[JT87NA]

Just wondering how the cylinder bores look...I had 60 psi in the third cylinder so I pulled the engine. To me they look pretty good, still have the cross hatching.

Third Cylinder

 

[supraboostin]

they look good to me

 

[toyota_supra_1988]

yeah they look alright

 

[QWIKSTRIKE]

Get that thing together. Make sure all psitons are in great shape and tune the engine to avoid detonation. Looking good....

 

[JT87NA]

Get that thing together. Make sure all psitons are in great shape and tune the engine to avoid detonation. Looking good....

Yup, I really need to get going on this if I want to make the Englishtown meet, I still need to figure out how much was taken off the head and block so I know what size MHG I need. Later.

 

[mullenc525]

how did the headgasket look when you disassembled it? Might want to look there for your bad compression...

 

[Faded87T]

You don't need to know how much was taken off the deck. You only need to know how much the pistons sit below or above the deck. With variations in bearings, piston pin heights, rods, cranks, etc., etc. etc. every engine will be different. So it doesn't matter what the total deck height of the block was or what it is now, it only matters what the deck height is relative to the piston at TDC.

You don't need to know how much was taken off the head either. Every engine will have slightly different characteristics (i.e., the valves will sit further in or out depending on the valve job, porting, casting differences from the factory, etc., etc.). Just like the the bottom end, every head will be different, so it doesn't matter where you started out in total, it only matters where you are. And you can only properly determine that by CC'ing the head.

Once you know how much the pistons sit in or out of the bore, and you've CC'd the head - you can calculate the HG you need to obtain proper squish.

Dale H
87T

 

[NegativeGeForce]

You don't need to know how much was taken off the deck. You only need to know how much the pistons sit below or above the deck. With variations in bearings, piston pin heights, rods, cranks, etc., etc. etc. every engine will be different. So it doesn't matter what the total deck height of the block was or what it is now, it only matters what the deck height is relative to the piston at TDC.

You don't need to know how much was taken off the head either. Every engine will have slightly different characteristics (i.e., the valves will sit further in or out depending on the valve job, porting, casting differences from the factory, etc., etc.). Just like the the bottom end, every head will be different, so it doesn't matter where you started out in total, it only matters where you are. And you can only properly determine that by CC'ing the head.

Once you know how much the pistons sit in or out of the bore, and you've CC'd the head - you can calculate the HG you need to obtain proper squish.

Dale H
87T

good points :bigthumb:

 

[cnewingham]

lmk if you want to replace the pistons and rings. I can get ITM pistons and Chromoly rings for $200. ITM makes a lot of parts for OEM suppliers.

 

[stroked_7m]

you can still see hone marks so its probably fine. Have you checked your ring gap?

 

[sponsored1]

You can't really tell if they are allright unless you can feel the roughness of the bore. You can completely wash down the cylinder walls, and you will still see hone marks. You need to check the roughness. If they walls are too smooth, they new rings will not seat, and you will have massive blowby.

 

[turbotoy]

No one can tell you if they are OK from lookin at pictures, you need to measure the bores and check against the specs in the TSRM. Likely, there will be excessive taper. In any case, a deglaze will always be required before installing new rings.

 

[JT87NA]

No one can tell you if they are OK from lookin at pictures, you need to measure the bores and check against the specs in the TSRM. Likely, there will be excessive taper. In any case, a deglaze will always be required before installing new rings.

Even after just 20k there will be excessive taper? I will be taking the head and block to a machine shop so they can both be lapped for a MHG. If the bores are out of round then I can have the shop bore them out. If they are all good can I just hone the cylinders myself? Will honing deglaze? Thanks and sorry for all the questions.

 

[sponsored1]

Even after just 20k there will be excessive taper? I will be taking the head and block to a machine shop so they can both be lapped for a MHG. If the bores are out of round then I can have the shop bore them out. If they are all good can I just hone the cylinders myself? Will honing deglaze? Thanks and sorry for all the questions.

There probably wont be excessive taper with only 20k miles, unless the machining was not done correctly the first time. It is pointless to measure the cylinders anyway without a torque plate bolted onto the block. And if you had the block originally bored/honed without a torque plate, chances are the cylinders wont be round and they will be smaller at the top of the bore, and bowed in the center. All measurements on cylinders should be made with a torque plate bolted on with the fasteners that will be used on the motor, and with the main caps torqued in place, also with the fasteners that will be used in the motor.

 

[JT87NA]

Thanks for all the info guys, I will take it to a reputable machine shop and see how everything goes. Later.