440 Timing

[Bicylindrico]

How was it hooked up by the factory? Not offended, but explain?

The 70's were all about one thing, clean up emissions with old polluting large displacement engines. They would essentially run late timing at higher engine speeds to help clean/heat up exhaust emissions. This all at the sacrifice of engine performance.

The easy way to think about it is lean fuel mixtures need more time to completely burn=idle and cruising. Rich fuel mixtures need less time=load. All these guys running no vacuum advance would be amazed how faster their engines would idle if the timing was advanced properly which would lead them to have to adjust their throttle plates and idle mixtures screws to bring the idle speed back down. That is what timing advance does for an engine.

 

[oldbee]

Woah, we're just gonna fry the OP's brain function. Go with 'ed's' idea && maybe put a chalk mark at 36* to more easily see that mark. Then we go from there.

 

[Derwud]

The 70's were all about one thing, clean up emissions with old polluting large displacement engines. They would essentially run late timing at higher engine speeds to help clean/heat up exhaust emissions. This all at the sacrifice of engine performance.

The easy way to think about it is lean fuel mixtures need more time to completely burn=idle and cruising. Rich fuel mixtures need less time=load. All these guys running no vacuum advance would be amazed how faster their engines would idle if the timing was advanced properly which would lead them to have to adjust their throttle plates and idle mixtures screws to bring the idle speed back down. That is what timing advance does for an engine.

Going to take a bit to wrap my head around this.. Goes against everything I was taught.. Read your welcome to the site thread, and except the Ky part and MBZ thing, we aren't to far apart..

 

[hunt2elk]

If your advance is coming in to quick, that could also cause pinging. You could try heavier springs to slow things down. If you are running the 2 blue's, try a black and silver.

 

[Johnpat]

Look up( Lars.How to set timing)on the
Internet.
Good info on there.

 

[Johnpat]

I know my post for( Lars timing info)is for
BB Chevy's, but would apply to most any
performance engine

 

[moparedtn]

Ballancer is marked.

Most of them are. The question I asked, however, is "have you verified that the indicated (marked) TDC is actually accurate?"
You'd be surprised how often it isn't. It's a simple thing to check, too. Just need a piston stop tool (preferably) in place of the #1 spark plug.
Spin the engine with a torque wrench in one direction until the #1 piston "stops" against the tool and make a mark on the harmonic balancer; then do the same thing by spinning the engine in the opposite direction, marking the balancer when the piston again hits the stop tool.
Measure exactly halfway between your two marks and wala, that's true top dead center.
Mark that prominently if different from where the balancer was originally marked.
That is where you should actually be setting timing from.

This pic is an example of what I came up with on my current 440. In this case, the engine was a recent rebuild and the balancer was new, so I got lucky and the factory marking was dead on:

 

[Cranky]

Man, I've run some high total timing before (50 degrees!) but were mostly on low compression engines....never on anything with 10.5-1! I would also like to know what cam was being run with 48 and if it was advanced or retarded. On another note, many get cornfused with ignition timing and cam timing....both are different but both will have an effect on engine tuning and so will compression and so will altitude etc.

 

[moper]

So what's the rest of the build? There are a bunch of ways to tune engines - but you want to make sure there's not a problem to start with. The .484 is not normally associated with big cylinder pressure that would cause pinging. Nor is timing the only cause. What carb? What heads? What fuel? What have you done to tune the carb?

 

[Officer Higgins]

Recently installed mr 6 pack cam, had similar issues with pinging. Bob says disconnect vac advance plug off at carb port. Set total timing 40 degrees, let initial be what it is you can check it if you want. So i tried that and works great will even start hot, just as precaution moved it to 38 degrees give or take and runs great no ping no hard start hot.

 

[1967coronet]

I am running ported vac on my motor home 440 low compression engine prob 8.1.
I had to open up the vacuum canister a turn { it was closed or all the way clockwise }
I have a mild comp cam 462/470 lift 218/224 duration @50%
I had to switch the advance plate in the distributor and have a 9.5 in it now
I have 15" of vacuum at 800
also 15 degree advance at idle
total mechanical is 34 all in at 2600/2700
with the ported vac set one turn out on the can its 42/44 total at 3000 and stays put
Starts and runs fine, shuts off fine , no ping on a pull.
Like Ed posted starting with a true TDC is the best way.
Vacuum leak ? Your 8" seems low at that rpm
I think that counter clockwise on the can will reduce were the advance comes in, It seemed to on my stock mopar distributor when hooked to ported vac.

 

[Bill Monk]

I agree with Ed on making sure tdc is true tdc, but you already stated initial idles best at around 14. That tells me that your timing marks are probably spot on or very close. At 14 initial, you should get around 34-36 total mechanical advance at 3000 rpm. Once all this is confirmed, adjust vacuum can counterclockwise 1/2 turn at a time until you still only have the 34-36 at 3000 rpm. Use manifold vacuum. Try it and get back to me

 

[moparedtn]

I agree with Ed on making sure tdc is true tdc, but you already stated initial idles best at around 14. That tells me that your timing marks are probably spot on or very close. At 14 initial, you should get around 34-36 total mechanical advance at 3000 rpm. Once all this is confirmed, adjust vacuum can counterclockwise 1/2 turn at a time until you still only have the 34-36 at 3000 rpm. Use manifold vacuum. Try it and get back to me

I agree with everything you say here with the exception of where to hook up the vacuum.
According to the factory service manual, there should be no vacuum advance at idle and the dizzy should be connected to ported vacuum on the carb.
Now, having said that...
I still haven't dialed in the distributor's diaphragm on mine - but the engine hates it when it's connected, acts all jittery and surges at part throttle, so
it's obviously in need of adjustment if I'm ever going to use it.
As it is, the car runs great with it totally disconnected and I get my 36 BTDC total right at 2500RPM or so, which the car loves in current configuration.

In any event, I suggest we let the OP get dialed in on his initial setup first, then he can experiment with vacuum advance and carb settings and such.

 

[Bill Monk]

I agree with everything you say here with the exception of where to hook up the vacuum.
According to the factory service manual, there should be no vacuum advance at idle and the dizzy should be connected to ported vacuum on the carb.
Now, having said that...
I still haven't dialed in the distributor's diaphragm on mine - but the engine hates it when it's connected, acts all jittery and surges at part throttle, so
it's obviously in need of adjustment if I'm ever going to use it.
As it is, the car runs great with it totally disconnected and I get my 36 BTDC total right at 2500RPM or so, which the car loves in current configuration.

In any event, I suggest we let the OP get dialed in on his initial setup first, then he can experiment with vacuum advance and carb settings and such.

You are correct on the service manual, but the reason was to reduce emissions, just like they recommend an initial timing of 5 BTDC when we all know our cars run better with more advance than that. Before the emissions stuff started, all vacuum advance was manifold vacuum, even Edlebrock recommends manifold vacuum for max performance with their carbs. Manifold vacuum allows us to set the initial where you don't get kick back and gives immediate advance at idle. This increases engine vacuum and you have a cooler idling engine. It also increases the rpm of the engine at idle allowing more closing of the butterflies. As the rpms increase, the manifold vacuum decreases. Properly set up, at 2500-3000 rpm, there is no vacuum signal to the can and you are operating at only mechanical vacuum.
I am ONLY stating this to explain the logic, not to argue. Believe me, until a couple of years ago I would have never used anything but ported advance because as you stated that's what the book says, I never questioned it.
All I can say is it works for me but either way, I couldn't agree more with getting the distributor set right right before going anywhere with the vacuum advance. Thanks man, great thread!

 

[Bill Monk]

Are you confirming everything stated with a timing light and vacuum pump? I too found my engine vacuum low at around 9-11" at idle and around 15" at cruising. With the vacuum canister I had this would not even begin to pull any advance at idle. It wanted around 15" to start pulling in so vacuum advance was doing nothing at idle.

I found a slant six vacuum canister that had the specs I needed. The VC239 canister started pulling in at 7" vacuum providing 7 degrees and was all in by 11" vacuum providing a total of 10 crank degrees advance. I had to slightly modify the arm to work with the V8 distributor but she works perfectly. The engine idles much better requiring less air/fuel and fires right up when hot. I should be around 50 degrees total timing at cruising RPM. I am running 10.5:1 static compression and run 93 octane and have never heard a ping from this build.

Not meaning to offend anyone but if you think ported vacuum is correct for timing advance then you don't truly understand how/why timing advance is utilized.

FYI, for anyone running into this issue with too little vacuum, Don at 4secondsflat is selling the correct vacuum canisters with modified springs that will come in with as little as 4" vacuum

 

[Bill Monk]

I am running ported vac on my motor home 440 low compression engine prob 8.1.
I had to open up the vacuum canister a turn { it was closed or all the way clockwise }
I have a mild comp cam 462/470 lift 218/224 duration @50%
I had to switch the advance plate in the distributor and have a 9.5 in it now
I have 15" of vacuum at 800
also 15 degree advance at idle
total mechanical is 34 all in at 2600/2700
with the ported vac set one turn out on the can its 42/44 total at 3000 and stays put
Starts and runs fine, shuts off fine , no ping on a pull.
Like Ed posted starting with a true TDC is the best way.
Vacuum leak ? Your 8" seems low at that rpm
I think that counter clockwise on the can will reduce were the advance comes in, It seemed to on my stock mopar distributor when hooked to ported vac.

That cam (I run it too) is notorious for low vacuum

 

[Derwud]

Thanks all for the education.. Interesting info here.. And I wonder why I want to get away from Carbs and distributors..

 

[moparedtn]

You are correct on the service manual, but the reason was to reduce emissions, just like they recommend an initial timing of 5 BTDC when we all know our cars run better with more advance than that. Before the emissions stuff started, all vacuum advance was manifold vacuum, even Edlebrock recommends manifold vacuum for max performance with their carbs. Manifold vacuum allows us to set the initial where you don't get kick back and gives immediate advance at idle. This increases engine vacuum and you have a cooler idling engine. It also increases the rpm of the engine at idle allowing more closing of the butterflies. As the rpms increase, the manifold vacuum decreases. Properly set up, at 2500-3000 rpm, there is no vacuum signal to the can and you are operating at only mechanical vacuum.
I am ONLY stating this to explain the logic, not to argue. Believe me, until a couple of years ago I would have never used anything but ported advance because as you stated that's what the book says, I never questioned it.
All I can say is it works for me but either way, I couldn't agree more with getting the distributor set right right before going anywhere with the vacuum advance. Thanks man, great thread!

Yep on emissions, which is why it isn't breaking my heart not to run any vacuum at all - and this particular engine absolutely hates vacuum advance at
any RPM. It's a 30 over stock '72 motor with the purpleshaft and mild porting, pretty stock stuff really.
I grew up working on all brands of American stuff from the 60's and 70's, and stock for stock never saw one with the dizzy hooked up to anything other
than ported vacuum, so I'm kind of predisposed to going that route, especially since the book says so too, that's all.
Reckon it depends on each individuals' stuff as always...
I fully recognize that some rigs might love direct manifold vacuum there, too.

 

[beanhead]

Oh boy! Ported! No, manifold!

 

[threewood]

Oh boy! Ported! No, manifold!
View attachment 672161

Hahaha!!! This gets a lot of people going alright. I have one car running off manifold, another off ported. Both run very well.