440 Timing

[junkpile]

440 .030 over 484/284 cam, 2800 stall. had timing set at 15 BTDC without vacuum hooked up. Car ran great around town, no bogs, easy starts. Accelerating from cruise or at highway speed acceleration, pinging and ratteling. I Have adjusted the base timing to 12 BTDC w/o vacuum, but did not get a chance to run it as weather has come in. I followed a timing guide but the numbers did not make sense for total advance. I am trying to learn this stuff so I can do it all myself and not rely on others so much. I will give the numbers I got last night if someone can help me figure them out. Funny I have an engineering degree and still cant get the math

base timing w/o vacuum 12 degrees
base timing w vacuum 32 degrees
@3000 RPM with vacuum 48
@3000 PRM without 28/29

i have 8" vacuum at idle (12 degrees) did not get other vacuum reading. I was doing this myself so I was using a piece of old base molding to push the throttle open and check the timing so accurate RPM is 2800-3000

I have seen sources that say check at 3000, some at 2500 dont know which is the correct way.

Also what way do you turn the hex nut in the vacuum can to reduce the vacuum advance.

thanks in advance for the help.

 

[junkpile]

oh forgot......I want to get the total advance between 34-36.

I may have to just bit the bullitt and get a new cam an lifters. Any suggestions for a power brake, street performer would be great. (dont want to crack into it but i may have to so I can get rid of the issues)

 

[Bill Monk]

You have too much total advance with the vacuum hooked up. I run the same cam in my 440. Try this: set initial timing (no vacuum) at 14, connect the vacuum advance to manifold vacuum (not ported) then run the rpm back up and you should have around 32-36 all in. The reason for connecting to manifold vacuum is that as rpm increase, manifold vacuum falls off and mechanical advance kicks in. The manifold vacuum will also add advance at idle where you need it. If you do this and still have more than 36 at 3000 rpm, your distributors mechanical advance is providing too much advance and will need to be addressed but try this first and let us know what you have. You didn't say what compression you are running or what fuel you are using but compression is a major player here. I run 93 pump gas

 

[Cranky]

Yup, need to know more about your engine like static compression ratio and knowing how much cranking PSI it has is a good idea too. You can get pretty technical with all of this but on the other hand, trial and error works good too. Keep in mind that engines with higher CR's do not need a lot of timing, initial or total than engines with lower CR's. Also, cam timing can be a factor too....

 

[Derwud]

1) you should have no vacuum to the vacuum advance at idle..
2) Back in the 80's the most I could run in a stock block 440 with that cam was 7 degrees at idle..

 

[Bill Monk]

1) you should have no vacuum to the vacuum advance at idle..
2) Back in the 80's the most I could run in a stock block 440 with that cam was 7 degrees at idle..

With all due respect, I run this cam with 14 intial and I get 34 total using manifold vacuum which does advance the timing at idle and light throttle but by the time the mechanical advance is all in, the vacuum advance is virtually nothing and is nothing at wot. I have no pinging and she runs like a scalded dog. I realize that the topic of manifold vs ported advance has been and will continue to be controversial subject but the hard truth is that the use of ported advance began with attempts to reduce emissions. Junkpile, try it and let us know what you have

 

[Derwud]

With all due respect.. The vacuum advance as designed, is to run off ported vacuum.. If you are you using it differently and getting a different result, well there you go... And in case you missed it, again out of all due respect, my results were in the 80's when Gas was even worse then they are today..

 

[junkpile]

I am connected to manifold vacuum, edelbrock 750 connected to right side port (mamifold vacuum).

Not sure on compression (sorry) but not stock, pistons have slight dome top with notches for valve clearance. I am running 92 octane pump gas with 104 booster. I have always had slight pinging on pump gas.

i am still not sure where my total timing is, my math was coming with an outrageously high number. But my total with vacuum hooked up was 48. if I put the base timing at 10 the car will bog at WOT or when heavy throttle pulling into traffic. So I started at 18 with no issue then back to 14 with no issue but both with the ping under acceleration or up hill acceleration at speed, so I am trying 12 but have not got to test yet.

I am assuming that the 48 is my all in at 3000 from what is being said. If that is right, backing off my base timing will kill the car because 10 degrees dont work, Would one of the firecore distributors help? I am trying to avoid tossing the cam if i can.

 

[Bill Monk]

With all due respect.. The vacuum advance as designed, is to run off ported vacuum.. If you are you using it differently and getting a different result, well there you go... And in case you missed it, again out of all due respect, my results were in the 80's when Gas was even worse then they are today..

10.4

 

[Derwud]

I am connected to manifold vacuum, edelbrock 750 connected to right side port (mamifold vacuum).

Not sure on compression (sorry) but not stock, pistons have slight dome top with notches for valve clearance. I am running 92 octane pump gas with 104 booster. I have always had slight pinging on pump gas.

i am still not sure where my total timing is, my math was coming with an outrageously high number. But my total with vacuum hooked up was 48. if I put the base timing at 10 the car will bog at WOT or when heavy throttle pulling into traffic. So I started at 18 with no issue then back to 14 with no issue but both with the ping under acceleration or up hill acceleration at speed, so I am trying 12 but have not got to test yet.

I am assuming that the 48 is my all in at 3000 from what is being said. If that is right, backing off my base timing will kill the car because 10 degrees dont work, Would one of the firecore distributors help? I am trying to avoid tossing the cam if i can.

I use to have to tune to the ping, it sucks cause you do loose performance, but a happy engine is a good engine.. Try capping the vacuum advance and seeing if that helps.. Also what distributor are you running now?

 

[Bill Monk]

I am connected to manifold vacuum, edelbrock 750 connected to right side port (mamifold vacuum).

Not sure on compression (sorry) but not stock, pistons have slight dome top with notches for valve clearance. I am running 92 octane pump gas with 104 booster. I have always had slight pinging on pump gas.

i am still not sure where my total timing is, my math was coming with an outrageously high number. But my total with vacuum hooked up was 48. if I put the base timing at 10 the car will bog at WOT or when heavy throttle pulling into traffic. So I started at 18 with no issue then back to 14 with no issue but both with the ping under acceleration or up hill acceleration at speed, so I am trying 12 but have not got to test yet.

I am assuming that the 48 is my all in at 3000 from what is being said. If that is right, backing off my base timing will kill the car because 10 degrees dont work, Would one of the firecore distributors help? I am trying to avoid tossing the cam if i can.

Gotcha, try adjusting the vacuum can, turn counterclockwise about 1/2 turn at a time, you should be able to dial it way back. You are fine at idle but too much under throttle

 

[Cranky]

How are you checking total?

 

[oldbee]

How are you checking total?

+1, do you have a timing tape on balancer or is it fully marked. Not a whole lot of math involved, timing light shows what you actually have.

 

[moparedtn]

Having gone through all this just recently when setting up this new to me engine - and with my own 440 running that exact same cam - I'd suggest first getting the basics down pat - and don't even worry about hooking up the vacuum advance right now.
The following assumes your distributor is in good working order and if it's a points type, they are set correctly and are clean:

1. Do you know for fact the timing mark on your balancer is accurate? Oftentimes, they aren't.
If not, time to find out by determining "true TDC" (top dead center). There's several threads on here on how to do that, including one I did.
Once you have that, go ahead and set your initial idle timing at 10 degrees BTDC. This is just a starting point for now.
(Vacuum advance is disconnected and all vacuum ports on engine and carb plugged off).

2. Once you've gotten an accurate mark on your balancer of TDC, then either a)make another mark on the balancer at 36 degrees BTDC (or use your timing light if it has the capability of dialing in such).
I want you to adjust your timing so that at approximately 2500 RPM, it hits that 36 degree BTDC mark.
(Once again, all this is done with vacuum advance disconnected).

Once you've gotten that far, see where that leaves your initial timing at idle.
Check your vacuum reading at idle as well - that engine should be making more than 8 Hg vacuum at idle.

At this point, you can make minor adjustments to your carb (mixture, etc.) to get best vacuum reading at idle, then set idle speed again.

Take the car out for a drive with the distributor set like I described (again, still having vacuum advance disconnected) above and see what you have then.

We can go to advanced tuning once we get the base set on this.

 

[ksurfer2]

Having gone through all this just recently when setting up this new to me engine - and with my own 440 running that exact same cam - I'd suggest first getting the basics down pat - and don't even worry about hooking up the vacuum advance right now.
The following assumes your distributor is in good working order and if it's a points type, they are set correctly and are clean:

1. Do you know for fact the timing mark on your balancer is accurate? Oftentimes, they aren't.
If not, time to find out by determining "true TDC" (top dead center). There's several threads on here on how to do that, including one I did.
Once you have that, go ahead and set your initial idle timing at 10 degrees BTDC. This is just a starting point for now.
(Vacuum advance is disconnected and all vacuum ports on engine and carb plugged off).

2. Once you've gotten an accurate mark on your balancer of TDC, then either a)make another mark on the balancer at 36 degrees BTDC (or use your timing light if it has the capability of dialing in such).
I want you to adjust your timing so that at approximately 2500 RPM, it hits that 36 degree BTDC mark.
(Once again, all this is done with vacuum advance disconnected).

Once you've gotten that far, see where that leaves your initial timing at idle.
Check your vacuum reading at idle as well - that engine should be making more than 8 Hg vacuum at idle.

At this point, you can make minor adjustments to your carb (mixture, etc.) to get best vacuum reading at idle, then set idle speed again.

Take the car out for a drive with the distributor set like I described (again, still having vacuum advance disconnected) above and see what you have then.

We can go to advanced tuning once we get the base set on this.

I have been struggling to figure out all the timing info that I have been reading. This post is fantastic. Thank you. I am anxiously awaiting the next installment!

 

[junkpile]

distributor is new performance distributor bought at chain auto store (should have got a Firecore). I checked total one with vacuum disconnected at 3000 rpm it was 29-30 ish (hard to read) with vacuum hooked up same rpm it was 48. Ballancer is marked. It runs good at 12 but i had it running really good at 14 base NO vacuum hooked up. pinged like crazy under load.

this advise is great. I will try disconnecting all vacuum and find 36 degrees at 2500 and see where it sets from there. This cam like to idle around town at 950 rpm in gear or a little over 1,000 in park. I had the timing set at 10 degrees but had a lot of run on issues when the car was shut down. it seemed happy at 14 but the dreaded ping.

i will try to get back to the car this weekend and run the suggested timing from moparedtn. and run it with no vacuum hooked up and let you know what is happening.

 

[junkpile]

distrubut is electronic with the external orange box. forgot to mention that.

 

[Bicylindrico]

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.

 

[Derwud]

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.

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

 

[Bicylindrico]

distributor is new performance distributor bought at chain auto store (should have got a Firecore). I checked total one with vacuum disconnected at 3000 rpm it was 29-30 ish (hard to read) with vacuum hooked up same rpm it was 48. Ballancer is marked. It runs good at 12 but i had it running really good at 14 base NO vacuum hooked up. pinged like crazy under load.

this advise is great. I will try disconnecting all vacuum and find 36 degrees at 2500 and see where it sets from there. This cam like to idle around town at 950 rpm in gear or a little over 1,000 in park. I had the timing set at 10 degrees but had a lot of run on issues when the car was shut down. it seemed happy at 14 but the dreaded ping.

i will try to get back to the car this weekend and run the suggested timing from moparedtn. and run it with no vacuum hooked up and let you know what is happening.

I am running the Firecore also. The canister on this distributor will only function with a stock engine's manifold vacuum meaning it's worthless with a decent camshaft.

Engines run much more efficient, cooler and more responsive if the ignition timing is correct for the conditions. If you run wide open all the time like at the track, then vacuum advance is worthless. Otherwise get her tuned for the conditions you drive.