Retimed 440 with dial back light

[mvent]

Received an Innova dial back timing light and went to work. Prior to having it I was just doing the bump until it pings and backed off a bit, ran pretty good but was curious what my timing numbers were. Disconnected vacuum, set total to 36* at 2800-2900 rpm, checked at 750 rpm and landed at 20*. Reconnected vacuum to ported for now. Starts fine hot, no pinging uphill under load seems to pull harder when getting on it. Will try manifold vacuum as well just to compare but my thought was 20* idle was more than enough didn’t think necessary to add more with manifold vacuum at idle. Know idea what cam is in it but surely nothing radical. It’s an auto with 3.23 rear gear.

 

[Don67Satellite]

I have an Innova as well. Great timing light.

 

[davek]

In 1985 my mom bought me one from Sears,it still works.

 

[68Moparmaniac]

In 1985 my mom bought me one from Sears,it still works. View attachment 1731292

Had one from the same era.... worked great until I loaned it out to a friend who gave it back without a word. Didn't know it was DOA until I needed it...a$$hole

 

[icetech]

Received an Innova dial back timing light and went to work. Prior to having it I was just doing the bump until it pings and backed off a bit, ran pretty good but was curious what my timing numbers were. Disconnected vacuum, set total to 36* at 2800-2900 rpm, checked at 750 rpm and landed at 20*. Reconnected vacuum to ported for now. Starts fine hot, no pinging uphill under load seems to pull harder when getting on it. Will try manifold vacuum as well just to compare but my thought was 20* idle was more than enough didn’t think necessary to add more with manifold vacuum at idle. Know idea what cam is in it but surely nothing radical. It’s an auto with 3.23 rear gear.

Just got my timing light yesterday, haven't played with it yet... Just curious.. why would you want to hook to manifold instead of ported?

 

[Frank Mopar]

o manifold when it's supposed to go to ported

Depends who you ask.

 

[HawkRod]

Received an Innova dial back timing light and went to work. Prior to having it I was just doing the bump until it pings and backed off a bit, ran pretty good but was curious what my timing numbers were. Disconnected vacuum, set total to 36* at 2800-2900 rpm, checked at 750 rpm and landed at 20*. Reconnected vacuum to ported for now. Starts fine hot, no pinging uphill under load seems to pull harder when getting on it. Will try manifold vacuum as well just to compare but my thought was 20* idle was more than enough didn’t think necessary to add more with manifold vacuum at idle. Know idea what cam is in it but surely nothing radical. It’s an auto with 3.23 rear gear.

Were you at maximum advance at 2800 - 2900 RPM? Assuming you were then your distributor is only pulling 16* of advance. That's low. They should be pulling about 22*, give or take.

If you can, pull the distributor and find the extra 6*

 

[padam]

Just got my timing light yesterday, haven't played with it yet... Just curious.. why would you want to hook to manifold when it's supposed to go to ported?

Uh oh…

 

[icetech]

Uh oh…

didn't realize it's a controversial topic Forget i said anything..

 

[DanielSlocum]

Seems like you might need to just lose the vacuum advance because its aparently advancing your timing well past 36 causing pre-ignition. I would think that running say 18-34 would work quite well using only the mechanical, although you likely only need about 15 at idle for good response. Depends on how aggressive your cam is as rough idling cams tend to want about 17 initial.

 

[padam]

didn't realize it's a controversial topic Forget i said anything..

Lol do a search.

 

[WileERobby]

Hatfields vs. McCoys. Ported vs. Manifold.

In 1985 my mom bought me one from Sears,it still works. View attachment 1731292

Yea, I got one of those newer models. As well as my first one that the "springy-thing" as I always called it, attaches between the plug and the cable.

 

[oldbee]

Hatfields vs. McCoys. Ported vs. Manifold.

Yea, I got one of those newer models. As well as my first one that the "springy-thing" as I always called it, attaches between the plug and the cable.

“Springy-thing” brings back olden days memories! Haven’t thought of those for ages.

 

[AR67GTX]

The Innova is a great light. Just be cautious to keep the plug wire clamp away from the exhaust manifold as it’s not heat resistant material. Not a problem for a Mopar for the most part but being used to the springy-thing I tended to hook the timing light down close to the plugs on my Chevy. Not a good idea.

I agree with you that if you stay at 20 degrees initial timing, you have enough timing at idle to keep the engine cool and have a strong, smooth idle, and no need to use manifold advance for the vacuum advance.

 

[mvent]

Were you at maximum advance at 2800 - 2900 RPM? Assuming you were then your distributor is only pulling 16* of advance. That's low. They should be pulling about 22*, give or take.

If you can, pull the distributor and find the extra 6*

Just curious, what would be gained by doing this ?

 

[oldbee]

Better throttle response, cooler running.

 

[AR67GTX]

Just curious, what would be gained by doing this ?

I agree. I run 16/17 degrees centrifugal advance on my 66 Hemi and 67 440 GTX dual points with total of 33 on the Hemi and 34 on the 440. Both pull hard from idle and run great on 91 octane non-ethanol. Both run cool also.

But if your engine can handle 36 degrees OK finding 2 or 3 degrees more centrifugal advance and backing down the initial timing slightly would give your starter a bit of relief. Have you looked inside the distributor? It might have one of these in it.

 

[HawkRod]

Just curious, what would be gained by doing this ?

I think @oldbee and @AR67GTX covered it.

But to add a bit: There are basically two reasons we want advance:
1) The air fuel mixture does not explode. At a given air/fuel mixture, it burns at the same rate. So as the engine goes faster we need to light the fire sooner so the pressure wave hits at the ideal spot (fractions after piston TDC). This is the job of centrifugal advance in the distributor.
2) The air/fuel mixture is not constant. As fuel mixture gets leaner the flame burns slower, so we again need to light the fire sooner. This is the job of vacuum advance.

Most basically, if you agree with #1, then it is better if the distributor can give us more timing rather than less. If your distributor could only provide 12* of timing would you then want the engine set to 24*? What if the distributor could only do 10*? You can see were this is going.

As an additional point: Typically, at idle your engine runs lean, so getting vacuum advance involved to increase the timing at idle is a good thing. And, as mentioned, we don't want too much static timing as it can make the car harder to start. So lowering the static timing and letting vacuum advance take over provides the timing the engine wants. Then when you mash the throttle, vacuum goes away, and so does the additional timing. BUT you have introduced a fat air/ fuel mixture by the accelerator pump, so you don't need as much. Now as your engine speeds up centrifugal advance takes over.

Hope some of this makes sense.

 

[gtxrt]

As an additional point: Typically, at idle your engine runs lean, so getting vacuum advance involved to increase the timing at idle is a

i would think if your engine runs lean at idle you would want less timing advance not more ?

 

[mvent]

Thanks for all the replies, got back on it today and confirmed 20* idle full advance seems to be done around 25-2600 rpm and that’s at 36*. Hooked vacuum to full manifold and idle timing was 30* at 750rpm. Vacuum in gear read just about 10hg. FWIW I neglected to check where I started numbers wise but car always needed 1/2- 3/4 throttle to start hot, today while turning on with heat soaked engine turn key no throttle fires right up like half revolution. If it stays this way I’ll be good with it.