engine timing

Lonestar Rider said:

I have a stock 2002 ZZ4 350/385HP. I checked the timing per the manual and found it was advanced beyond the 10 degree mark. I reset to the 10 degree mark and it seems to have a flat spot at low rpm that didn't use to be there. Is everyone running 10 degree above TDC or is there a better spot for lowend torque?

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You will get the best results if you set the total advanced at 36 degrees. If the engine is idling a little fast the distributor will be already advancing and give you a bum reading. Slow timing will cause a flat spot.

Adrian

I have found 14 degrees at idle to be optimal. Try it, you'll like it.
Also, I have found 38 degrees total mechanical advance to be even better than the 36 degrees recommended by almost everyone else. This is a question of getting the most advance you can without pinging and each motor seems to like a little more or less advance. These engines have very little load on them due to the comparatively light weight the engine has to pull and can, therefore, take a lot more advance much sooner in the RPM curve. I advanced mine until pinging under load and then backed off two degrees at a time until it stopped. Trial and error.....Joe

Timing Marks

I recently bought a 2002 SB 385HP and don't have the manual. Where are the timing marks on the engine as it doesn't have a traditional harmonic balancer? I have added the #7 converter and nitrous. Have not had the nitrous on yet as I havn't gotten comfortable with how hard the converter hits yet. Probably tomorrow :twisted: !! Yes there will be nice weather in Atlanta tomorrow!

Phil

Phil,

Sitting on the bike the tab is on the top left side of the pulley.

Tim

Phil,
Also the marks are on the back side of the pulley, so you'll be looking toward the front of the bike to see the pointer and the timing marks.......Don

Found Timing Marks

Thanks Guys. Found the marks and now just need to find my old Snap On timing light. Think I left it at the hanger while timing an electronic ignition on an experimental airplane 10 years ago!

I assume from what I have read on the board and from the mark I see on the pulley that the "proper" timing is 10 degrees btdc at low idle or 36 degrees @ 2500 rpm +. All with vaccum disconnected and plugged.

Thanks,

Phil

Phil,
First, you may want to get a timng light with an adjustable scale. Makes things easier.
Yes, vacuum advance disconnected and pluged, the mark is 10 degrees. But I think most have found 12-14 gives the best response. Your total cenrifugal advance is
good @ 36 degrees, although some like Joe, have found 38 to work well for them. All depends on what your motor likes. Some of the guys (myself included) have installed the Crane Vacuum Advance kit, and like it a lot. It gives you a choice of spring strengths, which will bring the centrifugal advance in a little faster, and an adjustable vacuum advance diaphram.

I'll send an article that is pretty good on the GM HEI ignition to your e-mail address. Good luck.......Don

Phil,

I've got a 385 small block & I run 14 degrees, 38 degrees and 50 total with 125hp NOS kit & #7 converter......works awesome and no detonation. I do run a progressive computer on my system though so it doesn't get 100% initially on the button normally.

You're gonna love it :lol: 8)

Tim

Thanks

Thanks again. Got the article and have ordered the Crane advance kit from Summit. Will install and time asap. The converter change brought this puppy to life, with some additional and more quickly advanced timing it should be a real handfull when the nitrous kicks in. I do not have the progressive computer, it justs come on 100% at full throttle after arming. Is this a problem?

Phil

Re: Thanks

AcroPhil said:

I do not have the progressive computer, it justs come on 100% at full throttle after arming. Is this a problem?

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Phil,
I don't know, as I haven't put Nitrous on mine yet. So I guess I'll wait to hear from you after you hit the button the first time. Ha Ha! Good Luck!!

Phil,

I would think not, I really added the controller 'cause I want ed be able to control the wheel spin a bit..........I actually wanted to beat somebody

Lots of guys running your combination and are very happy :lol: ]

The converters make a ton of difference and really make the bike feel strong.

Tim

GRUMPY said:

Phil,

I would think not, I really added the controller 'cause I want ed be able to control the wheel spin a bit..........I actually wanted to beat somebody

Lots of guys running your combination and are very happy :lol: ]

The converters make a ton of difference and really make the bike feel strong.

Tim

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Hi Tim

The real reason to add the controller is to get consistent runs with your NOS (such as bracket racing). It also looks good. The way we use Nitrous is not trying to get the same run within a few thousands of a seconds each time but to beat your buddy or light the tire up at all speeds and so forth.

Adrian

Jack,
I sent it to your e-mail. It's the part that deals with the advance mechanism.
You, and anyone else that might be interested, can also go to Wag's site to see the complete article. I'll include a link to it.
Scroll down just past half way, and you'll see the "Help" files. On the left, under "Engine" you'll see "HEI Performance." We are concerned with the Non-computer controlled distributors.....Don

http://webpages.charter.net/wag1/

Howdy Adrian,

How you & Cozaey doing?? Say "Hi" for us.

I've tried mine at 100% & no delay, and it will light the tire up to any speed I've tried so far :lol: I think the fastest is about 70 that I tried it with no delay, and it spins the tire pretty hard.

With the delay & stepped down to about 30% to 40%, you can just nail it and the tire stays pretty well hooked up....hazes just a bit when the NOS kicks in according to the guys behind me.....then stays glued until you let off. Not sure what it would do with the stock 230, think it'd probably go up in smoke unless the "hit" was 25% or less on the initial.

I only tried getting into it once with the tire really smoking, and it just buried the tach as soon as I hit the button 8) Way cool :lol:

Tim

Crane Vacuum Advance Kit

Hey guys, I just received my kit from Summit. Think I can install per the instructions in the article on wags site. Is everyone using the limiter plate that comes with the kit or not.

I used the limiter................Don

Me too.........as did Wag.

Re: Crane Vacuum Advance Kit

Lonestar Rider said:

Hey guys, I just received my kit from Summit. Think I can install per the instructions in the article on wags site. Is everyone using the limiter plate that comes with the kit or not.

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I have done 5 Boss Hoss's and I tried it both ways. It works best for me by leaving the limiter out.

Adrian