I'd like to know who is running their dizzy with the Mech advance locked out and how big is your cam? (duration @ .050 and center line), and if your running a starter saver? I am going to be locking mine out because the large cam and high comp seems to love as much advance as I can feed it. Also the starter doesn't seem affected at all. I'm debating between a lock-out Mech only dizzy and a locked out plus vacuum advance dizzy giving more idle advance. Also I'm running 4:10s out back and an M:22 inbetween.Thanks :bowtie:

I'd like to know who is running their dizzy with the Mech advance locked out and how big is your cam? (duration @ .050 and center line), and if your running a starter saver? I am going to be locking mine out because the large cam and high comp seems to love as much advance as I can feed it. Also the starter doesn't seem affected at all. I'm debating between a lock-out Mech only dizzy and a locked out vacuum advance dizzy giving more idle advance. Thanks :bowtie:


Im interested to read the post on this one. I would imagine having absolutly no advance would give you issues.

.

Locked out on all of mine.

I use auto retard, but have heard some guys have stopped using it??
I have no plans to stop using it, been fine for 20 plus years.

Cams are usually between .790-.950 depending on engine, duration 300+.

I've had zero issues with locked dist, and glad I did it.
Less moving parts, more precise, and I had nothing but trouble before locking it out.

If starting from scratch, you can't beat a crank trigger for reliability and dead nuts timing.
I will never use a distributor for timing again!!

.

I've been running mine locked out for years.

It's a 406 sbc, 10.5:1, 300/308 advertised duration intake/exhaust, 232/234 @ 0.050 int/exh, .488 lift, C/L 108.
The distributor is an MSD 85551.

It's locked in @ 36*.
It's killed a few weak starters, but now I've got a real good starter on it and it cranks fine now.
The thing runs like a raped ape, I have no plans of putting the springs back in.

I've been running mine locked out for years.

It's a 406 sbc, 10.5:1, 300/308 advertised duration intake/exhaust, 232/234 @ 0.050 int/exh, .488 lift, C/L 108.
The distributor is an MSD 85551.

It's locked in @ 36*.
It's killed a few weak starters, but now I've got a real good starter on it and it cranks fine now.
The thing runs like a raped ape, I have no plans of putting the springs back in.


Is this something that can be done on the street? Reccomended?

I run one on my bigblock. I always have. The engine doesnt have as much comopression as it shoulod have. It is 11.2:1 with a cam that iis 262 at .050 with a 106 intake centerline and makes about 175 psi of cranking compression. I run 38 degrees locked out with no start retard. I used to have one when I ran nitrous,but the box burned up and I went to changing the timing by hand when I shot it. I have a Tilton super starter,a single optima blue top battery iin the trunk and single 0 welding cables from front to back. It starts with no iissues even under the most extreme heat. It has no issues as far as driveability. I can street drive it on 93 octane pump gas,but I race it on race gas.The shortage of compression makes it run a little dirty so with pump gas it is hard to keep the plugs clean,and I think the locked timing actually helps that a bit.

Is this something that can be done on the street? Reccomended?
Mine is 100% street driven, no issues with a good starter.

Thats strange to me, So you run 38 deg initial at idle??

I'd like to know who is running their Distributor with the Mech advance locked out and how big is your cam? (duration @ .050 and center line), and if your running a starter saver? I am going to be locking mine out because the large cam and high comp seems to love as much advance as I can feed it. Also the starter doesn't seem affected at all. I'm debating between a lock-out Mech only dizzy and a locked out vacuum advance Distributor giving more idle advance. Thanks :bowtie:

Street car? Bad idea.

Race Car? Bad idea.


JMHO.

.

Explain, is there a HP level, compression level, cubic inch, or just never on racecars??


As long as the wheel clears the balancer, it makes no difference.
You must be within 50 thou for the pick up to function properly.
I've seen plenty of big wheels on small balancers, photo coming.

The crank trigger could care less what's behind it, 4, 6 or 8 cylinder, of any size.
All that matters is you get rock solid timing, which is what every race engine likes.

Edit: ?? asked

.

These results are sounding great, my combo is begging for it to be locked out it seems, I've just been debating about giving it a little more with a vacuum dizzy to clean up the idle and low speed burn even more? The crank trigger sounds very inviting Mr D. Great replies guys, keep them coming. Thanks :bowtie:

Thats strange to me, So you run 38 deg initial at idle??

Yes,it idles at 38 degrees total timing.I have tried it with as much as 44 degrees total,but it didnt make any more power with more then 42,and cranks hard wiith more then 40. This is a race car,and one that has relitivly low compression for the camshaft it has,so probably needs at least 22 degrees of timing just to idle at all. My DCR is nearly as low as a stock smog 350,and my engine doesnt reach peak cylinder pressure until about 4500rpm,so having a lot of timing at low rpm isnt an issue.
I would never recommend this for a mild street/strip engine.Street/strip engines with power peaks below about 6000 rpm make plenty of low speed cylinder pressure and dont need much timing at low speeds. As a comparison,a 9.5:1 street engine with a typical 280 degree haydraulic flat tappet cam might make over 200psi of cranking compression while my full race engine with close to 11.5:1 make only 175psi. I had a larger cam in it along with standard rings{I now run gapless) and it only made 145psi cranking. I literally couldnt get the engine to start without ether when the temps dropped below 30 degrees,but I hardly ever started it in the winter so it was a non issue.with the old engine,it would run faster as the engine got hotter,a lot hotter,like the best E.T.'s were when the engine was at about 210 and the heads were at about 240 degrees,with less then that it couldnt even fully burn the fuel at full throttle 7000 rpm,and consistency suffered. With the current setup it is a tad faster much more consistent.
In the case of my engine,the cam is fairly mild by race standards with 262 degrees at .050,and an intake closing of about 72 degrees ABDC. Typically race engines with 13:1 or more compression could have cams with as much as 285 or more at .050 and intake closings of 80 degrees ABDC or more,so while the compression ratio seems high,the low rpm cylinder pressure is so low that these engine can barely make enough torque to move the car across a parking lot at under 3000rpm.
So this explains the setup a little better.

running one locked out also for a few years on the street and strip.

sbc, 11:1, 630 lift, 300 plus duration and using a csr starter

have it set at 36 on street and 38+ at the track

msd 85551

no problems here

Whats that do to the bottom end power?

I have a locked in on my camaro. The only time it did not work well was when I ran the stock vortec motor in it so I used a dizzy with a curve that time.

Whats that do to the bottom end power?

I improves the bottom end power a bit on engines that have a lot of cam.By a lot I mean engines that begin making power at 5000 rpm. If you think about it,low compression stock engines get about 50 degrees of timing at about 2500rpm when cruising at a steady speed with the vacum advance hooked up. A stock engine with the vacum advance hooked up and 10 degrees initial timing might idle at 25 degrees of timing. A street strip engine with a healy cam such as a 292 hydraulic will idle with 14 degrees or so if initial and get close to 28 degrees with the vacum advance hooked up. A small block race engine with the timing locked out will run best with about 32 to 34 degrees,so it isnt much of a stretch to run with the timing locked. Big blocks like 38 degrees or more and thats a little tougher on starters.

Ive been running locked out for years as well.

.

Photo's of a mismatched crank trigger, hope it helps??



http://img10.imageshack.us/img10/6789/hpim0943k.jpg

http://img831.imageshack.us/img831/1565/hpim0944.jpg


.

If you only run full throttle a locked out distributor makes sense. If you run part throttle you're giving up mileage and driveability. Most cars like 45-55 degrees advance at part throttle. Cruising around with 36 is a waste. Saying the car runs great with 36 only makes sense if you've tried cruising with 36 and 50 and 36 was better. A street car needs some kind of advance curve.

Running locked-out timing on my medium-serious 454. Cam is a Comp XS282-S. It's 244/252 @ .050 on a 110* LSA (installed on 106* ICL). Compression is only 10:1 (pump gas motor) and it cranks about 170 PSI on the compression gague.

It simply wouldn't idle without locking it out (currently at 36* but it might take a little more). I also run vacuum advance ON TOP OF the locked out timing. Only about 10* more, hooked up to a ported vacuum source so it isn't kicking in at idle.

While I wasn't expecting to have to resort to these extreme measures to get decent street manners out of it, that's what it required (and I tried everything I could think of before locking out the timing). The huge ports and old-school chamber design on big block heads just seems to need more timing, especially down low, than modern-design small block heads (I've run similar combos on small blocks and not needed to resort to locked-out timing to get good behavior from them).

Locked out timing is a BAD idea if you don't have at least a 3000+ stall converter (mine is 3200). Cwentrifugal advance would be basically maxed out at 3000 anyway so the engine, when running, doesn't care about locked out timing unless you lug it down lower than that.

I chewed up one starter with the timing locked out (no start retard on my vehicle), but the first starter might have been bad from the get-go, so I can't give you an absolute answer there. The new starter (from a Vortec SBC truck motor) seems to be whipping it over with no problem, no kick-back, in the short time it's been on the engine.

Yup,I run mine with 5000 stall convertor and 4.88 gears with 29" tall slicks. Getting about 2 MPG on $8.50 a gallon gas on the street. Just to cruise nights and street races.

mine is locked out and my stall is fairly tight and it still ran a pile better with it advanced and locked. the vacuum advance was iffy at an idle. fine in park but when put in gear it would lose enough vacuum that it lost its timing, so either idle high or stall in gear, im getting mid 16's in mileage with a 496 . im sure if it put more timing into it on the highway it would get even more. i have ran it this way for 3 years, one year without the turbo's and 2 with. about 30000 kms locked.

I think others have touched on the important parameters to run locked ignition timing but since I do I will add mine:

1) Loose converter - so the engine is never under a full load at low RPM with max timing!

2) Start timing retard box OR switched ignition. I pull 15 degrees with a Mallory HyFire VI AND run a gear reduction Vortec starter.

3) A camshaft with a lot of duration ESPECIALLY with low compression - it really helps boost throttle response and low RPM torque. It will definately smooth out a lopey idle.

It really helped my car when I locked it out and best of all was a FREE modification.

Another thing to think about with locked timing...

Most engines need more idle timing than what many enthusiasts believe.

Start it, get the fuel close, and turn it for max idle rpm and vacuum. Record the number. You can back it off from here slightly for some safety cushion but this is what the engine wants as long as emissions isn't a consideration.

Total timing requires more time to determine what the engine will tolerate and on what fuel.

Once you determine both, you CAN build the distributor to give some mechanical advance. On many combos this would be more ideal than locked out, but it's not easy for the DIY'er to do, so locking out the timing is more common.

Jake I was thinking of doing that idle test to see how much more it wants and then limit the vacuum can to add the difference only. I have heard of a few people running locked out and a vacuum advance on top, I'm just wondering if adding the vacuum advance is going to make it a little more dangerous on the street to hit Detonation. I'm kinda doubting it though because of the 4:10s out back and the M22.

Yup,I run mine with 5000 stall convertor and 4.88 gears with 29" tall slicks. Getting about 2 MPG on $8.50 a gallon gas on the street. Just to cruise nights and street races.


yikes....hope your making 2000 hp...im getting mid 16's on a cruise and dyno 980 hp

My timing is locked out at 36*...I run a 461 BBC with a 598/598 cam...I have a Mallory 6AL and an MSD Starter Saver...I run 3:90 gears and 12 bolt with a Turbo 400 through a 4700 stall converter....