Headwork

[andyb]

Couple of questions for the collective.

First, the backstory.  I've got about 20k on my FJ, the motor is apart.  It's getting wiseco stock bore pistons (not the 12:1 version).  I've got the bottom end back together now, after some miscues.  I was going to swap to a different cylinder head from a Legends car, but it's got a broken exhaust stud, and I'd like to reuse the original head for now (and eventually swap to the other after it's had work done to it).***

My overall goal is to get this FJ to the dragstrip and produce 10.3 @ 128 times, or around that.  The chassis is 58" WB, strapped on the front, lowered in the rear, running around 2" of ground clearance.  Further, I've got a wet nitrous setup ready to go on once the motor has achieved decent ring seal, with the final goal being a nine second pass.

The current build includes a boatload of preventative maintenance parts (cam chain, starter chain, starter guide, etc) and a few performance bits (10.25:1 forged wisecos, later model/longer shift forks).  The clutch is a coil spring version with OEM plates.  Intake side is individual UNI pods and stock carberators with #125 mains, #40 pilots, DynoJet needles.  The stock cams are riding on adjustable sprockets, and I've got a single big megacycle (X6) weldup cam to experiment with after the motor is running and basic problems have been sorted out.  Exhaust is handled by a V&H SS2R system, and I've got a Yoshi RS-3 cannister to fit to it in search of less restriction--again, something to deal with after it runs.  Electrically it's currently stock except for a V&H advancer, with a set of Accel coils in the wings for later.

Current best time prior to tearing it apart was 10.91 @ 124, 60' times in the 1.68-1.72 range.


So now, onto the questions.  The head that I'll be using is stock, 20k miles on it, and for many of those miles the bike ran poorly, as it was overjetted and pig rich (114mph at the strip when I got it, going to the 125 main jets gained an instant 8mph...).  As such, the head is quite carbonized in the chamber as well as both the intake and exhaust port areas. 

The first step:  What's the best way to get this relatively clean, without screwing anything up?  I've got a dremel, a smallish parts washer (whole head won't fit but I can take the entire thing outside and make a mess if need be).

Second step:  I'm going to only do mild porting, such as portmatching the intake rubbers to the head, cleaning off the casting flash, and smoothing down the step above the valves.  The valves will be lightly lapped in.  Is there anything else I should try while I'm at it?  I'd love to send it out for a 3 angle valvejob, but I'm unwilling to send it away becuase I'd like to do as much of this as possible myself, to learn from.  I'll rough the intake ports as best I can with a flap wheel on the dremel.  I've got another idea for this but it's super top sekrit... and if testing shows it to be smart, I'll do it to the other head at a later date.  Anything else to do "while I'm in there"?



***I have to thank Randy (RPM) for his work and assistance to this point.  I'd still have a half mess pile of shit on the bench had he not saved my ass and done awesome work fixing a couple key problems with the crankcases.  I'm tempted to just send the head to him; after seeing how kick ass his work is I'd have no problem doing so... but I'm more likely to do that with the "later" head, I want to learn on the original and then later see just how kickass it can be done.

[threejagsteve]

Andy,

I've done some decarbonization on my Jags, but I've always done it on a running motor (spray carb cleaner down the carb throats after running the shit out of it for a bit) so I don't have any direct experience doing it on an unmounted head.

But I got curious, so I looked on the Jag-lovers(dot)org forum to see what the Jaguar gurus were saying about it. Wire brushes (brass) and scraping seems to be the only way, unless you want to reassemble your motor and do it my (more fun) way.

HTH...

[ccsct203]

it sounds like you have some work ahead of you.
I have a fj1100 with a wiseco 1200cc 10.5 to 1 setup
the head is a fj1200 with 3000k miles, stock valves, Ape springs, titanium retainers shim under bucket and a mild lapping.
I'm running megacycle x2 cams and adjustable sprockets, barnett spring conversion, Dyna 2000, Accel Coils, Mikuni rs 36 carbs, 125/17.5 jets,
K&N pods, V&H SS2R with a removable straight thru pipe, direct to battery wired coils, plus plus plus.
My gearing is a 18/38 for "touring" and I run a 16/42 for "non-touring".
I found that to remove carbon buy a large plastic storage bin and soak the valves in "purple degreaser" you can find at any Advance auto.
I had my head bead blasted and had the ports and the machined areas covered and soaked the ports and the combustion chambers and valves came clean quick.
if your cams are "high lift" the Ape springs, titanium retainers shim under buckets are a must at high RPM.
the NOS is a interesting add. I sold my FJ turbo system 4 months ago otherwise that would have worked for you too.
Look into your final gearing as that will make or break all the work you have planned.
I'm not a racer, but I like a classic that will scare the pants off me.

[RACER111V]

 We use a sonic cleaning tank at work.It does a great job removing carbon and returning it to an as cast finish.Lots of shops use them.I have heard of people using oven cleaner with good results,it will take several tries though.I've used it on two stroke power valves and exhausts,but never cylinder heads.
If you plan on having the head professionally ported in the future DO NOT do anything to the ports yourself now.To be honest,your more likely to remove material in the wrong place than the right place.Minor flashing and mismatches rarely hurt performance.Every porter wants to start with an untouched head.The best port job is achieved by getting the most flow with removing the least amount of material.
The same goes for the valve job.Porters use their own valve job specifications to go with their port work.
My advice would be to clean it up and put it back together with out touching the ports.I'm sure any other head porter will give you the same advice.

[threejagsteve]

I'd be real careful using that purple shit... it will EAT aluminum! Leave any aluminum in it too long, and you'll just have oxide (?) sludge in the bottom - and no part!

But it's great for iron and steel - leave your part soaking for a couple of days, and it even takes the paint off!

[thuber3040]

I believe oven cleaner does a good job eating aluminum also, I would avoid that.
Extrude hone might be a good choice for you, it is a paste they force through the head at high pressure, and it does a pretty nice job of a light port and polish.
If you want to do it yourself (maybe keep a spare head and send it out later for comparisons of performance)
get a air compressor that can run a die grinder and make or buy a 6" shaft that you can use for polishing.
You will need a assortment of carbide cutters(they dont go dull in a few minutes ) and various grades of sandpaper.
Or they sell premade rolled up sandpaper kits for porting and polishing.
But all of that adds up and depending on how far you get carried away you might make the head worse in the long run.
Two valves are more forgiving than 4, and easier to move around inside the head.
Tapered guides, undercut or proflow valves also make a fair difference, but it can get pretty pricey fast!
But if your looking to go low tens it should not take that much work, it will be more traction and rider skill first.

I'm rambling.

Good luck

Price out a worked up pro head and then see how fast you want to go, I already paid for all that a while ago on another bike.

[andyb]

Sonic tank or a hot tank is what I'm leaning towards, but I'll have to take it someplace to get that done.  Probably worth the time and expense though.  Oven cleaner does eat aluminum.  Works great on valves though.



I have another head that will be professionally done.  This one is really just a learning experience.  The only reason why I'm bothering with portmatching the intake side is that under nitrous I don't want a sharp corner, as the fuel will not be as atomized as well as it is from the carb, and it's too easy to knock out of the air.  I agree that most guys get into a head and just start hacking away, and usually lose power in the process.  I'm looking at very minimal things, for specific reasons only, rather than going bigger = better.

Of course on the spare head, some experimentation will happen   Either via having a pro do the work on it and comparing/measuring vs the mostly stock head, or by epoxying it or.... That's the fun of having a spare

ccsct203:  Did you race that at all?  There's a lot of guys that are out there with built up FJ's, but I don't know that they ever go to the track!  I was pretty sure that I was at the limits of what I could do (short of losing 50lbs) with the bike as it was before, so I decided to add nitrous.  Then the motor came apart to ensure that everything was strong enough and working properly... one thing lead to another...

We use a sonic cleaning tank at work.It does a great job removing carbon and returning it to an as cast finish.Lots of shops use them.I have heard of people using oven cleaner with good results,it will take several tries though.I've used it on two stroke power valves and exhausts,but never cylinder heads.
If you plan on having the head professionally ported in the future DO NOT do anything to the ports yourself now.To be honest,your more likely to remove material in the wrong place than the right place.Minor flashing and mismatches rarely hurt performance.Every porter wants to start with an untouched head.The best port job is achieved by getting the most flow with removing the least amount of material.
The same goes for the valve job.Porters use their own valve job specifications to go with their port work.
My advice would be to clean it up and put it back together with out touching the ports.I'm sure any other head porter will give you the same advice.

[racerrad8]

***I have to thank Randy (RPM) for his work and assistance to this point.  I'd still have a half mess pile of shit on the bench had he not saved my ass and done awesome work fixing a couple key problems with the crankcases.  I'm tempted to just send the head to him; after seeing how kick ass his work is I'd have no problem doing so... but I'm more likely to do that with the "later" head, I want to learn on the original and then later see just how kickass it can be done.

Andy,
     Thanks for the kind words. I would just like to pass on to all others...If you break off a case stud, head stud, etc. flush or below the surface send it to me or seek professional assistance for removal/repair.

See Andy's dilemma here; http://www.fjowners.com/index.php?topic=479.0

While I did have to make an oversize bushing to repair the additional damage created while Andy was trying to remove the stud, it would have been cheaper and easier to have me remove the stud and heli-coil if required. But hey the end result is that it got fixed, and no cases had to be replaced.

I am here and will to help each and everyone one involved with the FJ.

Andy;Thanks again,
                Randy - RPM

[the fan]

Do you have any interest in working with other machines? I know a few on the YZF600 boards who could use a little help.

[ccsct203]

I've never raced it but I would like to have put it on a dyno
I have to talk to my bike club buddies and see if they do a dyno day
and I never had an issue with the degreaser I used.
After soaking the combustion chambers, I washed the head well and did not dissolve the head.

Best online porting info I found

http://www.mototuneusa.com/think_fast.htm

[andyb]

Best online porting info I found

http://www.mototuneusa.com/think_fast.htm

That's a good read, and actually led me to one of the ideas that I'm going to be trying.  He's also got an interesting take on valve lapping, if you can find it.

However, I'm not going to epoxy this head, just a very mild cleanup to get it 100% to where it's supposed to be.  The second head may get some more extensive work done, but I'm going to have to test first and ensure that the bitterly cold nitrous doesn't break the jbweld down.  I'm far more likely to epoxy the head on my ZX9, though the wife says if I take another bike apart in the garage before the FJ is done, she'll kill me....