Fuel Injection: Restorer Article, Fuel Percolation Cure

[Jim L.]

Vinnie Peters did a remarkable job turning my abstruse, rambling, and mostly incomprehensible text into something readable in the current issue of the Restorer. Thank you, Vinnie!!

There are two points, however, I would like to clarify:

1. I don't advocate insulating fuel lines. My temperature measurements failed to uncover any benefit in doing so. If you look at the last photo in the article, the one of my mongrel, modified FI unit, you'll see there is no insulation anywhere.

2. The graph which shows how much longer it took for the onset of fuel percolation relates ONLY to the effect of recirculating fuel using stock, copper fuel lines. Since I converted my mongrel FI to have steel fuel lines and nylon nozzle block retainer bolts I haven't experienced fuel percolation at all. Not once. Not a single time, even when ambient temps were around 97 degrees.

For those who have emailed me since the publication of the article, thank you all for your kind, encouraging words.

Jim

Edit: For what it's worth, the attached picture shows the copper fuel line configuration which was in use when I collected the data for the article's graph.

8457.jpg

[Gary C.]

Re: Fuel Injection: Restorer Article, Fuel Percolation Cure

Jim,

On '57 FI's did you ever put insulation between the base plate and the big one piece gasket to help with fuel perculation?

BTW, nice article!

Gary
....

[David G.]

Re: Fuel Injection: Restorer Article, Fuel Percolation Cure

Jim, Thank you for all that you do for us Rochester Fuel Injection fans and also for our entire hobby.
Dave Gray

[Leo G.]

Re: Fuel Injection: Restorer Article, Fuel Percolation Cure

Jim, I to really appreciate you sharing your knowledge with the fans of Rochester fuel injection. They are a breed all their own but I am glad that I have the opportunity to own a car that was delivered with one and it runs rather well ( or at least it did till the high pressure pump seal let go) I am in the process of repairing that. Again thank you for being so gracious to share your knowledge and insights.

Leo

[Jim L.]

Re: Fuel Injection: Restorer Article, Fuel Percolation Cure

Jim,

On '57 FI's did you ever put insulation between the base plate and the big one piece gasket to help with fuel perculation?

BTW, nice article!

Gary
....

Thank you, Gary, for the compliment.

My friend who wrote the second of the two testimonials which appear in the article had some insulating board cut for each of us. Before I could evaluate its effectiveness on my engine, he tried his and concluded it didn't help. Once I learned that, I lost interest in doing anything with it.

One key thing I discovered in my research is that most of the heat which reaches the fuel does so through metallic conduction. Radiated heat, though significant, is much less of a factor in causing fuel perc.

To that point, the next changes I intended to evaluate were thermal isolation of the fuel meter from the plenum and thermal isolation of the engine-mounted fuel pump from the engine. I haven't tried either of these yet since the three changes I made have proven to be adequately effective.

[George J.]

Re: Fuel Injection: Restorer Article, Fuel Percolation Cure

Great information, Jim. Thank you for publishing it!

[Frank D.]

Re: Fuel Injection: Restorer Article, Fuel Percolation Cure

Congrats on the article Jim, there were so many requests for it on that "other" forum that I just mailed my copy of the magazine off to a friend from over there fighting with his F/I setup.

[Jim L.]

Re: Fuel Injection: Restorer Article, Fuel Percolation Cure

Congrats on the article Jim, there were so many requests for it on that "other" forum that I just mailed my copy of the magazine off to a friend from over there fighting with his F?I setup.

Have him contact me directly, Frank. I'll help him any way I can.

[John D.]

Re: Fuel Injection: Restorer Article, Fuel Percolation Cure

Hi Jim, As I told you before what a wonderful job you did on the project.
QT: Will the idle air tubes still fit? The two tubes shaped like a cross that connect the 4 nozzle blocks together.
Now Pontiac did not use those idle air tubes. At least on the '58 unit I did. Thanks, John

[Jim L.]

Re: Fuel Injection: Restorer Article, Fuel Percolation Cure

Hi Jim, As I told you before what a wonderful job you did on the project.
QT: Will the idle air tubes still fit? The two tubes shaped like a cross that connect the 4 nozzle blocks together.
Now Pontiac did not use those idle air tubes. At least on the '58 unit I did. Thanks, John

Thank you, John!

Yes, everything fits with the Idle Air tubes in place. I removed the Idle Air tubes only for the purpose of the pictures to clarify the fuel line routing.

Jim

[Dan H.]

Re: Fuel Injection: Restorer Article, Fuel Percolation Cure

Hi Jim, could you give me a source for the nylon bolts for the nozzle blocks ? ( for a 380 unit )
Thanks,
Dan

[Jim L.]

Re: Fuel Injection: Restorer Article, Fuel Percolation Cure

Hi Jim, could you give me a source for the nylon bolts for the nozzle blocks ? ( for a 380 unit )
Thanks,
Dan

The best source is an un-reliable dude named Jim Lockwood.

Seriously.

I had to buy 100 to get the 16 I've consumed to date. PM me your address.

Caveat Emptor: I don't claim and won't guarantee that simply replacing the steel bolts with nylon will cure fuel perc. The only claim I make is that after a hot-restart, the nozzle lines shed heat significantly more quickly. In and of itself that is a good thing.

[Jim L.]

Re: Fuel Injection: Restorer Article, Fuel Percolation Cure

Thank you, John!

Yes, everything fits with the Idle Air tubes in place. I removed the Idle Air tubes only for the purpose of the pictures to clarify the fuel line routing.

Jim

Since the publication of the article, the one question I've answered repeatedly is whether or not the Idle Air tubes will still fit with my modifications.

The answer is an unequivocal "YES". The picture of the steel fuel tubes was made with the Idle Air tubes removed only for the purpose of clearly showing the fuel tubes.

When I hand formed the steel fuel tubes, the Idle Air tubes were present specifically so I could ensure the fuel tube routing would clear. And it does.

[Roger W.]

Re: Fuel Injection: Restorer Article, Fuel Percolation Cure

Excellent article Jim. I was really impressed on how you had a hunch that the later model year fuel injection factory improvements would help prevent fuel percolation and the improvements could be adapted to earlier models.

[Jim L.]

Re: Fuel Injection: Restorer Article, Fuel Percolation Cure

Excellent article Jim. I was really impressed on how you had a hunch that the later model year fuel injection factory improvements would help prevent fuel percolation and the improvements could be adapted to earlier models.

Thank you, Roger.

I came up with the idea and the means of recirculating the fuel to keep the spider cool on my own. However I've heard from a couple of people that they did this in the '60s.

That puzzles me.

If true, then why isn't this kind of conversion as common as, say, the electric anti-siphon valve or the electric replacement for the cranking signal valve.

It doesn't add up.

Jim