Technical Locked out Vertex Mag on the street- Yes or No?

I know it's been hashed out here a hundred times, at least, but the info I got while searching really didn't answer my question's... Or maybe it did and I'm too dense to realize it! Here's my dilemma, I'm running a Vertex mag in a '56 Chevy with a kinda' healthy 327. It's got 11.3 to 1 compression, solid lifter cam (Isky 505T) with a 250* @ .050 duration I&E, .505 lift, and a 108 lobe center. Heads are 461 Fuelie's with a mild hog job and a tunnel ram with 2 Edelbrock 500 cfm AFB's. The mag has 12 degrees advance built in (24* @ the crank) and I'm running 20 degrees initial, I know that seems like alot but there are no sign's of detonation on the plugs or pistons and there's no rattle under load, yet the engine is still a little on the lazy side and slow to start. The jetting seems to be pretty close, plugs are a nice carmel color after a couple thousand miles on 93 octane E10 with octane booster. (This is why I'm thinking it's a timing issue) NOW... Here's the question, do you guy's think I'd be better off running the mag locked out with 34*-36* of timing to get the throttle response up or should I reduce the mechanical and add the remainder in initial for the sake of easier starting? The car is on the heavy side, at what I'm guessing is about 3,600# with an M-22 and a 4.57 gear with 28" tall tires. Just seems like it takes forever to get to 6 grand while going through the gear's. Maybe I'm hoping for too much. What do you guy's think? Any and all opinion's welcome! TIA, Jedd

 

when does the advance come in? Maybe the springs are too tight?

 

The only times I have seen locked distributors has been on older supercharged race cars. Back when I raced, all of the supercharged cars had set timing with no advance.

 

Advance starts at 700 rpm's and is all in by 2,500 rpm, according to the tag that came with it. The 2,500 rpm part seem's legit according to the timing light.

 

That's something that has me scratching my head also. What does a blower have to do with it?

 

If the advance is all in by 2500, and you are concerned about lack of power between 3000+ and 6000 rpm, then locking the timing is not going to change a damn thing about that.

time to swap pistons and put a blower on it

 

Hmmm... I do have a 6-71 and a Hilborn 4 holer ready to go...

 

You are not going to appreciate this I am sure but perhaps the sluggishness in part is the weight of the vehicle. I am a big fan of the SBC and have played with them for years. I have also run locked magnetos on the street with much success as well. But what I know from experience is that the smaller displacement small blocks are not torque monsters and it takes torque to make one spin. That or you have to get your tires spinning but that is not optimal for normal street driving.

I did usually run a lot of lead on the street. That can become problematic with modern pump gas.

 

If they are locked you need to get it spinning before you switch it on…

 

Locking out any disturtor or mag is not a good idea for the street! Works good for a full race engine, but brings some problems to the street. The street asks for varing timing. The track can benefit from locked timing!





Bones

 

I run a Magtech mag in my 383 locked at 34 degrees in a 2200 lb car. It runs like a champ anywhere in the rpm range. I have thought about having a mechanical advance put in it, but it runs so well I never bothered. The 383 is pretty hot. 11.1:1 CR, Profiler aluminum heads, big cam, 850 DP, etc. I have it on a kill switch so I can get the engine spinning over and oil pressure up, before giving it spark.

 

Rest assured I have NO delusions...This S.O.B. is heavy. I just figured that the 4.57 gear would get me past it... Obviously not! Like I said earlier, maybe I'm just expecting too much from it. Maybe I should just get rid of the tunnel ram and run an Edelbrock C26 intake. How heavy were the car's you ran a locked mag in?

 

I agree, 44 degrees does seem like a ton! But if I back it down to 36 total (which would make it 12 initial) it won't idle for shit and it's really a pig. That's why I was thinking that having a constant 36 degrees would help the bottom end acceleration and not be too much on top. I do understand where you're coming from with too much advance, though.

 

Not a mag, but I ran locked timing at 36* on a 427 that later turned 454, then upgraded to solid roller cam and AFR heads, final number was 650 at the crank. Ran in a 3600# car with Muncie M21 and 4.56 gears. Never was a problem on the street or strip. I did have it set up so that ignition was seperate from cranking. Since then I've learned much about tuning, and always set up my street car with a curve both for mechanical and vacuum advance. locked works, but it's not ideal on the street.

Devin

 

I degreed the cam when I put the engine together and it's actually 1 degree advanced. I figured that was close enough for government work and left it as is. I can't imagine that being a problem, but anything is possible, I suppose.

 

Have you verified your timing marks?

 

Verified and correct.

 

I have run locked vertex mags in everything from motorcycles to X frame Impalas. In a heavy vehicle you need to build your torque off the bottom unless you are leaving with your tires spinning. Spinning tires are not a street thing and in that case you depend on revs.

Your tunnel ram is not prone to low end grunt. You would be better off with a smaller open plenum intake (like a tarantula for instance or a TM1) than with a tunnel ram. Your C26 would be a great option for a street vehicle heavy or light. They work good. If you want it to work like a 360 intake a power notch is a good trade off. It does not work as well on a 2x4 as a single but it still works.

I am going to guess that induction is as big a problem as the ignition in your case. Hang in there you'll work it out.

 

People have said that about me but my cars can usually get out of their own way.

I run the L79 in my 355 (the timex) slightly retarded. Gives me a little more spin than it should. This is delving kind of deep into theory, perhaps too deep for this discussion. But I got to make myself look smart.

 

The amount of ignition advance the engine can tolerate is relative to the cylinder pressures, with a regular vacuum advance system you get a bunch extra advance in idle/small throttle openings to improve mileage on the street, once you step on the fun pedal and let more air in cylinder pressures go up and that extra advance has to be taken out.

I'm sure the best overall performance and economy requires the ignition advance to change both with rpm (mechanical advance) and cylinder pressures (vacuum advance, and in boosted engines, also applying to the boost), BUT as always, the more things there are to tune, the harder it is to tune them all right. Sometimes the simplest compromise is to just focus on full throttle, high rpm performance in a race engine, and lock the advance where that works best. It'll be a fuel thirsty snail driving around town on low rpm, but that hardly matters for a race engine that only sees city streets from the trailer while going to and from the race track.

 

At what rpm does the engine idle? It must idle below the dist advance starting point, below 700rpm. With a 250° cam I don't think so. AND 4.57 is not enough gear, 5.13 and it will be way happier. I think 1000cfm is on the high side.

 

'''The only times I have seen locked distributors has been on older supercharged race cars. Back when I raced, all of the supercharged cars had set timing with no advance.''

A mag with advance at some point in the curve looses intensity. Not sure if adjustable to where in the curve, beginning or end.

 

It idles at 1,100 rpm and that's still kinda' low. There's no way in hell it will idle at 700 rpm.

 

OK, thats what I figured as I have 292 [289] with 242° and its happy at 1000rpm idle with advance starting at 1100. For you at 1100 timing has already advanced some. Get the advance to start at 1200 and report back, should be able to do by bending dist spring mounts some but may increase total rpm, in my case it didn't, its in by 2200.

 

I'm gonna have to study up on how to do this, I've never been inside the bottom of a Mag before. The real pisser is that I can't test any of these mod's until the weather breaks and the road's clear up. It's colder than a well digger's ass here and the road's are white and crusty with salt! Gotta love Chicagoland winter's...
Also... Would it be wise to switch to a 7 degree advance mechanism instead of the 12 degree one that's in it now?

 

Call Cirello:
https://www.tomcirellomagnetos.com/index.htm

 

I've run locked out timing on the street, but that was a 548" BBC on pump gas, so I can not comment on doing that with a 327"er. I strongly suspect those carbs might be the issue, I've only run holleys on tunnel rams, the best article ever on reading plugs.

 

A Rat motor might help and yes , loose the eddys.