Jeep Strokers

Russ Pottenger wrote:I guess I'm not understanding the question.

If your machinist is saying you don't have enough wall in your Rod to allow a bushing he is simply wrong.

If you talk to Randy at RaceTec, I'm sure he was under the assumption you are bushing the rod.
Otherwise he would have built you a piston/pin combination allowing you to go the press pin route
utilizing the stock .931 pin.

Last question. Why would you have a custom piston made for the short 242 rod?

BTW, I've done the stock 4.0 with 927 pins with no problems whatsoever.

Russ, thank you for showing interest in helping.

I will try to explain better, the problem is I have very basic knowledge about internal components of engines and while I write and ask am trying to understand.

I ordered custom pistons for the 242 rods because as far as I know these rods are long (6.125"). The 258 rods are shorter (5.875").


When I placed the order thru bulltear, The notes I added to my order were:

I want to build a 4.7L Stroker in Venezuela with following specs:

4.0 Block (53020569) bored to 3.935 (0.60)
Head 0630. (assumed 58cc Combustion Chamber, please confirm)
4.2L Crankshaft.
4.0L connecting rods.
Comp Cams 68-231-4 (Intake Duration= 250, Lobe Separation Angle=111, Advance or retard=4).
Victor Reinz 0.043" Head Gasket.

I want 0.0 deck clearance so I need the pistons to have 1.380 compression height, please confirm this, and the pin compatible with 4.0 connecting rods.

I am pointing to have 9.6 SCR@ 1600 feet. I live in a city where altitude varies from 0 to 3200 feet so I am assuming this SCR will be OK for both. No problem with premium fuel. Any recommendation here is highly appreciated as I am not an expert in engines.

Desired pistons should be (please suggest or correct anything you consider):

Custom forged +0.060" bore pistons, compression height 1.380", dish volume 20cc

The rods I am using are brand new stock, donated by a friend who didn't use it. As I was not the one who bought it, I am suspecting the problem could be wrong rods (as optmaxx mentioned). The cast number is 207, and in the forum FAQ for rods, it says that cast number is for 232 rods. However I did measure the length from center to center and it is 6.125".

FACTS:

I lost the wire locks, and when I wrote to Bulltear and to Racetec, the answer is that I do not need the wire locks because am using stock rods. After this, I took everything to the machinist and he tells me that either I need the wire locks or I need to bushing because The problem is that the pin goes inside the rod and inside the piston tight but with no need of press.

When I look at the specs page from Racetec, they say the pin diameter is 0.927" and then optmaxx tells me that the stock pins for 242 rods are 0.931. So, something is not ok here, may be the rods, may be the pin diameter.

I contacted Randy, and he says I have to buy stock pins and open the hole in the pistons for correct clearance. I am guessing he is looking at the specs of the order (i gave him the order number).

So, at this point I am not sure where is the problem. I took back to the machinist all to take measures, Hopefully we will have an answer tomorrow and will know where is the problem. I do hope the rods are the problem.

I attached a picture of the Racetec specs page and the rods am using in the previous page of this thread. Please take a look.

Thanks,

Leonardo.

Yeah, mine says .927 also. I talked to my machinist and asked if he had any issues when installing the pin and he said no. He said that he used heat and installed them by hand, but once they cooled they locked themselves into place. I tried moving mine by hand again to make sure, but they don't move no matter how hard I try. I hope you find a solution lcolina.

Thank you my friend, I really hope that too

Leonardo,

Randy has givin you the easiest solution to your problem if you want to do a press fit pin in your rod.
If your willing to buy a replacement set of stock diameter .931 pins, your machinist can hone your
piston pin bore to the correct clearance of the new pin. I'm guessing between .0006 to .0008

Your other choice would be to bush your rods for a floating pin and acquire the necessary locks.

Russ

Guys, finally I got an answer from the machinist. The problem is in the rods. He told me that the rods are for 242 but were honed for some reason, may be to use some bushings (we will never know). They are supposed to be brand new, that's why my first suspect were the pins-

He checked with other 242 rods and everything is ok. I will be buying some rods.

I apologise for not checking this first and appreciate your help. Will be posting for sure the next results.

Just an update guys. Finally will turn on the engine on Saturday. Waiting for an o-ring for the FPR. Will update the configuration tomorrow.

Thanks all for your help.

Sexy!