Well I'm getting to the point where I need to get the little stuff. I need part numbers and sources for the motor mounts and alternator. I'm going to be using the SPF brackets on the front of the motor so it’s V belt. I think a 100amp alternator will be enough but if someone has another opinion I’d like to hear it. Thanks for the help.
Parts Info Needed
- Thread starter RWoerz
- Start date
Summit sells a 100 amp, single wire, Ford alternator that will work.
Olthoff sells polyeurthane motor mounts, that is I used.
Dave
Olthoff sells polyeurthane motor mounts, that is I used.
Dave
Jack Houpe
GT40s Supporter
The polyeurthane motor mounts are for a BB chev. Don't use the metal backing plate they come with. I agree on the single wire, I used a 200 amp GM model but have a lot of extra electrical going on, I think 100 would work well.
I come from the school of over-engineering and over-spec..
You can install an alternator with a 200 or 230 amp rating and it will see to your needs if you only use 90 amps of it's rated capacity. However - if you install 90 or 100 amp alternator and your needs are 120 - the alternator will not be able to keep up with the demand.
Myself - Using startup current for all devices (save for starter motor) and AC at it's peak - I calculated my needs at 120 amps and have a 130 amp single wire. Can't speak to how well it works, but I suspect it will be fine.
That said - I like Jack's alternator (call it alternator envy
) and I rather like the idea of being well beyond the spec'd capacity requirements.
You can install an alternator with a 200 or 230 amp rating and it will see to your needs if you only use 90 amps of it's rated capacity. However - if you install 90 or 100 amp alternator and your needs are 120 - the alternator will not be able to keep up with the demand.
Myself - Using startup current for all devices (save for starter motor) and AC at it's peak - I calculated my needs at 120 amps and have a 130 amp single wire. Can't speak to how well it works, but I suspect it will be fine.
That said - I like Jack's alternator (call it alternator envy
) and I rather like the idea of being well beyond the spec'd capacity requirements.
I am hard pressed to see what you guys are running that takes over 100 amps in a GT!
Uless you have installed a competition level sound system with high draw amps, electric water pump, extra fans for the AC, etc. I can't add up a draw that comes close to 100 amps! Also, I think the concern might really be the amperage available at low RPMs as compared to the max amps an alternator can provide. Spinning at 3000 engine RPM a 100 amp rated alt is fine but what does it put out at 1000-1200 RPMs? Many of the high amp units do not have much output at low rpm. If street driving with extended red light idle an AC running, etc. is in the plans, I would look at low speed output more than the rated "max" output. For the time where the output is exceeded by the draw, well that's what a good battery is for!
Also consider that alternator output goes down as ambient temperature goes up. The alternator in a GT40 is in a spot where cooling airflow is minimal. That 200 amp unit might only be delivering 130-140 at the temp it is operating in. Something else to consider.
JMHO
Uless you have installed a competition level sound system with high draw amps, electric water pump, extra fans for the AC, etc. I can't add up a draw that comes close to 100 amps! Also, I think the concern might really be the amperage available at low RPMs as compared to the max amps an alternator can provide. Spinning at 3000 engine RPM a 100 amp rated alt is fine but what does it put out at 1000-1200 RPMs? Many of the high amp units do not have much output at low rpm. If street driving with extended red light idle an AC running, etc. is in the plans, I would look at low speed output more than the rated "max" output. For the time where the output is exceeded by the draw, well that's what a good battery is for!
Also consider that alternator output goes down as ambient temperature goes up. The alternator in a GT40 is in a spot where cooling airflow is minimal. That 200 amp unit might only be delivering 130-140 at the temp it is operating in. Something else to consider.
JMHO
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Thanks everyone for your input. I was looking on eBay and saw that many of the alternators had strange mounting ears and wasn’t sure if that was the norm these days. When I was working on a lot of cars back in the 60s they all looked alike so I was confused.
Do most of the Ford/GM/Dodge alternators still have the same mounting points? Also I would like to use an original 289 HiPo pulley I have but wasn’t sure what alternator would have the right shaft size and spacing and even if that would be a good idea given the question of low speed output. Maybe a trip to my local auto parts store with my pulley is in order.
I find it strange that the right motor mounts for my small block Ford would turn out to be for a big block Chevy. This is the part that bolts directly to the block so is the bolt spacing the same? I have copies of quotes from two different places (not Olthoff) that supply parts “kits” for SPF GT40 and the both list “Urethane MM 351 Motor Mounts 1114” on their list but so far I haven’t found anything on Google searches. Olthoff would seem to be the easy answer on this one.
David is the car running? You were close when I came to visit so I assume it is. You did say the bellhousing I got from you uses a 157 tooth flywheel, right?
Thanks again for the help.
Do most of the Ford/GM/Dodge alternators still have the same mounting points? Also I would like to use an original 289 HiPo pulley I have but wasn’t sure what alternator would have the right shaft size and spacing and even if that would be a good idea given the question of low speed output. Maybe a trip to my local auto parts store with my pulley is in order.
I find it strange that the right motor mounts for my small block Ford would turn out to be for a big block Chevy. This is the part that bolts directly to the block so is the bolt spacing the same? I have copies of quotes from two different places (not Olthoff) that supply parts “kits” for SPF GT40 and the both list “Urethane MM 351 Motor Mounts 1114” on their list but so far I haven’t found anything on Google searches. Olthoff would seem to be the easy answer on this one.
David is the car running? You were close when I came to visit so I assume it is. You did say the bellhousing I got from you uses a 157 tooth flywheel, right?
Thanks again for the help.
Ron Earp
Admin
Second that. Most modern cars don't have 100 amp alternators and have far more electric equipment to deal with.
MSD6AL ignitions are known for sucking juice but even then it is only about 1 amp per 1000 RPM. Figure a high value of 20 amps for electric fans (I got 17 amp draw off a recent SPAL fan that is one of their thirstiest, most fans are far less), 15 amps for a electric water pump and I'm not sure where the rest would come from.
Most all of the old (1960's/70's) Ford and GM alternators share the same input shaft diameter so the pulleys will interchange. The Hi-Po alt pulley (used on 289 Hi-Po and Boss 302) is available as a steel repro or as an alloy unit. I would use the alloy myself.
The old style mounting of the alt (bolt to block/head with boss for bolt/nut to arm to adjust tension is also similar between Ford/GM/Mopar. The GM one wire atlternators are handy and have the internal voltage regulator. The alternator on P1116 was a GM unit that ate a couple of aftermarket regulators until I installed a genny GM regulator and then no further problems.
Ron, most current Fords have a minimum of 120 amp alternators from the Focus on up. Some cars have a 150 and trucks go to 200 on a single and 320 on a dual alternator system. I think 70-100 is more than enough on a '40 dependant upon the ignition and injection system. With EFI you don't want to drop amps/volts and not have the injector fire properly.
Most new alternators bolt direct to the block/head to eliminate any brackets. Belt tension is controlled by a tensioner in the drive belt system so no adjustment is available on the alt. The direct mount takes a lot of resonance out of the system and cuts NVH greatly but these alternators will not work on a small block Ford engine without a tensioner and special fabrication.
The old style mounting of the alt (bolt to block/head with boss for bolt/nut to arm to adjust tension is also similar between Ford/GM/Mopar. The GM one wire atlternators are handy and have the internal voltage regulator. The alternator on P1116 was a GM unit that ate a couple of aftermarket regulators until I installed a genny GM regulator and then no further problems.
Ron, most current Fords have a minimum of 120 amp alternators from the Focus on up. Some cars have a 150 and trucks go to 200 on a single and 320 on a dual alternator system. I think 70-100 is more than enough on a '40 dependant upon the ignition and injection system. With EFI you don't want to drop amps/volts and not have the injector fire properly.
Most new alternators bolt direct to the block/head to eliminate any brackets. Belt tension is controlled by a tensioner in the drive belt system so no adjustment is available on the alt. The direct mount takes a lot of resonance out of the system and cuts NVH greatly but these alternators will not work on a small block Ford engine without a tensioner and special fabrication.
Ron Earp
Admin
I didn't know they were that high. My old 98 BMW M3 had a 80 or 90 amp unit, pretty sure, and it had plenty of electrical accessories plus EFI, and so on. Never had any trouble except when it finally failed at around 90k.
I suppose I should check my Ford Lightning alternator since I use it for towing, lots of lights, and recharging my trailer battery pack (two marine batteries with inverter)......hmmm, shows only 130 amp unit for the F150 with 5.4LSC Triton V8. Still, seems just fine with lots more going on than a GT40 replica ever will.
Ian Anderson
Lifetime Supporter
What sort of amperage can be drawn out using a V belt pulley as opposed to a serp / flat belt type?
I had read somewhere over the 90 amp range and the belt will slip on the pulley
Ian
I had read somewhere over the 90 amp range and the belt will slip on the pulley
Ian
Depends upon the current draw. If a small load it will not slip. Keep in mind a 90 amp alternator does not put out 90 amps all the time.
Another thing to consider is where the alt pulley is in the belt setup. You need on a "V" belt over 40% drive contact on the pulley. I have seen systems where the belt is only contacting 20-30% of the pulley drive surface, a sure recipe for slip.
I think I need to apologize to Jack about the big block Chevy comment. It turns out that is exactly what I need. Even after going through the “box of parts” that came with the car I didn’t see the metal part of the motor mounts that come in the box. They are warped in a way that makes it hard to recognize. What is missing is the polyurethane part which appears to be from a BB Chevy. Thanks Jack.