OST-054: 3 rib with snap

[oldeskewltoy]

OST-054's owner is "local" (no shipping). The first head he brought to me, back in early December, had seen an "attempt" at changing the squish pads He had bought the head a few years ago as the one he would build - he wasn't too happy once I showed him the flaw

At this time I'd like to STRONGLY recommend that if you "try" to port a head, and you don't know what you are doing... STOP. In the past 3 years I've bought 3 heads that had to be scrapped because of very poor "attempts"..... that ruined the casting If you are going to try... just make sure that head isn't sold on.......


So my client disassembles his engine to get me his current head... and it too has seen a hand inside it. On this one it wasn't "fatal"..... the roof of the port has seen some "work"... along with a lot of "smoothing" inside the exhaust port.




This type of work (tapering port roof) I try to reserve for ITB equipped heads to try and and match the angle of the ITB adapter. In this case some care was used by the previous "porter" so that this head could be re-used.

disassembled, prior to cleaning





This head has been machined once as well




more to come....

[oldeskewltoy]

what should the head size be if it hasn't been machined before?

116mm


work begins..... #4 on the left...




Oh... as the title states... this is a 3 rib, and my client manage to find a set of high comp TVIS pistons 13103-16030, the same pistons I used in OST-050.



His short block is being built at a local machine shop - with my technical assistance.


more to come.....

[oldeskewltoy]

work begins..... #4 on the left...

Short turns look beautiful.

and #3 and #2




more to come.....

[oldeskewltoy]

Intake side finished... on to the exhaust side and the chambers....


more to come....

[oldeskewltoy]

on to the exhaust side

3 down so far.....




more to come....

[oldeskewltoy]

3 down so far.....

and now the exhaust side is done.....






and from a slightly different perspective...






Next is getting the chambers deshrouded.....




more to come.....

[oldeskewltoy]

Next is getting the chambers deshrouded.....

simple progression photo....





and a little before and after before it gets its 3 angle




more to come...

[oldeskewltoy]

the head is back... briefly... so I can check and set chamber volumes....



Now it is back @ the machine shop about to get .016" taken off to set the chamber volumes @ 35cc. A 35cc chamber, along with the proper squish should net my client a static compression ratio of about 11.0:1.


Mix in a set of Cat cams 252/222 8.5mm lift cams, and this engine should pull (make power) to low/mid 8000s


more to come.....

[oldeskewltoy]

Chambers down to 35cc, ready for re-assembly. Cams are Cat cams 252/222 8.5mm lift.




more to come.....

[oldeskewltoy]

14 of the 16 valves came in too tight for my shim bank (.001" variance from .110"-.125"), so I brought them back to the machine shop to get tipped (shortened) so they would be in my shim banks shim range.



As you can see the valves got tipped by different amounts, from as little as .003", to a "big" .012".


Final assembly will have all the intake valves with a clearance of .008"(0.203mm), and all the exhausts clearances at .009"(0.228mm).

[oldeskewltoy]

As many heads that you rebuild, take 25 minutes and make a holding fixture from small section of angle iron, that will bolt on to your bench grinder. As long as you set the valve stem square to a fine grit wheel, you can easily remove a couple thou by hand at a time. Just have a container of water handy for cooling the valve stem be measurement checks. Sure is better, then waiting on a machine shop, so you can finish the head assembly. davew

If tipping was the only thing I needed, something along those lines would work... but I've been thinking it might be time for my next equipment upgrade. My last significant change was switching from Dremels (yes plural - I used up about 6) to the Foredom 1/6hp SP hanging motor, and hand tools.




I been thinking it might be time for my own valve grinding machine.




This would allow me to do some experiments on valve back cut angles, along with precisely tipping the valves. Now, a new kwik way will run me about $7000. I might find a good used one for about $4000-$5000. The keys are the stones, and the chuck - the chuck needs to be accurate to .0005"