dennisbernal91z

iTrader: (2)

OK, well everything seems to be running good in my camaro right now. It has a forged 383 with a holly 750 DP.

Now I know the car idles with only 8" of vacuum (big *** cam) with initial timing set at 17*. But if I up it to around 23* I can manage about 10".

And when I rev I don't here any knocking while I run 91 octane gas. So does that mean I should leave the timing higher like that?

Thanks.

- Dennis

Sonix

iTrader: (1)

With that much cam, you want a lot more timing.
I'd run full timing. Just pop off your dist cap, remove the springs and weights, and ziptie it to full advance. then put it back on.
Or adjust it so your mechanical advance is only like 10* or so, then run about 26* base timing (what I was doing with my xe268h cam). Now I run full timing on my iskyz25

what is your cam?

dennisbernal91z

iTrader: (2)

Thats the cam card. Right now the timing was set to 17 and went up to like 35 total. I adjusted my initial to 23 but never changed the bushing or springs yet from what I had them at.

Sonix

iTrader: (1)

oh ok 246/254, in a 383.
Yea, i'd lock it out at full advance for best performance.

dennisbernal91z

iTrader: (2)

does that mean take the little bushing out too?

or just get rid of the weights and springs?

Why is it best to lock it out?

Sonix

iTrader: (1)

Full 36* of timing all the time. Better off the line performance, better idle, better vacuum, etc.
It's harder on the starter when hot, but if you've got a newer battery and starter you'll be fine. You can always use a starter timing retard too.


do a search, f-bird'88 has posted a how to many times before. search for "locked out timing."

Batass

What dizzy? My pro-billet msd had a way to lock it out, I know I had to pull it and pop the gear off though. But its the RIGHT way to do it. Don't have to worry about any slack or loosening, especially in a nitrous or blown environment, which I'm guessing your planning on, looking at that cam.

I locked mine out at 32 and I always was a little concerned about some possible detonation when lugging and low rpms. I dont hear squat over my exhaust and blower whine.

I havent noticed any problems starting when hot. If I ever do though, i have a start button, so I will turn the motor over with ign off and once it is spinning well, turn ign on.

dennisbernal91z

iTrader: (2)

I have a new pro-billet, they is a way to do it, but I have to pull the dizzy. no big deal.

Other people say I would be crazy to lock out timing. I am so confused now.

AlkyIROC

Initial timing is only needed to start the engine and run it at an idle without building a lot of heat in the cylinders. The engine should be at full advance by 3000 rpm. Vacuum advance is for part throttle operation on the street and isn't calculated for performance use.

Set the initial as high as you can without it kicking back when trying to start the engine. Adjust the mechanical advance to give a total where the engine makes the most power. Usually in the 32-38* range. A dyno is the best place to find out what is best. Any tuning you do such as jetting, spark plug gap, valve lash etc won't change where the engine likes it's timing however playing with fuel mixtures and timing can change cylinder temperatures and change what spark plug heat range works best.

If you have a distributor that allows you to lock out the timing, set it to full advance. If the engine kicks back when trying to start get a start retard ignition box.

My old Holley ignition has a built in start retard up to 20*. My timing is currently locked out at 36* and I think I use 10 or 15* of start retard and the engine doesn't kick back at all when cranking it over. As soon as the ignition sees over 500 rpm, it goes back to full advance.

Bumping your initial 6 degrees also bumped your total 6 degrees so your total is now 41*. You'll probably get a lot of pinging with that much advance. You need to change the mechanical advance to lower the total back down 6 degrees or to a more reasonable number.

Read the instructions for the MSD Pro Billet on how to lock it out. You can also download the instructions from the MSD web site.

dennisbernal91z

iTrader: (2)

yeah I know i made the total too high, but I didn't get any pinging, or if I did I didn't notice. I will do step one of what you are saying and advance it and try to turn the car on. I have an optima and high TQ mini starter. I also have an MSD 6 Digital Plus box. That has start retard built in. Something like 5 degrees I think. I will have to read the instructions again.

But I will do those steps first tomorrow and post results and go from there. Thanks.

dennisbernal91z

iTrader: (2)

I was playing with it today, I decided to swap 1 spring so that all the timing would come in at 3000 instead of 3400. Thats all I changed. I checked my base timing. it was 24*, then I double checked the bushing, it adds 18* to that. So my total timing was 42*. Much higher than people ever say to run Then I turned on the car and was REALLY REALLY trying to hear any detonation or anything abnormal at all. So I backed it out of the driveway, slowly up the hill and got on it after it leveled out.

3rd gear, at about 2000 RPM, (30 or so MPH) Mashed the gas till about 5500 PRM. Not only did the car not have any problems, it seemed to pull harder than ever before.

- factors
- cam never got degreed in, so I guess it could be a bit off
- Timing tab dodn't come installed on my cover and so it might be off as it was added later.

Thats all I know so far. I will try to see what happens tomorrow when there is dry roads and warmer weather.

anesthes

iTrader: (12)

This is a street car? How do you pass emissions??

-- Joe

dennisbernal91z

iTrader: (2)

magic, hehe.








No j/k. It helps to be a nice guy and a smooth talker. I found a fellow thirdgenner in a shop and he helped me out after a couple months of me not even asking for help. Guess he felt like he needed to help. Very good people around here