Can't maintain fuel pressure

[siteunseen]

Didn't the '73s have bigger exhaust vales on the later e88?  

I'm just being curious so don't bother with me too much. But thank you for the knowledge, I like to learn.

[Mark Maras]

  Has anyone run 4 screw carbs on the later manifold? The answer may help point a finger at the probable culprit.

 Never had "the problem" with a mechanical fuel pump.

 Here's another puzzle piece to throw into the pile. What about a poor fan clutch? It would contribute to heat build-up sitting in traffic, not when the engine is off. Years ago I swapped the stock metal fan for a flex fan. The flex fan pulled more air at an idle than the original fan.

[SteveJ]

I was thinking of trying to mount a shroud on the radiator for the fan, but I haven't gotten around to it, yet. I know my fan clutch isn't in perfect shape, but I do hear the fan kick in still.

[siteunseen]

I'm sure Steve has his reasons for the electric pump but I like to believe the mechanical works fine. Dizeased runs them on his built up motors without issue. My guy told me the mechanical pump would run triples until higher rpms.

[SteveJ]

Yes, I do have a reason for the electric pump only. I don't want to remove the head and open up the window for the mechanical pump.  

[siteunseen]

That's a darn good reason! What are using, p79?

[Pat Carr]

My 73 had a much larger and heavier exhaust manifold than the earlier models. Thus more heat sitting under the carbs. I changed to the earlier one when I swapped out to round tops. Thanks to Chet Wittel for the idea. The attached photo gives you an idea of the size difference.

[siteunseen]

There it is!

[SteveJ]

19 minutes ago, siteunseen said:

That's a darn good reason! What are using, p79?

N47 Maxima head

[siteunseen]

3 minutes ago, SteveJ said:

N47 Maxima head

You get the bigger valves too? More air flow = less heat, I think.

[SteveJ]

Just now, siteunseen said:

You get the bigger valves too? More air flow = less heat, I think.

I'm not sure. Since I didn't put the engine together, I didn't have a chance to take measurements. I'd have to research that. The combustion chamber is smaller, so I get higher compression.

[jalexquijano]

Steve,

I want to know the outcome of your Project. You see in addition to the stock heat shield which was installed in the car by the Factory originally, i have mounted a stainless Steel heat shield extension that reaches the bottom of both 3 screws SU Carburetor float bowls and the percolation is still present. The gasoline in Panama has no ethanol so this should not be happening. The heat comes from the manifold and thus there must be away of lowering that amount of heat so it does not affect the fuel that is inside the foat valves and that will evaporize and consequently shut the engine down. I am hereby enclosing pictures of the heatshield extension and the new downpipe of the MSA PREMIUM EXHAUST that is connected to the stock manifold for your perusal. Some guys in these fórum only throw out ideas such as swapping metal fuel rail with 5 inch rubber hoses or driving with the lid off? Is this really going to help and avoid the car idle becoming lumpy at traffic jams which leads to a sudden shut down of the engine? Wouldnt it be better to put an ice cooler to lower the temperature at the manifold?

Edited April 25, 2017 by jalexquijano