OK I just bought a L98 out of a 1989 GTA a few weeks ago. I really don't know a lot about these engines. I have done some reading and know I have to have the valve guides milled if I use a cam over a .480 lift which will be done(looking at running the 847 cam), but I do have a few questions. My first question has to do with the flywheel(it didn't come with one). I will be putting the engine in a 1971 Nova SS with a M21 4 speed. Can I use a LT1 manual flywheel or does it have to be a L98 flywheel? My next question has to do with the distributor. With the engine being a roller cam and the distributor that I will be using came out of a flat tappet cam engine will I have to change the cam gear to make it work? And my last question is will the LT1 cam work in this engine? From what I have read it will but I want someone that has worked on these engines to conferm this. This is my first roller engine I have ever messed with. I'm used to the gen 1 small blocks but I want the benifits of the roller engine.

Thanks for your help,
LKTNA

 

As far as the flywheel you definitely want to use the L98 flywheel. The M21s were designed for 2 piece rear main seal engines (just like the older SBC motors) and the LT1 and above is a 1 piece rear main. As far as the LT1 heads are concerned I honestly do not know the answer, although personally I would chance it. The LT1 is a whole different animal from the L98 and so many of the components are vastly different. Now as far as the distributor, I would actually get an L98 distributor. Roller camshafts require a special gear on the distributor so that it doesn't tear the other one up. I hope what little info I have can help you out. Good luck.

 

The L98 is also a 1 peice rear main. I didn't know if the LT1 and the L98 were balanced the same or not. For now or at least the rest of this year I am going to use the L98 heads with a little port work and then I will change them out over the winter with an aftermarket set. So I will have to change my cam gear. I thought that I would but wanted to make sure.

 

Yes you need the L98 flywheel. Change the dist gear definately!! I just went through this. The LT1 cam will fit no problem. The dowl pin may need to be ground down a bit though.

 

Thanks. I have been looking for a L98 manual flywheel. Seems they are kind of hard to find. LOL But I have a little bit of time before I will need it. Waiting on heads to come out of machine shop now. I still have my old engine in the car so have to get it out as well. So there is time. LOL

 

Well the L98 never came with a manual in the F-body. I don't know if the Y-ody one would work. You may have to look to the aftermarket, such as centerforce, to find the flywheel that will work for you.

 

I don't think the original poster asked this question but, just in case, LT1 heads will not work on an L98 block without a lot of extra work. There are much simpler ways to get the benefits of improved cylinder heads without the expense and hassle of this conversion.

c

 

i second this!!!!!! worked at COMP for the past 5 years and thats one thing alot of folks dont know is to change the diz gear with the cam. a poly gear would work super and can be had thru COMP. mic your diz shaft and see if they have one. a stock GM diz shaft is .428 oor so and the smallest poly gear they have is a .490. i had one of my cam shop friends cut me a sleeve and it worked like a champ.

as for the flywheel, i had issues. a GM tech friend told me the flywheel is balanced specificlly to that motor. i found this out when i bought an exact stock GM replacement flywheel. dang near rattled my fillings out.

 

OK? So maybe I just need to buy a new balanced assembly with the balancer and flywheel included? I thought the stock HEI dist was a .491 but I could be wrong. I can go with a bronze gear since the car will not be drove all of the time. Mostly just comes out on the weekends to play on a Friday night and back in the shop Sunday night with a trip here and there to work.