Sorry Another Timing Question

[martiy1971 0]

So I inherited a 1970 MAch 1 from my father in law. He restored in about 15 -18 years ago and I am in the process of changing plugs, wires etc and I wanted to check the timing. It has a 351W that is mildly done, Edelbrock 1411 (750cfm), Edelbrock Performer RPM heads and intake; however I don't know if it is overbored or if its a stock crank. Apparently it was dynoed at about 350Hp if that says anything.

Back to the timing - at idle the timing shows exactly at 0deg TDC and when revved up to 3000 RPM it rolls to 30deg (Vacuum line disconnected and blocked off). Based on what I have read thus far shouldn't the timing be set somewhere around 10 deg BTDC, and not 0? When set at 10 BTDC and revved again the balancer slides to 20 deg, so I am assuming that the mechanical advance on the dizzy is 30deg. Does that sound correct? Should I be rolling it back to 10 deg BTDC and try it out?

I don't have a vacuum gauge yet (tomorrow), I know there is a way to set timing with vacuum pressure as a guide - any advice here? Sorry, I am a bit of a newbie when it comes to timing etc. but am learning fast.

Thanks in advance,

[69ShelbyGT350H 61]

If it goes to 30 when set to 0 initial, you should set initial to 6 btdc so it maxes out at 36 total advance. 

[martiy1971 0]

The marks on my balancer at 10 0 10 20 30

based on that I would move it 6 deg to the right as the 10/20/30 markings should represent BTDC correct? 

I would then reset the idle on the carb to what I want, correct?

[Bob & Sue 110]

Welcome,

Without more info on the cam specs I can't say what the initial timing should be, it sounds like it should have a healthy cam in it.

With your initial set to 0* 3000 rpm 30* BTC total timing.

Somethings not right if you set it 10* before TDC timing shows 20* BTC at 3000 rpm.

It should be 10* +  30* = 40* BTC at 3000 rpm  total advance are you sure you didn't set your initial at 10* ATC that would = 20* BTC

Your mechanical advance is 30*  + initial setting = Total Advance at 3000 RPM

Your initial should be somewhere around 10* if that engine is built like you said. You'll need to get it set close, then advance your initial by ear till it runs the strongest at idle, then check your initial timing & total timing it shouldn't be over around 36*-40* BTC if it sounds & runs good take it for a ride listening for any pinging if it pings back it off 2* at a time till it doesn't ping that is as close as you can get without knowing the cam specs.

You'll need the vacuum gauge to set your low idle speed mixture on the carb not the idle speed adjustment for rpm's at idle go to Edelbrocks site for info on that.

http://www.edelbrock.com/automotive/misc/tech-center/dl/carb-owners-manual.pdf

 

[martiy1971 0]

49 minutes ago, Bob & Sue said:

Welcome,

Without more info on the cam specs I can't say what the initial timing should be, it sounds like it should have a healthy cam in it.

With your initial set to 0* 3000 rpm 30* BTC total timing.

Somethings not right if you set it 10* before TDC timing shows 20* BTC at 3000 rpm.

It should be 10* +  30* = 40* BTC at 3000 rpm  total advance are you sure you didn't set your initial at 10* ATC that would = 20* BTC

Your mechanical advance is 30*  + initial setting = Total Advance at 3000 RPM

Your initial should be somewhere around 10* if that engine is built like you said. You'll need to get it set close, then advance your initial by ear till it runs the strongest at idle, then check your initial timing & total timing it shouldn't be over around 36*-40* BTC if it sounds & runs good take it for a ride listening for any pinging if it pings back it off 2* at a time till it doesn't ping that is as close as you can get without knowing the cam specs.

You'll need the vacuum gauge to set your low idle speed mixture on the carb not the idle speed adjustment for rpm's at idle go to Edelbrocks site for info on that.

http://www.edelbrock.com/automotive/misc/tech-center/dl/carb-owners-manual.pdf

 

You are correct, in my initial post I was using 10 ATC and that's why when revved it only went up to 20deg. Wherever I set it at idle, it appears to advance 30deg when revved up to 3k

[martiy1971 0]

 Right now the car has decent plug wires and plugs however it looks like it has remanufactured distributor and coil. I am just trying to get my head wrapped around where the timing is currently Set before I change out the coil and distributor and plugs to a full set of MSD components. 

[Bob & Sue 110]

31 minutes ago, martiy1971 said:

 Right now the car has decent plug wires and plugs however it looks like it has remanufactured distributor and coil. I am just trying to get my head wrapped around where the timing is currently Set before I change out the coil and distributor and plugs to a full set of MSD components. 

Your going to need the cam specs or set it by ear even with an MSD setup you need to know what advance curve to set it to.

It sounds like you have 15L curve cams in it that is 15+15 = 30* mechanical curve

[martiy1971 0]

Appreciate the advice! I will keep tinkering, and see how it goes.

 

With respect to the cam Bob, when you say "15L Curve Cams", I assume that is a shortened name? Are you able to tell me the full name, and at least I'll have a starting point to investigate further?

 

Thanks in advance.

 

[Bob & Sue 110]

I'm referring to the advance curve cams inside the distributor they very by Ford engines 5L, 8L, 15L etc depending on how much total mechanical advance the dizzy puts out,  you double the number 2 revolutions = mechanical advance a 5L would give you 10* mechanical advance. The photo shows a 10L & 15L the 15L is the one controlling the curve it's positioned on the stop, you can rotate it to the 10L for 20* mechanical advance. The springs control at what rpm the mechanical will come in lighter springs means less rpm's heavier more rpm's.

Example light springs total mechanical advance 1800 rpm

---------------heavier springs total mechanical advance 3500 rpm

Hope this helps, that's why you'll need to know what curve your engines cam needs to set up an MSD box it's controlled by electronics not parts in the dizzy.

The dizzy in the pic has a light & heavy spring if I remember right it had total advance at 2800 rpm.

 

 

[martiy1971 0]

Sorry, my misunderstanding, and yes I see now what you are referring to, and will check both the dizzy's (the in car, and the one I want to use) for the curve and spring type.

Appreciate it!

[barnett468 418]

what you are saying is impossible. it can not have less total advance with more initial advance.

[martiy1971 0]

I was reading the numbers on the HB incorrectly: I was working backwards. So last night, I moved the timing to 6deg BTDC plus the 30Deg the car advances from the dizzy at 3,000 RPM should equal a total advance of 36 degrees, or am I still not interpreting this correct?

[Bob & Sue 110]

That's right