354 crank-flywheel holes(tap or no tap)

i am getting ready to put in my 354 hemi crank in the block, i plan on using a adapter plat for a chevy trans. can i tap the rear treads on the crank flange 1/2-20 or leave it like it is, i remember the %$%#@#$ i had to take the old bolt out, if i can tap them and make it easier to work on later i would like that, i don't have the adapter kit now, so i don't see how the new automatic flywheel will attache, has anyone been there?

 

Run a tap in them that is the same size as they already are. Your old flywheel bolts may have had lock***e or the equivalent there of on them, that was a common practice in the 50s.

 

the hole have no tread from the factory, you have to get inbetween the block and crank flange with a wrench to hold the nut and unscrew the bolt on flywheel side, not fun when the engine is seized. i heard that people tap the holes and put bolt that tread directly in flange.

 

Get your kit first and see what you need to do it. Don't sieze your engine.

 

the engine was seized when i bought it, i am rebuiling it now, i want to find out now if i can tap the holes, i would like to install the crank tonight

 

If the engine is siezed you will remove it from the car & tear it down so it dosent make any differance how the flywheel is attached to the crank.

 

You can tap the holes for bolts. I've done a few Studebaker cranks this way. Good sharp taps and lots-a-lube.

 

The usual is to run the 1/2-20 tap through it & use whatever modern flywheel/flex plate bolts you'd use on a newer engine. Beats the nuts & bolts OEM set up.

 

thanks, George do you kno if adapter kits come with nut and bolt or bolt to srew into flange, and if i tap them anyway and end up using the nut and bolt option the treads in the flange should not affect anythings?

 

The most common fasteners will be ½-20 cap screws so you will need to tap the holes in the flange, HOWEVER, you should verify this with whomever makes the adapter.
For manual trans, some adapter packages can actually use the original style flywheel and the clipped head bolts...but only some...verify.

Word of caution at this point. Be damned sure that the tap runs perfectly parallel with the crank centerline. Bolts running on some ******* angle will not be able to provide the necessary clamping force and you could have the flywheel/converter in your lap.
I have pics of a simple tapping fixture on my web site.

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Get modern flex plate bolts @ a ****** shop. If you're going to use a 727 the Poster of comment #10 make a good adaptor! Actually if you needed to run the OEM bolt n nut set up you could still install 1/2-20 bolts & nuts if you could find the right head thickness.

 

The bolts come with my adapter kits. They are Grade 8+ and 1/2-20 thread.

 

Tom, are you making a shiverlay adapter? If so, I'll send those stray calls to you instead of ignoring them...

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thanks guy's, i will tap them 1/2-20 for now and when it comes time to get an adapter kit will check with you's.

 

The 1/2-20 Tap trick is the most common modification. Run the Tap and don't look back.


Tim

 

I taped mine1/2 -20 using a hot heads flywheel

 

Never used a flywheel for that before!

 

^^^^ Now that is funny!

 

I havent been able to bring myself to doing that yet. Like yourself, I get calls about them. My part of the conversation is usually "no, sorry" followed by "why would you want one?"

 

Late reply! Had to tap my 331 crank. Couldn't get a wrench behind the flywheel with the Hemi to Ford man adapter plate on

 

One last note...the holes are already the correct diameter to tap 1/2-20. No drilling
required. DO make sure the tap runs straight.