Can someone please explain how timing affects your operating temps? I think I read somewhere on here that retarding your timing too much can cause your engine to run hotter, but what about advancing it too far? How does retarding and advancing affect how easily the car starts, hot and cold?

I also know that advancing timing increases your idle speed, and vice versa. So how does all of this affect your engine manners?

When you advance your timing, do you then need to go back and adjust your idle mixture screws, or just adjust your idle speed screw. Or both?

Im chasing down some issues where it starts to stumble when nice and hot, and its running a little warmer than I would like but nothing alarming, and just want to make sure I have a good understanding of tuning adjustments before I start making changes.

I have on a clear fuel filter up top, and when the motor is hot it gets low on fuel, pretty much dry, and the motor starts to run lean, which I presume is contributing to motor running hotter, and it just keeps going in this direction. The stock fuel line and factory style filter is sandwiched pretty close between the inner fender and the exaust manifold. Close enough that I can only change that filter when motor is dead cold because my hand would be scorched otherwise. Cant avoid touching something extremely hot.

Just to experiment, I took some cool water and poured it on the fuel line and fuel filter and it was hot enought to make the water sizzle off of it, and thats with a heat reflector tape already installed. I did this long enought to cool it and as soon as it was cool the fuel level in my clear filter filled back up as it should be and the motor ran much smoother. This signals to me that its gettting too hot there and contributing to a vapor lock condition. Would you agree? Im going to try it again and see if the fluid level raises because I cooled off the line/filter, or if it was just a coincidence.

Also, is it possible for the fuel pump to be clogged up with debri and slowing down my flow? The factory filter is before the pump and the clear filter is after the pump, and I can clearly see where my clear filter is still filtering little granules out of the fuel. If so do I pull it and clean it, or do I replace it?

Heres my plan: Cut the factory fuel line shorter, re-route with flexible hose in a cooler route, likely incased in a heat sheilding insulation similar to what I have around my trans fluid lines. Going to put in a 160 deg thermostat (its 195 now). And Im planning on getting a repro fan shroud from Mancini, there is not one on there now and I know that is killing me at idle and low speeds. I'll then be playing around with my timing, and carb settings to see what it likes. I dont remember exactly where it is now, but somewhere around 17 initial with a stock '71 replacement points dizzy from the parts house with whichever springs come in it for the advance curve, but upgraded to Pertronix Ignitor 2 system and Flamethrower 2 coil, bosch platinum plugs, eddie 1406 (600 cfm), high volume oil pump, new stock fuel pump, its a 360 with edelbrock performer intake, 9:1 hyper pistons, 268* duration, and .458" lift (factory 340?) cam, 904 trans, stock converter, 2.76 IIRC rear gears.

I know its long, but I tried to give you any info that might help, and I want to know what Im doing before I start trying to tune it. The motor actually is running pretty darn strong, and I love to take it out and get on it, but I also want to get this squared away.

Thanks
roe

i wouldn't do anything until you've moved the line. once you've done that then re-assess the remaining issues.

You,my friend are experiencing classic signs of vapor lock.If water is boiling the temp is WAY past the boiling point of fuel. Your plan seems quite good except for the thermostat change. I would stick with at least a 180 Deg. The fuel line rerout will be the biggest help,of course. The fan shroud will also become more necessary as outdoor temps rise. God luck.
Ron

I agree, gas can start boiling at 100*. I would definitely reroute the fuel line first as previously said, then try it and see where your at.

I have to go with the others on this as well.
My M-body was well known to have vapor lock issues and the lines really couldn't be moved.
The factory-recall answer was a small electric pusher fuel pump just after the tank. It worked.

I installed a full-blown electric fuel system on my M and have had no issues.

But- You will never get your tuning sorted out until you solve the vapor issue.

Good Luck,
CC

ok guys, I will re-route the fuel line first

If the engine does not ping, then the advance is probably not too much AND the engine is not running too hot. I WOULD NOT go to a cooler stat until you resolve fan/ shroud/ radiator issues.

I don't know what you mean by "flexible line" but if you mean "rubber hose" I'd re-think.

ONE BIG THING I believe in is a fuel "vapor return" system. You can easily set these up on the later cars which had a carbon can because they have at least one extra vent line coming up front. Wix filters (and others) make a steel inline filter in either 5/16 or 3/8 line with a built in 1/4" return port. You install the filter either vertically or horizontally with the 1/4 line UP and plumb that line back to the tank. This returns a constant supply of fuel through a SMALL ORIFICE and helps keep the fuel cooler, as well as returning any vapor starting to form.

THESE WORK, and more guys should use 'em, especially with today's fuel. First one I ever saw was on my '70 440sixpack.

If you are running a factory mechanical pump, ABSOLUTELY any restrictions in the rear WILL cause vapor lock problems, because the pump is "sucking" from the tank. THIS CAUSES fuel to be lower pressure coming to the pump and when it is heated it enhances the tendency to boil and cause vapor.

(Just like a coke--they don't bubble in the bottle--they bubble when the pressure is LOWERED)

Roe,
You shouldn't use rubber fuel hose under the car for safety reasons. The tires could kick up road debris and cut the line. Rocks, sticks etc. If you do use rubber fuel hose make sure it is rated for alcohol based fuel.Not sure about where you live but the 10% ethanol fuel we have here in CT will cause problems with the rubber hoses and seals in older cars.

would it be better if I made sure to protect the hose with with something? I'm planning on running it through a tube of insulating heat reflecting casing. I've got some around my trans lines and it looks like it would protect the line from debris damage.

The hose I'm running now is just the standard stuff from autozone. It's the same stuff they sell for new cars so I think it should be rated for modern ethanol blended fuels, bit I will double check.

And what about a braided fuel line, would that be better?

dude, the autozone cheapo stuff is fine...........

cool, come friday I will re-route and go from there