Hi Since its about my turbo build 350 i wanted to post this here qnd seperate from my build thread. I was wondering If i can use the msd start and step box 8987 via msd 6al boxWith a locked out gm hei distributor. (timing round 25* + vac adv. Main use would be Cranking the engine at start. Will the 8987 adjust the locked out distributor? Further can i use the 8987 to retard more timing if needed via locked out distr? I also read if the 8987 is installed and activated it will retard 4* timing right away at "0 setting" is that true? Any infos
I don't think you want a locked out timing setup on a boosted motor. There are plenty of ppl that have more experience than me with them, but form everyone I've talked too it's kinda like nitrous the more boost you run the more timing you need to be able to pull back off. Msd does make a 6 series box that performs this, you might be able to use a locked system with one of them, but I would think you would want more than 25 degrees to start with that way when your driving with no boost its not being lazy. My digital 6 plus pulled 20 degrees out on starting with the start retard. So my 32 total was 12 cranking, which would be another point to think about using a low number like 25 cause if it pulled the same 20 you would ting to start with only 5
Kinda right but im definitly running low boost and i would like to avoid another box to add. The rule of thumb is 1* per lbs boost. Means 8psi =8 *. The 25 is just a estimated #. The lock out dizzy is a way to do it as well as i understand. I will use the vac adv. To add timing while cruising. +5-10* And was wondering if i can use my 8987 start and step to retard the timing for cranking to possibly 15* As you know that box has the start and step option to retard timing.. The step version would not be used in my case since i locked out the dizzy at a certain initial and mechanical timing. https://www.msdperformance.com/products/rpm_and_timing_controls/rpm_controls/parts/8987.
I would lock it at 25 to 28 and should have no issue at all cranking it. Or you can and kinda need to anyway run the ignition box thru a toggle switch if it's hard to start for some reason you cut the ignition off and spin the engine then throw the switch, gives it a running go, plus it's a good theft device
I see great advice i confirmed with msd that the 8987 start and step box works with lockout dizzy. So i can hook it up and simplify the starting + i could retard extra timing if needed by activating the step retard function. If the step retard gets activated it retards 4* At activation (0 mark on the box) That would give me a extra retard if i crank up the boost later. And simplify the timing.
I locked out my dizzy and saw the msd adapter cable was damaged..lol no wonder i couldnt start it ahahah.. Well i soldered everything and cant wait to crank it up. I might start at 22* and work my way up.
Yea with it being intercooled and under 10lbs, you can probably get away with close to 28 I feel sure, but like you said start low and see what it will take
@hugger I wanted to come back to the locked out timing question. Since i get different inputs and recently got recommendet a 6BTM Box over locked out timing when locking out the timing , lets say Initial 12 and Locked out 25 would you use the vac at all? if not why? If yes ( i prefer it since i think it will give "cruisability") when would/should the vac advance come in rpm? and how does the Vac adv. proportion wise goes down from lets say cruising = +5-8 * Vac adv, to full throttle = 0 Vacuum which would put me back to locked out timing (25) I just try to simplify my turbo timing but want to be safe as well
Locked out and limited to are 2 different things. Locked out mean you have the same amount of timing all the time. Cranking, idle, 2000, 7000. It's all set at the same. So there is no longer be an initial lower number, no need for vac line. It is what it is. With the btm box, you could luck it out at say 34....the set the box to pull 1,2,or 3 degrees out for ever psi of boost. Let's say you set it at 1 degrees per psi, and your running 8 psi, that 8 degrees under full boost pulled. Leaving 26 under full load. This is nice because you get the lower timing you need under boost but not loosing drivability under light load and will idle nice with that much timing at idle. The issue comes in cranking with 34 I don't know if the btm has crank retard light the digital 6 plus does. The digital 6 does have the ability to pull timing but in....but it's down at set amount when 12 volts gets apply......you would need a boost activated switch to turn on at like 2 psi or so and set the box to pull out 8 degrees. Not a smooth linear swing like the btm that responds to your boost on demand.
I See Does the BTM work only with a locked out Dizzy? 34* timing and throwing the swithc for the MSD box (6AL or BTM) should help cranking. compression is 9:1
I have never owned a Buick with operational Vac advance, probably never will to be honest. With you being intercooled and low boost there just isn't a need to pull timing, will the BTM box work sure it will. I myself just wouldn't fool with it, if I was wanting to run 15lbs yea I would run something to pull timing unless it was meth injected then I wouldn't. Either approach is fine , I do run stuff on the edge I guess, always have, I just like to get the most out of what I'm working with. I run my Stock long block GN on 28lbs with 93 and meth WITH NO less than 22° I ran as much as 26° in first gear. If e85 would have been available back then I would had that poor thing on 26° or more in every gear I highly doubt you will have a cranking issue with 24° of locked timing tho. I've had big blocks with 30°+ that cranked with a good reduction starter. It's free to try , if it doesn't work get a 6al2 with the programmable curve if you goin to buy a box, it will allow you put the curve where you want it/need it
Very good!! Yea i feel the same about the boxes The Vac adv can still be retained and i could add another 5-8* and see how cruising feels. Its still a street car If its pinging i just plug it off and run full locked all the time i guess.
