In a prvious thread there was a discussion about how to reduce fuel line heat sink in 67 GT500s.
If you have attempted to live for any period of time with one, you may have noticed that they can be temperamental and difficult to re-start a hot engine?
Several remarked that they were convinced that the Ford fuel log used was part of the issue
This is what I did for that particular issue.
This black tubing is Delrin. It is generally about 98% or more non absorbent of heat or cold. It always seems to be cool to the touch regardless of how hot it gets and your hand will never freeze to it in sub-zero temps.
This particular piece is 1 inch od, and half inch id. That's a 1/4" thick wall. You can't insulate the fuel much more than that.
These support brackets are aluminum, and rather then running to the intake manifold bolts run to the mounting studs for the carbs.
At the moment I like it in black. I had intended to paint it with Eastwood bronze carb renew to make it look a little more stock but for the moment I'm holding off on that.
It's been installed and pressure tested but hasn't been put through the paces yet. So far, so good.
This is just a hypnotic subliminal suggestion to some of you still searching for more help on the heat sink issue.
I'm not attempting to corrupt those away from the purity of the original part. Just maybe whispering in your ear? ;)
This ones on my 347 in my 68 so if all goes well, the 67 GT500 can expect one also.
Doug, how did you attach the mounting tabs?
The tube is drilled and tapped for two 8-32 Allen socket screws on each bracket.
They are hidden beneath the brackets.
I have a friend with vapor lock problems and was thinking about doing something similar for him. I told him to add some phenolic carb spacers and wrap the fuel log with header wrap to start. He hasn't done that yet, so I'm not rushing to help him.
I was thinking about doing an inner and outer metal tube with either an air gap between them, filling the void with heat block paste, or make a thin wall nylon tube to fill the void. Your idea is much easier to build, so I'll be waiting for your update. Thanks
On my hot engine, the carbs and the fuel log are cool to touch.
This Delrin machines easily and you can do it with a moderate variety of tools.
Did you drill into the ID of the Delrin when you mounted the tabs or stop short and use a bottom tap? Seems like it would be tough to use a bottom tap with only 1/4" wall.
Any concerns with Delrin over long term exposure to gas and or ethanol?
Quote from: KR Convertible on September 01, 2020, 10:09:38 AM
Did you drill into the ID of the Delrin when you mounted the tabs or stop short and use a bottom tap? Seems like it would be tough to use a bottom tap with only 1/4" wall.
Any concerns with Delrin over long term exposure to gas and or ethanol?
I made a bottom tap and a bottoming drill bit also. I used a stop on the drill bit and got just about 3/16" of thread.
Delrin is impervious to most compounds such as gasolene.
You could delete the mounting screws and modify the bracket to take a zip tie.
I think that you need at least a drill press for this. That's how I did it. I admit that 3 way mill would be better.
I bet scuffing the Delrin and mounting tab and using JB weld would hold it place quite well.
Quote from: 2112 on September 01, 2020, 01:21:45 PM
I bet scuffing the Delrin and mounting tab and using JB weld would hold it place quite well.
Possibly but I can tell you that not much will stick to the Delrin. Silicon caulking will not.
We make Delrin fuel manifolds at my work and bond in the stainless steel hose tubulations with Reltek B/536 two part adhesive.
ww.reltekllc.com/productlist/b536adhesivesealant(variantb575).aspx
Mike
What do you do to prepare the surface of the Delrin? This tube is very slick and I haven't found anything that will bond to it but I hadn't evolved to this thought as of yet?
I have 3m panel adhesive that mixes in 2 parts and bonds steel and aluminum panels together like they are welded? Hum. Off to experiment.
What is the temperature range that YOUR manifolds are expected to operate under at the extremes?
Your input helps as this is an evolving solution. You opened a train of thought that I hadn't gotten to yet.
Thank you. ;D
The phenolic isolation is also expanding into isolating my ignition coil as well. I'm having a continuing problem of difficult hot restart and it keeps pointing at the ignition coil being overheated.
My entire fuel system, including the carbs are now cool to the touch on a hot engine, so vapor lock is unlikely now. It has to do with a Petronix ignition coil becoming intermittent when the engine is hot.
Doug,
I checked with the designer of our fuel manifolds and the first thing is I was incorrect about using Delrin, we use high-strength glass-filled polycarbonate (McMaster-Carr #85665K84 is a 3/4" rod),I apologize.
The surface is as machined, with the tubes placed in drilled holes that are stepped so there is a pocket for the epoxy to encircle the tube.
We keep the temperature below 194 degrees (90C).
I hope it helps,
Mike
No need to apologize. You started another way to approach the bracket mountings.
I currently have fuel log #2 clamped in a vice on the workbench. I mixed up some 3m "panel adhesive" and so far it looks very promissing.
This panel adhesive is now used to bond replacement sheet metal, like partial quarter panels instead of welding the thing on.
You have to see the results to believe it. You can't knock it loose with a 40 pound sledge AND it is workable like body filler is.
There is a benefit to group thinking. Often I get too blind to see simple solutions until well after the fact.
Of course I will definitely field test the log but there is no safety facter involved here since the panel adhesive mounting has nothing to do with fuel or solvents in this case.
Without looking at the data for either adhesive I'd guess that they have very similar properties and the significant factor would be compatibility with the base materials?
I give you an A++ for the initial suggestion.
How about mounting with adel clamps? Another layer of isolation. https://www.mcmaster.com/adel-clamps/
Anyone is free to design their own.
My initial intention was to remain in the same period/antique mindset of the 427 dual 4 Holley Ford installation.
Making it look like the original.
If you have not done one like the '67 GT500 you would not realize that the original design of the linkage is an original Ford design, very visiable and in effect makes the multiple carbonation very streetable because of it's progressive throttle opening design?
That linkage requires a good deal of space and as a result the fuel log can't be right up against the carbs as the Adel clamps would place it.
If you want to take off all of the limits then why not put a blower on the car, cut a hole through the hood and put some kind of a three foot high tunnel ram on it?
That's not where I'm going on this and if you remember the original motivation it was to reduce the heat sink through the original Ford fuel log?