Checking cylinders

[GotaT]

I have a 2.4 that I am donig a Top end job on. I have looked into the cylinder walls and they look decent... I am thinking I will be able to hone them out and re ring with no problems.

After talking w/ Pelican they mentioned they sell 2 different size ring sets. One is apparently an oversized set. I am wondering what is the correct way to take measurement of the cylinders to verify which set to order?

I have read many many posts... but not come up w/ the exact answer.
Thanks in advance!

Mitch

[Bobboloo]

The cylinders need to be measured at several places for ovality and wear limit.

They should to be measured at the top and the bottom of the stroke to determine ovality. If your looking at the top of the piston from the side of the motor imagine north-south and east-west axis points. This is where you measure at the top and bottom of the ring stroke. If the difference between north-south and east-west is greater than .04mm then the cylinders are oval. These points are a and b in the factory manual. The top and bottom of the stroke are D1 and D2.

To measure wear limit measure 2-3mm below the top of the cylinder (D1 top of stroke). If the measurement is .1mm beyond the original spec then the cylinders are beyond the wear limit.

The measuring points are illustrated in the factory manuals as well as Wayne rebuild book.

[GotaT]

Thanks for the info.. Should help me get started.

[euro911sc]

You will need a dial bore gage with decent resolution to make the proper measurement. Also, apparently this is not an easy tool to use... I'm about to find out soon

c this thread:

Dial Bore Gauge Graduation and Range?

-michael

[tom1394racing]

I am using a dial bore gage that I bought from Eastwood.

http://www.eastwoodco.com/jump.jsp?itemID=11109&itemType=PRODUCT

I have found it to be very easy to use and repeatable for both cylinder bores and crankcase bores.

[CBRacerX]

Thanks Tom, I bought one of these last night, so look for your comission check in the mail

I also ended up buying a few more items that I "needed", so the total bill was almost $200. Be sure you get your % on that...

A cylinder measurement procedure that I think you might like reading can be found here Another 3.6->3.8 Rebuild Thread...

[euro911sc]

Tom-

Whats the resolution on that piece and who is the mfgr? Doesn't say on the web site.

Thanks,

-Michael

[tom1394racing]

The dial gage is graduated to .0005".
I've found it to be repeatable to within .0002 to .0003".
There is no indication of the manufacturer on the box or the gage.
This size range also works well for checking the big end ID on 911 connecting rods.

I've found every tool I've bought from Eastwood to be good quality.

[snowman]

You can also use a $20 snap guage plus a $10 micrometer to do the job. Much more difficult, but just as accurate. I don't recommend this solution, but you should know its there.