OST-024: It's been way too long

[oldeskewltoy]

Its been way too long... way back in August... and that was just an assist. I've been busy helping Arnie with a few tasks, but with the ever lengthening day... and potential clients dreams of ripping through a back country road with a 4AG @ full song....


Let me introduce to you OST-024......

It began with a choice between 2 later type TVIS heads.....




Upon close inspection the head on the left was chosen. The main reason I chose the head on the left is the chambers are all nearly perfect... not like #2 and #3 chambers of the head on ther right.... Look carefully... the chambers were cast poorly requiring deep machining. This deep machining left some pretty significant chamber flaws




Remember I did say the head on the left was almost perfect...

you decide......



Those intake seats look like I just had them cut... nope, that is a fresh disassemble. Thinking it was a low mileage head? The valve seals were old and crumbling, many of the exhaust seals turned to grit in my fingers. Also the guides are nearly perfect. Also, note how nearly perfect the bowl to seat alignment is. This is a VERY good head!

Even the exhaust ports look pretty good.....


Well its off to Loynings to get it cleaned....


More to come.....

[onnaj]

I'd say polish that exhaust chambers when you're there

[MisterJerk]

wow, that head is a good casting. Looking forward to seeing your work, OST.

[oldeskewltoy]

I'd say polish that exhaust chambers when you're there

the exhaust ports when finished will be well polished

wow, that head is a good casting. Looking forward to seeing your work, OST.

This is a VERY good casting... almost worthy of a "spec" build...





A few additional photos while I wait to get the head back from cleaning, and pressure testing

The intake side...

straight on



and at a bit of an angle to view the seats



As already noted... the seats are not excessively off one direction or the other. Bowl-to-seat alignment is superb on this head.


More to come.....

[oldeskewltoy]

Well its off to Loynings to get it cleaned....

Well.... I had it cleaned and pressure tested... but not @ Loynings. Loynings is VERY busy this January, and it would have taken 2 to 3 days to get it cleaned AND pressure tested there, so I had the head cleaned and pressure tested @ Portland Engine Rebuilders... They did a pretty good job, and the 2 services cost me about what Loynings would have charged just to do the cleaning.


So now that I have it back, the job begins with a complete and total deburring. No sharp edges will remain.

Here is a view @ the first 3 exhaust spring chambers, before and after...



There is a LOT of material removed in just that little area, the material removed helps speed oil shedding/drainage, and it just looks better...


Now that the head is completely deburred, I move on to working #4 intake bowls and seats.


2 slightly different views of the same thing... #8 bowl/seat shows work, #7 bowl/seat still undone


and the short radius



With both bowls and seats done in chamber 4, we compare the short radius to the as yet untouched bowls and seats in chamber 3. Note how there are no longer any defined machining marks in either of the bowls of #4 chamber (chamber on left)





Once both bowls and seats are blended, the roof of the port gets a gently taper from what was the bevelled edge all the way back to the leading edge of the splitter, this ever so slight taper will help to bend the air charge towards the valves






More to come.......

[Rogue-AE95]

Always great to see another OST ported cylinder head I've been saying this for a while, but someday you'll have another on the bench.

There is a LOT of material removed in just that little area, the material removed helps speed oil shedding/drainage, and it just looks better...

And I thought I was crazy for wanting to do the same thing with my build. I practiced some of this on a "junk" bigport head. I wouldn't call it easy work, but it was in a way fun. Although I like cleaning up casting marks and smoothing things out, I just don't think I can do cylinder head porting. Not like you do!

Would the same be worth doing for the block? There can be some nasty casting lines in there. I did some casting line removal on the '97 4A-FE block I'll be using for my build. Hardest place to reach was the oil drain back from the head, with the divider, whatever that's called. I couldn't get my Dremel attachment far down enough to get all the casting flash out of it.

[oldeskewltoy]

Would the same be worth doing for the block? There can be some nasty casting lines in there. I did some casting line removal on the '97 4A-FE block I'll be using for my build. Hardest place to reach was the oil drain back from the head, with the divider, whatever that's called. I couldn't get my Dremel attachment far down enough to get all the casting flash out of it.

yes....... there are a few builders out there who have used a ceramic coating to further improve oil shedding. The area you speak about is not a drain... it is the blowby passage for the blowby gasses.... there are 2 oil drains on a 4AG... both on the exhaust side. One between cylinders 1 and 2, the other back by #4

That is a very pretty "noggin" you have there Dan. I'm very jealous. Oh so pretty.

thanks..... Lets hope I can find a buyer for it...

the roof of the port gets a gently taper from what was the bevelled edge all the way back to the leading edge of the splitter, this ever so slight taper will help to bend the air charge towards the valves

maybe this will be a bit more telling..... I haven't change the port roofs gasket edge(blue line), just tapered the whole roof.

[oldeskewltoy]

Here is a view of the last 2 chambers. Chamber 4 has had preliminary deshrouding.



The main purpose of this photo is to show the lighting for the exhaust ports.



A 2 panel to show not only the short radius, but it also shows the re-tapered exhaust port





More to come.....

[oldeskewltoy]

Looks good! When you are using the burrette to cc the combustion chambers, how do you keep them the same volume?

Not easy... BUT I typically do the following... 1) remove the material that promotes pre-ignition clear to the "joggles", 2) measure chambers once all are @ 90% complete, 3) knowing volume, decide on how much to machine head, 4) machine head, 5) recheck volumes, and adjust if necessary before final chamber finishing


more to come....

[oldeskewltoy]

Further progress...


3 chambers deshrouded(not yet finished).... 1 to go




3 exhaust ports to size.... 1 to go




2 intake ports reworked... 2 to go





and an OST 3 panel of the exhausts so far....





More to come.....

[oldeskewltoy]

Four chambers fully deshrouded... waiting for CCing




more to come......

[oldeskewltoy]

4 panel showing combustion chamber progression....



The #1 intake and exhaust ports should be done by the end of this week... next week on to Loynings for the 3 angle w back cut, and machine the surface....



More to come......

[oldeskewltoy]

This looks awesome! Do you sell these heads or just making your own for more power?

thanks... I do try my best on every head I work...


I do sell these heads.... OR if you have a decent head you would like me to port, you can send it to me.

This head WAS for sale, it has been sold, and paid for. The client will be using this in a boosted application.

[oldeskewltoy]

A few multi-panel photos for your enjoyment....


Exhaust side.....




and a few of the intake side...




This view is based on roof angle




So now that the ports, the bowls and seats, and chambers are nearly done, next on the list is checking chamber volumes, and adjusting them to the largest. Once they are all adjusted I'll get the 3 angle and the surface machined... and then recheck chambers and adjust if needed, and then polish the chamber walls.....


More to come.....

[oldeskewltoy]

[oldeskewltoy]

Well... I got the head back today... nice, perfect surface.. ready to get bolted down



Note this was only a thin cut... the manifold mounting lugs show no contact yet.



Those nice shiney seats are each carrying a 3 angle valve job




Now that the head has been cut, we'll get chamber volumes and adjust as necessary.


Finally able to get this one back so I can finish it....


More to come....


btw... also doing a 2.2 liter Mazda/Ford head - OST-025... if you want to follow along - http://hachiroku.net/forums/showthread.php?t=35439

[oldeskewltoy]

have you experimented with more angles and different angles?

No... If I had my own valve/seat grinding equipment I'd consider different angles, but for now I trust Loynings....

i changed my valve grind angles and added a dual backcut,
I gained an average of 16.8 cfm from .200" thru .600" lift. :thumbsup:


My final grind was a 75/60/45/35, and 22/33/45 on valve.
the air was much smoother with the string test also. :thumbsup:

What head are you working? (.600" lift) I don't know of any 4AG running 15+mm lift cams....

Also are you running the SuperFlow recommend 90% throats?

intake 86%(26.2mm throats), exhaust 86%(22mm throats)



I managed to get 3 of the 4 chambers checked for volume...





all are 36cc so far....




More to come....

[Rogue-AE95]

Well... I got the head back today... nice, perfect surface.. ready to get bolted down



Note this was only a thin cut... the manifold mounting lugs show no contact yet.

What would that thin cut be (in inches or mm)? Just wondering since a terrible shop took it upon themselves to cut my SP head when I didn't even ask them to, it was there only for a cleaning... they claim they took off .006" but it took out some of that manifold mounting lug material (and the water passage). And they didn't do nearly as good of a job as the one you've shown. That whole experience still burns me

At what point do you worry about the head being milled too much so that it becomes an interference engine (say, with stock pistons rather than custom)?

[onnaj]

Really nice pictures!

How much is 36cc compared to stock?

[oldeskewltoy]

This head was cut .008"

I go to Loynings because I know they KNOW what they are doing....

a stock 4AG combustion chamber is 36cc... by my careful deshrouding, and polishing, and then a minimal cut I can offer stock chamber volumes - while offering near perfect chambers (see photo below)

my 20R race head. my cam's lift is .566 max.. so i had head flowed to .600
and it was still going up.
that wasn't really the point of tell you this..

this was.. vvv

my head gained 18.5 @ .200, 15 @.300 and 19.2@ .400
only changed the angles and added the backcuts.
those should some lifts you might like to hear about. :thumbsup:
and a 4age might have even more curtain area.

Edit..
nope less curtain area but the ports are better for breathing then a sohc
with guide coming out of corner of port.

Surreptitious carries radius back cut valves - they were turned to provide a smooth back all the way to the seats contact point - the same principle as a velocity stack.

In a chat with a few folks @ Loynings... in a boosted application, there is little if any advantage to using the radius back cut... the single back cut offers similar flow figures - in a boosted application



The chambers are now all to size, and polished





A few days ago some goodies arrived from Ted's... a pair of KK108E camshafts, and a set of Kamikaze 4AG springs



So... what appears different... anyone guess what I see? (Hint: its in the specs)



briefly speaking about springs... I managed to get the KK, stock, and Toda side by side by side




Now... to accommodate 10+mm cams in some cases clearancing of the head is required, these cams are 10mm, not 10+. I laid each cam in its respective (one cam is geared the other isn't) journals and they do rotate without hitting anything... but they are close...







VERY... close!!






I've sent an email to Ted's to inquire as to if they have, or know of someone who used these cams and had to clearance the head. I'm waiting for a return email.....


More to come.....

[oldeskewltoy]

VERY... close!!






I've sent an email to Ted's to inquire as to if they have, or know of someone who used these cams and had to clearance the head. I'm waiting for a return email.....


More to come.....

Depends on the casting give 0.015” clearance minimum between the casting and the camshaft.

Well, I now have a spec so I can measure... but I think I'll end up opening up the buckets just a touch at the corners...




more to come....

[Rogue-AE95]

That is so close, it would scare me to think it was running like that as I drove. I'd worry that heat expansion would bring the cam a little too close to the bucket area.

[oldeskewltoy]

That is so close, it would scare me to think it was running like that as I drove. I'd worry that heat expansion would bring the cam a little too close to the bucket area.

I think I'll end up opening up the buckets just a touch at the corners... :thumbsup:

Times 16.....

I've assembled the head, fitted a set of buckets.... now I need to pick up my shim tools so I can set valve clearance


More to come....

[oldeskewltoy]

I've assembled the head, fitted a set of buckets.... now I need to pick up my shim tools so I can set valve clearance


More to come....

All ready... cams, shims, calipers... I've even polished up the cam cap journals...


I load up the intake side with 2.85mm shims. I did this because this was the thinnest shim size I had a full set of to begin with.



Oh... the shim tools... that's right....



One levers the shim and bucket down, the other gets wedged between the buckets edge, and the underside of the camshaft.



The intake side is now done...




next is the exhaust side...


More to come.........

[MisterJerk]

Shim tool is awesome. I've been doing it the long way. Make all measurements at once, pull cams, then measure all the shims. Do the math and find closest shim and do all 16 at the same time.

[oldeskewltoy]

Shim tool is awesome. I've been doing it the long way. Make all measurements at once, pull cams, then measure all the shims. Do the math and find closest shim and do all 16 at the same time.

This works... my only issue is making sure I've done the math correctly... sometimes I add, instead of subtract... mistakes like that cause repeated removal... which can cause wear to the cam journal threads. I also will sometimes work in one shim, and then try another if I find the first one a bit loose, or tight. Again repeated removal and installation of the cams can cause added wear to the journal threads.... and in rare cases... a broken cam I still remember a certain HKS cam fiasco from about 6 or 7 years ago....

added the backcuts

It's funny how I try to stage a photo to show what I'm trying to explain.... I work at it and sometimes it just doesn't happen.....

and then sometimes, purely by accident a photo has a reveal....


The photo above was just to help show the viewer how much 10mm of lift looks like... Once I saw the photo... it makes the back cut very obvious... (royal purple assembly lube on right valve)


Anyway... the above photo showing 10mm of lift, here are 2 more...

intake..



exhaust..



I began the exhaust side with 2.85mm shims down the line as I had with the intake, but this time none of the 2.85 shims lasted. ALL the shims on the exhaust needed thin shims - from 2.60mm to 2.75mm. Typically, when you strip a 4A of its shims it usually has mostly 2.90-3.05 shims fitted, rarely do you find thin shims under 2.8mm.

I had to go out and purchase 4 shims: 2-2.65mm, 2-2.60mm so I could finish the job.




The head is now finished... A STRONG recommendation for my client is to run a Kevlar toothed timing belt on this engine. Between 62# seat pressures, and short duration, high lift cams, a STRONG belt tooth is recommended. Power Enterprises has such a belt, as do a few other companies.

[Rogue-AE95]

Looks great! Those cut-outs for the cam lobes would definitely give me peace of mind.

[sekang0]

The owner did not go with shimless buckets or underbucket with the high lift here?

[oldeskewltoy]

The owner did not go with shimless buckets or underbucket with the high lift here?

nope.... look back, Ted's, the supplier of those cams says there aren't needed. BUT... as I noted, this is new to me.