I have a 85 Trans AM that came with 305 that was bad, so I put in a 350 which ran good with no starter issues.. Since then I've built a sbc 400 with some goodies in it.. My problem is since the new engine went in I've had starter issues, like this loud grinding noise I've replace the starter twice and as of last night with another one it will not start at all and it makes this very loud noise it sounds bad...

I went back to retrace my build and I notice I brought a flywheel from summit Part# ATP-Z112 this flywheel is for 82-92 firebird T/A which came with the sbc 305... So I just looked up a flywheel for sbc 400 from Summit SUM-G100SFI ....

So my question is should I have brought a flywheel for the sbc 400 and not for 82-92 firebird..

 

Stock 305, 350 engines are internal balance. Both a 153 and 168 tooth internal balance will work. Model number is ATP-Z112 is a 168 tooth external balance flexplate which should be correct for a stock SBC 400. If you had a 153 tooth internal balance flexplate on your 350, then your starter nose cone will not work with the 168.

What starter are you using? Are the starter bolts straight across or are they offset. Stock starters are usually straight across for the 153 tooth and staggered for the 168.

 

That's not a flywheel. That's a flex plate.

If your motor has a stock 400 crank or one with stock 400 balance at least, you need a 400 flywheel (or flex plate since you hopefully have an auto trans) with the 25 oz-in or so of unbalance. That one doesn't have that. It'll vibrate you right out the window.

Most 400 flywheels, or flex plates as well, that you can just buy, will be 14". Which that one is, it's just that it's a 350/396 one, not a 400. But if you want you could have your balance shop weld up a weight onto it and then you'd have the right thing for about twice the $$$$ of just buying the right thing in the 1st place.

That also means you can't use your stock 305 starter. It's for a 12.8" wheel. About 5/8" too close to the crank. You'll need to use either a 3510 starter (the part # that would have come on a 400 back in the day) or maybe a later-model truck 350 starter since those had a 14" wheel as well.

The horrible grinding / gnashing / shredding noise is probably due to your block having The Problem, wherein the starter bolt hole pattern is drilled too far from the crank. Especially likely if you bought the motor for an impossibly good price and the reason the PO told you he took it out of his car doesn't make any sense. EXTREMELY common in all the 70s blocks which of course all 400s are.

 

So he needs a 153 tooth flexplate with the 25 oz-in or so of unbalance, correct?
Does anyone make this yet? I had to go through this with my 334, 20 years ago.

 

No I don't think anyone makes that. At least, not mass-produced. Just way too few potential buyers. Not flywheels either.

When I put a 400 in my car back in the 80s, I took a stock L69 T-5 flywheel to my local balance shop and had it "adjusted"... took about 25 or 30 ½" dia ½" deep holes around one half of it. Pretty easy as far as that went.

 

check the outside starter bolt hole in the block. they're notorious for cracking. then the starter works loose and makes that horrible sound or will break nose cones. the added brace from the front of the starter to the side of the block can help.

 

I don't know what you looked up, but both of those flexplates are for the same SBC 400 external balance application. The only difference is the SUM-G100SFI is SFI rated. Both are 168 tooth, as mentioned above, and all 3rd gen V8s used 153 tooth flexplates - and 3rd gen starters are not compatible with 168 tooth flexplates.

Get a starter for 168 tooth application (like 1970 Chevy Impala), and it should engage properly. But check your bolt mount holes while you're at it.

 

I am starting to second guess everything anymore. I had to go look again, maybe summit is messing with me.

ATP-Z112
Ring Gear Tooth Quantity: 168-tooth
Engine Balance: External




SUM-G100SFI
Ring Gear Tooth Quantity: 168-tooth
Rear Main Seal Style: 2-piece
Engine Balance: Internal

 

Hmmm, you're right. Most likely my bad.

Good catch. It won't work on a 400.

I was trying to find the listing for an external balance tab that bolts on with the flexplate mount bolts so you can use a neutral/internal balance flexplate on an external balance engine. Either I wasn't using the right search terms, or they don't have it anymore.

 

This is what I had to do for the 334. (attached)

I was trying to find the listing for an external balance tab that bolts on with the flexplate mount bolts so you can use a neutral/internal balance flexplate on an external balance engine. Either I wasn't using the right search terms, or they don't have it anymore.

You mean a counter-balance plate. http://www.competitionproducts.com/B...ductinfo/4161/

The way I installed mine looks wrong. I did this on purpose. It is supposed to install between the crank flange and flexplate, but I did not want to change the position of the ring gear in relation to the starter. Also I did not want any chance in the future of it getting installed backwards or even left off. So I welded it to the flexplate so that it sits between the flexplate and torque converter.

 

Mine was cut by the place that did the engine balancing. I don't think you can just bolt that plate on and everything will be correct as far as balance goes. But I could be wrong.

I happen to have a 168 tooth FLYWHEEL that has a removable weight so it can be used for either internal or external balance. I will take a couple of pics and weigh the weight for you so you know the location of where it needs to go.
That is your other option - weld a weight to whatever flexplate you are going to use.

But I think you need to use a 153 tooth flexplate. I originally tried to use the 168 tooth setup with my engine and either the flexplate was too big for the "bellhousing" or the starter interfered with my headers/y-pipe by being moved outward by that approx 3/4" difference. I can't exactly remember which - it was 20 years ago. That left me no choice but to go the 153 tooth route.

 

OK, I have the info for you. I will edit and attach pictures later after I resize them.
Here is what you need to know: this is from a ProComp #2502 168 tooth (14") FLYWHEEL. The bolt-on weight (with the bolts) weighs 132 g or 4.6 oz. Without the bolts it weighs 120 g or 4.15 oz. The weight is directly in line with the dowel pin hole and is located 4 7/8" on center from the center line of the flywheel. It's dimensions are 3.110" at the longer arc, 2.420" at the shorter arc, and is .300" thick.

 

4 more pictures:

 

I'm using a staggard bolt pattern..

 

Thank you all for your input, think I will start with changing the flexplate and a starter I purchased POWERMASTER 9200 HIGH TORQUE MINI STARTER and hopefully I can be lighting the streets up soon.. Thank u and ill get back with results..
)

 

good info in here about starters and using the correct bolts, hardware;
http://www.crankshaftcoalition.com/wiki/Starter_motors

 

From my experience with my 400, purchase a higher quality (B&M, TCI) flexplate. I had years of problems that was cured by a TCI flexplate and quality starter due to slight warp causing the starter gear to move away from the flexplate then slipping teeth.