High Performance Starters

[Ron Earp]

I’ve been thinking about what to do with my starter on my race car (I know, not GT40 but the discussion might be useful for GT40 starters).<o></o>
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I’ve got a hot start problem on the Z. Not just any old hot start problem, but one that had put me in harm’s way once and could have had some disastrous consequences. Once my car is hot, as in it is warmed up to about 180F and has done a few laps, it will not restart if it is turned off or stalled. It will push start though – easily, very easily. (EDIT - to be clear, spark, fuel, adequate power, etc. are all present, she just won't light off until push started).<o></o>
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Another racer I know had a similar problem and he solved his with a gear reduction starter. Once the gear reduction unit was put on he had no more hot start problems. <o></o>
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I wouldn’t mind doing a gear reduction unit but there are two problems:<o></o>
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<!--[if !supportLists]-->1)<!--[endif]-->It is illegal.<o></o>
<!--[if !supportLists]-->2)<!--[endif]-->Installing it would cause me to replumb my entire oil system due to an interfering Olberg oil filter that is in line with everything and right above where a normal starter fits. A gear reduction unit would have it relocated and I’d have to make all new lines.<o></o>
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But, it got me to thinking, how can I get more performance out of the starter I have?<o></o>
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Clearly we’re limited to a 12V system. P = i^2 * R, or since R = E / i, then P = E * i. E is limited, so if I can get the starter to use more juice I’ll get more power, which I assume will cause it to turn with more authority?<o></o>
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I do not notice any difference in how fast the starter turns when hot or cold – seems about the same to me. <o></o>
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But, I assume the push starting is turning the motor over far faster than what the starter can do. Hence, I’d like to try and get my starter to perform better (wiring is 100% fine and way more than adaquote for current draw) – how does one do that? Can the starter be re-wound by a competent starter/generator shop to perform better?<o></o>
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I went through a lot of changes last year with fueling, timing, carb heat shielding, air flow control, and so forth to try and stop this heat issue, but to no avail. If a starter could do the job for me I’d be all over it. Any starter knowledgeable folks out there?<o></o>

 

[Gary Kadrmas]

Ron,

Before you spend alot of time on this.......have you talked to other "Z" owners to see what they did about the issue. Their has got to be more Z guys out there that have had to overcome the same issue......and.......

When you say it will not start, does that mean it turns over, but does not light up? Because if it turns over and does not fire, thats a good indication its ignition related. If it does not turn over, I would make sure that you are getting 12V to the starter. Could your + cable be corroded on the inside, creating resistance that would prevent it from getting 12V to the starter?

Any which way....good luck, and hope you find an answer to get 'R done.

 

[Ron Earp]

when I say "does not start" I mean that it will crank fine when hot but she won't start - she has spark, fuel, and all of that - just won't start. However, do a 2nd gear push start at a walking/jogging pace and she'll fire up in 1/2 second.

The cables and so forth to the starter are brand new as I re-did the entire electrical system last year - and the problem was around before that too so I didn't cause it. The ignition system works well - no problem on power to the MSD while cranking. Seriously, I'm pretty good with electrics and I've gone down those paths and the system is strong. I've measured current draws at various places and so forth and the system seems good. When cold it'll start up on the first couple of cranks within 1/2 second of pushing the button.

The other Z guys, well, some have problems and use a gear reduction unit. I've heard the bore washing theories and stuff like as being the cause and necessitating the need for a push or more starter speed, but I'm not sure I agree with that theory.

If I could use a "blueprinted" modified stock hi torque starter that'd be fine with me. I'm going to check some local shops and see if they can build them.

 

[Jac Mac]

You still using those Japanese SU's? If so warm it up and try starting it with some choke applied, this might richen it enough to fire! ( the choke is simply a cam or ramped shaft that lifts the piston/needle out the jet while still blocking off the air intake to create a greater depression in the carb/manifold ) no accelerator pump on these dinosaurs.

If you have played with carb by using lighter oil in the dampers etc the piston might lift a bit much after a hot soak when trying to restart and kill any signal at the needle/jet. Try holding the palm of your hand over the carb inlets while cranking- does it fire straight up then?

Jac Mac

 

[Ron Earp]

You still using those Japanese SU's? If so warm it up and try starting it with some choke applied, this might richen it enough to fire! ( the choke is simply a cam or ramped shaft that lifts the piston/needle out the jet while still blocking off the air intake to create a greater depression in the carb/manifold ) no accelerator pump on these dinosaurs.

If you have played with carb by using lighter oil in the dampers etc the piston might lift a bit much after a hot soak when trying to restart and kill any signal at the needle/jet. Try holding the palm of your hand over the carb inlets while cranking- does it fire straight up then?

Jac Mac

Worse still, I WISH I could use the Jap SU's the 240s get to use. I have to use the 260Z one year only Hitachi flat top SU types (don't think anyone but the US got these great carbs and for one year only since the 260Z was a one year only car here) which really are an ugly duck.

I've messed around with oil in the dampeners and will do so in depth next week again to mess around a bit with throttle crispness. Didn't seem to have an affect on the hot start. Ditto on the enricheners and ether spray, didn't help at the last outing in October.

It is amazing how easily it'll fire up on a push start. I don't need to anything other than drop the clutch on it in 1st or 2nd at basically a jogging pace - blamo, fires right up.

 

[Jac Mac]

Those 'UGLY' carbs dont happen to have an auxiliary passage that pass's thru a hot box in the intake manifold do they?

 

[Ron Earp]

Used too, but not anymore. These things had all sorts of water passages and so forth, truly a horrible 70s era emissions nightmare. Mine were built by a fellow who is legendary for his Z carb work on racing Z's. Reported to be the only guy who can make the flat top Hitachis run. They do run well as far as making power, I'm not losing anything to the round top guys there .

 

[Randy V]

Sounds more ignition related Ron...

Look at it this way - If the starter is pulling a lot of current when hot (normal), there is less amperage left for the ignition system.

Hence a low speed push start does not suck up amperage and it's all available for he ignition system.

Run a separate hot wire from the battery positive to the ignition switch to power the coil / ignition amplifier etc..

Nice big fat ground strap from one of the starter bolts to chassis also...

 

[Ron Earp]

Run a separate hot wire from the battery positive to the ignition switch to power the coil / ignition amplifier etc..

Nice big fat ground strap from one of the starter bolts to chassis also...

Done and done. All ignition components are on separate breakers as are about everything else on the car too. Makes like simple. Current on the MSD is the same hot and cold, she fires plugs with no issue. Starter the same too as I've investigated the power stuff fairly throughly. Probably because it is one of the few things I seem to be very competent with on race cars, wiring and electrics.

 

[Randy V]

Hmmm...

I've helped a couple of cars get past this kind of issue by just cleaning up the electrical system - sounds like you've already covered those bases..

There are other hot-start gotchas as well..

* Valve clearance hot is too tight. Not enough compression to get them to light off at normal cranking speeds..

* The age old vapor lock in the fuel pump - normal cranking speed is not fast enough to push the air out of the pump and start moving fuel. I'm sure you've got that covered too with an electric pump.

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Back to starters for a minute..

It's my experience that the gear reduction starters don't really spin the engine over any faster than the standard direct drive starters - just that they draw less current.

If you put a booster-pack on your car when it's hot, and it starts, you may have a lack of amp hour capacity in the battery.. Even if the car is spinning over quickly - try putting a booster pack on as well and just see if it makes a difference..

 

[Ron Earp]

* Valve clearance hot is too tight. Not enough compression to get them to light off at normal cranking speeds..
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Back to starters for a minute..

It's my experience that the gear reduction starters don't really spin the engine over any faster than the standard direct drive starters - just that they draw less current.

If you put a booster-pack on your car when it's hot, and it starts, you may have a lack of amp hour capacity in the battery.. Even if the car is spinning over quickly - try putting a booster pack on as well and just see if it makes a difference..

Thanks for thinking about it. I do think my electrical system is in good shape and isn't the culprit here and the fact the car pushes insanely easily made me think of starters.

Hmmm, never looked at or considered valve clearances with the hot start issue. I can do that.

I have jumped the car before with the spare battery we keep and it didn't help. Alternator charges great, battery is always ready to go on race weekends as I keep a tender on it before traveling.

We did discover something yesterday that has a minor change of being related. The car had some foam type air filters on it that were absolutely horrible for flow. Almost like a lawn mower air filter, the ones that don't flow for squat. Seriously - if you try to blow air through them with an air compressor you don't feel anything. I'll put up some pictures of these "bad" filters. I replaced them with the K&N round filters from the Jensen (Jensen already being used for parts, shame), made some modifications to the Z and the housings to get them to fit. Air really flows through these. Could be something to it, hard to say. I know I'm concerned about my EGTs and getting the mixture right for next weekend.

 

[Pat Buckley]

Ron -

Did you check to see if you are getting current where needed while cranking it hot?

 

[Ron Earp]

Ron -

Did you check to see if you are getting current where needed while cranking it hot?

Yep, we did last year on a test day. Did hot and cold comparisons and made notes on it in my race notebook. I have a really nice Fluke meter with a lot of accessories such as inductive clamp, thermo couples, etc. that makes electrical work fun. I don't have the notes handy at home but there was no difference. If I'm confident on anything on that race car it is that the electrics are ok with respect to current draws, wire size, proper connectors, breakers, feeds, and so forth.

I'll still look at it though - I don't want to rule it out, but the electrics are simple since it is a pure race car and I did the wiring. Not much to it.

One thing I can't do though is compare actual crank RPM when hot and cold. It could be something along the lines of when cold it cranks at 200 RPM which starts it and when hot it cranks at 175 RPM, which is just enough not to start it. Not sure about that or why it'd be.

 

[Jac Mac]

Have not changed the plug on the MSD by any chance. Orange striped wire from Dist goes to purple from box---purple striped wire from Dist goes to green from box.

Jac Mac

 

[Ron Earp]

Have not changed the plug on the MSD by any chance. Orange striped wire from Dist goes to purple from box---purple striped wire from Dist goes to green from box.

Jac Mac

Nope, solved my "MSD issue" last year when I found out the previous owner had wired the dizzy into the MSD incorrectly. It caused a mysterious timing advance that was not built into the dizzy. Now that it is wired correctly it has a good advance from the dizzy and times well. Hot start problem though existed before and after the "MSD issue" was solved.

 

[Jac Mac]

Nope, solved my "MSD issue" last year when I found out the previous owner had wired the dizzy into the MSD incorrectly. It caused a mysterious timing advance that was not built into the dizzy. Now that it is wired correctly it has a good advance from the dizzy and times well. Hot start problem though existed before and after the "MSD issue" was solved.

That might also partly explain the Head gasket problems you had- have you checked that the rotor is correctly phased to the towers of the cap, just in case the previous owner had phased them to his incorrectly wired MSD & now that you have corrected the MSD-well you know what I mean.

 

[Ian Anderson]

Ron

I am not up on any MSD product so kick this into touch if it is far out from what a MSD system does and it does not use a coil or puts something different after it.

Some old Brit Cars (And most Jap Cars of the 80's era originated from these) had a coil with a resistor fitted.

On cranking a full 12 volts was fed in to the + side (Direct from the Starter connection) on crank but in normal run it went through the resistor dropping the pre coil to about 9 volts.

This was because during cranking the coil would not produce enough spark to fire. (Older batteries not giving enough to maintain the full 12 volts during the cranking for other ancilliaries / ignition)

So does it have one of these coils and is it missing the one wire?

Ian

 

[Ron Earp]

That might also partly explain the Head gasket problems you had- have you checked that the rotor is correctly phased to the towers of the cap, just in case the previous owner had phased them to his incorrectly wired MSD & now that you have corrected the MSD-well you know what I mean.

I know what you mean, but we're good there. My timing was sorted before Roebling and that was a simple belt failure. Removed the head, checked for square, put it back on and never changed a thing. She's done five hours since then, pulled in a second place in a 1.5 hour mini enduro too, so she's ok in that department.

 

[Ron Earp]

So does it have one of these coils and is it missing the one wire?

Ian

It might have, but that was before it because a race car. Now it is straight up MSD ignition all the way using a magnetic trigger stock Z dizzy - but uses nothing else from the Z.

Ron

 

[Bill Musarra]

I am willing to bet yor problem is only temporary. I seem to remember that when we rebuilt engines in our GTOs(Pontiac) we had basically the same problem. One of the guys got around it by running two batteries in series(?) I believe. My engine was bored out to about 400 cu. in. and after a week mine started the same thing being hard to crank when hot. After a few weeks it seem to rectify itself, but then we were working with non transistorized ignitions. I wonder if you are developing some kind of vapor lock that is being overcome with higher velocities on the push start?? What are your water temp readings when you attempt to start?

Bill