timing at 30 BTDC?!?!?!?!?!?!?!?!

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green67cuda

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yup....weird...is that even possible???
mech advance only, 800 rpm....i checked the balancer mark when i had the heads off and #1 at TDC, and it was dead on 0.....and yet the timing indicates 30 BTDC at idle.....
it starts easily and quickly, and runs great......
 
Sure it's possible. As long as the starter system can turn it, no harm done. There are racers who set total timing with the distributor, as opposed to running any type of advance at all. However, there is a point at which too much hurts. Also, do you have a timing tape on the balancer, or a timing light that can advance? You need one of those to properly set a timing curve.
 
i have marked my balancer using the existing pointer, since i know it's right
i set the pointer to 10 BTDC, and marked the balancer at 0, then put that mark at 10, and marked again at 0, and did one more....
so when i checked it just now, the second mark was lined up with 10, which is 30 degrees...(the first mark, add 10 to the pointer reading, the second mark, add 20 to the pointer, third mark add 30 to the pointer....so i can read up to 45 degrees right now...since the pointer reads to 15

anyway....my thoughts are that since I have about 8.5-9:1 compression ratio, and a MP .509 cam, that i can afford more timing....sound right?

if so, i need to do some research to find optimum with my setup.....or find a chassis dyno here.....somewhere...
 
Right. More initial (the distributor setting) is better response, and low end. But, like I said, too much is not good. If you run 30* initial, you need to limit the other advance(s) to 5-8*. Otherwise, as you rev up, the centrifical begins to come in, and your total timing jumps from 30* to 35* then 45* and depending on the distributor, may end up around 50*. That's way too much for good power under full throttle. Add to that if your vaccum advance is functional during light throttle cruise situations. It is better to have not enough low down, then way too much all the other times. So, you need to know how many degrees the centrifical advance is.
 
You could mark it around more the same way you have been, then unhook your vacuum hose from the distrubitor and put your timming light on it and bring the RPM's up to see what the timming goes to.
Like said I wouldn't want it up more than about 38 maybe 40.
 
ok....
Idle: 30
1000: 32
1500: 37
2000: 43
2500: 50
3000: 55

(i have no vacuum advance....mechanical only)

and like i said...it runs great....maybe it's ok with te cam/CR arrangement?

if i brough initial down to where total was 35, i'd only be at 10 at idle.....
 
I had one of those 509 cams in my low compression 383, in my runner. It also loved gobs of timing. Was using a stock elec distributor with out the vacuum advance and was running around a total of 45deg.If I remember right(mid 80's) Less and the headers would start to glow cherry red. More and it would surge at cruising speeds.
 
Mines at 20 initial right now. Doesnt seem to feel ant differant then were I had it before though some its going back to 18 intial 34 total
 
I've never run more than 35 degrees total in a small block, (40 in a big block) and my current engine likes 32 degrees total.

More timing just because the engine will take it is not necessarily better. You are most likely slowing your car down that way.
 
Guitar Jones said:
I've never run more than 35 degrees total in a small block, (40 in a big block) and my current engine likes 32 degrees total.

More timing just because the engine will take it is not necessarily better. You are most likely slowing your car down that way.
Click to expand...


yup.
 
I am running a 360 auto. My timming is set @12 advance idle. It still uses vacuum advance.

I see on a lot of posts guys are running sometimes 20 degrees at idle and still using vacuum advance. How is this possible? Won't it go over the "Hump"

What total timming should the 360 have?
ALso should I keep advancing base timming?

Car has poor power on the bottom and mid then starts to wake up at the top.

I am wondering if timming is the cure.
THanks for any help.
 
40, 50 degrees? A SB Mopar needs 34 total! Has your dist been phased?
Like 18 initial and all 34 in at 2800,2900 RPM. Do yourself a favor if not. Send it to Don for proper set up. Maybe your timing light is wack.
 
Back again!!

I just checked the instructions that came with my Mopar converstion kit.

It says setup as follows.

1) Set for total mechanical advance. Run engine at 2000RPM and set at
@ 35' BTDC total. (Vacuum advance plugged)
2) Run engine at cruise speed and note vacuum produce by engine btw
2000 - 4000 rpm.
3) Start engine and run at 2600 RPM and apply noted vacuum to dist with
vacuum pump.
4) Total advance with mech@35 and noted vacuum should be 50' BTDC.

ALL "A" engines 50 BTDC total
ALL "B/RB 56 BTDC total
ALL Hemi 53 BTDC total

Sound right to you?????

THanks
 
I should note that the total mech specs very based on year and size of motor.
the specs for the mech total I indicated were for A engine pre 89 (iron)
 
Those numbers sound about right but every engine/combo is going to be a little different. Also, remember vacuum advance only comes into play at part throttle cruising. Once you jump on the gas you have no vacuum advance and you have no vacuum advance at WOT. That is the reason perfromance distributors have no vacuum advance.

The only way to get the timing optimized for your engine is on a dyno or with many runs at the drag strip.
 
i need to find a chassis dyno near nashville....i need a bigger carb too, so i might as well take it to a dyno place and have it timed/jetted right...
 
If your going to go to a Dyno you may want to weld a couple of oxygen sensor bungs in the header collectors. This way they can get a accurate air fuel reading for you.
 
Well, I set mine to the Mopar specs.

I had it set at @12 BTDC. When I rev to 2000rpm (no Vacuum adv) it was only about 28 BTDC. I then reset the timming to @34 BTDC as per spec. Base
Timming is now well over the 12 degrees.

I then checked the vacuum advance including the mech at 2600 rpm. My new total (with the mech set for @34) was @53 all in at 2600. I then adjust the vacuum advance back down to @50 as per spec all in.

THe engine does idle better and I just did a short burst and seems to have more power.
Will keep you posted.
 
green67cuda said:
yup....weird...is that even possible???
mech advance only, 800 rpm....i checked the balancer mark when i had the heads off and #1 at TDC, and it was dead on 0.....and yet the timing indicates 30 BTDC at idle.....
it starts easily and quickly, and runs great......
Click to expand...
YEA I"D LIKE TO KNOW IF YOU DEGREED THE CAM...4" ? BECAUSE I HAVE THE SAME PROBLEM ??????
 
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