55.2-59 Flexplate rabbit hole

[regan56]

Hey there. Been a while since I’ve posted. I’m starting down a rabbit hole here that I will need a lifeline for.

‘68 327 SBC with both bolt holes for staggered or straight bolt pattern starter
Newer 700r4 with 10-3/4” converter bolt pattern (ID number DG5F)

I have no flex plate or starter picked out yet so here I am confirming my searches on the interweb regarding this as my outcome:

I’m looking for a 153T flexplate and matching starter either straight or offset pattern. The flexplate may have two bolt patterns to attach to the TC.

Am I right, or am I not right?

[starterman99]

The 153 tooth flex plate will use the straight across bolt pattern with one long one short bolt. The 168 tooth uses the offset bolt pattern and 2 long bolts.

[regan56]

Originally Posted by starterman99

The 153 tooth flex plate will use the straight across bolt pattern with one long one short bolt. The 168 tooth uses the offset bolt pattern and 2 long bolts.

Originally Posted by Rickysnickers

Well, looking at this one, as an example, there seems to be two different bolt patterns on it. Is that what you are referring to or are you talking about the starter? Some starters can be used with either the small or large flexplate.

https://www.speedwaymotors.com/shop/...oth_count:8760

Ok it seems there can be multiple answers to this scenario. I’m asking about both the FP and the starter I guess, but it’s almost like i can go either way as long as I get a matching set.

Is there any reason to go with either a 153 or 168 and their respective starter options?

[Rickysnickers]

Well, looking at this one, as an example, there seems to be two different bolt patterns on it. Is that what you are referring to or are you talking about the starter? Some starters can be used with either the small or large flexplate.

https://www.speedwaymotors.com/shop/...oth_count:8760

[1project2many]

[quote]Ok it seems there can be multiple answers to this scenario. I’m asking about both the FP and the starter I guess, but it’s almost like i can go either way as long as I get a matching set.
Yes, but there are limited options.

The 153 tooth flex plate will use the straight across bolt pattern with one long one short bolt.

You probably realize this, but starterman99 is referring to the starter. The correct starter for the 153 tooth flexplate will have two bolts inline, one long bolt and one short bolt.

The 168 tooth uses the offset bolt pattern and 2 long bolts.

If I happen to call this a truck starter it's from years in the dealership... Shout out "Truck starter for smallblock" to the parts guy would usually get one that worked in a pickup.



Although you can sometimes drill a second set of converter holes in a flexplate, It's best if you get a flexplate with pre-drilled holes for the torque converter. Many aftermarket flexplates have two converter patterns. With the one below you'd use the inner holes.

Is there any reason to go with either a 153 or 168 and their respective starter options?

Probably not.

Sometimes it can be tougher to find a 168T flexplate with dual converter patterns. 168T flexplates do have a little more rotating mass... very minor. Sometimes the bolt holes for the starter aren't always threaded in the block (check first) which forces you to use one or the other starter and sometimes a bellhousing doesn't accept the 168T starter or flexplate (700R4 should be no problem). For higher compression engines the 168T gives more mechanical advantage when cranking but there are starters today that will crank anything short of a diesel with just one battery. And sometimes a particular starter doesn't play well with manifolds or headers or an oil pan.

For your application I'd probably favor the 153 unless something prevented it.

[mr48chev]

With that setup the deciding factor with 153 tooth or 168 tooth is the size of the bellhousing. Some bellhousings on certain transmissions won't handle the 168 tooth flexplate or flywheel.

You should be able to walk into your local parts house and buy order a flex plate for about 40.00 US so there is no viable reason to order from Speedway or another US mail order outlet.

O'Reilly's (US wide parts house) shows three flex plates for a 68 impala with a 327 all 168 tooth. Cheap, decent and race. https://www.oreillyauto.com/shop/b/t...q=at+flexplate

For a 67 Chevelle 327 they only show the 168 tooth flex plate. https://www.oreillyauto.com/shop/b/t...q=at+flexplate

You can find This 153 tooth Pioneer at a lot of parts houses FRA112+100-2901

Amazon link https://www.amazon.com/PIONEER-tooth...01MRFZVSR?th=1 There are some other brands and numbers there that you should be able to find locally.

As far as starter. The best grade of oem style starter that your local parts house sells. I am absolutely no fan of the aftermarket gear reduction mini starters. If you need a smaller starter case there is a GM factory gear reduction starter that bolts right up and actually fits right.

[dsraven]

once decided, before you buy a flex plate, check the local parts stores and/or transmission parts supplier. the transmission shops buy their parts from the local trans parts guy, not usually the local auto parts store, so that's where the deals can be had. they can usually supply anything related to the transmission, flexplate, starter, shim packs, etc. no use paying for shipping or waiting with fingers crossed that you will get what you need from a mail order place. buy local, support local if the price is good. transmission parts suppliers deal in those parts exclusively.
on the starter also check the local starter/alternator rebuilders for a new unit (or rebuilt unit if you are ok with that). sometimes a locally rebuilt unit can be better than a new aftermarket part simply because it is a guys reputation that keeps the store open. they also know what parts work and last better than others. they are also probably not inclined to sell you a poorly put together new unit. they deal with starters and alternators exclusively.

[mr48chev]

DSraven's comments in post 7 apply to any and all hard parts you need for your truck. Find out what the local prices and arability are before you order online and especially for Canadians ordering from the us and having to pay extra fees and expensive shipping.

Also you can look a lot of parts up on Rock Auto, get name brands and walk into a Canadian parts house with that part number and they can cross it. Or you can check their online prices and calculate the differences in total costs.

The main thing on this flex plate besides tooth count is that it has to be for an internally balanced engine with a two piece rear main seal. Meaning that you can go up to 85 model engines as far as the flex plate goes. 86 started the one piece rear seal and a different bolt up setup.

[jwhotrod]

also, do yourself a big favor and use genuine GM starter bolts with the knurled shank and washer heads. the starter holes in the block are 3/8-16 with a .375 c'bore above it for that knurl. that knurl/c'bore combo is there to act as a dowel pin to properly locate and hold the starter in position. that is especially true if you use a mini starter, which a lot of us use with headers, etc. that starter has a 10mm hole thru it above a 3/8-16 thread on the bottom. the correct bolts are cheap at your GM dealer, last time i bought them it was $8 for 5 of them. i was breaking bolts on the 409 in my streetrod until i figured this out. good luck.

[mr48chev]

Originally Posted by jwhotrod

also, do yourself a big favor and use genuine GM starter bolts with the knurled shank and washer heads. the starter holes in the block are 3/8-16 with a .375 c'bore above it for that knurl. that knurl/c'bore combo is there to act as a dowel pin to properly locate and hold the starter in position. that is especially true if you use a mini starter, which a lot of us use with headers, etc. that starter has a 10mm hole thru it above a 3/8-16 thread on the bottom. the correct bolts are cheap at your GM dealer, last time i bought them it was $8 for 5 of them. i was breaking bolts on the 409 in my streetrod until i figured this out. good luck.

This is an absolute must.

[regan56]

Lots of good info here fellas. Thx. Picked up a 153t flywheel today for $70 plus taxes from a local transmission shop.

OE style starter and bolts are next.

[1project2many]

Never hurts to use blue loctite on the starter thread bolts. Not as necessary if installing new bolts into clean, dry threads but will save the day repeatedly if swapping the starter on an old, greasy rig.

Late model "PM" starter is not the same as modified "Mini-starter." Late model PM starters often go many more miles between failures than older design. Late model PM starter for 153T flexplate can be obtained by ordering Delco 323480 or 3361580A or GM 88864469 (or equivalent). Original application is 94-96 Caprice 5.7 engine.



Compared to old, heavy Delco starters these new ones feel like they're helium filled.

Be sure to order bolts for the same application as the starter.

[jwhotrod]

they are rare earth magnet starters, start better, less amperage, and will not heat soak next to headers. they are great.

[G&R's57GMC]

There are shims available for the starter also .

You've heard some starters sound like they are grinding corn , that is the result of being to close to the block and need a shim for correct engagement .

I'm not referring to a sound a bad flex plate gear that has been damaged makes .

[mr48chev]

Rebuilt starters are usually the ones that need shims and the more times they went though the rebuilder the thicker the shims they need. After they take the starter apart and clean the end frame they run the surface across a sanding belt to slick it up and every time they do it it takes a bit more metal off it.

One thing, scrape that paint off that mounting surface where the starter contacts the block before you bolt the starter to the block. Even if you have to hold the starter up to it and trace around it with a sharpie and then only scrape the contact area if you are anal about the paint. That way you aren't posting and asking why it won't crank over good with the reason being that paint is insulating the starter from the block.