Timing for a Magnum 280H

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danielb927

danielb927

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What should my initial timing be on a 360 with a comp cams Magnum 280H? My idle is 1200 or so in park, any less and it dies going into gear, and I think the vacuum advance might be kicking in a bit by then, but the spark fluctuates a fair amount too so it's hard to nail down to 1 or 2 degrees.
 
I run that exact cam in my 360. My initial is 16 degrees and 34 degrees total, all in at 2500 rpm. What kind of ignition are you running?

Jack
 
I'll have to check but I'm pretty sure it's electronic ignition with an MSD blaster coil. Just wondering, how did you time it at idle, does yours vary a fair amount or do I have some other problem that's causing it to wobble at idle? And, am I right in remembering that you should plug the vacuum line when timing?
 
I run an all MSD ignition, so mine bounces around a lot at idle as the timing light sensor picks up varying spark discharges. I set the stops in my dizzy at 18 degrees of mechanical advance. Then I set the dial on my timing light to 34 degrees. I then brought the rpm up to 3000 and set the timing at 0 degrees. This method will give you 16 degrees initial. Wobbling 1 or 2 degrees can be some sloppyness in your timing chain or just about anything. Very hard to put a finger on it over the net. I think your idle is kind of high. I have mine set at 900 rpm. I think you should get your idle down to below 1000, then set the timing and see if it still stalls out. I don't know anything about the street avenger to say how to set your mixtures, maybe somebody else will chime in there. Yes, plug the vacuum hose to set your timing.

Jack
 
this is interesting...anybody else have any input? i have the same cam in my 69 340 motor with the MP smallblock distributor currently with 15 initial, and about 36 total...ive had more than one person now tell me i need more like 19-20 initial...why is this? would i benefit from this?
 
1wild&crazyguy said:
as much initial as it will still start with fully warmed up is what you want for performance.

time re curve.
Click to expand...

thing is, im not sure if the distributor i have can go any higher unless i modify it (i've had it mentioned to me that i would have to limit the springs or something??im not a distributor expert by any means, but is this true?)...I am running vacuum advance if that does make a difference btw
 
limit the slots by welding them closed some,time light testing and grinding open lil by lil till you get the desired amount of mechanical advance.
the welding takes up the amount of it=mech advance.
 
Or you can shell out about $400 and get an E-curve dist from msd. Then you just turn two dials to electrically changed the advance curve8)

Its overpricedl but sweet-at first I got a kick out of watching the timing marks move so steady. No matter how fast I winged the throttle open and close the timing marks moved like they should--with no bounce or delay.
 
1wild&crazyguy said:
limit the slots by welding them closed some,time light testing and grinding open lil by lil till you get the desired amount of mechanical advance.
the welding takes up the amount of it=mech advance.
Click to expand...

thats what i thought, my dad was doing that the other day to a BB distributor...thanks for the info!
 
dist. degrees X 2 + initial= total


dist. degrees / slot length
6.............. .340
7............... .355
8............... .375
9............... .390
10.............. .405
11.5 ........... .420
12.............. .435
13.............. .445
14.............. .460
15.............. .475
16.............. .490
17.............. .505
18.............. .520
------------------------------
Set your initial with a vacuum guage,second chance garage has a nice write up on how to use one
or this www.tuningmadeeasy.com/
good luck
 
bigdemo1 said:
dist. degrees X 2 + initial= total


dist. degrees / slot length
6.............. .340
7............... .355
8............... .375
9............... .390
10.............. .405
11.5 ........... .420
12.............. .435
13.............. .445
14.............. .460
15.............. .475
16.............. .490
17.............. .505
18.............. .520
------------------------------
Set your initial with a vacuum guage,second chance garage has a nice write up on how to use one
or this www.tuningmadeeasy.com/
good luck
Click to expand...

thanks for this!
 
No problem,I had one of the welders from work do mine and got a small square file and it was the right width,whole thing took no time at all,huge difference though.
 
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