New Here, 347 Block Question!

Hi everyone,

Im new on here, but have been a subscriber for a few years!

I am in the UK and planning on building a 347 for my 93' Fox GT.

Which block is the strongest for a nitrous/supercharged application?

I have a stock roller 5.0 and a stock 70's 302.

Are all parts interchangeable between these two blocks? How do I convert the 70's block to roller cam?

Any help is greatly appreciated!

Thanks,

Tom

IMO, there's little difference between the 2 in strength. The roller block is a much better block to build and converting the older one to roller is a hassle and can get expensive, because of the cam base circles. Go with the roller. The heads and some of the exterior parts may interchange. You won't use the crank, rods or pistons from either. The cam, lifters, pushrods,waterpump, and timing chain cover are most likely not interchangeable. The heads are about all you might want to use off the 70's, to get higher compression, (depending on what you have), but going supercharged that may not be the best thing.

The early blocks are generally considered stronger then the later roller blocks. If you're planning of stroking and using a power adder I'd go for the early block. Bepending on the sort of power you plan on making, it might be a good plan to start with an aftermarket block.
A set of drop-in linked lifters will allow you to use any standard base circle roller cam in your early block. The linked lifters are expensive, but imo the only way to go when using an early block.

I think which to choose depends on the year of the early block. While the early blocks are stronger, I've read alot about the mid-late 70's blocks experiencing core shift, and generally just not being a good block to build upon. I don't know if this has been dispelled or not, but I think it would be something to look into. That being said, the later roller block would be much easier (and cheaper) to go roller with.

there are the mexican blocks which are cast thicker in crucial areas. That being said Ive never seen one and im from california, so they could be very hard to find/ship to Europe. Ive heard about 450-500 HP is the limit for stock blocks, so if you are expecting more than that, get an aftermarket block from dart, world products, or Ford Racing.

Early blocks are cast just as thick in the crucial areas as Mexican blocks. I've had a '72 mexican block and a '79 302 block side by side. They weighed exactly the same (10lbs more then a 5.0 block) and they both have more material between the main bearings and cam bearings then a 5.0 block. Plus blind bolt holes for the cylinderheads. The mexicans do have the heavy duty main bearing caps, like the 289 HiPo.

As for roller blocks being easier for roller cams, what so difficult about dropping a set of linked lifters in your early block?

Originally Posted by Neverunning67

I think which to choose depends on the year of the early block. While the early blocks are stronger, I've read alot about the mid-late 70's blocks experiencing core shift, and generally just not being a good block to build upon. I don't know if this has been dispelled or not, but I think it would be something to look into. That being said, the later roller block would be much easier (and cheaper) to go roller with.

Whether to use an early or late model block is up for debate, but here are a few of my thoughts on the matter: The early blocks from 67 to the early 70's are considered strong, desireable blocks. From 1975 to 1984 the blocks suffered core shift, were prone to cracking, and were generaly uglier castings, and are pretty much agreed on by most builders as the blocks to avoid. I think the later model blocks have been given a bad rap because of this. In late 1984, with the roller blocks, the casting techniques and quality improved dramatically in every respect. The newer blocks ARE thinner, but with better casting techniques, are veiwed by some to be as strong or stronger than the early blocks.The 5.0 has been proven as a reliable platform for high performance engines. Thinner = lighter=faster. It's already a roller. It has the new, improved one-piece rear main seal. Finally, of all the things that can go wrong in an engine, the block is way down the list. You can pretty much count on a failure of the valvetrain, rods, mains, pistons, or bearings over a block problem.