I'm in the planning process for a stroker. I have a 4 bolt main block that I'm getting prepped at the machine shop next week and want to be sure I understand the process. The block has already been bored and clearanced for 6.00" rods and has O rings installed that were for a blower application and has very low miles since it was set up for a stroker. Before I even buy the rotating assembly I'm going to have the block checked for align bore and squareness as well as have the block hot tanked and magnafluxed. Once I know where the block is at I'm going to order a forged rotating assembly with appropriate pistons and rings. I'm then going to deliver the rotating assembly to the machine shop for balancing. I'll then have the machine shop torque plate hone the block for the appropriate piston to wall clearance and ensure that the hone finish is appropriate for the rings once I choose what type. I'll also have the machine shop ensure that there isn't any clearancing problems with the rotating assembly.

I'm going to go with a higher end I-Beam rod and I'm hoping to go with off the shelf pistons, but if I understand correctly I can't make that decision until I know where I'm at with the block. Most of the pistons that I've looked at seem to have a compression height that works out perfectly to a zero decked 9.00 smallblock. I'm shooting for a SCR between 11.8 - 12.0 to one and a DCR between 7.8 and 8.3. I'd like to have a quench around .040.

I'm going to go with my stock ported LT1 castings that I have on my car right now. My heads are relatively fresh and I don't expect that they'll need to be milled, but again I'll check before final assembly.

I'm planning on doing the assembly myself. I've got a decent Dial Indicator with a magnetic stand and a set of outside micrometers in the 1.0 - 6.0 range with standards. I'm also planning on buying a bore guage cause I like to have tools and I'm expecting that this won't be the last block that I rebuild. This is my first bottom end rebuild and I really wan't the experience. I've been doing alot of reading and research and will do more. Does it sound like I've got at least the basics covered. Sorry for the long post, but I wan't to gather as much information as I can.

Thanks.

 

It sounds like you have a good handle on this. As you posted, most off the shelf pistons are designed for a 9.000" deck height and a gasket with ~0.040" compressed thickness. So, as long as you are having block work done, a 9.000" deck height makes sense. Most people like flat top (or dished) pistons to get the desired static CR, so you may need to have your heads milled to get that 12:1 CR. But you already seem tuned in to the fact that it's really DCR that counts. So, don't have your heads milled until all the other dimensions are set. This will allow you to calculate the combustion chamber size needed to achieve the desired CR.

Rich Krause

 

What is meant by 'deck height'?

 

Deck height is the distance from the crank centerline to the block deck at a perfect 45* angle. I've also seen deck height refer to the distance that the top of the piston is from the deck surface. A zero deck would mean the flat portion of the piston, (used for quench), is exactly even with the deck surface. I believe from the factory that our deck height spec is 9.025, which means that the top of most pistons would be at least .025 below the deck. surface.

 

Yes, the terminology is confusing. That's a good explanation. I sometimes use "block deck height" or just "x.xxx deck" to refer to the distance from the crank centerline to the block deck and "piston deck" to refer to the distance that the top of the piston is from the deck to avoid confusion. But others use different terms.

The distance between the center line of the wrist pin bore is referred to as the "compression height". This dimension plus the rod length plus 1/2 the crank stroke minus the block deck height gives you the piston deck. It can be negative (piston down in the hole), zero, or positive (flat part of piston crown is above the deck). The piston deck plus the gasket thickness is the "quench". Most engine builders want a quench of 0.035-0.045" for efficient combustion. As you said, a stock rod/piston/crank gives ~-0.025" piston deck. With a stock gasket (0.049") this gives a quench of 0.074" and the stock LT1 seems to work fine with that. So, it may be that a quench of 0.035-0.045" really isn't that important. I don't know the quench on a stock LS1.

Rich Krause