grumpy10956

bump

Pry

The problem with the ingition was dwell angle which was 20 degrees off. Took me a while to find a meter to measure it.

The problem with the fuel isn't the ethanol as it doesn't idle any better with the ethanol free small engine fuel than with the pump gas with 5% of ethanol.

Does the idle mixture screw affect also the cruise mixture or is it just for the idle? The economy stop obviously affects both.

jerrybramlett

I don't know of any auto pump gas (with or without ethanol) or aviation gas that has a high enough 20% boil-off point to give a reliable idle in a '57 - '62 FI unit during warm weather. Ethanol doesn't help the low-pressure boiling problem, but just eliminating it alone isn't a fix either. But I don't blame you at all for trying to find a cheaper fuel.

The idle mixture screw doesn't seem to have any effect on the cruise A/F ratio over ~2,000 rpm. At that speed the venturi vacuum signal is usually stronger.

Pry

Thanks, that makes it easier to adjust.

Is it possible to update the older fuel line design to the newer better one?
Edit:
Doesn't seem like it..

John E. DeGregory

Hi Pry, I read all of your comments between you and Jerry. He's one of the best and has told you a lot of great information.
Hope you don't mind me butting in but I do see why you are having some problems.
You may have answered one of your big problems above when you ask,"Is it possible to update the older fuel line design, etc"
That's a must as your fuel line is touching the valve cover. Hugging the valve cover big time. The fuel is boiling before it even gets to the fuel injection. The repro lines made in the USA are better than the one of your car but still they aren't that great as they are too close to the valve cover.
Won't take much to custom make a line in Finland. A friend has an original '60 FI car with the original line. I can put two fingers between the line and the valve cover. So work on that.
You mentioned you have popping, etc when you accelerate. If it's not ignitions problems then it could be the spill valve like Jerry said.
By now with all the poppping and even before it sounds like you may have a bad cranking signal valve. I didn't see if you have a manual or not. My favorite manual for your car is "Corvette Servicing Guide".
Where are you ordering your parts from. Most of the USA repro catalogs have this manual.
Cranking signal valve is located on the right side of the plenum (center section that has fins) It screws into the right front corner. Since you might not have a spare take it out of the system by doing this. Get a longer piece of rubber hose that will go from the CSV to the vacuum line. No room as is so unloosen that line at the T fitting on top of the main diaphragm cover. (Round cover that's on top of the fuel bowl)
T fitting on that cover. Unloosen the vacuum line and swing it up in the air. You will need a piece of 1/4" ID hose about 4 or 5 inches long. Start the car and then clamp off the rubber hose. Use whatever tool it takes to clamp the hose shut. I use what we call Vise Grips.
So the CSV is not out of the system. See if that helps you.
Jerry and I do not like the original spill valve that is possible in your unit. The thumbtack style spill valve will wake that unit up.
You are having problems with the accelerator rod going from the firewall to the fuel injection unit. You also have two accelerator return springs and you only need one. I bet the gas pedal is hard to push.
First things first. Remove the air meter to bellcrank rod. It's got an angle bend on it. Attaches to the bottom of the throttle shaft and then goes up to the part that swivels with the accelerator rod and spring attaches. That part is a Bellcrank. So now you have the rod removed. Put it in a vise with protected jaws. I want you to increase the angle of the bend a vew degrees. Your rod appears to be from a '57 fuel injection.The angle of the bend is not sharp enough. Use a rubber hammer (dead blow hammer) to bend the rod a tad. Your bellcrank is hitting the air meter or very close to it. Bending this air meter to bellcrank rod will help this situation by changing the geometry of the bellcrank. You will then have to adjust your round accelerator rod going to the firewall. That rod is not original but it should work.

Spring problem: Your have two springs. Only need one. Now I cannot see the one you have that goes from the bottom of the bellcrank to a L shapted bracket that is attched to the coil bracket mounting bolt. If it's the correct spring that's all you new Pry.

915 Distributor: Check to make sure your rare vacuum advance is any good. You will need a vacuum pump to test it. Put vacuum to the threaded front of the vacuum advance. Pump up and see if it holds without leaking down. If it leaks down then you need a new one.
Do you have an NAPA auto store in Finland? If so go there and order a B22 Vacuum advance. You can not readily buy the original one in your distributor.
In the future do not use the white teflon tape on the fuel filter inlet fitting. You are lucky now in that you did not break or split the casting on top of the fuel bowl. The inlet fitting area.
By the way Pry when you are working on a new fuel line at no time put any pressure on the fuel filter. IF you do you might break the fuel meter cover and those are very expensive.
The person that restored that unit used a rather sophiscated siphon breaker solenoid set up. He made an easy job difficult though.
Like Jerry said you need a 1/8" thick (almost) one piece gasket under the FI unit. Or see some of you car friends and see if they can suggest some readily available heat insulator for the time being.
Did you check the distributor points? You only have one set of points. You can order new ones at a NAPA store if you need them CS786 or CS786P. Order a new condenser why you are at it. I forget the part number but will get it for you. Email me at johndegreg@aol.com
Check your points. Without using a dwell meter you should have a .016 gap( approximaely) If they are burnt maybe you can cheat for the moment and sand or file the contacts. Make sure you have the spark plugs installed correctly. Firing order in the front of your intake manifold.
Look on Jerry's website for a good affordable spark plug. Or buy a set of AC 46 plugs on Ebay. To save major money buy the commercial plugs instead. Buy AC C46. Same heat range but very heavy duty and the fellows restoring their cars don't want them for judging. That plug will last you a long time.
NAPA also has a nice replacement distributor cap. RR168.
If you need an igntion coil buy their's also. U12 I believe is the part number.
Spark plugs again. Jerry lists the Autolite cross over number. Use it and order those from NAPA. Set the gap at .035".
If you need a new fuel filter element NAPA has it also. I think it's part number NAPA 3001. Original part number is AC GF157. Maybe someone here can get Pry the right number if 3001 is wrong.
Don't forget that your fuel line is really bad from your engine fuel pump to the filter. Causing you a lot of problems.
If you ever need an new air cleaner element and you shouldn't as yours is reusable. The part is a K&N E-1935.
You may have some dirt in the fuel injection nozzles. Clean them without taking them apart. I say that because of you loose an orifice or disc inside the nozzle you are in trouble. Just leave them together and spray some good cleaner thru them. I have no idea what you have in Finland but get a strong clean in a spray can. CRC or whatever they have. Remove the nozzles and spray thru them in both directions.
If you want to learn about fuel injections and I hope you do Pry. Then buy that manual I told you about. Read the theory many times over the years. Read the trouble section in the back of the fuel injection section.
That's the best manual for your fuel injection. Dont' waste money on any other one.
I have a part catalog with most everything you would need. Customs is heavy though. Do you have a USA mailing address?
Notice on Jerry's wonderful website that he sends fuel injection owners to me for parts. Thanks, John DeGregory.
P.S. That's a very rare fuel injection Pry. What's so unique about it is that is has a 7 digit number stamped on the side of the fuel bowl.Number ends is 202 or should. Can't read it.
You also have the original tag that is riveted to the plenum. That's a very rare distributor also.

Pry

Thanks John that’s some great info!
I’m gonna have to look into most of that during the winter when I have the time.

No NAPA stores in Finland so I'm probably going to have to order most of the parts from the US.
I don’t have an US mailing address. My cousin lives there but maybe it’s too much trouble for the little savings I might have.

The popping issue was fixed by adjusting the dwell to 30 degrees. It was around 10 degrees before so no wonder it was causing problems.

I’ve been using the 1953-1962 Corvette Servicing Guide.

The cranking signal valve was one of the components I was suspecting myself. When I block the line it doesn’t seem to have any effect on idle though. The valve leaks a little when I pump a vacuum to it but apparently not enough to cause problems.

How does the thumbtack style spill valve differ from the original one? Do you happen to have pictures of them?

Checked one of the injection nozzles and it seemed good as new. So I didn’t open all of them.

Pretty much the only issue I’m having now is the idle. When I start the engine it idles fine up to the point the fuel starts boiling and the idle comes very rough.
When I go for a drive on a country road the engine runs fine until I need to stop for a junction. Then it may idle or it also might have lost the idle completely. I would suspect the fuel to be reasonably cool at that point due the high flow of air and fuel I just had before stopping. Still I may not have idle at all.

Good to know it's a nice unit! This is the car it's mounted in


Thanks, Pyry

Pry

So here's my solution at the moment for the fuel vaporizing in the spider hub. I attached a 10 amp blower in front of the radiator and used the heater's fresh air line to deliver cool air with two 45 mm tubes to the spider hub. Seems to work so far what I have been able to test it.


















Next I think I'm going to replace the rather bulky blower with one of these once they get it for sale and install it directly inside the fresh air sleeve:
https://www.sanyodenki.com/news/news...ace_92cra.html

jim lockwood

Nicely done. Pumping that cooler air over the spider will definitely help. Consider running the blower for a couple of minutes before you do a hot start, if you are not already doing so.

Jim

wmf62

cool... (no pun intended...)
Bill

jim lockwood

Does this mean you would consider removal of all that eeeelektronik falderal on your car and going back to a righteous and pure Rochester unit?

wmf62

Jim
if I didn't have to deal with the very problem he is trying to fix I would never have done what I have done... (and it still amazes me that it worked/works...)

but, the original is complete and in a box, could be put back on in a heartbeat...

still doing the Bodie reenactment thing?



Bill

jim lockwood

Believe it or not, I do understand why you did the conversion. If I lived in a truly hot climate..... weeeeeellllllll..... I might be similarly tempted.... but only sort of. Read on.

On my own mongrel FI unit (put together from pieces and parts not suitable for use on a customer unit), I've been experimenting.

I've modified the fuel path to recirculate fuel to the spider like on the Sting Ray units and that has helped measurably..... as it should. More recently, I've added a 9th nozzle to provide supplemental fuel when fuel perc starts. This shows promise, but it needs more development.

Yep, Friends of Bodie Day is coming up in August, and we'll be there once again in our period costumes. Wouldn't miss it for anything.

Jim

wmf62

Jim
short of having a C2 fuel pump, I can't figure how you did that...

and, I seem to remember TPI units had a '9th nozzle' for cold start, but I think they abandoned that.. again, I can't figure where you would add another fuel source unless it was into the plenum...

i'm sorry I didn't get to spend more time with you in Bodie, but I got there just as they were shutting down for the day and the ranger ran me off...

Bill

jim lockwood

Probably not of general interest, so PM being drafted now.... As Radar used to say "wait for it".

tobi1310

Pry, nicely done cooling for your spider! At the moment I am working with exactly the same problem and bought parts to realize a cooling for the spider, too. I plan to use the same hose with a radial blower. My plan is to use some electrical circuits - a PDM circuit to regulate the rev of the blower and a tracking circuit that is connected to the ignition switch (you turn off the ignition and the blower will immedately start to blow air on the spider for a defined time - ideal for refueling stops). An additional thought is a temperature regulated circuit that starts to blow air on the spider if a defined temperature is exceeded.

During the last real hot day here in Germany (around 90°F to 95°F) I had enormous problems to get the engine alive during standing at traffic lights - there was no more than 2 seconds to react and keep the engine running with playing on the throttle.
Yesterday we had around 75°F and I had no problems. My air heater hose is removed at the moment - maybe this added a little bit of cooling?

My FI unit was rebuilt by Jerry some weeks ago (thank you again, Jerry!) and I had some winter gas in my tank from the last year. I hope to find a gas that has a higher boiling point to minimize the problems. I also have no chance to get racing fuel for an acceptable price (a "normal" US gallon is around 5 USD here in Germany, racing fuel would be a lot more expensive if I would get it easier). I heard from the carb guys that the "racing" fuel offered by Shell (V-Power) should work and I will give it a try. I also will show you my spider cooling solution as soon as it's finished.

Greetings from Germany from another young (28) FI Corvette owner ,
Tobi

Pry

Will do

That's an interesting plan! Keep us informed how it turns out.

I also tried to find a fuel with a higher boiling point from Finland but had no luck. Maybe the Shell V-Power has a different formula in Germany as it has gotten worse in Finland in the recent years (more ethanol). Hopefully you find a solution. It's definitely much nicer to drive when the engine doesn't stall every time you push the clutch pedal in.

63Corvette

Great and informative thread Thanks to both Pry and Jerry
Garrett

macster

FWIW - My 74 Fiat X1/9 had a factory blower system for the carb to combat fuel perc problem. It was thermostatically controlled by a small sensor mounted on the carb. It was wired to the battery hot circuit and ran even when parked during hot soaks.

I removed my FI unit because of the exact problems Pry was having with poor idle I think over the winter I may reinstall the unit and add the insualation to the fuel lines and the blower system and see how she goes next summer. Gives me some hope.

Mac