230 4 bolt or 8 bolt flywheel

[Loren]

I got two engines recently, one is Plymouth with 4 bolts in the flywheel and one is a Dodge with 8 bolts holes in the crankshaft flange but 4 in the flywheel.

I have truck flywheel with 8 bolt holes but it is really heavy and I would prefer a lighter car type.

If you examine the 8 bolt pattern it is not evenly spaced. This is so the flywheel only fits one way.

Obviously more bolts are better especially since I am taking advantage of the stock flywheel being drilled for a 10 inch clutch.

 

I have machinist friend who has Jig Boring machine ( which is an extremely accurate machine for making drill jigs and other precise parts )

so I am thinking of having him make me a drill jig to drill the extra holes in a flywheel. This way a simple drill press can do the job quick and easy.

The drill jig could also be used to drill the crankshafts as well. You’d have a set of dowel pins to located the original 4 holes.

Anyway my friend is really meticulous so I’ll get an honest opinion if it’s feasable. 

[Dartgame]

To my knowledge the 4 bolt flywheel and cranks are for 218's. Furthermore there is supposed to be an offset on 218 vs 230 flywheels. Not sure why chrysler did that; but an easy way to check would be to install the flywheels on your motor and check the offset.

[Sniper]

2 hours ago, Dartgame said:

Not sure why chrysler did that; but an easy way to check would be to install the flywheels on your motor and check the offset.

 

Assuming we know the offset, I don't.  I seem to recall Don Coatney having this issue and his solution was, well less than optimal, imo.  He had the bellhousing machined to sit the starter deep in.  Not sure why why didn't have the flywheel machined instead, it would have lightened it up a bit too.

 

 

 

[Loren]

The 230 Dodge engine was in a car and running when I first saw it. The owner drove it on a 1900 mile trip and had zero problems.

I got the engine with the flywheel, the bell housing and the starter he used. The only issue is the number of bolts in the flywheel vs the crankshaft.

The shop manual is pretty clear about keeping the bell housing with the engine it was made for. They do tell you how to check it however.

 

The Plymouth 230 engine block is cracked beyond economical repair so I plan on transferring the crank and rods to a 218 engine in my Suburban.

This engine has a 4 bolt crankshaft. So I need to drill both the crank and the flywheel.

[FarmerJon]

When installing my clutch, I measured the 4 bolt 217 flywheel and the 6 bolt 230 flywheel, and can confirm that the 230 flywheel is around .065 deeper. This means that a 217 flywheel would be that much further from the starter drive. It could be fine, but also could cause problems. I chose to harvest a 3rd flywheel from a spare 217, that was in much nicer shape than my original. 

Now, the 217 flywheel on a 230 could be machined deeper, or as others have done, the bellhousing could be machined.

A 230 fw could (in theory) be used on a 217, but a shim would need to be made up to push the ring gear away from the starter.

[Sniper]

Loren, If you are going to machine the crank and the flywheel to make this work Have the machinist tap the holes in the crank so you could use normal bolts instead of that crazy nut and bolt combo.

[Merle Coggins]

It's been my understanding that the 8 hole crank flanges were made to accommodate the Fluid Drive couplings. Generally you'd find them in the 230, and larger, engines. However, the 218 in my truck does have the 8 hole crank, because my truck has a Fluid Drive, with a standard 4 speed spur gear transmission. 

From what I've read, over the years, the 8 hole crank flange is thicker. Probably to accommodate the heavier FD. This added thickness is accounted for in the flywheel mounting flange offset. If you attempt to interchange the 4 bolt and 8 bolt flywheels you may encounter improper starter spacing, as mentioned earlier. It may be wise to do some measuring before going too far down the 're-drill' rabbit hole. 

[greg g]

Another variable, my 56  Plymouth 230 had a six bolt assementric pattern.  Maybe to carry the overdrive?  I used my 4 bolt (lightened) 46 flywheel.  The od I found matched the 56 engine but I chose to use the light 4 bolt flywheel. 18K on the setup, no issues.

[Young Ed]

13 hours ago, greg g said:

Another variable, my 56  Plymouth 230 had a six bolt assementric pattern.  Maybe to carry the overdrive?  I used my 4 bolt (lightened) 46 flywheel.  The od I found matched the 56 engine but I chose to use the light 4 bolt flywheel. 18K on the setup, no issues.

I would guess it was to prepare for the possibility of the powerflyte

[p15-1948]

Tearing a 55 Plymouth 230 down and it has an 8 bolt flywheel and a stick shift behind it.

[greg g]

Assembly line foreman to engine builder " I don't  care what the build card sez, USE THEM TILL THE DAMED BIN IS EMPTY!"  " Are we clear on that? GOOD."9