corners

Hello all. First off, I know I can buy a short block all put together (and will probably be better), but I WANT to learn and do it myself. I've been around some people who have built engines, but have never done it myself.

For my soon to be future project, I want to rebuild a 302, then install a cam and heads (and blower). Question I have is, after you take the block down, what machine work is required? Do the cylinders just get honed, or is it recommended to go ahead and put a small bore in it (say 0.030" over). If you do a small bore, will the stock pistons work with bigger rings, or do you need new pistons? Now for the crank. I assume you get the bearing surfaces polished, but when that occurs, do you have to buy different bearings to account for the slightly smaller crank?

If someone can recommend a good rebuild kit that includes everything I need, please let me know.

Anything else I'm missing as far as block prep/machine work goes?

mjr46

when a block is bored .030..you will need larger pistons and rings the same size...boring it will depend on the ridge at the top of the cylinder...a bore gauge will determine tapper and necessity of such action...when the crank is ground usually to.010 under bearings of the same nature are needed labled .010 under..just polishing a crank will be determined by what the journals spec at

5spd GT

Larger bore = new pistons and rings.

You can reuse the stock crankshaft and 5.090" rods.

Do not forget to resize the rods, polish or "cut" the crank, balance the assembly.

Some have the block decked (shaved).

A compotent shop should take care of everything you need.

corners

So, in other words, I won't know if I can get away with a simple hone, or a small bore until I take the block apart. I guess in that case, I should just go ahead and do a small bore. Is there a rebuild kit you'd recommend that has all the gaskets, rings, bearings,and pistonsappropratly sized for a 0.030" bore and a small grind on thecrank?

Oh, and I don't want the deck shaved. I'm going FI and don't want to increase the compression ratio.

BTW, what are your thoughts on a complete shortblock from some of the large auto parts chains (Advanced, Autozone, etc...). I've heard mixed reviews. I know I'd have to swap out the cam they install (no biggie), but would the quality of the build support my 400 whp build? I know the stock 5.0 HO Mustang bottom end is stronger than the block, so I'm not looking for some crazy forged internals or anything.What I don't know is if there is a difference in short blocks between other 302's, like the Ford Exploder, that might offer a weaker bottom end. I would want to make sure I got the correct "mustang" set up.

my77stang

rebuilt engines from autoparts stores are absolute garbage. as a automotive machinist you can take my word on that.

as far as milling / resurfacing / shaving the deck surface of the block, you WANT to do that. not to raise the compression, but to ensure that the sealing surfaces are true ESPECIALLY if you are wanting to increase cylinder pressure by adding any sort of forced induction. typically it would only take a few thousandth's off the surface to get them smooth, and that small of an amount will not affect your compression ratio in any noticable way.

northernautoparts.com has great complete engine kits for great prices, summitracing also has rebuild kits. however, if your wanting to really use forced induction (blower, turbo, supercharger) you should be investing in forged pistons. to be perfectly honest, your probably better buying each part separately.

you can count on .030 pistons and rings, .010 crank and rod/main bearings. you also NEED to be getting ARP rod bolts and have them installed by the machine shop because they have to chamfer the holes and recondition the rods after putting in the new bolts. also, spend 20 bucks on an ARP oil pump driveshaft - its the best 20.00 insurance policy you can buy for your motor.

corners

I kinda had a feeling about the auto store builds, but I just had to ask. Now, I have no personal experience with the limits of a 302, but from the research I've done, the stock internals are stronger than the factory block. So, what would be the point in upgrading the pistons when the block will crack before the pistons will even think about failing? The only reason I see for changing the pistons on a stock block would be if you wanted to change the compression ratio. If my logic is flawed, please let me know. I'm trying to learn all I can before jumping into this project head first.

corners

Ok. Looking on summit, this kit should do the trick (and support my 400 hp goal).

http://store.summitracing.com/partde...p;autoview=sku

It's bored 30 over, and has main and rod bearings undersized by 0.010". However, I assume you buy the kit AFTER your machinist has a chance to do his/her work and let you know how much they had to take out to obtain a fresh surface. Correct?

Am I missing anything? Probably new timing gears and chain. Anything else? What else would you recommend chaning out while I have everything torn apart (water pump)?

my77stang

the order of procedure is

1: block is checked by machine shop so they can tell you what size pistons you need
2: get pistons
3: give pistons, and block to machine shop so they can bore (they cannot bore without actually measuring your exact pistons that are going to be used, as there are always variances.

as far as stock internals, some years came with forged pistons from the factory but most years did not. but, that really doesnt matter because you'll be replacing them with your new .030 pistons anyways..... but the point is a stock assembly is only "stronger than the block" when its the correct year(s).

corners

Thanks for the help.

I was under the impression that the 86-95 5.0's had internals that were stronger than the block. No?

my77stang

your missing the point of the whole deal. the ONLY part of the motor that was ever "stronger" than other years were they pistons themselves in the late 80's. you will be boring your block, which means even if you HAVE the forged stock pistons they will find their new home in the trash can.

so, do you replace a forged piston with a inferior piston - and then add a blower? or do you replace it with an equally strong (or stronger) product?