Block Plate

[Torkman66]

Working on a friends bronco installing new starter. New BP 302, Bronco C4 (used to be a 3 speed), 164T 50 oz flexplate. New block plate from WH for C4.
This is the second starter he has replaced. In discussing it, he said when he went to put the starter on originally, the starter would not fit flush into the block plate starter hole opeing...the opening in the block plate was slightly too small for the starter. He figured it was a bad cut and just carefully used a Dremel to enlarge the hole very slightly. Starter went in, bolted up, and worked great for a month without issue. The starter began making noises then failed. Inspection of the flexplate shows no wear what so ever.
I seem to recall that there was a very small difference in Block Plate starter hole sizes for some reason but cannot find it.

1. Are there two different size holes in the block plates for starters?
2. If he used the smaller sized blocking plate and enlarged it (it is a very small different in size) would that affect the starter?
3. Because the starter worked perfectly for a month before failure, do you think it is just a case of a bad starter?

 

[Broncobowsher]

Just saw a post about this in the past month or so. It was news to me as well. You are on the right track. Someone will link it faster than I can find it. Give it a few more minutes.

 

[DirtDonk]

Correct. One of the starters has a larger register than the other.
Unfortunately, even though I read it too, I don’t remember whether the automatic had the smaller or the manual. But it sounds to me like, if we sent you the correct block plate, the automatic has the smaller opening.
Maybe he got a manual starter to work with his new automatic? Although I don’t think that really works. Usually when you try to run the wrong starter, it never works properly.

What type of starter is using? And what model/part number exactly?

 

[DirtDonk]

It was posted in the Tech section. Page 3 or 4 right now, in a thread from Bitch’nBronco titled “mini starter“.
Look there (page 2 of the thread) and you’ll see the data sheet provided.
It is indeed the automatic transmission, and the 157 to manual transmission, that use the smaller register.
About a .050 inch difference or so.

 

[Broncobowsher]

It was posted in the Tech section. Page 3 or 4 right now, in a thread from Bitch’nBronco titled “mini starter“.
Look there (page 2 of the thread) and you’ll see the data sheet provided.
It is indeed the automatic transmission, and the 157 to manual transmission, that use the smaller register.
About a .050 inch difference or so.

Mini Starter

I'm going to get my battery tested tomorrow when I take the starter back just to rule that out as well. It's about 6 years old and I'm wondering if it doesn't have the amperage to throw the bendix and rotate the engine over. I've done a bunch of research and this should pretty much be a plug and...

classicbroncos.com

 

[Torkman66]

Ok, read through that post. Very helpful. It appears that his enlarging the opening .05 so the starter would fit should not affect performance. He is running an Autozone stock starter for a 302 with 164t FP. I’m thinking he is fine and may just have a bad (cheap) starter.

 

[DirtDonk]

That's way more common than we like to think.
They don't happen to remember the actual application and part number by any chance, do they?

 

[Torkman66]

DL 3124. He just told them 74 302 auto. But this is def. a 164t flex.

 

[DirtDonk]

Ok, '74 "Bronco" with auto should be the right one. But it should not have had to have the hole opened up to fit either.
If he's still got it out of the engine, have him send a picture of the nose cone area with gear. Compare any of them that they have to the correct ones in the pictures in that other thread.
Just for that last bit of assurance.

Paul

 

[Torkman66]

Yes, confusing. The 3124 is a 3/4” offset and it should fit the smaller register size. Strange. So now that he has the backing plate enlarged, seems like the smaller registry of the 3124 is not right. Then again, it’s a two bolt starter with correct offset (3/4”) so even if his backing plate is for the larger manual trans and starter, he should be fine.

Interesting as well that looking at Summit you can get a mini start for 164t on a C4 that says it fits both MT and AT. Must have the smaller registry so it can be used on either block plate.

 

[DirtDonk]

Interesting as well that looking at Summit you can get a mini start for 164t on a C4 that says it fits both MT and AT. Must have the smaller registry so it can be used on either block plate.

Or it’s yet another case of a mistake in online listings. Apparently Summit’s not immune any more than anyone else is.

 

[Broncobowsher]

Or it’s yet another case of a mistake in online listings. Apparently Summit’s not immune any more than anyone else is.

Fox body mustang with a T5 uses the automatic starter. The oddity to the normal auto/manual starter differences.

 

[DirtDonk]

Yes, but that’s supposed to only be with the 157 tooth flywheel. Not supposed to work with any 164 I don’t believe.
For the 164’s you should always need an automatic starter for an automatic, and a manual starter for a manual.
At least that’s how I understood it.
If I read it correctly, Summit’s listing showed it working for auto and manual with 164 tooth flywheel.

 

[Torkman66]

It appears that there are only two Ford 302 starters and two registry options. A 3/4" and a 3/8". The autos call for a 3/4" with the exception of the T5 which also does. The manuals call for a 3/8". The 3/8" seem to all have the larger registry and the 3/4" have the smaller registry....confused yet? SO not sure how he had an WH auto block plate (small registry) and then got a large registry 3/4" starter. Im calling power Master today to see if they can make since of it.

Here is just one of a dozen examples where you can get a starter for a 302 that says works with either 157 or 164 tooth FP. Also states works with Auto or Manual.

• Weighs only 11 pounds (7 pounds lighter than a stock starter)
• Allows more room for long tube headers and larger exhaust pipes
• Works with both 157- and 164-tooth ring gears
• Compatible with manual or automatic transmissions
• All steel gear construction handles high compression and big block engines
• Clockable design to provide maximum clearance
• Gear reduction design reduces current draw demands on electrical system

 

[Torkman66]

Just off the phone with the tech folks at Powermaster. They said no issue at all with the block plate being ground .05 to accept a larger registry. They said that even if it moved it would only move half of that amount (radius) which is negligible to performance or position. Also said that when the starter is bolted in, it wont move.

Second, they said that starters for the 302 can play with the 157 and 164 tooth count. The difference is the bellhousing for the manual verses auto placement of the starter relative to the flywheel/flexplate. That is also where the 3/4" or 3/8" comes into play although there are exceptions for several manual transmission like the T5. So, basically, when it says for 157 or 164 only, that has nothing to do with whether or not the teeth "mesh" with fly/flex, it has to do with the distance the pinion must move (3/4 or 3/8) and the larger registry hole just helps to identify and mount the auto verses manual application.

They recommended thee two starters:
Powermaster 9603 or 9503. Reading the specs, both work for the auto (i.e. 3/4") and both work with either 157 or 164t. They also work with "some" manual trans. Going to have him get the 9603.

 

[DirtDonk]

They recommended thee two starters:
Powermaster 9603 or 9503. Reading the specs, both work for the auto (i.e. 3/4") and both work with either 157 or 164t.

What's the diff between the two?

They also work with "some" manual trans.

Yes, as described in the diagrams, the 157 tooth flywheels for manuals have the same ring-gear offset as the flywheel/flexplates for the autos do. So a starter that works for the automatics on either tooth count ring gear, will work for the manual trans ONLY with the 157t flywheel.

Paul

 

[Broncobowsher]

Yes, as described in the diagrams, the 157 tooth flywheels for manuals have the same ring-gear offset as the flywheel/flexplates for the autos do. So a starter that works for the automatics on either tooth count ring gear, will work for the manual trans ONLY with the 157t flywheel.

Paul

The 157 tooth T5 flywheels.
Not to be confused with the 157 non-T5 applications, such as 1st gen mustangs.

 

[DirtDonk]

Ahh, didn’t know that either.
What about the very early Broncos with six cylinder engines? Didn’t they also use 157 tooth flywheels?
I had thought at one point that all Broncos used the same larger diameter flywheel, but I remember hearing some of the six cylinders had the small clutch. Thought that might go along with a small flywheel.

Thanks

 

[Broncobowsher]

Don't know about the I6 flywheels other then they are neutral balanced and won't work on V8s. Unless you get a neutral balanced crank, in which case a flywheel off a 300 should work.

I just remember that the cars had the smaller bellhousing to be more compact. And the clutch was limited to 10" The compact cars also ran the small flexplate on the C4. When you got to the trucks, there was more room, the flywheels got bigger and you got an 11" clutch.
In the '80s the Mustang was still running the 10" clutch and they were killing them left and right. Engineering went in and made the biggest clutch they could fit on the small flywheel, and the late 80's the Mustang got the upgrade to the 10.4" clutch. Still died all the time, but not nearly as bad as the 10" version did.

 

[Torkman66]

9603 and 9503 are almost the same. 9503 has a bit more torque. One is a bit lighter. 9603 is $175 and 9503 is $200. I think he is getting the 9603.