you guys with bigger cams preferably around my size, what kind of base timing are you running? i seem to not be able to get away with anything less then 16-18 degrees. this seems a lil high to me. am i crazy or what?

 

16 - 18 should be fine as long as you have control of the mech advance. I just got done limiting the advance in my distributor so I could up the base timing and improve the idle. FBird88 has some great info around here on that. I kinda screwed mine up and limited the mech advance down to 10 - 12 degrees. I'm running 25* base right now.

 

16 sounds a little low for that cam, i'd try around 20-24 even, depending if your starter can crank over that kind of timing or not. f'bird88 has tons of info on this site all about it....i'd look into that.

 

ok thanks i thought i was just too high so thats why i brought it back like i did. Ill fix this asap and get it prolly up to around 22-24 i believe it sounded good. quite a bit difference then the ole' 6degrees the stockers use. lol

 

i'm running 30 degrees at 1500 rpm, can't get the motor to idle any lower to find out what it really is, i still need to take the dizzy apart and change out the timing curve anyways, but for now it works. i know it's too much timing for the starter though because sometimes it will stop dead in its tracks while turning the motor over when i turn on the ignition relay.

 

im running a high torque starter so hopefully i dont have too much problem

 

I have a little 4:1 gear reduction starter and mine spins right up.

 

hey another question with the higher timing, do i need to do anything to my spark advance tables? or is properly adjusting the base timing in the prom good enough?

 

definately need to limit the spark tables if you're running more initial timing, otherwise it would still be adding the 24 degrees or so already in the tables.

 

My distributor is locked out at full advance but then I also don't need a timing curve. The engine doesn't like running if I drop the timing much below 25*. Mine is currently locked at 37*.

 

how much should i really be pulling from the SA tables? this part confuses me, should i take out the 16 or so degrees all across the board? i know u cant tell me what is optimal or perfect, but i need a ballpark figure to know where to start and understand things better.

 

well if you're running lets say hypothetically 20 degrees advance at idle, then i'd have total spark advance set to 16 degrees which would be 20 + 16 = 36 total timing. now at part throttle i believe the tables add in more timing like a vacuum can would, in this case you can run another 10 degrees timing to keep it conservative. ultimately at WOT you'd want 34-38 degrees total depending on what creates the most MPH at a dragstrip. if you need help with the timing tables i'd check out the DIY prom board since i'm a carb guy.

 

not to jump over this thread but I have a post over there and I still am at the point of trying to figure out how I should have my timing set for my cam and how I should run the curve for a cam like that.


cam is a hyd. roller .544/.554 lift 230/236 dur. @.050 112 LSA
with 4 deg adv. valve timming is...
Open Int. 7 BTDC .. Open Ex 54 BBDC
Close Int. 43 ABDC .. Close Ex 2 ATDC


if you had total control over how much was added or pulled what curve should I have?

 

u basically have the same cam as i do.

i agree with these guys above, give it base timing what it likes, and then with the curve, have it run the base timing + about 10, then by 4grand, have the timing maxed at around 35 degrees.

 

12 base, 36 total here. I've got the springs setup so it's all in around 2000 RPM. It's also a full mechanical distributor. Motor is a 10.5:1 short-rod 383 that I spin to 6200

 

I am runing 230/235 560/560 112 lca solid roller with very agressive ramps (for boost) 8 deg initall adv. with 32 deg. max. Idles nice @ 800-850 rpm fair lope to it.

 

sounds like my car!
I'm glad this came up because I'm running a very similar cam (230/236 .544/.555 112 LSA) and need to the the timing right before it fires, again. So one should not go above 36* total at about 4k?
I'll try to give it about 12* advance to start it and hopefully it will idle so I can play with it and see where it likes it best.


[side question: what does the stock 730 ECM max the timing at during WOT?]

 

now what i dont understand if someone would clarify, is if im running 20degrees base timing (est disconnected) and then with the est connected is that all an additional 15-30 degrees timing as says spark advance table on top of my 20!?

 

You may have a "hard start" condition with that much initial, but you can always put in a timing retard for start up, pretty sure MSD has it all ready to go for you and will work with the stock ECM.

I think you have the understanding correct, as I can figure out.

Whatever timing you have in the chip, is added on to the initial, that's why you have to be careful with too much initial, without adjusting the tables in the PROM...otherwise you could do a WOT run and start clicking way past safe (beyong the "normal" 36-38* total), detonate and cause damage.

 

i ran a data log tonight and at max, from 4-6k i had a few counts here and there, no more then 15 total.

if im running 20 degree now, and with 17 timing in the spark advance map at 800rpm, does that mean im running a total of 37 degrees timing at 800 rpm?

at least i have a constant that says no more then 47 degrees total timing no matter what. should i bring down my spark advance table about 10 degrees all across the board?

 

You need to map it correctly...

47 is good at cruise...you want as much as advance as possible when on the highway, helps with fuel economy.

47 at WOT is too much, and could cause internal issues.

37 at WOT is pretty much good, depending on the top end MPH's, and knock counts (if any) that you may get.

 

i understand what u mean by mapping, gotta read what kind of load vs rpm under w0t im running and tune accordingly. no biggy. just making sure i got this understood correctly.

i took out 10 degrees all across the board which theoretically is like only having the base timing at 10 degrees rather then 20.

at 90load and 6400rpm aprox, its now only at 30degrees timing in the SA table rather then 40 as previous, now thats only a total of 50 rather then 60 even though the max allowed by the ecm is 47. but thats just how it is all across the board now so in the higher load and rpm range is now only about 20 degrees, 40 total. which i believe should be a good tuning choice to play with.

 

I'd bring it down a few more.

Normal wisdom is SBC;s run best in the 36-38 range, and fall off after that.

Even if the engine will take it, it's not doing any good and has a greater potential for damage.

If you're tuning on the fly, then G-Tech it for MPH's and see where she begins to lay down, or not increase.

Track is good, but an open stretch of deserted road (with a G-tech)can get you 10x the results in 1/2 the time spent.

 

keep it coming guys, im learning quite a bit here
Ive been waiting to actually use my gtech for something good.

 

are you still tuning? I am very curious on how you are doing. since are setups are pretty similar '89 ecm (6e) hsr, cam and head size. I would like to know how the rest of your tune is going and what you have done.

btw the other board told me to leave my 12 deg advance and then change the base timming in the chip to match.

I think I may be too lean on warm up since it won't idle on it's own until I have it warmed up. (which is odd because I thought it did several weeks ago??) and I also have a surging/chuggle while driving below 3000 rpms which I have no Idea what it is yet anyway my o2 seems use less at idle since it is so far back now

 

Yep, Everyone is giving this guy wrong information!!

Before you break something...

Set the initial(base) timing with the gun with the est disconnected.. I'd set it to around 10-15*. Then go into your chip and under constants, change "Spark Reference Angle - Base timing" to whatever you set your base timing to.

Alright, now what you see in the spark advance table is the actual timing the engine is recieving. Everything in the spark advance table is with the base timing included already.

Just to make things clear;

If you set your base timing to 6* and 6* in the chip's constant; 34degree's at wot in the spark advance table is the actual 34 degree's your engine is seeing.

Now if you set your base timing to 12* and 12* in the chips constant; the engine is still seeing the same 34* that is entered in the spark advance table.

 

i done a lil bit, i had 35 degrees timing all the way in by around 2500rpm. my car is down atm for more upgrades so i wont get back to playing with it for a week-ish.