Firecore Distributor Curve/Springs

-

Red_Duster

Well-Known Member
Joined
Apr 17, 2019
Messages
458
Reaction score
282
Location
California
Good morning everyone,

A quick question for those running the Firecore distributors. My 440 seems to like a lot of intial timing, I'm currently at 22 BTDC and think it wants a little more. I followed the instructions I found here to limit my mechanical advance.

I'm going to record when the mechanical start tonight and at what point I'm all in- I think its coming in too soon. I've been looking around and can't find any specific springs for it. Would the MSD springs work in the Firecore or are they different?
 
If you switch over to a full electronic setup you can dial in any curve that you want. I switched over to the Hyperspark distributor on my car a couple of years back and it lets me set the cranking timing as well as initial, WOT, cruise, high speed retard, rev limiter, etc. Just program it with a laptop rather than using springs and weights and bushings.
 
If you switch over to a full electronic setup you can dial in any curve that you want. I switched over to the Hyperspark distributor on my car a couple of years back and it lets me set the cranking timing as well as initial, WOT, cruise, high speed retard, rev limiter, etc. Just program it with a laptop rather than using springs and weights and bushings.

That is the goal. I’ve watched your thread and want to go to the Sniper setup as well, but still saving up for that.
 
When I set the MP distributor with Mallory guts, every .010 in the slot = 1* at the crank.
Before you change your setup see how many degrees of mechanical you have. Measure the slot and divide by degrees to figure out the 1* width.
 
Out of curosity....did your Firecore distributor NOT come with a few extra springs to tune your curve? Mine always have but I haven't bought one in maybe a year and a half...Are they cheapin' out on us?
 
Mine did not.
Ok, so here is where I am at, it idles the best at 22-23. I have two blue springs on the distributor. My curve comes in at 1800 at is all in at 2600 rpm and 45 degrees total timing. I’m pretty sure I need limit the mechanical? Where abouts do you think and how do the pros feel about the curve?

Edit: Specs might help.

440, 30 over, Promaxx heads, TRW -12cc Dometops, Mopar 296/.557 cam, RPM intake and Schumacher headers with a hughes 2800 TC and 3.55s . I don’t have a measure CR number but cranking PSI is ~160 across the board.
 
Last edited:
Mine did not.
Ok, so here is where I am at, it idles the best at 22-23. I have two blue springs on the distributor. My curve comes in at 1800 at is all in at 2600 rpm and 45 degrees total timing. I’m pretty sure I need limit the mechanical? Where abouts do you think and how do the pros feel about the curve?

Edit: Specs might help.

440, 30 over, Promaxx heads, TRW -12cc Dometops, Mopar 296/.557 cam, RPM intake and Schumacher headers with a hughes 2800 TC and 3.55s . I don’t have a measure CR number but cranking PSI is ~160 across the board.


So you are saying the timing curve is flat from idle to 1800? And then gains 21-22 more degrees? My question is why is it not pulling timing quicker? It may not want all that intial if it starts adding timing way quicker than 1800.
Yes, you need to limit the advance.
 
Yep. Flat 22 from idle (850) to 1800, then advances steady to 45 degrees at 2600 where its topped out.

more confusing to me is that I pulled my distributor tonight (looking at it right now) and the 14 degree key was snug.
 
Also, I’m pretty new to this but I thought too much initial made hot starts harder. It’s starts hot first crank- it’s cold that it struggles.
 
Yep. Flat 22 from idle (850) to 1800, then advances steady to 45 degrees at 2600 where its topped out.

more confusing to me is that I pulled my distributor tonight (looking at it right now) and the 14 degree key was snug.

It’s a lot of work to straighten this out with the distributor in the car. I’d be all for looking into why it’s taking so long to get the timing moving.

Off the top of my head, I’d say you need about 10 in the distributor. That would give you 20 at the crank in mechanical advance. At 20 initial you be at 40 total. That’s probably as high as you will go, and 38 total is more likely. In that case, you only have 18 initial which is probably ok. And if you get the timing coming in sooner and don’t need all that initial, you may need to add a couple degrees of mechanical to it to get the total where you want it without running more initial than you need.

I’d look around local to you and find someone with a distributor machine. What they can do in an hour will take you much more time than that.
 
I had it out to work on. I went ahead and used the 18 degree advance keys and replaced the springs with the new blues from the kit. I figured with 18 in the distributor i can get my all in between 37 and 40 and still have the 19-22 initial and keep it idling... fingers crossed.
 
Well, that seems to have done it. I popped it back in the morning and had time for a quick test drive before the rain came in. I have 22 initial, curve coming in at 1200 and all in by 2600 with 39 total. Ran well and no pinging I could detect. Hot started fine. Got it to idle down to 900 in park, 800 in gear and it seemed smoother. Might be a little rich but I assumed I would need to retune the carb after I got the timing figure out.
 
Ha they must be cheapin' out! I just saw your follow up, looks like you got it covered. I don't know where in cali you are, but around my area (central) it gets hot starting about a month from now and 39 total might get to be a bit much....just something to keep an eye on if you get hot weather. Of course it all depends on your particular build and CR etc.
 
Mine did not.
Ok, so here is where I am at, it idles the best at 22-23. I have two blue springs on the distributor. My curve comes in at 1800 at is all in at 2600 rpm and 45 degrees total timing. I’m pretty sure I need limit the mechanical? Where abouts do you think and how do the pros feel about the curve?

Edit: Specs might help.

440, 30 over, Promaxx heads, TRW -12cc Dometops, Mopar 296/.557 cam, RPM intake and Schumacher headers with a hughes 2800 TC and 3.55s . I don’t have a measure CR number but cranking PSI is ~160 across the board.
FORTY FIVE? This is without vacuum advance? WAY WAY too much total
 
Well, I had the opportunity to take it out with the sunshine yesterday and drive it a little harder. At 39 total, Im still getting a ping. Not like it was but its there. I pulled over and dialed it back by ear (no light with me) and bumped my idle back up a little bit and drove it home with no ping but it was noticeably not pulling over 4700rpm. Checked the timing when I got home and was at 18/34...shut it down and had some run-on. Im assuming the run on is from bumping up the idle screw and that I was was out of the idle circuit. So Ill pull it again tonight and back the mechanical down a little and try to get my 22 initial and 37 total and go from there? At 39 with a ping it was pulling a lot harder at high RPM than 34 with no ping, is that a timing issue?

Bare with me, I'm still learning. I know its different for every engine so Im not looking for "Your timing should be this and this" more want to understand all timings effects so I can contribute to all the timing threads instead of starting them like I did here.
 
Last edited:
It's a balance. I'd set the ignition where you want it. Then see about part throttle enrichment to fatten it if it's pinging. As you get it dialed in, you fine tune timing and carb. If there's more info on the engine and car combination I could be more specific. But if everything was good except for a light ping, I'd fatten that throttle position.
 
-
Back
Top