I need a mini starter to fit these two blocks if possible: The 400's casting number is 3951509. The 350 is just a 91 thirdgen 350 block. 1. Does anyone know what the starter bolt patterns are on these two engines?

The 400 has a 168 tooth flexplate. The 350 has a 152 tooth flexplate. 2. Can one starter fit both 168 and 152 tooth flywheels?

 

Yes, I know what the bolt patterns are.

A starter for a 168-tooth flywheel will not fit in the stock bell housing for one of these cars. So you will have to use a 153-tooth one, and have it "unbalanced" to the stock 400 balance spec.

A 400 block does not have the correct inner starter bolt hole for the starter for the 153-tooth flywheel. You will have to have it drilled.

The stock starter is different between the 2 fkywheel diameters. However, some of the mini-starters (the particular CVR I have had on my 400/T-5 combo for example) are equipped with both bolt patterns. Ones with a single bolt pattern cost less.

Been there, done that, there are no alternatives.

 

and now fit both flywheels. I have not seen one.. but thats the way they are advertised.

 

Thanks for the reply! Okay, so let me get this straight.... I need to use a 153-tooth flexplate on the 400. I thought the 153-tooth flexplates would not fit on a two-piece rms 400 shaft...is this correct? If not, what cars do I need to rob a 153 tooth flexplate from that will fit on a 400?

I need to purchase a "dual bolt pattern" mini-starter that is compadable with 153-tooth flexplates. Is This correct?
OR: I will need to drill and tap the 400 for the in-line starter bolt pattern so that I can use a mini-starter designed for in-line and 153 teeth.

Sort of confusing. Thanks for your help.

 

I can accept no responsibility for what you thought.

Some 153-tooth flywheels will fit on a 2-piece RMS crankshaft. Specifically, the ones for 82-85 305 F cars are what you need. You will have to take it to a balance shop and have it made into the 400 "unbalance" (this is what I recommend) or buy a "pork chop" weight, which works but makes me feel vaguely uneasy. I am using the stock 83 L69 one, with a bunch of extra holes drilled in it for balancing.

You will have to drill & tap the extra starter bolt hole on the 400 block. Again, there is no alternative. The 12¾" bolt pattern didn't exist when 400 blocks were cast, so there's no 12¾" hole ("feature from the future") hole there. If you look at where the inner bolt would go in relation to the 153-tooth starter if you put it in the hole that (maybe) is there, you will see that it would have to go right through the center of the starter drive. It is therefore not possible even to custom-create a starter nosepiece that will work with that hole. Starter bolt holes are special: they have a section before the threads that is large, and true starter bolts have a section right behind the threads that is similarly large, which acts as a "dowel pin" to positively locate the starter to the block. So drilling it is not an operation to be taken lightly.

There are some mini-starters (such as the particular CVR I have) that have both the 153-tooth and the 168-tooth bolt patterns on them so they fit either the 12¾" and 14" flywheels. They work fine. As I stated, that's what I had on my 400/T-5 combo. I don't know the part # off the top of my head.

 

i have a gm mini starter on my little engine and it has duel bolt patterns and the starter location is adjustable on the mounting plate. not sure what all it fits but it wouldn't hurt to check GMPP catalog.

 

Okay, I broke down today and bought a Chevy Small Block Parts Interchange Manual. Here is some of what I learned in case this question ever comes up again in searches.

All generation I motors with two-piece rear main seals were internally balanced engines with one exception: the externally balanced Gen I 400 small block. All two-piece seal cranks have a rear flange bolt pattern of 3.58" to fit their flywheel/flexplate.

This means that all two-piece rear main cranks will bolt up to all two-piece rear main flywheels/flexplates. However, since the 400 block is externally balanced, there were no production two-piece rms, 153-tooth, externally balanced flywheels/flexplates. The moral of the story is we have to find a 153-tooth flexplate that can fit on a two-piece block. Since it will be an internally balanced flywheel/flexplate, we need to have it converted to an external balanced one. This is what the fellow above was trying to tell me... Lastly, to use the small (153-tooth) flywheel/flexplate, you MUST use an in-line bolt pattern starter. To my surprise and contrary to the above post, I found that my sbc 400 WAS drilled for both bolt patterns. Because of this, I get to use a straight-line starter (which will fit both of my blocks as per the original post.) Thanks for the replies all...I learned something new. -Jerod

 

One more time...

You will need to get the flywheel for a 305 from 82-85, and have it externally balanced.

You will also find that the inner bolt hole is not the one you need, unless someone has already done it for you in a prior motor swap with that block into a later model F body. Rather, it is the correct one to fit the old cast-iron nosepiece version of the starter for a 14" flywheel/flex plate. It will not work with the 12¾" flywheel.

Of course, you can choose to ignore these facts; I can't be held responsible for that either. Once again, been there, done that, tried to tell people this over and over; they tell me what I'm full of, they install the motor, then post on this BBS wanting to know how to drill a starter bolt hole from under the car.

Get your starter and test fit it before you build the motor, or at least before it becomes impossible to turn it upside down and work on it.

 

Please don't try to talk down to me.

This is exactly what I said and meant here:
Oh, yes, and I also wanted to add the part number for the flexplate that will be needed: p/n 471529

I'm not sure on the history of the block, so for all I know it could have been drilled and tapped for the 12.75" flexplate starter.


Woah Woah...I'm not going to file suit nor am I going hold anything you say against you. Nothing on this board is a guarantee, it is just one of many thirdgen resources that I'm greatful to have.

I'm sure you have been there and done that...
I am not telling you that your full of it.

I will definetly test fit everything on the running engine stand before it goes in. The starter issue will be taken care of prior to installation, and I will not come to you asking how to work on it upside down, OKAY?

The straight bolt patterned mini-starter will be in next week. If it wont fit on the 400, we'll find out then.

 

No insult intended, it's just that I've answered this question about a hundred times it seems like, been argued with every which way by people who heard from someone who knew a guy whose father read it in a magazine article that it would work; then the person who asked the question heard the answer they wanted to hear, even though it was from somebody who had never even seen any of the parts in his life let alone actually made it work; so they put their motor in, and guess what...

You could search the archives and find lots of instances of this; either this board, or the trans board, or the motor swap board, it's been hashed over plenty of times on all 3.

This might even be a good subject for a tech article. If you aren't familiar with the variations, it makes no sense at all to describe it in words. A drawing or pictures would make the issue much clearer.

 

The mini starter came in today... I bought the two-piece RMS smaller flywheel today at the parts store as well. What do you know... a perfect fit on both the old 400 and the 91 350 blocks. It turns out that I did have both the diag and straight pattern on my 400 block.

 

dunno what good this will do-here goes take one 400 block\crank add 1985 small flexplate (which was set up for the external balanced 400)bolt together. toss in a (any)gm small block starter (aftermarket or oe) with a straight across bolt pattern, bolt together. do the rest of whatever your doing as far as hooking up and completing swap-turn key and start car-who is drilling holes. been doing this trade for a couple of days now and dont recall ever drilling holes for starters to mount (on a chevy?????) help walk me thru dat operation-yer talkin into the block casting? uh-uh somebody's got some mis-applied parts i suspect. 153=straight across 168=staggered. except aftrmkt jappie style "hi-torque" or "mini" style where straight across is both sizes depending on which 2 holes get used been starting my 85 iroc since 1989 406,305 fplate off orig.motor,small starter. dunno drilling
:lala:

 

RB83L69, I have a question about your starter. You said it has both bolt patterns. Can you use the diagnal pattern or do you still have to use the inline pattern. I have heard that the diagnal pattern will position the drive gear of the starter to far from the flywheel, is this still true with your starter that has both patterns? I ask because the knumbskull you drilled my block for the inline pattern messed it up .

 

I've never heard of drilling for the extra starter hole either??? All I can say is thank goodness I dont have to mess with it...

 

GTA383, I dont know about RB83L69's mini starter, but mine was the kind that "fits both 168 and 153 tooth flywheels." It uses the inline bolt holes only. The starter has just two pairs of holes you can use for either flywheel.

 

now your talking



:hail: halleluja

 

I know this is really old thread but I want to update it. I did a search and found this thread because I was having starter problems on my 406.

You can use a starter off a 98 chevy truck. I will get the part number this weekend. They use a 168 tooth flywheel and a staggered bolt pattern that year. It's a mini starter that will fit in the 700R4 bell housing. It works perfectly. I installed one last night. My friend that works at autozone found it. No more having to drill and do balance work. It was nice of GM to make this starter for us.

Jason

 

I'm with Jay about the 168 tooth flexplate fitting inside a 3rd gen 700R4 bellhousing. Done several swaps of 383s and 400s into 3rd gens using the large diameter (168 tooth) external balance flexplate (gen1 400-style flexplate). Haven't had any issues with it hitting anywhere on the bellhousing, although the factory ispections shield under the converter may not fit.

Some aftermarket mini starters are built with a bolt pattern that will allow them to be used with either 153 or 168 tooth flexplates. Factory-style starters (earlier full size or later mini starters from the 90s) are either one or the other, however.

 

I realize this is a longshot and I only mention it for educational purposes, but take a look at this pictre of an acdelco LT1 153 tooth starter.

Doesn't it appear to have the dual bolt pattern? In other words, if someone had a block drilled for the staggered pattern and wanted to use a 153 tooth flywheel, is it possible that this starter would accomodate that? It even appears to have the circular boss as part of the casting. I've never torn into one of the ministarters but it could be that there is enough room to run a bolt past all the internal components. If there's anyone out there who owns one of these or works somewhere that stocks them, I'd be curious if this is the case.
One other thing. Do any of the manual transmissions used on third gens have bell housings that can fit a 168 tooth flywheel? I didn't think so.

 

The 3rd hole is some sort of inspection hole/drain hole, not for a bolt.

The offset of the starter's axle shaft is different relative to the bolt holes as well. A 153 tooth starter the whole working guts of the starter is closer to the engine, while a 168 tooth starter is further from it. The difference is about 1/2-3/4" or so. So having both (factory style) bolt patterns on one starter still won't do you any good.

I beleive many aftermarket mini-starters use 2 sets of holes, both sets designed to use the bolt holes of a factory 153 tooth starter, but one set of holes offset from the other by that 1/2-3/4", which allows you to move the starter to line up with either size flexplate.

For example:

http://store.summitracing.com/partde...700+4294908216

 

The 153 tooth LT1 starter will not fit the 400 block with the 168 tooth flywheel. I tried that.

As far as the flywheel, I have not heard of a problem with it fitting, just the starter.

The third hole in that starter pic, it's so you can engage the starter drive manually with a screwdriver to check the clearance between the starter gear and flywheel.