Ignition timing Help!!

[DJF]

Please can somone help Im stuck. My motor runs great and pulls great!! Butt....

My car gets hot only a low throttle loads, cools right down when running at 50mph, I know advancing the timing reduces the temperature at low load. I cant just advnace the timing by moving the distributor becuase then it pings up the top end.
Im also pretty sure i can hear ping at about 2400-2800RPM when i start to put load on the motor in 3rd gear. But i dunno i might just be being paraniod. I have one of these Be cool huge rads with the dual fans that I had to sell a kidney to afford and i will be changing the mopar performance waterpump to a Mildon HV after reading some posts here.

My car has been on the Dyno to set up the carb and the ignition. The A/F is good all the way through and its around the 12.5 mark. The timing however was set using a very basic method .... retard a bit just so it doesnt ping at WOT and everything else up to then no one knows (yeah I know thats reallllllllllly dumb).

I dont know what the timing is doin because the markings on the fluid amper Harmoinic balancer dont make sense for my motor. I plan to TDC mark up balancer with some timing tape and see whats really going on.

As I understand I should be shooting to 16-20 degrees initial timing with the vacum advance unplugged? 34-36 Degrees total advance and i should see the advance come in at 26-3000 RPM? Should I even be using the vacum advance?

I have read that there is a plate I may need to weld or adjust? i think im goin to need to bump the inital timing up and keep the top end where it is? Is this right can anyone tell me where this plate is and if my distributor has this plate?

Mallory 4757801 stock setup.

My plan is to mark up the balancer with the timing tape, then run the motor up with the vacum disconnected. See what i have as is now at idle 800-1000RPM, then plot out the advance up the rpm scale every 200RPM. This way I will see when the advance is comming in and what the total is now (as I know it doesnt ping there coz we listened on the rolling road).
Then me plan is to bump the inital timing if that is necessary and reduce the amount of advance from the bob weights (this plate im reading about?) to keep the top end and perhaps change the springs, if the timing is coming in too early. I know nothing about where these springs live if anyone can help he here id appreciate it. I have never looked in the distributor. If I need to change the springs what should I be buying??


My motor set up is

440 + 30 10.5 CR
Indy SR1 Fully ported Heads
Indy Dual Plane
0.511 cusotm comp cam indy supplied, 500-550HP rated
850 Mighty Dominator
3.73 posi
3k stall convertor
93 octane pump gas


I'd really appreciate any help or pointers

Daryl

[firefighter3931]

As I understand I should be shooting to 16-20 degrees initial timing with the vacum advance unplugged? 34-36 Degrees total advance and i should see the advance come in at 26-3000 RPM? Should I even be using the vacum advance?

Daryl

Daryl ;

Base (idle) timing is "combination dependant" in that every engine will want/need something different. The larger the cam...the more base timing it will want (and tolerate) 

Get your balancer indexed and map out your timing curve in 500rpm increments and report back 

How much compression does the engine have ? What is the duration @.050 valve lift on your cam ? How much vacuum is it making at idle now ?


Ron

[DJF]

Thanks Ron,

I'll get on timing marks.

10.5:1 compression

Cam spec is

Grind CRB-5209-5209-H108

Gross Value Lift Intake (0.511) Exhaust (0.511)

Duration @ .050    Intake (246) Exhaust (246)
Lobe Lift              Intake (.3410) Exhaust (0.3410)
Lobe separation 108.0


Vacum at idle is maybe as much as 8" and is erratic. Should I be changing this cam out for somthing more interesting while i got it all in pieces  

[Chryco Psycho]

I would not use the Vacuum advance at all you want to get approx a 20* curve with timing at idle around 16-18* & total timing at 36-38* . Did you do a cruise pull on the dyno ? Your fule curve could be ok while ramping up the rpm but at a steady speed it may go lean as the squirts no longer add fuel , this will cause heating . The cam has a fiar amount of duration without much lift , depending on valve guide clearances & piston to valve you should be able to get into the .550 lift range with similar duration , this will help asuuming the heads are ported & do not stall at .500 lift .

[firefighter3931]

Thanks Ron,

I'll get on timing marks.

10.5:1 compression

Cam spec is

Grind CRB-5209-5209-H108

Gross Value Lift Intake (0.511) Exhaust (0.511)

Duration @ .050    Intake (246) Exhaust (246)
Lobe Lift              Intake (.3410) Exhaust (0.3410)
Lobe separation 108.0


Vacum at idle is maybe as much as 8" and is erratic. Should I be changing this cam out for somthing more interesting while i got it all in pieces  

That's a decent cam for your combo...it'll be a bit knarly at idle but will pull hard from 3k-6k in a 440 ci combo. I'd recommend degreeing the cam in on a 104* intake centerline to give it a llittle more bottom end punch.  

I'll bet it'll run really good with 20-22* of base timing and 35-36* total all in by 2500-2800 rpm. You might have to do some tuning on your distributor to dial in the ignition curve.   Increasing the base (idle) timing will make it more responsive down low and increase manifold vacuum which will make it easier to tune. Like Chryco said in the post above ; plan on eliminating the vacuum advance...it'll run better.  


Ron

[DJF]

Thanks guys thats a great help!!! 
I got a delivery on route with some timing tape, soon as its here i'll be on it and let you know how it goes 

[DJF]

OK so i got the delivery, installed the new Miloden HV water pump and thermostat to match at the weekend, I drilled a 1/8th inch hole in the thermostat to help clear the air.
I TDC'd the motor and found that the balancer is indexed correctly. I cant explain why i thought it wasnt perhaps i was mis-using the timing light or even more embarrassingly perhaps i connected it to the wrong bloody lead.

Finished late on Sunday and it was too late to start up and play with the ignition so a job for this weekend comming.

My question is how do i get to the part where i can limit the amount of total advance on the distributor? Cap off? roator out and there are some screw heads or somthing? Is here anything i need to be careful of?

[firefighter3931]

My question is how do i get to the part where i can limit the amount of total advance on the distributor? Cap off? roator out and there are some screw heads or somthing? Is here anything i need to be careful of?

Here are the instructions for your unilite distributor :

http://static.summitracing.com/global/images/instructions/maa-29014(2)1.pdf

You will need to purchase this tuning kit :

http://www.summitracing.com/parts/MAA-29014/?rtype=1


It's not difficult, just follow the instructions once it's up and running. 



Ron

[DJF]

Perfect thanks Ron

[DJF]

I orderd the timing kit so just waiting for that to turn up before I go head first into that.
Had to drive the car today as it was booked into a body shop to fix some damage I caused after replaceing a hinge pin a while ago
That Milodon HV Water pump and thermostat have completly transformed the car. I cant believe the difference it has made, I was running a Mopar performance pump the car used to sit around 190 degrees but traffic caused the temperature to rise real quick and i was always frantic trying to get some open road to cool things down.
Today the car sat at 170degrees I even sat in a traffice jam for 20 minutes with the motor running, it perhaps got to 175 degrees the electric fans kicked in a pulled the temp stright back down. It was behing like my daily driver. I cant believe it!

On a separate note, value cover breathers, Im running a fully vented system with mopar performance valve covers and two filtered breathers, what do I need? My current breather suck!! They drop oil on the headers now and then and it bugs the life out of me, car stinks. I stop somewhere and a drip of oil will happen ppl think my car is on fire. Ron you have an interesting set up in your pic there. What do you recomend? I need a solution thats as awesome as the water pump :-)