Technical Chevy small block guys. need your help

Got a crate 350 block #10066036. It had a 5 speed on it and I am switching to automatic. Question is the flex plate. Tranny is a Turbo 350. According to the motor shaft to starter gear measurement, outer diameter it needs a 153 tooth flex plate and needs a 2.5" diameter center hole. How do I know if it need an external balanced plate or other? I am really out of my comfort zone here. NAPA has given me two wrong plates and tomorrow one comes in that they say fits a 1984 Corvette. Do I need a plate with a balance weight on it?

 

No, the 350 is internally balanced.

 

That's a 2 piece main seal block so you need a 153 tooth flex plate for a 1969-'85 engine, those have no external counterweight on them. The only exception to that is when using a 400 crank which require the c/w.
One piece seal blocks use a counterweighted flex plate or flywheel to make up for the missing weight on the end of the later cranks.

 

Right you are. I do not know why NAPA would have a problem with this. Any 153 chevy flex plate will work with 2 piece rear main seal.

 

Here are a couple of pictures of the engine and tranny. So no external weight. And to cut NAPA some slack, they are dealing with someone with little knowledge and experience here. Only tranny I ever bolted to an engine was a 49 Chevy with stock engine and tranny. Did it for an old man who was as old then as I am now. Loong ago.

 

Make sure you get the correct bolts as well.

 

make sure the torque converter is all the way in, before trying to bolt up the tranny. keep spinning it and pushing it in. 3 "clicks". or you could damage the front pump.

 

^^^^ this is very important.
It's tricky especially if you've not done it before.

 

1) Ok, either i cannot count ( which is possible) or the notion that you " need "a 153 tooth flexplate for a 69-85 small block and/or 2pc rear main seal engine is hopefully not true?

 

If he has the old style starter that matches the 153 then he needs a 153. I myself would get the 168 and different starter. My thinking is that those old staters aren't going to be around and available forever. But that's just me.

Anyway, the starter and flex plate must match, regardless of engine, and they will swap around onto most any 86 and earlier engine as you see here

 

Swapping to another starter is another expense...and then you have to get the right bolts....

but Chevy did use the larger flex plate with most of the 350 engines.

(also, make sure to remove that dust shield, which is a manual transmission thing, not used on automatics)

 

Yes the right bolts - very important.
From the dealer usually, not the "HELP" isle
Sounds silly but it ain't

 

The "need" for that flex plate stems from his comment in his first post, he had determined that he needed a 153T f/p. In a later post the starter pictured on the block is clearly the correct one for that f/p.
I don't see the need to change to the other starter and 168T f/p, those starters will be available for a very long time. Look at flathead Fords for example, how many starters do you want?

 

The 84 vette flexplate should work.

http://www.oreillyauto.com/site/c/d...=Search_03232_5186816_3090&pt=03232&ppt=C0338

 

not the one piece rear main engines they have a weight on the flex-plate/flywheel.. but neutral balancer.. the two piece older engines, are indeed neutral.

 

we put an aftermarket flex plate on a crate 454, and it shook it's ass off. had the parts store double/double check it,and they confirmed it was correct,according to their sources , so i got one fro G.M> all good..

 

What you have engine-wise, is a Goodwrench 350, Hecho en Mexico, engine. Chevrolets most often sold/popular, over-the-counter engine, of all time Cam is REALLY mild, heads are the biggest drawback for power (76CC Chambers), and the dished 8.5:1 CR pistons also don't help. It's a 4 bolt main block with powered metal connecting rods, along with a nodular iron, cast crankshaft (all that's really good!!!). Swapping to some 64CC chamber heads will really help, especially if they're true Vortecs (but not traditional), but that would also mean a Vortec intake manifold. Or use the more "traditional" double hump heads with 64 cc chambers. 249 HP/304 ft. lbs. torque as the engine sits is how they advertise it. A neutral balanced, 153 tooth flexplate is what you need, and like Squirrel said, toss the inspection plate. The engine looks to be virtually brand new. You can leave the manual transmission pilot bushing in the end of the crankshaft; it should have no effect on the converter bung centering, but you can remove it if it "bothers" you. There are a few different ways GM bolted the torque converter to the flexplate; yours will take the old "bolt, lock washer, nut" arrangement; some with "crimped",locking nuts don't use the lock washer. When you install the flexplate onto the crankshaft, the center hole "bevel" needs to face the transmission; it will go on the other way, but the bevel will cause problems with it "drawing down" on the crank, and warping the flexplate. If GM would go back to using a locating pin on the crankshaft flange, there would only be one way to bolt the flexplate on.Don't use the flywheel bolts that held the flywheel to the crankshaft; automatics with flexplates use shorter bolts. I see an HEI distributor connector; what intake/carburetor are on the engine? It also looks like fenderwell headers are on it (???). What was the engine in? Is the throttle valve/passing gear cable attached to the transmission, and does it have the correct brackets; that will just make your job easier.
I am Butch/56sedandelivery.

 

Thanks for the info. I will do as advised. new bolts. Picture of engine below. Had 3500 miles on it before the wreck.
http://www.jalopyjournal.com/forum/threads/30-model-a-build-rebuild.1039933/ is the build post I am working on if you want to see the chassis before and after.

 

I read thru the posts and did not see any comments on the pilot bushing. I would suggest that you remove the pilot bushing from the crank that was installed for the stick trans, I am not 100% positive but there could be an issue with the snout of the 350 torque converter If it interferres and you torque if down when you bolt it to the block you could destroy the front pump as tb33anda3rd said make sure the torque convert seats.

 

There was a comment about the bushing, and as Butch noted, it's in all the way, and won't interfere.

 

Also take a wire brush to the surface where the flex plate bolts to the crankshaft. It needs to fit flat.

 

Now let me say this. I consider this stuff"late model "to me. But is the starter for the 5 speed the same as the one for a automatic? I thought they were different..Again this is kind of new for me.lol.

 

I keep a pair in my tool box. The have a knurl on them.

Funny I have a very expensive mini starter (that I like real well traditional or not) and it came with non stock starter bolts and a note that said not to use stock GM starter bolts. So I didn't. That gave me two sets of GM starter bolts for a while.

 

X3 on the getting the torque converter ALL the way in.

 

You can buy a Chevy hp book at a dealership with hp part numbers, I bought my flex plate at dealership

 

No need to remove bushing.