Timing a rebuilt 351 W

[69_fairlane_ragtop 10]

Just rebuilt my 69 351 Windsor - it is all stock and mated to an FMX tranny. Completed the break in but I am having trouble getting the timing set.

 

With my initial at 6d, vacuum line disconnected and plugged, I have full advance at 31d at 2,800 rpm.

 

With initial at 6d and vacuum line connected I get + 45d advance at 2,800.

Idle is ok but terrible as rpm increases.

 

I have tried initial at 11d with the vacuum line plugged and get 36d full advance. Idle is good but sluggish throughout.

 

I am planning on trying to connect to manifold but would like to hear from someone else about this before I try it. I haven't looked inside the distributor yet to see what the limiter is set to.

Thank you guys in advance for any insight provided...

 

Oh, I also apologize...I do not own a Mustang...I have a Fairlane 500 convertible. I hope that doesn't affect the responses.

 

P

[Max Power 74]

45 is way too much. I think 36-38 total is more the norm.

 

How down it run without connecting the vacuum at all?

[69_fairlane_ragtop 10]

It runs ok...misses occasionally. Ran better before the rebuild. Idle is good but above that it is not smooth. At 2700 rpm I am at 32 deg with out vacuum. With the vacuum I'm a t +45

I tried adjusting my vacuum advance but didn't get me any results.

I was thinking my mechanical advance in the dizzy would be my next step. I wonder if I can reduce the advance there by rotating the limiter.

 

Thoughts?

[69gmachine 15]

You stated the engine is stock, so I'll assume that includes the distributor. Autolite distributors are adjustable and use spacers to limit the total travel (and therefore timing). The spacers come in 2 different widths. Remove the nipple from the advance unit and see how many spacers you have (I'm using 3 thick ones). I would add more spacers until it stops over advancing. There are also different spring rates. The red spring is perfect for a performace application as it is light enough to allow the timing to come in quickly. It's fairly common, so there's a good chance you already have it.

 

Based on your timing events. the reluctor your using is 12 degrees (mathematically it comes out to 12.5, but I've never seen a 12.5 while I've seen lots of 12s). The other side is most likely much larger so you won't be able to swap it out to obtain less advance. If you want to reduce the amount of total timing you need to find a 10/15 reluctor from another distributor and use the 10 degree side. If you ever plan to upgrade to electronic ignition, get one from an 83-85 HO Truck engine, or just use the entire dizzy and switch to a Duraspark ignition.

Edited October 22, 2013 by 69gmachine
spelling

[69_fairlane_ragtop 10]

Thanks guys for the response.

To clarify, my dizzy is a new motorcraft that has the adjustable vacuum. I have gone in and out without any change.

This was on the engine before I rebuilt it and it all worked fine. Idle was good, performance was good. I chose to rebuild the engine due to lost oil pressure. I tore it apart and saw all my bearings were shot and the crank had to be ground. So I assumed this dizzy would have been fine on the rebuilt block. What am I missing?

[Max Power 74]

Did you change the harmonic balancer in any way? Did it shift and is giving you inaccurate numbers? If you retard the timing to 0 TDC does it run better?

[69_fairlane_ragtop 10]

Yes. It has a new balancer. I can't imagine it shifted because of how it mates to the crank. The numbers are engraved on the balancer. I didn't put a timing tape on it.

When I have retard it towards 0 it is close to stalling around 3-4d. When I compared it to my old balancer the numbers lined up.

[Max Power 74]

Yes. It has a new balancer. I can't imagine it shifted because of how it mates to the crank. The numbers are engraved on the balancer. I didn't put a timing tape on it.

When I have retard it towards 0 it is close to stalling around 3-4d. When I compared it to my old balancer the numbers lined up.

 

Hmmm....makes me wonder if the chain isn't a tooth off or something. Also balancers are commonly off in their markings, and it is good during assembly to determine true TDC while degreeing the cam. It's not good enough to eyeball em.

 

Not sure what direction to send you at this point.

[69_fairlane_ragtop 10]

Thanks for the info. The chain being off a tooth has always been somewhere in the back of my mind. I will be getting the tape and most likely check the chain. I'm getting good at taking it apart...should only take a couple of hours to pull it apart, correct it and put it all back.

If it is a tooth off, should I be worried about some part in my valve train being damaged?

[det0326 179]

Thanks for the info. The chain being off a tooth has always been somewhere in the back of my mind. I will be getting the tape and most likely check the chain. I'm getting good at taking it apart...should only take a couple of hours to pull it apart, correct it and put it all back.

If it is a tooth off, should I be worried about some part in my valve train being damaged?

 

Could you take a piece of flexible wire or something and remove #1 spark plug, shape the wire so you can feel the piston coming up to tdc (making sure you are on compression stroke and not exhaust stroke) then when piston is all way up just before starting down check your timing mark. If it

is on 0 timing chain should be OK. That way it might save you some work.

[69_fairlane_ragtop 10]

i'll try this first before i pull the timing cover. thanks for the tip.

[det0326 179]

Could you take a piece of flexible wire or something and remove #1 spark plug, shape the wire so you can feel the piston coming up to tdc (making sure you are on compression stroke and not exhaust stroke) then when piston is all way up just before starting down check your timing mark. If it

is on 0 timing chain should be OK. That way it might save you some work.

 

Second thought this may not be a good test, this would insure that the

markings on your pulley would be correct but the timing between the crank and cam could still possibly be off a little. If the timing chain was off a complete tooth do you think that it would even run? I've never intentionally tried it so I don't know but I personally don't think it would.

[69_fairlane_ragtop 10]

You know that for the past week I have had an exhaust leak that gave the motor a throaty sound. It also gave me the feeling the timing was off. I just had the leak patched and the motor runs smoother.

I visited the speed shop that did my machine work and they gave me the impression that my problem was the dizzy. The vacuum pot could be faulty or the mechanical advance bushings could be worn. I checked the dizzy and was able to jiggle the plate attached to the vacuum advance. I also noticed some back and forth play on the dizzy shaft. It moves back and forth a slight amount. Is this normal? I was going to go to a parts shop and see what a new one feels like compared to mine.