Measurement and Block Prep.
Block spec. recap
-F23A1 block and rotating assembly with approx. 60k mi. on it
-K20A3 Pistons installed in reverse (for pin offset)
-Kaizenspeed balance shaft eliminator kit installed
-deck resurfaced at Doug's machine shop in Cayce, SC
-cylinders honed with a "Flex-hone" in my garage
-H23A1 head studs from ARP fitted
Any time engine parts are swapped around, especially heads and camshafts and pistons- all at the same time it's good practice to check that no one part is going to collide catastrophically with any other part when the engine is started for the first time. I've seen at least one build very similar to this one run without issue, but the pistons and camshaft were different. On top of that I like to check things for myself and take measurements. So, before the head goes on for the last time (before it runs... there may be a ported head in the plans for future upgrades...) I'll be playing with a little modeling clay.
The process I'm using is commonly referred to as "claying" an engine. The purpose of this is to confirm adequate clearance between the valves and the tops of the pistons as they go through their respective motions. (The camshaft has been degreed in already as required prior to claying. I may discuss this process in a later post) To start I place four small nuggets of clay, one at each valve position and give each a light coating of oil to keep them from sticking to the valves instead of the piston tops. Then the head is installed with an old head gasket and snugged up. The timing belt goes on once the crank and cam are in time. I use the procedure from the service manual for installing and tensioning the belt to ensure conditions are the same as when the engine is first started. Finally, two full rotations plus a little extra to be sure... take the valve train and pistons through their full four strokes.
Time to pull the head off and see what the results are.
Notice I've cut away some of the clay near the center where the clearance should be the lowest and easiest to read/measure. I measure a touch over 4mm on the intake side and don't even bother with the exhaust side when I see that only one lump of clay was "grazed." Easily leaving me with 6mm or more on the exhaust side. These are massive clearances in terms of acceptable limits. No worries. On with the Assembly!
With the block clean, willing and ready and a few coats of copper gasket spray on the MLS gasket I work it down over the studs. This isn't as easy as it seems it should be if you don't keep the gasket parallel to the deck surface. Any sort of tilt with an MLS gasket going down over studs and it will snag and hang up. Determined, I got it in place without mishap.
Speaking of the oil feel through the block to the head- if you have been following the project for a while, or you just know your hondas well you'll recall that the block was originally fitted with a VTEC head which requires more oil supply to the head (where the mechanism is) than those without it. However I am using a non-VTEC head so this oil feed needs to be reduced back to "normal" as if this were an original, non-VTEC block. Fortunately for me honda made this, the last version of the FWD F-series in a non-VTEC variant. Therefore a "oil control orifice" could be ordered directly from the dealer (or in my case, an online discount honda and acura parts dealer). It even came fitted with required o-ring.
It slides in easily to the oil feed port in the block, adjacent to the "rear" central head stud/bolt hole with the threaded side up for easy removal if ever required. Likely the smallest part of the engine after the valve keepers but paradoxically hugely important to the engine.
The F22A4 Head
Specs on the head if you missed them:
-Remanufactured unit from NWCylinderheads on eBay
-Swapped in some "heavy duty" valve springs and Ti retainers from F22parts.com (no longer in business it seems)
-Had the camshaft reground at Delta Camshafts to their "272" street/strip profile
I did do a little cutting on the head before dropping it on. One more thing to do to make the head a perfect fit for the block it was not really designed for is to open up the chamber diameter from 85mm (the stock bore of the F22A4 that the head normally fits up to) to 86mm to match the bore of the 2.3l block. Again a seemingly small difference that I think will have a big effect. In removing this material I am able to de-shroud the valves which helps the engine to breathe the best it can. I also remove the sharp-edged rim which could, potentially become a hot spot and therefore source of detonation. In an engine with a static compression ratio of 11.1:1 anything that can be done to keep detonation at bay is a must.
It wasn't difficult to do but it was a little nerve racking. The results of one bad slip could fall anywhere between difficult and impossible on the continuum of repair. I first positioned the gasket on the head using the two hollow dowels that keep it all aligned on top of the block. Then I traced the bore openings of the gasket onto the head surface with a fine point permanent marker. With the gasket removed I followed up with two layers of masking tape everywhere I didn't want to make cuts or throw metal chips. Slow and steady work with a small oval "aluminum cut" or "single cut" carbide burr fitted to my Dremel got it done without much trouble. I gave one final wipe down before putting the lid on the pot(s). I brushed a little of the ARP moly lube supplied with the studs on the threads and the top of the washer then torqued to spec.
That's it for the major stuff. Next up is all of the various items that bolt to the engine. I'll leave you with this as a teaser for things to come:
Hope you're enjoying it at least half as much as I am!
-Mark
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