428 CJ and SCJ

I would not be penny wise and dollar foolish. I would not try a short cut route. If it were my engine I would want all the parts to be the same in a set regardless of CJ or SCJ pistons -C6 or C7 rods and then I would balance the assembly. I always balance the engine if i have a chance. Just my advice. Bob

 

I think there are some other rotating parts that need to be included in the balancing. Make everything match or you may destroy a good block and have to start over.

 

This is not something to mess with. Get four more SCJ rods, make sure you have a set of eight matched pistons, get it all balanced, and you'll be much better off.

A few years back I saw a 70 SCJ, pretty nice car, original engine, but there was a little something "off" about the way it ran. Eventually, the engine was examined more closely, and although the rods were a matched, correct set, they were swapped around, i.e., the rod stamped "1" was in the #5 bore, etc. The engine was taken apart, minor work done, and assembled with the rods in the matching bores. Ran very smooth after that.

 

The pistons are the same for the CJ/SCJ but the rods are different as you said. However the cranks were actually different and they used a different balancer and the hatchet counter weight. So you need see if you have the counter weight and then take a good look at your crank. People did a lot of mixing parts... Go to the 428 forums, it shows the difference in cranks.

If it turns out you have a SCJ crank then all you should need is 4 more SCJ rods.

Good luck.

 

Cobra427,I hate to disagree with you but there was one part number piston that was marked "428" and at least one other different part number piston that was marked "Super". I believe they were different weights. Probably the reason they were marked different . If you mix them up you will most likely end up with a imbalance situation. Bob

 

It appears that Ford went through at least three piston designs during the 428 CJ and SCJ production run to address durability problems. The later piston, which appears starting around December 1968, is marked "428" and "SUPER" (thanks to Randy Pollock for the picture), and differs from the earlier pistons by having additional metal in the pin boss area. The "SUPER" mark does NOT mean that the pistons were used only in SCJs! Though different part numbers were used for standard sized CJ and SCJ pistons (perhaps to provide slightly different installation tolerances), most folks that I've talked to believe that the pistons were in fact identical.

You can't mix parts, you need to find out what crank and balancer you have and get the right rods to go with the crank. If you like once you have the pistons off the rods, weight them and balance to ensure they are within standards, (pistons are not the problem), the mixed rod are, you just need to find out which 4 are right for your crank.

Gary

 

Gary ,as your statement that you copied from the Cobra Jet forum site indicates -it is not for sure if the weight is the same. It is logical to assume that a modification in design (different engineering number) may very well effect (mass)weight. It doesn't take much. It is best to error on the side of caution in this instance . The pistons are just ONE facet of the big picture. My advice has always been to balance the assembly which would include the pistons. I think we are on the same page with the rest of your last post . I would want everything to match weight wise. I have seen a number of engines that had vibration because they mixed CJ and SCJ parts. You should have one or the other not a mixer in most cases. Enough engines to know that with the mixed up parts that the poster claims he has - that may well be the culprit and getting that sorted out is the first order of business. This is of course is just my opinion based on my own experience given in a positive way and you or the author of this thread don't have to take it. Bob

 

Bob, No problem, I think by now that the poster knows what his problem is. I just wanted to make sure that he changed the right rods, and to know which ones to change you have to look at the crank to ensure you change the right rods. Just changing the pistons will not fix his problem. But like I said before, once you have the pistons out I would weight them to ensure they are in specs before I would reuse them.

I know a guy that wanted to up-grade his 428 CJ to a 428 SCJ he put the Lemans rods in and has never got the engine to run right.

 

Well it looks like you found your problem. I wouldn't be so sure that Ford put the Lemans rods in your engine, but you never know, unless you are the original owner, and the car was never taken back to Ford for any work.

Lemans rods are easy to find, just have your machine shop check them out before you install them, they are now over 40 years old and you don't know there history. I have heard there were two different type of Lemans rods, one with different cap screws, so be sure you get the correct ones.

Gary

 

I am sure that you can buy a after market set of rods/bolts that are as durable if not more so then the stock Le mans rods . Back in the day the drag racers pitched the Le mans rods for the lighter CJ rods so that the engines would rev faster. I would venture to say when comparing the cost of reconditioning as well as initial price of the various replacement rods and pistons that you would be better off with a set of new good after market forged pistons and after market rods/bolts. You also wouldn't have the hassle of rounding the used parts up. Sell the old parts to some deserving soul to off set the expense. That is what I would do if it were my engine. For what ever it is worth. Bob