I'm new here... but looks like a lot of good info here. Just a little info on the history of my truck. It's a 73 F-100 Ranger. 360 engine. Auto trans. I picked the truck up from a guy I worked with. The engine and trans are both freshly rebuilt right before I bought it. I've been working on cleaning things up a bit and getting it running smoother.

As of right now it has a new stock 2bbl reman carburator no adjustments since it came out of the box. It seems to be running strong, but is having a hesitation problem when just getting on the gas slightly from a stop. I was told the timimg may need to be set. Having grown up in the age of fuel injection and electronic ignition, i'm a bit out of my element here. I know the basics of carbs and distributors, but not sure if i'm applying them properly. I chased down and repaired or plugged up any vacuum leaks I could find. After tinkering with the timing it is running a lot smoother, but still has the hesitation. With the vac advance line off and plugged, timing at idle is at 24 degrees... which sounds high, but seems to be running better than if I retard the timing. I have a Haynes book, and an original 1973 factory service manual, neither of which have any specs for timing. I guess my first question would be what the timing is supposed to be set at. Second, is it possible this could be an issue with the carb? The distributor looks pretty old... could there be a problem with the points?

 

With the timing at 24° initial you WILL burn up your engine, if it is actually at 24°. With 24° initial and a normal 24° advance in the dist., you end up with 48° total advance. Since these engine will not tolerate more than 36° total advance you will melt a hole in a piston or two. Second your hesitation is probably because the accelerator pump on the carb needs adjustment. To check, remove the air cleaner and with the engine off, advance the throttle. You should see fuel squirt into the throttle bores instantly. If not take the slack out of the pumps linkage. OH and you need to check that engine TDC is actually TDC on the damper. And until that back that timing off to about 10° where it belongs.

 

i will back it off. i'm a diesel mechanic... not experianced with carbs or ignition systems at all. I was looking at point elimination kits over at summit.com... that sounds like a good place to start since I couldn't tell you what a point even looks like. the complete dist. assemblies are a bit pricier than I want to go and don't think its necessary since the motor is remaining stock.

as far as the damper being at TDC, i'm 100% positive that was put together correctly.

i'm gonna go tinker with the carb.

thanks for the info.

 

Pertonics makes a good replacement set up and will be cheaper than Summit. I've put several hundred of them in boats while I was working in the recreational marine industry.

 

This might have more to do with the vacuum advance than anything else.

If the distributor is "old looking" the vacuum advance diaphragm is probably toast.

Back the timing down to 10 degrees like Bear said. Then, with the timing light AND the vacuum advance hooked up, see what happens as you slightly touch the gas like where you say there's a hesitation. Does the timing advance at all? If not, that's probably the problem.

If I understand correctly, if you romp on it, it doesn't hesitate, but if you lightly touch it, it does hesitate?

 

If the timing doesn't advance with throttle application that would indicate a stuck mechanical advance more than vacuum advance, since unloaded it takes hardly any throttle plate movement to get revs and without throttle plate movement the vacuum port does not get uncovered.

 

correct. only dies out when in gear and slight throttle application.

thanks for the info guys.

 

That definitely sounds the accelerator pump linkage too loose.

 

ACCEL 2020 - ACCEL Points Eliminator Conversion Kits - Overview - SummitRacing.com

http://www.summitracing.com/parts/PNX-1281/?rtype=10

PerTronix IGNITOR FORD 8 CYL

looks like summit carries pertronix for less $ than through pertronix website. any advice about the Accel unit?

 

going to check that tonight... been raining here. thanks

 

I never even charged customers $90 for the Pertronics.

 

Take a look at eBay and you may find the same unit for a lot less $$. The Petronix units work great and while you are looking see if you can find a centrifugal distributor and then you won't have to worry about the advance curve in the vacuum side of the distributor. Your initial timing should be at 10 degrees at idle with the vacuum line disconnected and plugged. Assuming your distributor has not been tampered with you should have about 38degrees total advance at a bit over 2,000 rpm. another thing that makes the Petronix unit worthwhile is due to the fact you no longer have points you will no longer have rubbing blocks to wear out.

 

All distributors are centrifugal, some just have the vacuum advance in them also. Don't want vacuum, don't hook a vacuum source to it. However, no vacuum advance will adversely effect gas mileage. You should set up all dist. the same way. Then plug in the vacuum to the dist.

Oh and only a performance dist will have the advance curve you are talking about or one that has been recurved.

 

You are right, all distributors are centrifugal but the OEM distrubutors have a longer curve with more total advance built in and the difference in economy would depend more on the tight foot if all else is correct.

 

After some more tinkering this weekend, i have the initial timing back down to 10 deg. at 1500 rpm its at about 23 deg. accelerator pump is squirting as soon as throttle is touched. still having the hesitation. I also put hose clamps on most of the vacuum lines that I suspected were leaking. the "carb cleaner" spray test was making the RPM jump about 50-100rpm pretty much anywhere I sprayed on top of the motor.

I'm not getting any readable vacuum from the line that goes to the vac advance at idle. there is a little plastic cylinder in line... i'm assuming some kind of check valve... does this need to be in here?