
Here's a factor that your survey question didn't address. If an FI engine sits idle during hot weather, the gas in the fuel bowl will evaporate. That adds even more cranking time to a set-up with a CSV since the bowl has to fill a little before the gear pump gets gas.
While your CSV test is interesting, it's not the ideal method for checking valves. A CSV is supposed to pass intake vacuum to the main diaphragm while the engine is cranking but then shut tight as soon as the engine is running. So to test for proper operation, you must slowly increase the amount of vacuum sucking on the threaded port (while leaving the hose nipple open) to find out at what vacuum level the CSV seals. Of course you want the CSV to stay sealed while the engine is running, even if the intake vacuum level drops low (like when you floor the car).
Let's face it, the CSV design is one of those good ideas that just doesn't work well in the real world. Here's the story I was told. GM finally eliminated the CSV for good in mid-'64 at the insistence of the St. Louis Plant. The Plant was fed up with injected Corvettes that would not start or run right at the end of the line. They contacted Rochester and told them to get rid of the CSV on FI units or the Plant would stop installing FI on Corvettes. This threat led to the solenoid controlled starting by-pass system that was first used on the 7380 series.
In your shoes I would send those two old valves to Frank Antonicelli for testing and repair. I believe I've already given you his number.
Thanks Jerry. I can relate to St. Louis telling Rochester we have a "no build" situation and have the horsepower to stick to their position.
It seems from the responses I got, it is normal crank time for one of these units to start either instantly or take a while.
The whole purpose of my inquiry was to make sure I wasn't chasing something that wasn't broken.
By the way, the same engine I reported on that had only 1" of cranking vacuum is the same engine I used to install the 7380 unit on that you calibrated. In spite of the low vacuum and stuck rings, it would start instantly. Even after sitting un-used for several weeks. Just more Meat for the story you heard about not starting on-line.
By the way, since the last post, I put the CSV on the injector that would bleed off from 15" to sero in seven seconds on the engine. It hadn't been run in two days but there was definitley an improvement in starting response. Must be something to this.
Thanks. Mike
Slightly off subject but, many years ago, I installed a fuel by-pass solenoid from a 64-65 380 unit on a 375 unit, in place of the CSV. Used a short 1/8" pipe nipple to connect the new valve to the enrichment cover, used a new line from the plenum and wired it to the starter solenoid. Was ugly but that 63 sure fired quickly. I think an old TCS solenoid would have worked as well and looked a little better.
If you bought five new CSV's, even back in the late 60's or 70's when they were still fresh, only two or three would work properly.
The sad truth is that the "unreliable" reputation of the '57 - '65 Rochester FI system was well earned. I assume that GM didn't bother to fully address the design problems because of FI's low sales volume.
It's possible to construct a unit that has most of the design flaws worked out. Of course it wouldn't be stock for any one year model, so no NCRS member would have it on his car.
I know Rochester flirted with good engineering design throughout the nine year life of the FI option. They just never produced the right combination of features to make the units as reliable as a Quadra-jet. They got the system to the point of matching a Holley for reliability and said "that's close enough - ship 'em".
They then followed that poor decision with service support patterned after the Jaguar business model. If you broke down in Chickenlips, Texas, you were on your own. Local car mechanics had no idea how to diagnose or repair even the easiest problems to fix (like CSV failure). That left FI owners to become Do-It-Ur-Selfers. The results were disasterous. You should see the mutilated and homemade parts in my "Hall of Shame". I'm sure there are some classic cob-jobs I haven't run across yet, but I've already seen so many I have nightmares about being chased by Gyro Gearloose and his little lightbulb friend.
You sure you don't want that Restorer Editor job?
It sure is fun to read your posts.
I'm just hoping you write down half of what you learn on these old FI units. I can't imagine what us young pups are going to do in 20 years to figure them out.
Patrick
Vice-Chairman (West), Michigan Chapter NCRS
71 "deer modified" coupe
72 5-Star Bowtie / Duntov coupe. https://www.flickr.com/photos/124695...57649252735124
2008 coupe
Available stickers: Engine suffix code, exhaust tips & mufflers, shocks, AIR diverter valve broadcast code.
Actually, the 64-65 units were getting to the point of being very reliable but, as you mentioned, the cost involved was a lot more than GM wanted to invest. Plus, the writing was on the wall when the new 396 was due to be released and it's retail price was less than the FI option.
I've heard, several times, that GM's cost for the unit from Rochester in 1965 was near what they were charging the retail customer for the L84 option. They were still coming out on the plus side though, because they saved the cost of a carburetor and intake manifold etc.
Another big problem with the FI all through it's production was not the FI itself but the lack of knowledge in the field for diagnosis and repair. If a car came in to the dealer or local service station in Chickenlips, TX with a driveability complaint, the FIRST thing every mechanic tinkered with was the lean/rich stop settings on the FI. When that didn't help, (because there was nothing wrong with the settings) some actually found the real problem which was not at all FI related. However, by that time they had the settings so screwed up the car would never again run correctly with the FI so the next step was to remove it. If something is new and mysterious, that has to be the problem, right?
One of the biggest complaints through the years was starting, both hot and cold. As you mentioned, it seems they tried everything to solve the cold start issues but it wasn't until the 380 unit arrived that they finally had a handle on it. I'm surprised that the early 50's systems ever worked, ever. That was Rube Goldburg in his finest hour. I still love em tho. When their right, they sure run well.
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