might I add that yes I have experienced vapor lock as well, very annoying, but it was on a motorcycle, and big block chryslers are new to me... so please chime in, is 8 to 10 inches clearance going to be enough between the manifold and a push lok line? because thats how much I have right now, my hand pinky to thumb is 8.25 inches, and thats about the closest it comes, varying between 8 and 10. I know heat rises, and its trapped in a steel box, but its got a fan running and places to escape to as well. thanks for the input.
Joined: Thu Mar 01 2007, 09:30PM
Location: Houston
Posts: 1735
Plumbing a Holley has always been a bit of a trick, and one that has been done a million different ways. Most of them are unattractive and/or prone to give problems.
Aside from the clamps and being near and exhaust manifold, I also am not wild about the positioning of the 90 degree fittings at the carb which cause the greatest amount of stress on the hose to occur as soon as it exits the fitting. Over time and heat, the hose will tend to relax and sag in that area, which will cause potential loss of flow and closer-to-the-exhaust issues.
I'd start by relocating the coil to someplace else...I usually put it under the alternator for a cleaner look and it is out of the way of other things. Then I would move the regulator closer to the carb.
Joined: Tue Oct 11 2005, 01:33AM
Location: Calgary, Alberta
Posts: 5893
BenH wrote ...
what exactly is wrong with typical fuel line
Standard hose has a high permeation level: 30R7 is 37 times 30R9. Permeation level is a measure of the ability of a solid to block the passage of different size molecules. A most common example, the kids party balloons handed out in shopping malls. The balloons are made with a material which has a high permeation level for helium. Without the slow passage of helium through the membrane the balloons would end up on the ceiling to stay. With the leak, after a few hours they all end up on the floor.
Modern fuels are a witches brew with many different molecule sizes, some large and some small. All the Gates sheet is saying is that 30R9 blocks the small molecules 37 times better than 30R7 hose.
While the engine is running the differences will not be significant because the fuel flow rate is too high. However, when you shut it down the hose will slowly "sweat" small molecules. If the small molecules are volatile and lighter than air, a spark under the hood could cause an explosion. If the leaking molecules saturate the hose, they could cause the hose to become brittle.
All sounds scary, maybe it is, maybe it isn't, but $20 will get enough 30R9 hose to eliminate the potential risk.
Running the hose over the manifold and "keeping an eye on it" is not a good practice. After a typically short time, you forget to "keep an eye on it" and bad things may happen. Think fail safe, what happens if it sags, or leaks, or some idiot runs into your car.
The very last thing you need is an engine fire fed by a high flow rate electric fuel pump.
Joined: Sat Aug 19 2006, 05:03PM
Location: Ontario, Canada
Posts: 2919
If you retrofit an electric pump, I recommend adding a "rollover safety switch", which shuts off the electric fuel pump in an accident.
Painless Performance #80160 is $100, but it's identical to the Standard Motor Products FV7 inertia switch which you can get from Rockauto for $63. You could also recover one from a car at the scrapyard. Inertia switches from Ford products seem to be popular for some reason. See this link for details on the Ford switches:
perhaps this was never mentioned, or ignored, or forgotten, but I do not have an electric pump, I have a mechanical block pump. I did all this because the pump was pushing out nearly 9 psi.
I have 4 feet of mr gasket -6an R46 push lok line coming to me, and I am going to do what I can about getting it all plumbed on the front side of the motor rather than off somewhere around exhaust.
Joined: Tue Oct 11 2005, 01:33AM
Location: Calgary, Alberta
Posts: 5893
Could the high pump pressure be a symptom of some sort of problem with the pump itself? If for example the push arm on the pump is incorrect so that the stroke is longer, you would get more pressure. This could happen if the wrong pump is used. Upstream errors in labelling and/or packaging could easily get you something the "looks" correct but isn't. Might be worth while to pull the pump and try a different one to see if the readings return to normal.
I guess what I'm really saying is: The pressure is too high because something is wrong and you need to find the cause rather than treat the symptoms.
its just one of those rare things I kept. I bought the car in scrap condition, but a guy before me had made a sad attempt at fixing it and getting it running, so there was a very short list of things on it that were new, among them being shocks on all 4 corners, a fuel filter (lol) v belts, and a fuel pump. When I put the motor back together with my machinist, we both looked at it and it seemed fine and looked new inside and out so we shrugged it off, got a new gasket out, and put it back on, being that it isnt a very complex mechanism.
so in truth, I couldnt really tell you what the hell it is. but being that the small block HP pump is rated 80gph/8.7 psi, and the big block 383/426/440 HP pump is rated 82 gph, I dont find the fact that it pumps out exactly what it claims to pump out to be very startling.