Inliners International Forums General Discussion Engines Need GMC 302 flywheel help

I'm trying to install a 302 in my 51 GMC 1-ton and have a problem with the flywheel. I can't use the bellhousing that came with the 302 because it mates to a Clark 5 speed and my truck has the SM420. My 228 bell housing won't accept the thicker 302 pressure plate even when I try the washer trick. I can't use my 228 pressure plate on the the 302 flywheel because the flywheel has a raised lip where the PP bolts go, such that my 228 pressure plate would be held too far away from the flywheel to engage. I can't use the 228 4 bolt flywheel on the 6 bolt 302 flange.

My question is, can I have the ~1/2" lip machined off of the 302 flywheel and then use my 228 pressure plate?

Hi Sidehill...I should have an answer for you but I don't seem to remember the type of flywheel you describe for the 302..The four bolt flange on the 228 doesn't ring a bell but it sounds like you need a later 270 or so setup..Just can't remember the four bolt ..Maybe a Jimmy man out there can describe when the four bolt flange was used....Al...

[This message has been edited by inlineidiot (edited 10-04-2003).]

[QUOTE]Originally posted by Sidehill:
Sidehill. I'm sure you can machine off the lip from the flywheel, just so the bolt holes line up w/ your 228 clutch. The bolt holes are perhaps for a stronger and bigger clutch that the 228 clutch, which I believe is a 10 incher? With all the power you will be making with that 302, perhaps it would be better to go with an 11" clutch anyway.

Do you think the 228 clutch would be strong enough?

Perhaps there was a dual disc clutch w/ the Clark transmission?

Another option would be to get a 270 or 302 flywheel from a wrecking yard. I have seen several just laying around because no one knows what they are and they don't fit anything else.

Ed

Ed

I'm having second thoughts about using the 302 clutch. I understand that that it may have originally used a hydraulic clutch so I'm wondering if my manual linkage, or my leg, will be strong enough for the beefy pressure plate. I asked a guy at an auto machine shop about milling off the ridge on my 302 flywheel but he was concerned that the FW face on the 302 might be at a different depth, or distance from the motor, than my 228 flywheel such that my linkage wouldn't work. I guess I need to do some measuring. However, I'm thinking that the 248 or 270 flywheel is the way to go since you and others think it should work.


Sixpack from the SB forums replied to my query:

First is to find a late 248 (54 or 55/1st) flywheel with the 6-bolt crank bolt pattern. This flywheel uses the smaller clutch, which will work fine on a 302. You don't need the big 11" truck clutch used on the heavy trucks that came with 302s. You might have to swap ring gears to work with the 228 starter. A 55-62 270 flywheel will also work, if from a pickup. It will have the same small clutch pattern.

Now the trick is to find one.

Sixpack be me...on my Inliners membership soapbox. The web is great for exchange of information, but for finding obscure stuff like GMC flywheels, you can't beat the network of contacts available to club members - most of whom aren't online and probably have this stuff stashed in their garages.

There are some serious GMC guys in the Denver area - Joe Umphenour, the Mitchells, Bob Corbett to name a few. I'd be real surprised if one of these guys didn't have a flywheel that will work for you, or know somebody that does. Most Inliners, especially the sub-cult of GMC freaks, operate on the principle of "What goes around, comes around". There's a lot of swapping parts, stories, tech info, (and lies, too) going on and it's win/win for everybody.

This web site is our way of sharing some of the vast amount of experience and resources in our membership base. If we can pick up a few new members along the way, that's great! So if you're already a member, check your roster and make a few phone calls. If you're not a member, it will be the best $24 you ever spent.