Cobra Jet pistons at 4.145 coming soon.............(.015 over)

[CaptCobrajet]

I just ordered a run of Cobra Jet forged replacemant pistons at .015 over.  I got an engine in here for a moderate budget rebuild the other day.  It was a running, standard bore 428.  It bugs me to waste a good block going to .030 on budget pistons, so I am having CP do me a run of custom Bullet forgings (CP's lower budget, high quality line), for those who are rebuilding a good std block that just needs a good hone job.  At 4.145, any running std block should clear up nicely.  They will net 10.0 static at 70 cc's, plenty of valve relief, and sport .980 Pontiac pins so the rods won't need bushed..........only a freshen up hone on the small end.  The pistons, pins, AND RINGS will be $699 plus shipping.  I will have five sets in about four weeks........I only need the one set right now, but I am sure there is a need for a quality piston at .015 over.  These pistons are also MUCH lighter than the OEM were, and much lighter than a .030 Sealed Power forging, with great durability. If you are in need of such, my email is captcj at hughes dot net.

Thanks,

Blair Patrick

[rcodecj]

A friend of mine has a 428 block that has .012 taper on one of the cylinders.
Would a .015 over piston work after machining, or would it have to be bored/honed more?
Thanks.

[CaptCobrajet]

A friend of mine has a 428 block that has .012 taper on one of the cylinders.
Would a .015 over piston work after machining, or would it have to be bored/honed more?
Thanks.

I would say that depends on where the taper is.  If it is big in the bottom, I would bore it .010 from std first.  That would get rid of most of the taper and still leave .005 to straighten it up some.  You would probably get it right for all of the ring travel.  If the taper is in the top, it would be tricky. You could never hone that kind of taper out without making the cylinder alot bigger.....boring a little will straighten it rather than trying to follow what is there.  I think I would rather run a cylinder .002 "big" for the piston if it is only one, and  could get it straight and round.  The seal will be better big than it would be if the cylinder is not round and straight.  Most engines would not know if one hole was a couple of thou big as long as it is a nice, round, straight hole.  I would do that cylinder first and see.  If you wanted to sleeve it, the sleeve will upset the next door neighbors about .002.  If you decided to sleeve the one, you could do that BEFORE honing the ones next to it.  For the sake of durability, I might be inclined to sleeve the one, with no damage behind it, and leave the block as small as possible on the others, rather than going right to .030 with the whole block.  They don't make them anymore, and once you remove that material, it is GONE!

[rcodecj]

It is big in the bottom.
Thanks.