Project Defiant1: KA24DE Build-Part 2


While the proper way to check this clearance is again, with a bore gauge and micrometer, there is another way! At 72 degrees Fahrenheit and using a feeler gauge, JE Pistons recommends measuring .500″ above the bottom of the piston skirt and have a clearance of .004″ for the 244514 shelf piston set. If you use different pistons or measure at a different temperature, your measurements WILL vary! Again, the NAPA guys didn't disappoint as the measurement was spot on!

Project Defiant1
Yes, a feeler gauge can be used to measure for piston to bore clearance, if used properly!

I then move on to checking deck straightness and this is far more important when using a Multi-Layer Steel head-gasket like the Cosworth gasket I am going to be using! If must be flat or it will never seal properly and eliminate the advantage of the MLS gasket or could let coolant escape into the cylinders, which is NEVER GOOD. I have no real tricks to avoid using a specialized tool here.

Project Defiant1
That specialized tool is the Machinst Rule, also known as a “Ground Bar.” It is ground true, flat, and should be the only tool you use to check straightness!
Project Defiant1
Check across the head, both ways!
Project Defiant1
Also check across the front, rear, intake, and exhaust side of the deck. It must be straight within .001″!

After making sure the block is ready for its duty, you now set the ring gap and doing so will vary with your application and ring set. With my JE Pistons supplied JG1004-3524 Ring Set I did have to gap my rings more than they had come. This is because I am setting this engine up for turbocharging! Using their formula, my ring gaps were .017″ for my Top Ring, .019″ for my Second Ring, and all Oil Rings are set to .015″.

Project Defiant1
Yes, you use a feeler gauge to check the ring gaps. You place the ring in the bore, use your piston to straighten the rings out, then insert the feeler gauge in the gap. If it's too small, take a small amount off. DO NOT TAKE OFF MORE THAN YOU NEED! If you do, order new rings.

Once everything is set, it's only a matter of installing the pistons, torque down the rod bolts, and have a drink! That's all I can do for now, but next up will be the head! Here the Jim Wolf Technology C78 camshafts (aka the BIG ONES!1!11), VQ35HR Valve Buckets, and JWTCam Sprockets will be installed along with some minor head-work. I'm serious about the minor part, as while this still a BUDGET BUILD, the valve sealing and head straightness must be checked and/or repaired. So, the next article will be about the tear down and packing the head and detailing theJim Wolf Technology Valve Spring Compressor!

See y'all then!

Thanks to these supporting companies of Project Defiant1! Look for articles on these parts very soon!

Jim Wolf Technology

JE Pistons


ACT Clutch

RC Engineering

Defiant1 Articles

Project Defiant1 – The Concept

Project Defiant1 – KA24DE Build Part 1


Leave a Reply

Your email address will not be published. Required fields are marked *