roller cam block

Discussion in '1974 - 1978 Mustang II Talk & Tech' started by dmoody, Dec 2, 2003.

  1. I'm thinking about getting a roller cam 302 short block, however if I went this route... do I simply bolt my original flywheel and harmonic balancer to the new block... I know small blocks are externally balanced... would I have to have everything rebalanced with my old flywheel and harmonic balancer and new crank, pistons, block, etc?


  2. To my knowledge the later model roller engines were balanced 50oz instead of the 28 oz that the earlier 302's that came in the II's. I think that they would have to add heavy metal to take a 28oz blanced crank to make it 50oz balance and I heard this might not be a good idea. It might be cheaper and easier to replace the balancer and flywheel with matching 50oz parts. There is nothing wrong with a motor balanced to 50oz. The advantage to having one of the modern roller blocks is that the block already has tapped holes to accept the spider used to hold the roller lifters and could be used for either setup. An old school block and easily be modified for the spider or you can use the roller lifters with the H connectors instead of the spyder, just a little more costly.
  3. HaveII, how come the newer blocks are balanced at 50 oz? What if I were to reuse my old crank, rods, etc.. would this allow me to balance at 28 oz? There is a huge advantage to the newer roller cam block which I failed to mention... the lifter bores are much taller. Using the old block retrofitted with the spyder, you still cannot run the newer roller cams due to the shorter lifter bores. Using the old block, you have to buy those expensive roller lifters ($400) with the crossbars. I can get a used roller lifter block bored, decked and alignhoned for that price.

  4. Can't do it. You have to use the new 50 oz. imbalance crank with it's matching roller block, the 50oz. dampner, and have your flywheel rebalanced. You can buy new automatic flywheels with the proper balance from art carr, or get your manual flywheel rebalanced. i had to get mine done.
  5. You can rebalance it without adding metal to the flywheel. The machine shop drilled holes and took weight out on the opposite side of where you would add metal. Basically the same concept, because they also said adding weight would be a bad idea.
  6. 77CobraII

    Why is it that you have to run 50oz balance in the roller blocks? You are probably right, but I thought that you could use 50oz, 28oz, or even a 0oz balance in any of the blocks just as long as the spinning internals were matched. I looked into upgrading my non-roller block to be drilled and tapped to accept the spyder and planned to run a small solid roller (588 lift which is small in terms of solid roller). None of the places I checked told me I could not use this conversion with my non-roller block. I ended up finding a good deal on a set of used solid rollers with the crossbars, but never got to implement due to lack of budget. Not trying to argue, just trying to learn so next time I open my trap I can be more accurate and understand why. Thanks!
  7. crane cams has a conversion for your block. If I recall correctly, it uses a special lifter, but you can use standard late model 5.0 cams with it. That way you have a wide assortment of sticks to go with. these guys did it one one of their project cars, but you need a subscription to read the rest of it. I would stick to an early block, they seem to be a bit stronger.
  8. You're right...if the flywheel/flexplate, crank, harmonic balancer, and at least one rod/piston are balanced together everything works out fine. The only issue I'd see with using the older crank in a roller block is that the old crank would need machined to work with the one piece rear main seal.

    As for the conversion kits...they are designed for use with the non-roller block.
  9. Your right, I think that the old crank can be machined to work with the one piece rear seal, then you can use and old crank with the II's flexplate/flywheel,
  10. The original question was, if he purchased a roller short block what is needed. As far as my research shows all you need to do is use your original 28oz. flywheel and harmonic balancer and your good to go.
  11. Only part of the balance weight is external. Some of it is in the crank throw counterweights. That's how the engineers originally were able to make the block casting so compact. The later cranks are a lighter casting, so there are differences other than the damper/flywheel. That's why the external weight changed.

    At least one person on the mail list tried this (inadvertantly, I believe) and had a BAD vibration.

    Sleeper, do you have side-by-side comparisons of the 2 cranks? I looked all over the net for a pic, couldn't find one (to check into the turning early rear main seal area to late specs idea.)
  12. If this was myself, I would do it either of two ways ( retain the newer 50oz stuff, crank balancer, and have art carr provide a flexplate/flywheel to work with the engine and II's tranny, the benefit of this is that no machine work would be required, but it would be expensive. OR I think I would go with this route, is to have an older 28oz crank machined to work with the newer one piece seal, this way, once the work is done, standard II parts can be used, such as balancer, flexplate/flywheel. Perhaps it wouldn't be as hard to find parts later on down the road. A side note: somtimes balancing a crank to a differnt balance can be a royal pain, check this out
  13. gimmie a day or so, I think I do, but the ususal computer is packed up for the move, I am on the notebook
  14. I agree this is a good idea for a fresh rebuild, but won't really help in a swap if the engine is sound, as having to disassemble it would kinda kill the whole point of swapping in a good used unit.

    Personally, I think buying the correct flywheel is the better path, since OE flywheels aren't particularly (readily available) anyway, and the cost of the machine work to rework the crank might put a sizeable dent in the cost anyway.
  15. Ask Stang2Man......I don't remember where I got the 50 oz flywheel for my II....but I told them what I had and they sent me a II flywheel with the 50 oz balance welded on. I had the same dilemna, newer 5.0 in a II. But it's cool with the spider plate in there and roller rockers. Problem is that I'm still working around the Gt-40P heads :(
  16. Art Carr
    if anyone else has had a history of installing a GT40P headed 302 in a II, I'd love to hear info from ya. I'm hoping to complete the swap in 98CobraClone's car as well as put the new rack in. Just so long as I can make sure he has the heater gassed up, since it will be the week between christmas and new years