altenator question

[gordo428scj]

What amp altenator should be used. I have a 70 mach 1 with a 428 scj. It has msd ignition and after its been driven seems like the battery is draining like alt isnt keeping up.

[Sandman5000]

In old cars your battery is only used to start the engine, your alternator will maintain your battery and run accessories. If you have a new battery or one that you know is good, and after your car sits for awhile and you then have a hard start problem you might have a drain or load on your battery when the car is shut off. If you disconnect your battery cables when the car is going to be parked for a while and come back and you do not have the hard start problem you most likely have something draining your voltage when the car is off. You can also use a multimeter to check for a load on the battery. You can also use a multimeter to check what voltage your are generating at the battery when the car is running and I believe it should be above 14 volts. Hope that helps

[1969_Mach1]

Tough general question. I don't like to fire back a bunch of questions. But, more info can help with this type of issue. Does it crank slow when hot? Are your battery cables and cable ends good (no clamp on battery cable ends)? Has the alternator output and regulator been checked? Has the battery been checked? Is there an electrical short causing a drain? Is the battery sized correctly? Are you running an electric cooling fan?

As far as MSD, I run an MSD ignition and the instructions for my 6ALN ignition box state 1 amp draw per 1000 RPM. The original alternators in these cars were 55 or 65 amp. Which should be okay if you don't have any accessories added to the car. I installed a late model 2G Ford alternator because I wasn't happy with the operation of the original style and mechanical voltage regulator.

If it's hard to crank when hot, that wouldn't be surprising. Big motor + small engine compartment = a lot of heat. The original style starters don't seem to tolerate much heat, especially with a high compression engine. In my experience with my 351W in my 69 Mach 1, and years ago with a 390 in a 1956 F100 pick, slow cranking when hot was an issue. The cure was a permanent magnet gear reduction type starter. When I made the switch to the new type of starter I was amazed at the improved performance. All the cranking issues were solved.

Give us whatever additional info you can.

Best Regards,
Mike

[gordo428scj]

Battery is new and so is alternator,battery cables, and voltage regulator. I have no extras on it as far as electric fan,etc. It is high compression engine and does seem to crank hard when hot or after being drove so maybe it is a starter issue. Drove it yesterday about ten miles and it was cool outside the engine temp didnt even get up past 150. I put gas in it went to start it had about 3 slow cranks and it fired right up.

[gxr02190]

Knock your ignition timing back 2 or 3 degrees and see if that solves your issue without affecting performance too much.

[1969_Mach1]

Retarding timing might fix it. If your timing is currently too far advanced, retarding it back to or closer to stock is fine. But if that is not the case, retarding it further from stock is just a band aid and the performance will suffer, engine temps tend to rise as timing is retarded, and you may experience "engine run-on". Engine "run-on" is when the motor keeps running after you shut it off. Some call it dieseling.

I apologize and don't like to sound blunt, but, likely the best solution is to buy an aftermarket permanent magnet gear reduction type starter, and better battery cables and battery as needed. You can try a battery first since most original equipment equivalent batteries are marginal in capacity for these cars.

If it were mine, I would not retard ignition timing lower than stock if that is the only issue you are trying to fix. I fought my 351W with the same issue many years ago before there were these types of forums. I talked to a Ford technician. First thing he suggested was replace that original type starter with one like I am suggesting here. I was fortunate and able to get one from a Ford dealer that also fits a late model truck. I never had any more issues, hot, cold, always cranks the same.

Best Regards,
Mike

[gxr02190]

I was only trying to solve your issue with the turn of a wrench instead of a $250.00 starter. However, that may be what you'll end up doing if you can't successfully play with the timing. FE's are pretty forgiving though if your cam is installed "straight-up" and not advanced 4 degrees (like most guys install them) IF you have indexed sprockets.

[gordo428scj]

Thanks guys for all the posts. I dont think timing is an issue. I will try better battery and starter and see what happens. If that dosent than maybe have the timing looked at. Thanks again

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I just had it tuned and timing set at by a mechanic. It did this before i had that done. Thats the only reason i dont think its a timing issue but ive been wrong plenty of times. Thanks again

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Definatley think its the starter now. Just went out and started it, cranked over great as to where last night when i parked it it was cranking over hard

[1969_Mach1]

Yeah, I feel your pain. It sounds like you've already looked into pricing. I went through four or five replacement starters from NAPA because I didn't want to invest in a permanent magnet gear reduction starter. Then I was shocked at the difference. There is a slight possibility your starter has a bad field winding that shorts when hot. It happens, but is rare.

The heat issue is more common with headers because the radiant heat from the headers, and close proximity to the starter, heat the starter. But it still happens without headers. Especially if your motor has high compression (by todays standards), 10:1 or more. There are starter insulation kits. I've never tried one. The permanent magnet gear reduction starters are so small by comparison I haven't heard of any heat related issues. Another benefit of the new style starter is the positive battery cable to the starter from the starter relay gets moved to the same post on the relay that the cable from battery is attached to. This eliminates the electrical circuit passing through the starter relay which is the highest electrical resistance component in that circuit.

I've been around these so long I remember if we would drive somewhere and need to shut off the motor, we accepted the fact we had to wait a while for the starter to cool down before restarting the motor.

Best Regards,
Mike

[gordo428scj]

Thanks, yeah i have manifolds on my car and amazed that the starter is basicly wrapped in the manifold looks like it is hard to manuver out. Havent had this starter out, my uncle had put it in in the late 70s or early 80 s when he owned the car. He had alot of work done to the motor done back then, so i know it has bigger cam than stock and etc. He said it was a high torque starter, but back then im not sure how good they were. Last summer the positive cable had a nick in it and shorted out and thats when i replaced cables,alt, voltage reg., and battery. I suppose it could of damaged starter too. Its about time to update it i guess.