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Discussion Starter #1
I have a problem with pontiac head, and big chief chev. alky injected engines ( three different ones) not starting properly or not at all, with a Magnito. vertex. and mallory super mags. compression not really that much on two of them . one 13 to 1 one 12 to one the other 15.6 to one . 112 and 114 center line cams. changed over to MSD ingnition no problem starting then. maybe somebody can put some light on this one, has anybody else had this proplem? thank you.
 

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"Need For Speed"
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Jim,

Just a couple of thoughts.

1) Generally the higher compression one goes with magnetos will also cause the need to close the spark plug gap tighter and/or to spin the engine at a faster rate. I don't know why this may be different on an 18 or less degree cylinder head style versus a 26 degree as you are experiencing.

2) Another thought to consider might be the head gasket composition, etc. What I am eluding to is actual ground in the cylinder heads. On the A/Fuel car we use copper head gaskets and big 44 amp mags. Even with a copper gasket and a 44 amp mag, the heads are not grounded sufficiently and will begin to erode on the gasket to the heads. This seems to be even worse with aluminum blocks. So, we actually have a 10 or 12 gage stranded copper ground lead connecting both heads and also connecting the heads to the mag ground.

This is not a bad practice in any race engine. Connect the heads with a large ground and also connect this ground to the ignition system and battery in a battery ignition system.

It would be interesting to see if extra grounding may help in your situation. Easy to try. Let us know.

Gear
 

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Let's see. Problem 1.. mag. Use them as anchors. Leave in the MSD.

OK, now for the helpful comments. Cranking speed. Is it cranking "slow"? Mags generate more voltage based on rpm. Or the inverse.. they put our crappy weak spark all the time, but even worse when engine is turning slow.
Some guys use 16v batteries. Or 24, or whatever. I say leave in the MSD.
Wags
 

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steelcomp was here
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Jim,

Just a couple of thoughts.

1) Generally the higher compression one goes with magnetos will also cause the need to close the spark plug gap tighter and/or to spin the engine at a faster rate. I don't know why this may be different on an 18 or less degree cylinder head style versus a 26 degree as you are experiencing.

2) Another thought to consider might be the head gasket composition, etc. What I am eluding to is actual ground in the cylinder heads. On the A/Fuel car we use copper head gaskets and big 44 amp mags. Even with a copper gasket and a 44 amp mag, the heads are not grounded sufficiently and will begin to erode on the gasket to the heads. This seems to be even worse with aluminum blocks. So, we actually have a 10 or 12 gage stranded copper ground lead connecting both heads and also connecting the heads to the mag ground.

This is not a bad practice in any race engine. Connect the heads with a large ground and also connect this ground to the ignition system and battery in a battery ignition system.

It would be interesting to see if extra grounding may help in your situation. Easy to try. Let us know.

Gear
To go one step even further..I just learned this... and that is to not use aluminum based antiseize on plugs, but a copper based.

This stuff, courtresy Warp Speed:

MolySlip Copaslip Anti-seize Compound
 

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Discussion Starter #7 (Edited)
Jim,

Just a couple of thoughts.

1) Generally the higher compression one goes with magnetos will also cause the need to close the spark plug gap tighter and/or to spin the engine at a faster rate. I don't know why this may be different on an 18 or less degree cylinder head style versus a 26 degree as you are experiencing.

2) Another thought to consider might be the head gasket composition, etc. What I am eluding to is actual ground in the cylinder heads. On the A/Fuel car we use copper head gaskets and big 44 amp mags. Even with a copper gasket and a 44 amp mag, the heads are not grounded sufficiently and will begin to erode on the gasket to the heads. This seems to be even worse with aluminum blocks. So, we actually have a 10 or 12 gage stranded copper ground lead connecting both heads and also connecting the heads to the mag ground.

This is not a bad practice in any race engine. Connect the heads with a large ground and also connect this ground to the ignition system and battery in a battery ignition system.

It would be interesting to see if extra grounding may help in your situation. Easy to try. Let us know.

Gear
tryed gapping plugs tighter to no avail,heads are o=ringed with copper head gaskets, never had a problem with a std head b/b but use mostly 110 c/l cam shafts also. seems like the 114 and even the 112 cam has something to do with it also. just guessing
 

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Discussion Starter #9 (Edited)
Let's see. Problem 1.. mag. Use them as anchors. Leave in the MSD.

OK, now for the helpful comments. Cranking speed. Is it cranking "slow"? Mags generate more voltage based on rpm. Or the inverse.. they put our crappy weak spark all the time, but even worse when engine is turning slow.
Some guys use 16v batteries. Or 24, or whatever. I say leave in the MSD.
Wags
run two starters and tryed 24 volt will start sometimes but kicks back etc.not relieable. MSD it starts right up. I think the weak spark and the fuel and compression is snoffing out the fire , I had that problem on a blower motor years ago when the boost went up to 26 lbs, at 6000 the motor litterly shout off with a stock ing. and started right back up again then I used a mag and it kept right on going. same on the dyno with MSD 7 box the blown alky motor drops hp at 6500, 28 lbs boost put a 10 box on and it keeps right on making hp.
 

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Highaboosta
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But they worked so well in model T's :D
hhmmmm... where's hass to enlighten everyone????
And Top Fuel Cars, and most really hard running blown alky stuff. But those guys only use'em cause they're silly like me :D:)hand


As for the OP's problem, it must be from cranking speed , also the mags are probably locked out and the MSD probably has an advance in it that allows it to start without kicking back. My stuff is lower comp with conventional heads and I've never witnessed any kind of starting problems. I hear of guys having to get them cranking over & then turn on the ignition but like I said my stuff starts just as good as if I had an electronic ignition. And I'm starting this thing with a tiny azz battery about the size of a motorcycle battery. Been doing it for almost 3 yrs now with the same battery. Never failed.

How long since the mag has been freshened up?
 

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Hass, they run them for 4.0 seconds and replace as required. They ran them at Indy, until they had to carry a battery, and then they threw them in the round file. Oh, hey, same with Henry Ford. No battery=magneto Battery=anything but a magneto

Here is the best thing a mag is used for, and just so happens to be my favorite way to test a mag. Clip one lead to a hind foot, the other to the lower lip. Spin with 1800+ rpm drill motor. If it kills the sum bitch, your mag is good. If it only pisses it off and it goes ballistic on your ass, you need to send your mag in. This mag checked out good:




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Highaboosta
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WTF is that rodent Bob ?
Doesnt look like anything we get around here.
 

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Hass, they run them for 4.0 seconds and replace as required. They ran them at Indy, until they had to carry a battery, and then they threw them in the round file. Oh, hey, same with Henry Ford. No battery=magneto Battery=anything but a magneto

Here is the best thing a mag is used for, and just so happens to be my favorite way to test a mag. Clip one lead to a hind foot, the other to the lower lip. Spin with 1800+ rpm drill motor. If it kills the sum bitch, your mag is good. If it only pisses it off and it goes ballistic on your ass, you need to send your mag in. This mag checked out good:
I know, and it just drives you guys nuts to only have to unhook one kill wire to remove the entire igntion system. To each their own.
 

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Discussion Starter #18
And Top Fuel Cars, and most really hard running blown alky stuff. But those guys only use'em cause they're silly like me :D:)hand


As for the OP's problem, it must be from cranking speed , also the mags are probably locked out and the MSD probably has an advance in it that allows it to start without kicking back. My stuff is lower comp with conventional heads and I've never witnessed any kind of starting problems. I hear of guys having to get them cranking over & then turn on the ignition but like I said my stuff starts just as good as if I had an electronic ignition. And I'm starting this thing with a tiny azz battery about the size of a motorcycle battery. Been doing it for almost 3 yrs now with the same battery. Never failed.

How long since the mag has been freshened up?
they are locked , tryed three different mags on this last engine. to no avail. the crazy thing it started on the mag in fla. and couple other times but the engine has been around for 5 years and was getting a little tired. just freshed it up put the mag back in and it wouldn,t start. didn.t have much time to mess with it because had a race to go to last weekend so changed it over to MSD
with advance distributor. use to run the motor in a race car with crank trigger, MSD and
20 degree retard button no problem at all. started great for years. I cann,t believe no one else has not run into this problem. Never had a problem with a conventional head engine even with big compression numbers, only 18 degree stuff. might have some thing to do with the bigger alky nozzles for the pontiac stuff burns alot more fuel in a 5 mile race then the std chev head. I use the mag on my blower stuff ( k boat )and works great. (conventional head engine.) i,m beside myself on this one ????
 

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they are locked , tryed three different mags on this last engine. to no avail. the crazy thing it started on the mag in fla. and couple other times but the engine has been around for 5 years and was getting a little tired. just freshed it up put the mag back in and it wouldn,t start. didn.t have much time to mess with it because had a race to go to last weekend so changed it over to MSD
with advance distributor. use to run the motor in a race car with crank trigger, MSD and
20 degree retard button no problem at all. started great for years. I cann,t believe no one else has not run into this problem. Never had a problem with a conventional head engine even with big compression numbers, only 18 degree stuff. might have some thing to do with the bigger alky nozzles for the pontiac stuff burns alot more fuel in a 5 mile race then the std chev head. I use the mag on my blower stuff ( k boat )and works great. (conventional head engine.) i,m beside myself on this one ????
So the mags were locked & the MSD had a start retard. If you had about 12 crankshaft degrees of mech. advance in that mag with it all in as early as possible I bet youd be fine.
 

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I think it may be a combinmation of a couple of the things. We have played with both conventional and Pontiac style heads and have to say I don't feel "That" is the issue. I feel (and this is just personal oppinion based off of my own experiances) that it is a case where the lack of retard AND slower cranking speed are hurting you. We delt with a similar issue and found that when we had a mechanical retard put in it helped it crank through the sputters well enough to get the cranking speed to light it off. We started off with a weak battery that did not even spin it fast enough to create spark to even have it kick back. Once we got the battery problem solved we then had it kicking back like a bad horse. After talking to a Mag rebuilder we decided to put a mechanical advance in it and have been happy ever since.

Paul
 
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