I’m not trying to add fuel to the fire but originally a 66 would use a 157 tooth flywheel. You would use the same starter for both automatic and manual transmission. This starter is for what ever reason labeled as the automatic starter. In 68 Ford used a larger diameter flywheel at least in the stick shift cars. This flywheel is 164 tooth. I don’t know honestly what size the flexplate is in the automatic cars, 157 or 164 tooth. But anyway on the stick shift cars with the 164 tooth, it used a different starter then the 66 cars. This starter is referred to as the manual starter. So the problem now is in the 65 to 67 stick shift cars which actually have a 157 tooth flywheel that uses the so called automatic starter are now sold the manual starter designed for the larger 164 tooth flywheel and doesn’t work.
The difference between the two starters is not the tooth count on the starter drive, both have the same number of teeth which if I remember right are 11 teeth. The difference is how far the starter drive protrudes. On the 157 tooth manual flywheel there is about a 3/8” set back of the ring gear to the engine side of the flywheel. On the larger 164 tooth manual flywheel the ring gear is flush with the engine side of the flywheel. That difference is made up in the starter. The so called 157 tooth automatic starter drive protrudes 3/8” more. If you install the manual 164 tooth flywheel on a 157 tooth manual flywheel, it’ll never engage. It’ll just free spin. If you install a 157 tooth automatic starter on a 164 tooth manual flywheel, it’s too deep and it’s going to grind. I honestly don’t know if it’ll even engage. When I converted my 66 from automatic to 4 speed I went through this. I bought a manual starter from DB electrical and it just spun, never engaged. I bought it off eBay. I called DB and they explained what was going on and swapped me the correct 157 tooth automatic starter which did work fine. A popular swap is to use the PMGR starter from the 90’s 5.0 Mustang T5 which uses a 157 tooth flywheel but balanced to 50 oz, into vintage Mustangs with 157 tooth flywheels and they work just fine. Apparently Ford got their act together and used the same 157 tooth starter size in all applications. The mid 90’s V6 T5 Mustangs used a larger 164 tooth flywheel then the 157 tooth 5.0 T5 but both use the same starter and this starter will work in your 66 with a 157 tooth flywheel. If you put a vintage 157 tooth manual flywheel next to a 157 tooth 5.0, T5 manual flywheel to the unfamiliar they will look identical. The only difference is a larger balance weight cast on the back side of the T5 flywheel and different pressure plate bolt pattern. Other then that, they are basically the same. Same number of teeth and same offset of the ring gear and either vintage or PMGR starters will work on each other.
As I said in my previous post if you do have the 157 tooth flywheel and correct starter which will be listed as the automatic starter for a 66 and it still grinds, it’s going to be the block plate. It takes very little mid alignment to cause grinding. The block plate is suppose to correctly align the starter and it’s suppose to be a precision measurement but in the aftermarket world, who knows? I went through this with my 66 2 years ago when I put my GT40P into my 66. I bought a new block plate and flywheel. I had a hard time getting the bolts started in the starter. When I started the car for the first time the noise and grinding were so bad I thought I had ruined a couple teeth on my billet SFI rated flywheel! I pulled the starter out and with a small 90* air grinder and carbide burr bit I slightly opened the block plate. Wasn’t a fun job with the headers and exhaust in place either. But now it works just fine. Post a close up picture of the starter drive and a picture of the back side of the flywheel through the starter opening and we can tell you what’s what.
Also, the bellhousing are different too between a 157 and 164 tooth. The 164 tooth is bigger and locates the starter farther out. Everything must be a matched system. You could install a 164 tooth bellhousing on a 157 tooth flywheel but no combination of starters will work. Nothing will engage. I don’t know if you could even install a 157 tooth bellhousing over a 164 tooth flywheel? If you could I’m sure neither starter would work and you’d be having totally different problems.
Last edited by Huskinhano (7/13/2018 7:39 AM)
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