I have a 86 F350 7.5 Carbed (460 Engine) . I installed the dist. with the timeing marks set at 6 degres on comp stroke. Vacume adv. is pointed straight forward. Idle is set at 800RPM. I put timeing lite in it with vacume line on dist. I get a reading past the 30 Degree mark. I pull the vac. line off reading is around 20 degrees. I check manfold vacume with a gague T between dist. and vac. source =18 Inch. vac. Truck runs great, no ping starts instanly no temp. problems. I bought a rebuilt from NAPA to try ,Same results. What am I doing wrong? Altude is 3240Ft. in Cal. Hi Desert.
Thanks for any help I can get.
Rodger

 

I'm having a hard time understanding the problem.

You are supposed to set the ignition timing to 8*BTDC at 800rpm with the vacuum advance disconnected and plugged.
(there should be a sticker on the radiator support)

18" vacuum is okay for an older engine, especially at altitude.

 

Jim - I think the issue is that he put the dizzy in on the 6 degree BTDC mark and he's seeing 20 degrees when the engine is running. But, that's just a guess from what I can understand of the post.

armashby - If I have it right, how did you determine that you put the dizzy in at 6 degrees? I find it very difficult to know where it is going to fire with any accuracy as I install a dizzy. Maybe you have a procedure I can adopt.

My experience is that the ignition module decides to light things up at a different point than I think it will. So, I put the dizzy in as close as I can in order to get the thing started, and then adjust timing using a timing light.

But, if you do have a way to know where it'll fire when the engine isn't running, then you must have very light springs in the mechanical advance because you are getting 14 degrees of advance at 800 RPM. I had a set of springs like that on my '69 Bee back in the day and found it was almost impossible to drive in the snow - just look at the throttle and the engine hit 1500.

Also, I don't think you should have vacuum to the advance at idle. Yes, it is done, but most recommend using ported vacuum so that you only get vacuum when you are above idle.

 

Gary,He may be a tooth off when he dropped the dizzy in, or he may have lined it up AS he dropped it in and the helical teeth moved the rotor around as the distributor seated.
I don't know. I don't really understand what armashby is trying to say.

My stock '87 (86 by default) has LOTS of vacuum advance at idle. So much so that I have to reset the idle speed after setting the timing and reconnecting the vacuum advance.
But I do have a recurved dizzy with a Mr. Gasket spring kit and a Crane adjustable vacuum advance can....

 

Yes, I thought about being a tooth off but didn't want to get that deep. Also thought about a slipped dampener showing 20 degrees before when it starts and runs good, but didn't want to explain that either.

As for the vacuum, I've run a lot of vehicles with manifold vac to the dizzy but have quit doing that as it is so hard to get a solid idle. But, I should explain that the last one I tried it on has way too much cam and lopes at idle. Anyway, I've had a lot better results with ported vacuum

 

I guess that's why these era Fords run manifold vacuum through a vacuum restriction and the overheat sensor on the thermostat housing switches to full manifold vacuum when temps get too high in order to increase idle speed, and therefore the the waterpump and fan as well.

 

There's a lot of decent stuff mixed in with the bad in the rat's nest of hoses, wires, sensors, restrictions, and one-way valves on these engines. Most of us, myself included, throw the good out with the bad when we redo the engines. My excuse is that I can understand "simple", but can't get my head around "complex". However, that's not really true as i troubleshot lots of computers back in the day and they were a bit complex. The truth is that I like a clean, simple, and orderly engine compartment.

 

Point well taken!

There's a lot to be said for the KISS principal.

 

Thanks to all for your input.
Gary, I set dist. by pulling #1 plug, usins a renote start button iI crank engine til comp. pushes my thumb off of #1 plug hole then I align damp. to 6 degrees at pointer. Drop dist. in with rotor aligned to #1 on dirt. cap.. I remove vac. line from dist. and plug. I can get yiming mark to 14 deg. by lite any thing lower and engine will faulter. with vac. line hooked up timing reading is 30 Deg. . All vacume line are installed to factory spec. all emission systems are stock form and hooked up.
Ard, I would like to know more about possible Dampner movement.

 

Actually, I mentioned the dampener movement, but Ard/Jim is more than capable of answering. Anyway, as the rubber in the dampener gets old it loses its grip on the metal - either that part attached to the crank or the ring on the outside that is the weight. It is gradual and at some point the outer ring can slip, which means the timing marks are no longer correct.

From what you are saying about not being able to run below 14 degrees BTDC I'd bet that is what has happened since that engine should run with the timing all the way down to 0. One way to check is to put something like a straw in the spark plug hole of #1 and turn the engine over, preferably with a breakover & socket on the crankshaft bolt. As #1 comes up to TDC keep a bit of pressure on the straw to keep it in contact w/the piston. When it stops moving out stop turning the crank and check the timing mark. That is TDC. You may have to rock the engine back and forth across TDC a few times, going a few degrees beyond before coming back, but you should be able to accurately find TDC.

If the balancer/dampener has slipped you really should replace it. Yes, you have found a way to make the engine run well, but some day the outer ring may well walk off and cause all sorts of damage.

 

Gary has explained it well.
Why do you install the distributor at an indicated 6*? (BTDC I assume)

Try doing as he said and find TDC #1 then check to see what the pointer indicates.

While you have a breaker bar on the crank snout take the cap off the distributor and observe how much you have to move the crank forward and back to get the rotor to change direction.
This is a good indicator of timing chain slop.
If your truck has the stock style timing set with an aluminum cam gear and nylon teeth, once the plastic starts to go all those little shards end up clogging the oil pump pickup in the sump.

A pre-emissions timing set or an adjustable aftermarket one will really wake that engine up.

 

I just had to replace both the balancer and chain on mine. I found that the late model roller chain is a "straight up" set so I went with that. If you buy a pre 72 chain set be sure that's what they are actually selling you, most parts stores only carry the 72 up set and their "catalog" will show it fits all 68 up 429/460 engines.

They are tough engines, but do have balancer issues, particulalry after 25+ years. As for vacuum diagrams, both Jim and I have posted ours elsewhere on this forum.

 

Thank You all For the input. I Use the 6 degree reference to set the dist. because thats the way my old mentor taught me 45 years ago. I have a lot of experince with finding tdc with a sofr probe through the spark plug hole from setting timing on 30s thru 60s english motorcycles. I will follow the advise to check dampmer. I have changed the timing chain set with NAPA preimun parts. I will update this thread with what I find with dampner. Thank you all again
Rodger

 

So, you speak Whitworth? Had a bit of experience w/a Norton myself. Good luck.

 

...and Lucas (Prince of Darkness) electrics!

The old three position switch on top of the headlamp shell.



I've been up to my ears in too many Triumphs, BSA's and Nortons NOT to be scarred for life.