As a general rule, smallblocks used the 153 tooth flexplate and bigblocks the 168 tooth. However, you can run either size flexplate on either engine as long as you use the appropriate starter.
Most engines 62-up are drilled with three starter mounting holes, two inline and one offset. The outermost hole is used by both starters.
Starter tooth count can be the same and work with either flywheel. On both 153T and 168T flyhweels, the tooth size and spacing is the same. That's because the 168T flywheel is 11" diameter compared to the 153T at 10.4".
Regarding the tooth spacing on the flywheel/flexplate/starte r drive, they're all the same. For example, on a stock starter, regardless of whether it is for the big (168 teeth) or small (153 teeth) flywheel, if you have to replace the starter drive, the guy at the parts store (NAPA, etc) will give you the same starter drive for either starter.
Comparing the units which are very different from the nose cone back.
3510S used STANDARD {SAE} Bolts while the 3510MS employs METRIC Bolts.
What is the difference between a 153 tooth starter and a 168 tooth starter.
Reason for the ? is I have a '86 5.7(350) out of a 2500 pu and am trying to get the correct starter for it.
I have a 168 tooth flexplate.
I have an older starter that I tried using and it jams.
Do I need a starter that is 86 or newer. The men at the boneyard think I'm nuts when I talk about the difference in tooths on the flexplate.
Also I used ordiary hardware store bolts (hardened) to mount it, MUST I use the knurled bolts?
Or do I just nreed to shim the starter?
Flywheels with two different diameters are used on Chevrolet small-block V~8, big-block V~8, and V~6/90-degree engines.
Large flywheels are 14" in diameter, and have 168 teeth on the starter ring gear.
Starter noses used with large diameter flywheels have two offset bolt holes.
Small diameter flywheels are 12-3/4" in diameter, and have starter ring gears with 153 teeth.
Starters for small flywheels have two bolt holes which are paralleled to the back of the block.
The difference in flywheel diameters requires two different starter housings.
This nose is the part of the starter that moves the starter motor in closer to the flywheel on the 153 tooth and farther out away from the flywheel on the 168 tooth wheels.
Most Chevrolet blocks are drilled for both types of starters. If you are changing the diameter of your flywheel, you can convert your present starter to fit the new flywheel by installing the appropriate starter nose .
The Knurled starter bolts are a must. The knurled part holds the starter in place it is actually a bit wider to keep the starter from shifting.
Keep in mind the difference of the metric & SAE bolt dia.
Might want to add that on the 168 tooth flywheel and starter, the the nose cone of the starter is different between and auto trans and a manual trans on many applications.
Main differance and application.
153 tooth is a high ratio/ low torque application. Used on low compression applications.
168 tooth is a low ratio/ high torque application. High compression, large CI and AC equiped application.
In Standard transmission also changes the clutch size, 153 tooth can be a 1 or 10.4 clutch
168 Tooth is a 11inch or up.
I really hate to disagree with you but I think a lot of high compression engines were original equipment with the 153 tooth flywheels.
There is no problem mix/matching these....but a few things to consider.
The few blocks out there that came with 168 tooth flywheels have starter bolt holes that are offset. Blocks that usually have a 153 have starter bolts in-line. An in-line block starter bolt pattern can adapt to 168 with a universal starter - or one made for that kind of block and a 168 tooth.
The 168 tooth blocks CAN NOT convert to 153 tooth, as there is no starter out there made for 153 tooth with the off set bolt pattern.
The 153 tooth is great for weight reduction. The 168 is massive, but gives a better gear reduction for high compression engines.
Clear as mud?
You are 1/2 correct. You can go from 153 to 168 - but you can't go from 168 to 153 if your block only has the offset starter bolt holes. Some blocks have THREE holes...and are able to do either - but two bolt offset blocks...no go.