351 HO mechanical advance plate

[FordFETruck]

Matthew, on your truck, do you have the sticker on your radiator support that tells you your factory timing and spark plug gap? Mine says 10° is my stock initial timing, but I have mine advanced to 12°. Anything higher than that like 14° I encounter the hard hot start you're talking about. With the distributor I have with the 10L/15L advance plate, I would have to advance my timing to 16° to get 36° total.

Yeah, my sticker says 10* BTDC base timing with vac advance unplugged and the sparkplug gap says .042-.046".

Not on this truck, but the distributor for my 64 galaxie I have filed the advance slot to get what I wanted, and if you go slightly too far the thickness of a piece of heat shrink seems to take off 2* of timing (I have a few layers of heat shrink built up) if you heat shrink it over the limiting pin like this.

This is a points distributor but the centrifugal advance is the same as a DSII distributor.

[ArdWrknTrk]

Yeah, my sticker says 10* BTDC base timing with vac advance unplugged and the sparkplug gap says .042-.046".

Not on this truck, but the distributor for my 64 galaxie I have filed the advance slot to get what I wanted, and if you go slightly too far the thickness of a piece of heat shrink seems to take off 2* of timing (I have a few layers of heat shrink built up) if you heat shrink it over the limiting pin like this.

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This is a points distributor but the centrifugal advance is the same as a DSII distributor.

Yep, pretty much the same distributor body with a points plate on top instead of the reluctor and magnetic pickup.

The $20 MrGasket spring kit comes with a brass bushing to go over the limit pin.

[Eriksf250]

Yep, pretty much the same distributor body with a points plate on top instead of the reluctor and magnetic pickup.

The $20 MrGasket spring kit comes with a brass bushing to go over the limit pin.

Jim, you wouldn't happen to have a part number for that spring kit do you? The one I got only had 2 springs in it. I appreciate all the help and wealth of knowledge on this topic for me, thank you all very much. Once I get my truck back, I will have try going into it and see what I can accomplish. The guy I work with who is doing my header and exhaust installation said it's running and performing alot better with the carb he put on for me.

[ArdWrknTrk]

Jim, you wouldn't happen to have a part number for that spring kit do you? The one I got only had 2 springs in it. I appreciate all the help and wealth of knowledge on this topic for me, thank you all very much. Once I get my truck back, I will have try going into it and see what I can accomplish. The guy I work with who is doing my header and exhaust installation said it's running and performing alot better with the carb he put on for me.

Embarrassingly, the kit I bought shows as 'for Delco distributors'...

I didn't want "all in between 2,000-2,800 rpm"

So I just bought the Mr. Gasket 928G Advance Curve kit

(link didn't work) https://a.co/d/bETRRzc

Back before stuff like this was available we used vacuum tube or brass tubing from the hobby shop, but I don't see any reason why heat shrink wouldn't work.

[FordFETruck]

Jim, you wouldn't happen to have a part number for that spring kit do you? The one I got only had 2 springs in it. I appreciate all the help and wealth of knowledge on this topic for me, thank you all very much. Once I get my truck back, I will have try going into it and see what I can accomplish. The guy I work with who is doing my header and exhaust installation said it's running and performing alot better with the carb he put on for me.

I've only ever bought the Mr gasket 925D kit and used either both of the springs, one of them with the factory medium and or factory heavy spring already in the distributors. It depends on how the spring ears are tweaked but I found two light springs typically have max advance in at 2500-2700 RPM, one light and one medium 2800-3000 RPM and one light and one heavy is all in at 3200-3400 RPM. As you can see in my photo I have it set up, so the heavy spring does nothing until about 50% advance slot travel then holds it back at a bit at higher RPM. That was my trick to keep my high compression 390 from pinging under certain conditions at mid-range to higher RPM but I still get plenty of advance off idle-2000 RPM for good response. Typically, the heavy spring is discarded but they do occasionally have their uses.

[ArdWrknTrk]

I've only ever bought the Mr gasket 925D kit and used either both of the springs, one of them with the factory medium and or factory heavy spring already in the distributors. It depends on how the spring ears are tweaked but I found two light springs typically have max advance in at 2500-2700 RPM, one light and one medium 2800-3000 RPM and one light and one heavy is all in at 3200-3400 RPM. As you can see in my photo I have it set up, so the heavy spring does nothing until about 50% advance slot travel then holds it back at a bit at higher RPM. That was my trick to keep my high compression 390 from pinging under certain conditions at mid-range to higher RPM but I still get plenty of advance off idle-2000 RPM for good response. Typically, the heavy spring is discarded but they do occasionally have their uses.

Yes, you can use one (or both) lighter springs.

But as you say, you get a dogleg in your curve. (In your case that seems exactly what you needed! )

The instructions that come with the Crane Cams advance unit are good.

https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.jegs.com/installationinstructions/200/270/270-99607-1.pdf&ved=2ahUKEwiL9uvAvaz9AhWUFlkFHf6YDi0QFnoECBgQAQ&usg=AOvVaw3dp7550K0OkXiQxo_8TLw3

Without something like a Sun machine you don't have hard data to back up what you perceive is going on under hood.

Not to mention pulling the distributor apart is a real PITA if you have to do it multiple times. (though this is more about getting the last tenths than driving a pickup down the road)

[Eriksf250]

Yes, you can use one (or both) lighter springs.

But as you say, you get a dogleg in your curve. (In your case that seems exactly what you needed! )

The instructions that come with the Crane Cams advance unit are good.

https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.jegs.com/installationinstructions/200/270/270-99607-1.pdf&ved=2ahUKEwiL9uvAvaz9AhWUFlkFHf6YDi0QFnoECBgQAQ&usg=AOvVaw3dp7550K0OkXiQxo_8TLw3

Without something like a Sun machine you don't have hard data to back up what you perceive is going on under hood.

Not to mention pulling the distributor apart is a real PITA if you have to do it multiple times. (though this is more about getting the last tenths than driving a pickup down the road)

What would you guys suggest the best total timing should be for a 351HO? I was thinking 36°, and if that is, I might go ahead and try to open up that 10L slot to get the extra 4° I need. 12° initial is the highest I can go before I get the hard hot start, so the 10L will only get me to 32°

[ArdWrknTrk]

What would you guys suggest the best total timing should be for a 351HO? I was thinking 36°, and if that is, I might go ahead and try to open up that 10L slot to get the extra 4° I need. 12° initial is the highest I can go before I get the hard hot start, so the 10L will only get me to 32°

36° centrifugal + static works in most cases.

You also have to be mindful that you can still get considerable amounts of vacuum advance in 'cruise'.

My truck will 'nibble' on tip-in on midgrade gas, so 91 it is.

Honestly, I think I should have welded my slot a little tighter or should open up the dizzy and bush the pin.

Because I don't want to back off the initial timing and the vacuum can is spot on.

I didn't build or tune your engine. I don't know what gears you have, and I don't know how you drive or what you haul.

The PDF instructions I linked above spell it out, but you have to follow them step by step.

[Eriksf250]

36° centrifugal + static works in most cases.

You also have to be mindful that you can still get considerable amounts of vacuum advance in 'cruise'.

My truck will 'nibble' on tip-in on midgrade gas, so 91 it is.

Honestly, I think I should have welded my slot a little tighter or should open up the dizzy and bush the pin.

Because I don't want to back off the initial timing and the vacuum can is spot on.

I didn't build or tune your engine. I don't know what gears you have, and I don't know how you drive or what you haul.

The PDF instructions I linked above spell it out, but you have to follow them step by step.

Jim, my engine for the most part is stock, other than emissions deleted, a 650 edelbrock, and headers with 2.5" pipes, x pipe and chambered mufflers. It has 4.10 gears, I drive pretty low key, not too fast because of the t-18 and no overdrive, so I usually stick to the speed limit.

[ArdWrknTrk]

Jim, my engine for the most part is stock, other than emissions deleted, a 650 edelbrock, and headers with 2.5" pipes, x pipe and chambered mufflers. It has 4.10 gears, I drive pretty low key, not too fast because of the t-18 and no overdrive, so I usually stick to the speed limit.

With 4.10's and 1:1 you should be spinning pretty good on the highway, so depending on your tire size maybe tip-in won't be any problem.

2.73's in a huge boat like my grandmother's '76 Country Squire would be a different story. Man! Did that thing just move out...

I think 36° @ 3K might be fine for you.

You might like it with faster on the bottom as described above.

If you get knock slowly accelerating on a highway hill try backing out some vacuum advance (if yours is adjustable)