Fuel Injection: Restorer Article, Fuel Percolation Cure

[Roger W.]

Re: Fuel Injection: Restorer Article, Fuel Percolation Cure

I agree Jim. I have seen the electric anti-siphon valve several times in different Corvette magazines, but have never seen the recirculating fuel fix.

[Scott P.]

Re: Fuel Injection: Restorer Article, Fuel Percolation Cure

Jim, what I see in this picture is a dog house that has been cut in half, probably for modification internally, and welded back together. Well, did that help as hoped. Scott

[Jim L.]

Re: Fuel Injection: Restorer Article, Fuel Percolation Cure

Jim, what I see in this picture is a dog house that has been cut in half, probably for modification internally, and welded back together. Well, did that help as hoped. Scott

Good catch, Scott.

Yes, that doghouse was split open so the lengths of the tuned runners could be reduced, ostensibly to improve high RPM operation. That was a popular modification by racers back in the day.

The tuned runners in that doghouse have been shortened by about an inch and a half, down to the floor of the plenum. As implemented, I think the value of the alteration is over-rated.

My own simulations using Engine Analyzer suggest the improvement is very slight and doesn't appear until close to 8000 RPM. Meanwhile, the mid-range boost effect, which is real, has been compromised.

If there is any benefit to that type of modification, it would have come from shortening the runners only slightly.... say 1/4" to maybe 1/2".

I knew what that doghouse was when I spotted it on EPay and picked it up for cheap because no one else wanted it. I like it because this is a mongrel FI unit anyway and the presence of the weld is consistent with other visual cues.... the fuel meter was in a fire and shows it, the hard lines I made approximate the appearance of those of a '57 FI, the Venturi cone is from a Sting Ray FI, and so on....

Since nothing about this FI unit is "correct", I'm not destroying any value by modifying as I get ideas I want to try.

Jim

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[Dan H.]

Re: Fuel Injection: Restorer Article, Fuel Percolation Cure

Hi Jim, finally installed the nylon fuel block bolts, total improvement in keeping the nozzles cool, bolt, nozzles and retainer run about 120 degrees, plenum about 135+ degrees. Restart was easy, still a little edgy until driven to get cooler gas flowing through. Notice no gas smell after shutting off in garage, nozzles felt cool. Still running junk 91 octane California winter blend, less heat tolerance, so bring on the summer good stuff!!!! Thanks again, works fine.
Dan

[Dan H.]

Re: Fuel Injection: Restorer Article, Fuel Percolation Cure

Jim, after a long run at 85 degree temps, when stopped I noticed idle speed decreased by about 150 RPMs. I think the full thread screws are not sealing in the nozzle block. I found some 1/4 20 1 1/2 nylon bolts with a shoulder like originals. I'll replace the all thread ones and report back.
Dan

[John D.]

Re: Fuel Injection: Restorer Article, Fuel Percolation Cure

Dan, Where did you find the correct fat aka .247 shoulder nylon bolts at?

[Dan H.]

Re: Fuel Injection: Restorer Article, Fuel Percolation Cure

John, not here yet, I'll measure and test them, got them on Ebay, search and you'll find them.
Dan

[Dan D.]

Re: Fuel Injection: Restorer Article, Fuel Percolation Cure

McMaster-CARR has them in stock. 1/4-20 x 1-1/2; 3/4" non-threaded shank. Their P/N 91244A546. $19+ for box of 100. McMaster-CARR ships everything overnight - you would have them tomorrow.

You only need 4 - one of us could buy them and supply to others for a nominal cost. Say put a dollar bill in an envelope.

Dannn

[Dan H.]

Re: Fuel Injection: Restorer Article, Fuel Percolation Cure

Hi Dan, will be getting some this week, the shank measurement is critical, .247 at least. I'll report back if they check out.
Dan

[Leo G.]

[Dan D.]

Re: Fuel Injection: Restorer Article, Fuel Percolation Cure

McMaster shows the shank at 3/4 (.750 - that's half the bolt length). Need to know the results of the testing - then we can make a procurement decision. I'm sure nobody would have any qualms about a buck - that's only about a pint of gas right now. Wont even buy a cup of coffee.

May need some guidance on torquing them. Not going to be very tight.

I will volunteer to buy and distribute them if it works out. I have an account with McMaster. Their delivery (one day) is unbeatable.

Dannnn

[Dan H.]

Re: Fuel Injection: Restorer Article, Fuel Percolation Cure

Received the nylon bolts today, wrong ones sent, are all thread, so I'll run my originals, they work quite well,
Dan

[Dan D.]

Re: Fuel Injection: Restorer Article, Fuel Percolation Cure

Okay, I think I am just going to buy the NcMaster bolts. $20 not going to break the bank.

Will advise. Should have them Tuesday - maybe even Monday.

Dannnnn

[Dan D.]

Re: Fuel Injection: Restorer Article, Fuel Percolation Cure

Okay, I am now the proud owner of 100 Nylon Bolts, 1/4 20 X 1-1/2 with 1/2" un-threaded shank.

They also had the same bolt in PVC, but they were $19 for a set of 5 - almost $4 each, so I opted for the nylon. But PVC is more resistant to gas and oils, and doesn't absorb moisture like Nylon does.

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I know, not a very good pic.

I will dispose of them in sets of 5, so you will have 1 extra.

The cost was $30 - 20 for the screws and 10 for shipping and tax. Don't know if a single postage stamp will be enough, but a couple of bucks for the set should do it.

Dannn

[Dan H.]

Re: Fuel Injection: Restorer Article, Fuel Percolation Cure

Dan, what does the unthreaded shank measure?