Hi boys just got my dizzy unstuck, pulled it out cleaned it all up new O-ring grease ect, put it back in were my marks were, pulled spark plugs and cleaned them up and gapped the plugs to .90 and the truck struggles to start, battery is fully charged, takes a bit to start and when it starts its revving at 1100 rpm at idle and can't idle it down any more. I'm assuming that the spark plug gaps are too big, but can you guys please let me know if that's tru and if they are too big what is the optimum plug gap for 351 Cleveland, thanks boys

 

0.90" ?? What did you use to gap the plugs with, a pencil?

edit. ****ing *******, you mean MM?

Crikey

 

I used a feeler gauge is set on .90 they are NGK spark plugs, and engine is bone stock, stock dizzy and stock coil, but I've put on 8mm leads

 

0.35" = 0.90mm

Good enough, should not cause motor derangements.

Have you put a timing light on it? If the distributor is installed a "tooth off" they will run badly, even though everything looks right.

 

Nah havnt hooked up a timing light yet I've just been doing it by ear it's just revving high and very hard to start it like Boggs down when trying to start and engine cranks really slowly almost like the batter pay is flat, might be s tooth out and gap might be too big

 

Sparkplug gaps that are too big cause miss-firing, not the symptoms you have. Sounds like your timing is too advanced. Get your timing light out or turn the dist with the engine running till it slows just a little bit. You can loosen the hold down bolt so you can just turn the dist with a little force with the engine running.

 

I think dizzy is one tooth retarded ford truck manual said for spark plug gap to be between .80 and .90 mm. So might gap plugs to .85 and advance dizzy by one tooth.

 

DuraSpark systems here in the US reccomend 0.044" (1.14mm) gap.

With good plug wires you shouldn't have any arcing problem if you were to open them up a bit.

 

You only have to move the dist one tooth if the dist cap/vacuum advance hit something while you are turning it. One tooth is a lot, unless it's hitting something and you can't turn it, I don't know if I would pull it and move it a tooth. If it was really a whole tooth out it would not run.

In other words, the teeth on the gear get you in a "zone" of adjustment. Only if you are on the edge of the zone and can't move it anymore would I jump it a tooth. And you will probably have to fiddle with the oil pump shaft, the teeth don't correspond to the hex on the driveshaft so it always hangs up and won't fall into place completely.

 

Move each plug wire over one terminal on the cap.
Turn the whole distributor back 45°.

Now your vacuum advance (or whatever) is not hitting anything.

 

Hi guys truck was starting yesterday but barely I twisted it till it hit and didn't improve anything then turned it a tooth and put it back in now it just cranks over doesn't even want to start at all, I've gapped plugs to .85mm and still doesn't want to fire, please help not sure what to do now and my truck won't start at all

 

Told you so, a tooth is alot. Take the #1 sparkplug out and turn the engine by hand while someone holds their thumb to seal the #1 sparkplug hole off. When air pushes their thumb off the hole stop and look at the timing marks on the front damper. Slowly turn the engine till your pointer lines up with TDC or around 10 degrees BTDC. Leave the engine alone and don't turn it anymore.

With the dist cap on, take a magic marker and mark on the dist body where the #1 sparkplug wire goes, and then take the cap off. See where the rotor is pointing. It should be at the magic marker mark. If not, fiddle with it till it does, either turn the whole dist or if you can't get there you will have to pull it again.

 

Good advice ^. Make sure to mark the metal on the body with the magic marker, not the plastic housing. Marking plastic with a magic marker will cause shorts in the system.

 

Thanks for all the help guys she is running good now figured it out, now just need to dial it in with a timing gun, I've heard that the best timing is 35degrees, is this right? If not what it the optimum timing for this 4v bone stock 351c ?

 

That's about right, but you need to make sure the vacuum advance is disconnected and plug the vacuum port on the carb or wherever the advance source is derived, when you check this. Then run it up in neutral through 1000, 2000, and up, stay out of the plane of the fan, in case it decides to let go at an inopportune time. But the idea is to see what the initial plus mechanical timing ends up at how much (35) and also RPM wise.

Usually a stock OEM curve, that's what you're probably looking at, is too slow. Usually most stock V8 might run good with about 12 degrees initial timing on the crank, and an additional 20 or so mechanical in the distributor. 36 to 38 with a stock engine, maybe 34 to 36 if warmed over. By running it up, we see what RPM the 35 is "all in", for better performance usually people like before 3000 RPM or even less. The stock OEM curve might not reach that till 4500. This is to prevent detonation with heavy loads, but is still a bit too conservative. So the mechanic can tailor when, and how much timing is used in the RPM curve by limiting the slot on the advance plate (see links below) and installing lighter springs on the centrifugal weights. On most Fords this is a pain, but it is well worth the time. You can do this yourself on your engine, or purchase a distributor pre-curved to your application.

When all this is done, then vacuum advance is reconnected and that part of it dialed in. Believe it or not, there can be 50+ degrees total timing BTDC when cruising along the highway at steady cruise and lightly loaded. The vac advance part of it adds better all around driveability, cooler engine temps and about 15% to fuel economy.

Remember though it's not simply a matter of giving the dizzy a big ole twist, 12 or 14 degrees of initial timing is great, but the mechanical will have to be dialed back first. The 34 or 36 degrees optimal timing BTDC never really changes, we just change _when_ in the RPM curve. Many stock V8 from factory were 4 or 6 degrees at the crank, with way too much mechanical timing way too late in the curve.


http://www.bob2000.com/dist.htm

http://www.gofastforless.com/ignition/advance.htm