Anonymous
01-21-2003, 11:56 PM
rejoice
1. SPARK PLUGS
There are many spark plugs on the market today, can someone recommend a plug that will work well in my 250hp, 351ci Indmar with electronic ignition.
Date: 10:35 a.m. on 03-21-2001
Leprechaun
premium member in standard member. 2. Re:SPARK PLUGS
R - I have a 250/351 in my rig, the original engine, with a retrofitted Prestolite electronic distributor plus an MSD6AL spark box. I use the standard plugs with the gap opened. If you go from standard point-type to an electronic distributor, open the gag gap from .035" to .045". If you add an MSD box you can increase the gap to .050-.055". You know the benefits of increased spark and gap -hotter more exposed spark, better fuel burn, better economy, yada, yada.
Don't really recall the spark plug #, but R43TS comes to mind, or is that for the Vette? Can't remember. Anyway, I only change my plugs every 3 seasons or 300 hours, with the electronic iginition and the MSD box the plugs come out (At 300 hrs use) cleaner than they went in. Another miserable job effectively sidestepped. More time for fishing, less bloody knuckles. A win-win if ever there was one. Rgds, Leprechaun
Date: 11:01 a.m. on 03-21-2001
capt_D
normal member in standard member. 3. Re:Re:SPARK PLUGS
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Leprechaun (03-21-2001 11:01 a.m.):
R - I have a 250/351 in my rig, the original engine, with a retrofitted Prestolite electronic distributor plus an MSD6AL spark box. I use the standard plugs with the gap opened. If you go from standard point-type to an electronic distributor, open the gag gap from .035" to .045". If you add an MSD box you can increase the gap to .050-.055". You know the benefits of increased spark and gap -hotter more exposed spark, better fuel burn, better economy, yada, yada.
Don't really recall the spark plug #, but R43TS comes to mind, or is that for the Vette? Can't remember. Anyway, I only change my plugs every 3 seasons or 300 hours, with the electronic iginition and the MSD box the plugs come out (At 300 hrs use) cleaner than they went in. Another miserable job effectively sidestepped. More time for fishing, less bloody knuckles. A win-win if ever there was one. Rgds, Leprechaun
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Leprechaun, did you notice a difference in performance or driveability when you installed the prestolite ign. over the point distributer. I was condidering this upgrade but never liked electronics in the saltwater invironment and it's easy to carry a spare set of points and cond. for a emergency. I don't mind changing plugs so unless it ran better the benefits may not offset the cost?
Thanks, capt_D
Date: 12:35 p.m. on 03-21-2001
chuckash
normal member in standard member. 4. Re:SPARK PLUGS
Cant help with the plugs, don't remember which ones I just put in, but I have questions on the ignition. Lep, did installing the MSD box help in any way, and why the 6AL instead of an off road or marine version? Can it handle the heat and vibration. I used a pertronix electronic conversion, but still keep the points and condenser with me for emergency. Love the electronic.
Date: 12:39 p.m. on 03-21-2001
Leprechaun
premium member in standard member. 5. Re:SPARK PLUGS
I wrote a nice long response to these questions but my friggin browser locked up and lost it, so I'll try one more time.
Capt D - No perceived difference between the newer Prestolite electronic distributor and the older Ford points/condenser unit. At first. But over the course of the season the electrical erosion of the points gap coupled with a gradual wear of the rubbing block tends to adversely affect the overall dwell setting. So if you keep after the points, once per month giving them a light going-over with a points file and then resetting the dwell, you should be O.K. The problem is that most don't do this, including me, I've always got some other repair/improvement/upgrade crusade I'm on and I never seem to look after the points. No problem when I'm buzzing along by myself in the bay, but comes the Fall, when my SERIOUS fishing starts and I've got 3 or 4 fat fishermen aboard and I'm slugging it out with a bad head sea, well now, THAT'S when the whole points issue come to a head. You (I) can most definitely tell the difference. The electronic ignition eliminates this concern. And as far as electronic parts longevity, I had big concerns there too, but 4 seasons now, about 450 hours on my current Prestolite distributor and its still dead-nuts - runs great. Good thing too, cause you ain't a-gettin' to that module in there from the top. The distributor has to come out to R&R the module. Which is why I have the MSD-6AL in there and hence part 2 of my answer.
Chuckash - The MSD-6AL in my boat is identical to the unit that's in my '72 454 Vette - no difference. I understand that MSD makes a "Marine" version, potting the boards in something called "Dolphinite", whatever that is, but the standard automotive version works just fine in a Shamrock, I know of 3 others with the identical rig, those boats also have the variable ignition timing computer which the owners seem to love, I don't think its necessary. Anyway, back on point, the regular automotive version is mounted on the rear of my battery bridge over the motor and I have a custom switch box that allows me to fire the distrbutor using the MSD as the ignition module, or in case of MSD failure, I can switch over to the in-distributor module and continue on my way. Redundance, redundance, redundance when you have a single engine and like to fish 30 miles offshore. Don't ask me how the switchbox is wired, I haven't a clue, it was done for me by my dock's resident genius and I can't follow his hand-sketched schematic worth a damn. But it works great.
As far as noticing a difference - absolutely! She's MUCH stronger climbing up the backs of big seas and doesn't strain at all with a full crew aboard. Plus about 0.5 gal/hr difference on fuel burn. Plus, as I wrote in response to another post, I can now effectively throttle down to 450-475 rpm and wire-line troll for hours without the engine missing a beat. Couldn't do that without ther MSD box. Plus, as I mentioned before, the plug gaps can be opened up and they come out of the engine after 3 seasons like new. After the Floscan, the best single improvement I made in the boat. Put one in, you'll like the results.
Rgds, Leprechaun
Date: 07:11 p.m. on 03-21-2001
1. SPARK PLUGS
There are many spark plugs on the market today, can someone recommend a plug that will work well in my 250hp, 351ci Indmar with electronic ignition.
Date: 10:35 a.m. on 03-21-2001
Leprechaun
premium member in standard member. 2. Re:SPARK PLUGS
R - I have a 250/351 in my rig, the original engine, with a retrofitted Prestolite electronic distributor plus an MSD6AL spark box. I use the standard plugs with the gap opened. If you go from standard point-type to an electronic distributor, open the gag gap from .035" to .045". If you add an MSD box you can increase the gap to .050-.055". You know the benefits of increased spark and gap -hotter more exposed spark, better fuel burn, better economy, yada, yada.
Don't really recall the spark plug #, but R43TS comes to mind, or is that for the Vette? Can't remember. Anyway, I only change my plugs every 3 seasons or 300 hours, with the electronic iginition and the MSD box the plugs come out (At 300 hrs use) cleaner than they went in. Another miserable job effectively sidestepped. More time for fishing, less bloody knuckles. A win-win if ever there was one. Rgds, Leprechaun
Date: 11:01 a.m. on 03-21-2001
capt_D
normal member in standard member. 3. Re:Re:SPARK PLUGS
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Leprechaun (03-21-2001 11:01 a.m.):
R - I have a 250/351 in my rig, the original engine, with a retrofitted Prestolite electronic distributor plus an MSD6AL spark box. I use the standard plugs with the gap opened. If you go from standard point-type to an electronic distributor, open the gag gap from .035" to .045". If you add an MSD box you can increase the gap to .050-.055". You know the benefits of increased spark and gap -hotter more exposed spark, better fuel burn, better economy, yada, yada.
Don't really recall the spark plug #, but R43TS comes to mind, or is that for the Vette? Can't remember. Anyway, I only change my plugs every 3 seasons or 300 hours, with the electronic iginition and the MSD box the plugs come out (At 300 hrs use) cleaner than they went in. Another miserable job effectively sidestepped. More time for fishing, less bloody knuckles. A win-win if ever there was one. Rgds, Leprechaun
--------------------------------------------------------------------------------
Leprechaun, did you notice a difference in performance or driveability when you installed the prestolite ign. over the point distributer. I was condidering this upgrade but never liked electronics in the saltwater invironment and it's easy to carry a spare set of points and cond. for a emergency. I don't mind changing plugs so unless it ran better the benefits may not offset the cost?
Thanks, capt_D
Date: 12:35 p.m. on 03-21-2001
chuckash
normal member in standard member. 4. Re:SPARK PLUGS
Cant help with the plugs, don't remember which ones I just put in, but I have questions on the ignition. Lep, did installing the MSD box help in any way, and why the 6AL instead of an off road or marine version? Can it handle the heat and vibration. I used a pertronix electronic conversion, but still keep the points and condenser with me for emergency. Love the electronic.
Date: 12:39 p.m. on 03-21-2001
Leprechaun
premium member in standard member. 5. Re:SPARK PLUGS
I wrote a nice long response to these questions but my friggin browser locked up and lost it, so I'll try one more time.
Capt D - No perceived difference between the newer Prestolite electronic distributor and the older Ford points/condenser unit. At first. But over the course of the season the electrical erosion of the points gap coupled with a gradual wear of the rubbing block tends to adversely affect the overall dwell setting. So if you keep after the points, once per month giving them a light going-over with a points file and then resetting the dwell, you should be O.K. The problem is that most don't do this, including me, I've always got some other repair/improvement/upgrade crusade I'm on and I never seem to look after the points. No problem when I'm buzzing along by myself in the bay, but comes the Fall, when my SERIOUS fishing starts and I've got 3 or 4 fat fishermen aboard and I'm slugging it out with a bad head sea, well now, THAT'S when the whole points issue come to a head. You (I) can most definitely tell the difference. The electronic ignition eliminates this concern. And as far as electronic parts longevity, I had big concerns there too, but 4 seasons now, about 450 hours on my current Prestolite distributor and its still dead-nuts - runs great. Good thing too, cause you ain't a-gettin' to that module in there from the top. The distributor has to come out to R&R the module. Which is why I have the MSD-6AL in there and hence part 2 of my answer.
Chuckash - The MSD-6AL in my boat is identical to the unit that's in my '72 454 Vette - no difference. I understand that MSD makes a "Marine" version, potting the boards in something called "Dolphinite", whatever that is, but the standard automotive version works just fine in a Shamrock, I know of 3 others with the identical rig, those boats also have the variable ignition timing computer which the owners seem to love, I don't think its necessary. Anyway, back on point, the regular automotive version is mounted on the rear of my battery bridge over the motor and I have a custom switch box that allows me to fire the distrbutor using the MSD as the ignition module, or in case of MSD failure, I can switch over to the in-distributor module and continue on my way. Redundance, redundance, redundance when you have a single engine and like to fish 30 miles offshore. Don't ask me how the switchbox is wired, I haven't a clue, it was done for me by my dock's resident genius and I can't follow his hand-sketched schematic worth a damn. But it works great.
As far as noticing a difference - absolutely! She's MUCH stronger climbing up the backs of big seas and doesn't strain at all with a full crew aboard. Plus about 0.5 gal/hr difference on fuel burn. Plus, as I wrote in response to another post, I can now effectively throttle down to 450-475 rpm and wire-line troll for hours without the engine missing a beat. Couldn't do that without ther MSD box. Plus, as I mentioned before, the plug gaps can be opened up and they come out of the engine after 3 seasons like new. After the Floscan, the best single improvement I made in the boat. Put one in, you'll like the results.
Rgds, Leprechaun
Date: 07:11 p.m. on 03-21-2001