[ss68396]

hey whats up guys,
i was wondering what do u reconmend i set my timing at for my best performance,

this is what i got 71 396/402
cam 238/248
http://store.summitracing.com/partdetail.asp?part=SUM-1303&autoview=sku
msd dizzy no vacum
6al box

and what springs and weights for the dizzy
i put the lite blue and lite silver with stock bushings, good or bad


thanks in advance

 

[65lkey]

16 initial and 16 mechanical for 38 total

 

[Jerry70]

16 initial and 16 mechanical for 38 total

Uh, that'd be 32º total. I'd use the black bushing (18º) with 18º initial for 36º total to start with. If you don't want to change out the 21º bushing try giving it 15º initial for the same total. If wants more initial (and it probably will) you'll need to swap the bushing. Spring selection will vary for different combinations. Light cars. low gears, high stall, etc. allow real fast curves while the opposite may need a slower curve. Generally, the fastest curve you can run without any problems will yield the best performance.

 

[65lkey]

16 initial and 16 mechanical for 38 total

oh duh i hate doing addition in public because when i get it wrong it's like you'd never believe I got an a in calculus ab

 

[SWHEATON]

BTW,that 238deg @.05cam needs 18-20 deg base timing,15deg base timing is too retarded as is the 32 total suggested too esp with that farily hot cam he has in his 396/402.

He should run 18-20 deg base timing along with 18 deg mech (in by 2800 rpm) in the dist for a 36-38 total all in by 2800 rpm with that cam.

For street he also needs a vac adv which will help it idle better,have better throttle responce,get better fuel mileage,and run a little cooler at idle & low engine speeds too.

But unfortunately for him he is not running a vac adv dist which is not good at all if this is a motor that will see street duty. If its a street duty motor you likely got suked into the you need a racing dist to go fast and have a powerfull/hot motor which is BS.

Also, you can setup any old gm points (or convert it to electronic) or gm HEI type aftermarket dist like summit/jegs sellsfor $90 with a mechanical & vac adv to perform extreeemly well for street duty. Many people get sucked into to buying the race only dist non vac adv for street duty which is a poor choice as the strip/race motors dont need a vac adv. Some people also run the timing locked out which is not very good for street applications either IMHO.

Good luck

Scott

 

[ss68396]

Ok so definetly set intial timing at 18 with big black bushing, rite?
now, I got a snap on digital timing gun I set it at 18 and point at crank....were should the line on crank more or less be?
Should It be near the bottom of the timin tab or closer to the top?
My 0 is the second number before the last at the bottom, if it matters

So whens that set, now I hold the rpms at 2800 and set the gun at 36 38 and the line on crank and tab should be lined up to were, do I have to play with the dizzy again?
Or just check it to see if its correct,

Also why does my timin hasto be all in by 2800 at 36 is because my cam power band starts at 3000?is it like that ex. Cam power starts at 45 does my total timing have to be in by 4 45 rpms.

Sorry for all the noobish ?s just want to get this rite, and thanks

 

[ss68396]

Bump

 

[dreis454]

when you set your gun @ 18 initial & then 36 or 38 total the pointer balancer mark should point at the 0 on the tab.

same thing when checking for total timing......set the light to 36-38,hold the engine steady @ 2800-3000 and the balancer mark should point @ 0.

OK PC?

 

[GRN69CHV]

Assume these are '71 vintage GM open chamber heads??

This is how I would approach it. Motor will want 38* total. Forget setting it by initial. Validate your balancer diameter. If 7-1/4" balancer, make a mark at 2.415" (38* on a 7.25" diam balancer) before dead center on the balancer, then set the timing to get your 38*. Let the initial fall where it may, but strongly consider limiting mech advance to allow as much initial as your setup can tolerate (hot starting). Use the lightest advance springs you can that allows the timing to still be stable at idle.

 

[69-CHVL]

How about an easier way:

Rotate the motor to TDC. Mark the balancer at say 12* BTDC. Then rotate that mark to the TDC mark again, mark the 12* again also. Rotate the 2nd mark to TDC again, make another mark at 12*

So now you have your balancer marked at 12, 24, 36*. Heck, make another mark so you have 48* show up. Now you can more or less see where your initial, total, and where you vac advance is.

If you have alot of free time on your hands, mark your balancer in 2* increments to about 55-60 so you really know where your timing is.

 

[kjett]

How about an easier way:

Rotate the motor to TDC. Mark the balancer at say 12* BTDC. Then rotate that mark to the TDC mark again, mark the 12* again also. Rotate the 2nd mark to TDC again, make another mark at 12*

So now you have your balancer marked at 12, 24, 36*. Heck, make another mark so you have 48* show up. Now you can more or less see where your initial, total, and where you vac advance is.

If you have alot of free time on your hands, mark your balancer in 2* increments to about 55-60 so you really know where your timing is.

Isn't that why they made timing tapes And who are "they"?

 

[69-CHVL]

The timing tapes that fly off you mean ?

Hey, lets bypass this nonsense altogether and get a fully degreed balancer.

 

[71 chevy]

I Got An A In Calculus Ab

Unbelievable!

 

[GRN69CHV]

Or, just do what I do. Cut a pice of masking tape to length and set in place on the balancer, then use it to scribe a line.

 

[ss68396]

you guys are funny but useless, can i get a real answer

 

[69-CHVL]

Wow...I see at least 3 guys tell you to set the total timing to 36 or 38*, dont know how much more real an answer you need than that!

 

[Jerry70]

you guys are funny but useless, can i get a real answer

You've had several REAL answers that have answered all of your questions. Tell us which question/answer you didn't understand and we'll try to explain it differently.

 

[bb67H-D]

Well you recieved some very informitive answers, as Scott said 36-38* total for your cam and if you have a standard t-light use Vince's masking tape method if you don't want to use timing tape.
fwiw my the cam in my 396 [well old cam now] was very close to yours and I ran about 20* base timing.

 

[dreis454]

I realize that I don't translate my thoughts into words very well,but someone would have explained it more if you needed it