Using Automatic Flexplate with 4 Speed Blowsheild to start an engine on stand ?

[dozz302]

Hello, I was just wondering if there was any reason why I couldn't use an automatic flex plate with a 4-speed blowshield to fire up an engine on the engine stand.  I am thinking all the measurements for the starter engagement should be the same for 4 speed and automatic between these parts. Thanks

[MeanGene]

I have done it, but only with a stock 352, as there is no flywheel effect to slow down the response. Even wonder why sprint cars rap quick? No flywheel

[Heo]

Have done it, no problem and got film to prove it

https://www.youtube.com/watch?v=b3qCOEWIrJg

[dozz302]

OK Thank you. I thought all the dimensions were the same. I like how you made your gauge pod by bolting to the bellhousing. I never thought of that.

[MeanGene]

You just have to be careful as it will rap real quick with a stout engine, as in breaking in a cam where you can't rev it up

[dozz302]

Yes Thanks, I'm just starting an engine that has already been run (not fresh) that I bought that came with flexplate already attached and thought it would just be easier bolting on a Blowsheild rather that a C6 just to run to check everything. 

[MeanGene]

This is my 65 352-4V on the test stand, auto flexplate with a C5TA bell

[dozz302]

Have you gotten the 352 in a car and if so how does it run and what did you do to it. I have a complete 1966 352 engine I was thinking about going thru to beat on at the track with the "R" heads. If I did it it would just be basic rebuild headers, aluminum intake, small cam, etc. I would do it for more curiosity just to see how it runs.

[MeanGene]

I just checked under the valve covers, pretty clean, and put a fresh timing set in it. Ran great on the stand, no smoke or noise. Sold it about a week ago to a gent with a 65 Bird. Those old 352-4V tended to run pretty good

[Barry_R]

You can do it.  I have done it.  But I do not like it. 
A lot of the strength of a flex plate comes from it being attached to the torque convertor. 
Without it being mounted to a convertor it's a "flex plate"....

[cjshaker]

You can do it.  I have done it.  But I do not like it. 
A lot of the strength of a flex plate comes from it being attached to the torque convertor. 
Without it being mounted to a convertor it's a "flex plate"....

LOL...Barry with the brilliantly simple, yet previously unmentioned tidbit of fact. 

[MeanGene]

Actually, when I pulled the 352 off the stand, the flexplate teeth didn't look good, and it was a little noisy in use- probably from the Barryflex. There's a steel manual flywheel on there now

[GerryP]

And in a different situation, I don't have a spare manual trans bellhousing.  I use the front half of a gutted C6.

[dozz302]

Well I never thought about that flex. But with no real load to speak of other than turning the engine over do you think it it would in any manner bend, get tweeked, etc. the flexplate? I do have a flywheel but didn't want to change for no reason. That flexplate is original to the engine and wouldn't want to hurt in any fashon. I could even bolt a converter to it. I think it would fit in the bell?

[MeanGene]

If I was going to use the flexplate again, I would add the converter. I will try to take a pic of mine later, it was pretty chewed up

[dozz302]

Oh,wow. Are you saying (you definitely noted) that the gear was fine before then after chewed up? Picture would be great.
Heo, who posted the video said no problem. I wonder if he looked closely at the ring gear to see any abnormal wear. Also how many times was his started. I will probally be starting mine many many times. Starting once or twice may be OK but 20 or 30 times maybe not?

[Heo]

Well i started it two times, one to brake in the cam one to make the video.
And as you hear it starts on first compression. Did it both times as i primed the floatbowls
before first start up so not much risk to chew up the ring gear

[shady]

I did it with a 63 cast bell and a auto flex plate with a bendix starter. Both 153 tooth. Started the engine 5 or 6 times with no funny sounds or problems. To chew up the ring gear, it would have to be making some awful sounds. In my mind (small) having a converter hanging on the flex plate without the support of the tranny input shaft would distort the FP somewhat. You always could borrow a manual flywheel and use it.

[pbf777]

I was just wondering if there was any reason why I couldn't use an automatic flex plate......... to fire up an engine on the engine stand.

You just have to be careful as it will rap real quick with a stout engine,

     True, but it really is better for the survivability to have a greater mass attached to the crankshaft flange for the reason of dampening the oscillations of acceleration & decelerations due to the intermittent firing pulses thereby lessening the crankshaft twisting and whip  (bending  ) effect. 

If I was going to use the flexplate again, I would add the converter.

     Remember the flex-plate is reliant on being attached to the torque-converter to not only in many instances to square it up, but also to support the flex-plate from deflecting/bending under the torsional load when the cranking force is applied by the starter motor.

     And I'm not sure in what fashion you mean as far as adding the converter, but it would require, if the converter is a complete unit, to properly support the snout/pump end and the internals or you'll really have some "shakin' goin on"   

     Scott.