Engine verification

[tahart]

I have a 70 GT500 drag pack. It now has the smaller crank pulley, so at least the original 428SCJ crank and lemans rods have been removed. I'm hoping somewhere along the path, someone just rebuilt the engine and replaced the rods and crank and pulley to shed that weight. Maybe the rest is still original. I've read that the only difference between a 428CJ and 428SCJ are the rods, crank, and pulley. I'd like to restore the engine to a 428SCJ if the rest of it is original. How do I go about determining if the rest of the engine is original? Where do I look? What am I looking for?

The car does have the oil cooler in front of the radiator support.

[Coralsnake]

I dont think the pulley being replaced is indicative of internal engine components being replaced

The only way you will be able to tell what you have is a complete tear down and evaluation.

Is the SCJ counter weight (hatchet) on the front?

Have you had the oil pan off?

What heads are on the block?

[Bob Gaines]

I have a 70 GT500 drag pack. It now has the smaller crank pulley, so at least the original 428SCJ crank and lemans rods have been removed. I'm hoping somewhere along the path, someone just rebuilt the engine and replaced the rods and crank and pulley to shed that weight. Maybe the rest is still original. I've read that the only difference between a 428CJ and 428SCJ are the rods, crank, and pulley. I'd like to restore the engine to a 428SCJ if the rest of it is original. How do I go about determining if the rest of the engine is original? Where do I look? What am I looking for?

The car does have the oil cooler in front of the radiator support.

It sounds like you mean the larger diameter SCJ dampner/harmonic balance since that has a relation with the proper SCJ rods , SCJ crank and SCJ flywheel and or flex plate where as the crank pulley doesn't. The factory SCJ pistons although marked "super" can be made to work in a regular CJ although they are regularly replaced with superior forged after market pistons. The big diameter SCJ balancer also needs the counter weight/hatchet head to mate up . A mixing of these super components with the regular CJ ones will typically cause a vibration because of the imbalance.

[tahart]

Yes, both the counter weight and scj pulley were replaced, which means the scj crank and those heavy rods are gone also. Can't have those without that counter weight and scj pulley. So, I guess I'm asking how do I check to see if the block, heads, etc are original to the car? If they are I might pull that engine and find some scj rotating assembly parts to put it back like it was originally.

[Coralsnake]

Casting dates will give you an approximation.

You will also find a partial serial number on the back of the block. Thats only going to possibly tell about the block.

There is no way to be certain unless you know the entire history of the car

[KR500]

There is no difference between a Super and a CJ outside the reciprocating assembly ( rods, crank. balancer, counterweight flex plate or flywheel. some CJ's have been reported to have come with pistons marked Super ). The block, heads and manifolds are identical. Some earlier Supers may have "Super" stamped in the block.  Check out www.cobrajet.org for info on CJ vs Super. I have one of each at my shop right now.

Rodney

[tahart]

Where do I find any serial number or other identifying numbers to see if it is original?
. KR500 I agree with you. And, other than an attempt to make it as original, it makes no sense to put a heavier rotating assembly back in, given the advancement in alloys and new products. But that's another debate.

I'm just hoping the rest of the engine is original. Where do I look?

[pbf777]

Yes, both the counter weight and scj pulley were replaced, which means the scj crank and those heavy rods are gone also.

    This is not necessarily correct, as the damper in each instance, though are of different masses for harmonic inertial vibration dampening effect, carry no imbalance value, popularly termed as neutral, and the "hatchet" was/is often removed in a balancing effort if only as it is popular to attempt to carry counter-weight internally versus hung out on the crank snout.   

    Not to mention, how may times I've seen were someone just installed the wrong parts for those needing replacement or were missing previously.   

    Meaning................   you really won't know what you've got until you pull the pan and look! 

    Scott.

[Shelbypat]

Hi. If you need a SCJ crank, I can help. I did the opposite on mine. I used an SCJ shortblock and swap it to CJ. I have now just the crank.Rods, damper and hatchet are sold. PM if interested

Patrick
Quebec, Canada

[tahart]

Where do I look on the block for a number to see if it matches the vin? Do the heads have a matching number also?

[Coralsnake]

The information on the Cobra Jet website applies to Shelbys.

There was one stamping on each motor. 1969 Dearborn assembly stamped the blocks (only)

https://www.428cobrajet.org/id-block