Fuel injection high pressure pump question.

[Bruce B.]

When using unleaded gas is it necessary to add lead additive to the gas to lubricate the FI high pressure pump?
Is there anything else that can be added to the fuel to keep the pump lubricated?
Thanks.

[Jerry G.]

Re: Fuel injection high pressure pump question.

many people have been running unleaded for years in FI units, The problem is not lubrication for the pump but rather fuel boiling points that are lower in todys fuels that casue percolation and idle instability and hard hot restart. Many of us use racing fuel or aviation gas.

[Dan H.]

Re: Fuel injection high pressure pump question.

Bruce, just put some Marvel Mystery Oil in the gas and not worry about it! No problems with many miles on many FI corvettes.
Dan

[Jim L.]

Re: Fuel injection high pressure pump question.

When using unleaded gas is it necessary to add lead additive to the gas to lubricate the FI high pressure pump?
Is there anything else that can be added to the fuel to keep the pump lubricated?
Thanks.

The pump shaft spins in carbon bushings. The gears, if the pump is assembled correctly, clear the cavity in which they rotate. No supplemental lubrication is needed.

Jim

[Bruce B.]

Re: Fuel injection high pressure pump question.

Thanks for the peace of mind.
3500 miles on my 4360 and no problems.

[John D.]

Re: Fuel injection high pressure pump question.

Bruce and others, The carbon bushings are self lubricating so not additives are necessary for these bushings. 3500 miles on a 4360 is quite commendable Bursten. My congratulations. At least someone is having fun. JD

[Bruce B.]

Re: Fuel injection high pressure pump question.

Well thank you Mr. DeGregory.

Now I have a question, over the 3500 miles I have put on my 4360 I have used about 300 gallons of gas.
Yup that works out to be around 11 MPG.
Gas mileage is not an issue, but should I expect better gas mileage?
Bruce B

[John D.]

Re: Fuel injection high pressure pump question.

bruce, my GMC 6.0 tanker gets about 9 or 10MPG on an average.
Yes you should expect better gas mileage for your 57 unless you are running 4-56 gears.
On the other hand you are probably doing mostly local driving and in traffic.
Is your FI unit running rich? Gail Parsons used to tame those units down by adding a bleed to the air meter to reduce the strength of the vacuum signal going to the fuel meter.
Just thought of something Bruce. Did your 4360 originally have a coasting shut off valve? Is so is it blocked off now?
Look at the branch T-the brass T on top of the main diaphragm cover. What is the number stamped into this fitting? Is the restrictor in this fitting pointing toward the firewall. Don't assume that someone didn't drill it out also. Stick a pin gauge into this restrictor fitting and tell me what size it is.
Instead of wasting all that time let me tell you that when the coasting shut off valve was removed RP went to a smaller sized restrictor in the T fitting. If you have the original one it will tell the fuel meter it needs more gas because of stronger signal and cause excess fuel consumption.
There was a service bulletin on this. Maybe Ken Kayser has it in his fine book. Bulletin concerned putting a different T fitting on.
You should have a 118 T fitting Bruce. Originally it was a 122 or 124, etc.
Numbers mean .118, .122, .122

[Bruce B.]

Re: Fuel injection high pressure pump question.

John,
Thanks for the info.
I'll check out the 4360 when it warms up a little.
Bruce

[Dan D.]

Re: Fuel injection high pressure pump question.

Back in the late 60s - 1970 I ran a 7375 unit on my 54 Vette. 327 - T10, 11.25 pistons, Clay Smith 284B cam. That thing ran like an animal and pulled 15 MPG. By today's standards that would be a disaster, but back then I thought it was pretty good! -Dan-

[Paul Y.]

Re: Fuel injection high pressure pump question.

I'm getting 21 with my 63 @ 85mph. 327 w/ 10.5 to 1, 3151 camshaft, stock exhaust,336 rear ratio, FI set up with manometer, distributor curve for optimum, vacuum advance pickup drilled out as per Duke Williams suggestion. Balanced motor has 100k miles on it.

[Dan D.]

Re: Fuel injection high pressure pump question.

That's excellent Paul. My same 7375 is now on my 57, throttled down 327. Hydraulic, new cast pistons. Think the rear is 3.70 but not sure. When I get it going (hopefully next year) I will try some of these high tech tune-up mods like you did and see just what I can pull. Sounds like a lot of fun.
Bruce should be getting better mileage than he reports. Especially with a little 283. The boys here should be able to help him out.
We have also hijacked his thread - so I am done. Until next year - I will report my performance.
-Dan-

[Tom P.]

Re: Fuel injection high pressure pump question.

DANG!!!!!!!!!!!!!!!!!!!!!!
This is an NCRS forum and other people (besides me) are talking about NON-correct performance Corvette stuff! What in the world is this world coming to????
SURLY NCRS can't finally be waking up to the fact that there are other Corvettes and Corvette owners besides those who adhere to absolutes!
What a concept!

[John D.]

Re: Fuel injection high pressure pump question.

Bruce, I have thought about your primitive 4360 FI while working this week and have a question for you.
Are you running the stock original 4360 nozzles?
Say a person has no elaborate way to test nozzle spray. And you want to get some idea if all your nozzles are spraying good.
Here is nice cheater. Go buy a spray can of Gum Out carb choke cleaner. Put the red plastic extension on. Wear some rubber gloves and face mask,etc.
Now go outside and spray thru the nozzle. If you try that trick with a 4360 nozzle you might say to yourself. Holy crap what a horrible spray pattern. You see those nozzles are just drilled brass.
Now in the old days when they were brand new they weren't too bad. But seeing as they are almost as old as most members here they probably aren't worth squat.
Thing to do on a 4360 is pitch those nozzles and get a nice set of '4520 nozzles. They fit right in although you may have to go to the late 57 to 65 nozzle retainer. Then you have a decent spray pattern and therefore better gas mileage.
Just though of something. Guys used to drill out the 4360 nozzles with back yard drill presses. You know the rest. JD

[Bruce B.]

Re: Fuel injection high pressure pump question.

John,
Ill put "check the nozzles" on my list of things to do when it warms up a little.
Thanks,
Bruce B