Ken  Try using a cutoff wheel on the dremel tool to slot the head of the screw and use a regular straight screwdriver on it. I,ve done this a couple of times and it worked.  George

I removed the screws on my LA's with the strange Phillips screw driver that came with the cabinets I assembled from Sam's Club.  It fit the screw heads perfectly.  Other wise I use a Dremel cut off wheel to cut a slot for a small slot screw driver.  Then go to Ace Hardware with the engine and get replacement Allen head/socket head screws.  Even the brand new engine I do that too no matter the manufacturer, especially Fox engines.  Yes I suppose that makes my Fox's illegal for Foxy reacing.

    What's nice to have is a set of Japanese Industrial Standard scewdrivers so that the screwdriver will
fit the head bolts on your Japanese-manufactured engine and not strip them out in the first place.  A
number of suppliers of these screwderivers may be Googled, if you're interested.  It's much less work
for you if you use the right tool for the job, though few hobbiests seem to have JIS screwdrivers.

    It's not only less work, with the proper screwdriver, it's darn near impossible to strip them out. I would say they are at least a secure in the slot as an Allen head.

    BTW, the other half of the issue is choosing the right size. The right size screwdriver is usually larger than you think. For some of our applications (like reaching down into the head fins) the right-sized screwdriver for the slots may have a shaft too big to fit in the hole. A grinder (be careful not to overheat the metal) or a hobby belt sander will solve that issue.

   The Hozan #2 JIS screwdriver (the brand you get from Central Hobbies) is the right size to fit the head screws and backplate on an LA40/46 and doesn't need to be ground down to fit in the fins. It *will not* strip the heads. I put a Craftsman #2 in the slots and you might have a problem there. A Hozan #1 will work with a slight risk, but with a US standard Craftsman or Proto #1 it bottoms out on the point and will very likely strip out unless you push it into the slot like you are the Incredible Hulk. If it feels like it's going to take tremendous pressure to keep it from slipping out, then you have the wrong size or wrong shape driver.

    Note that the use of the word "standard" is also not what it might seem. Each family of drivers seems to be made with slight variations and of course the screws are punched out at the rate of a million an hour. So while there is a standard some drivers fit some screws with variations. And the Phillips or Japanese cross-head design is much more picky about everything fitting perfectly than a slotted screw and if you mess it up once it's done forever (as we have all found - never look at the case bolts on my old Suzuki).  The same sorts of issues apply to slotted screw, but how many ways are there to make a slot?

     Brett

p.s. I had forgotten about this, but then I looked and it reminded me  - JIS crosshead screws are supposed to be identified with a little "pit" between the slots. I checked an LA46 and it has those little pits, telling you to *not use a Phillips head*. The proper screwdrivers are pretty cheap for a lifetime tool, it's worth getting them.

     

One of the problems with JIS screw drivers is that for the most part those that are available to us have thin handles 4 sizes of heads and really no way to get much torque to the job with the average set of hands. If your older and have some of the joint problems associated with maturity it only compounds the problem.. So what to do.
Suprisingly you can find screwdrivers that are perfect for the job at Lowes and a few other places. Even more of a suprise is that they are the cheap kind with the reversable head. You know flat and phillips head you switch back and forth. They fit because that aren't Phillips at all and actually fit most of the Japanese stuff quite well.

    If there's a grip issue, I would suggest the usual Gamma Gauze tennis racket grip like you use on control handles.
   As it turns out, the JIS drivers work pretty good in real Phillips screws but not the other way around. The shallower angle makes the JIS screwdrivers ride on the "cross" part of a Phillips. The Phillips drivers in the JIS scres bottom out and you don't get full engagement of the cross. The "driver-drill" type bits are not Phillips, either, they are "posi-drive" and intended not to "cam out" at excess torque. Phillips screws are intended to cam out of the slot so you can't over-torque the screw. Of course it also means that you can't get them loose easily if they are stuck, which is why we all hate them.
 
     Brett

       I managed to remove them. I used heat then I did purchase a few of the screwdrivers mentioned. I did bugger the screws last night but not enough that I couldn't get a bite on them. I tend to give stuff like this to my father who's been a machinist of 48 years who can get a bit hot when I give him stuff like this to fix. One thing I'll say is that he never fails to get the screws out no matter how butchered it is. Its quite amazing actually. He's got a full plate typically so I figured I'd give it a shot. The best thing I did was to put it down until I was thinking with a clear head and patience. Thats about the best advice he's given me to date. I was all set to try and slot the screws as mentioned above its just the fins protruding were in risk of getting damaged. I had a silver case La which I robbed 2 of the screws. This brings me to the next question. The silver engine has an additional port cut into the sleeve in which the blue one doesn't. Is this how all the silver case engines are?

  It does?  That's interesting, and explains some recent observations about the 25LA we had seen recently. The older 25LA were always sort of gutless compared to the 20/25FP. Recently Jim got a new 25LA and it was a killer - easily spinning 12,000+ on the ground to get a decent in-flight speed, generally 4-stroking at 4.6 second laps, etc. Much more powerful and much better. We never looked inside it to see if it has a functional boost port, but that's exactly what it seemed like.

    Brett

Brett,
Can't argue with you on your suggestions however, the sets that I have are oriented towards hobby use and really don't have more then a 5/8 handle.This makes it hard to use when trying to unlock a torqueed bolt on an engine.

    Given that we are talking about 2.5mm screws, if you use any more torque they will be breaking the heads off! I just tried it and managed to break the head bolts on an LA46 loose with two fingers on the small part of the grip.

     I guess I don't get your point about the grips, or we are talking about two different things - the grip on the Hozan #2 is 1 1/16" in diameter and I think we are only talking about 20-30 in-lbs. The grips are a little different shape but they are proportionate to any other screwdrivers or spin-tites I have.

   So I guess I am a little puzzled. I would recommend going over to central hobbies:

http://www.centralhobbies.com/Tools/jis.html

     These are the ones I have, I think you will like them.

     Brett

Brett,
I believe thqat we are on different pages.
My metric allen type drivers sre fine. I believe that we are talking about JIS screwdrivers. I have none that are set up to apply any amount of torque but are more in line with jewlery type. With these I have neve been able to loosen a head bolt on any manufacturers head so if it's me then so be it. 

   Clearly we weren't talking about the same thing. My comments had nothing to do with metric allen drivers, strictly JIS screwdrivers. The Hozan set from central hobbies certainly will remove any head bolts, might give those a shot.


     Brett

I have assembled a goodly assortment of French-threaded Allen head capscrews from Metrics Unlimited. 
I scrap out the Japanese + srews before I run the engine. They can't accurately be called "Phillips".

  I too have cut a small amount off a Phillips driver and it worked just as Jim said it will...

   Not to hijack this thread , but what are the recommendations for removing rounded out Allen head screws ?
Yes I have a T-handle Allen set but still manage to round out one Allen in my Brodak 40 .

    I would guess the same method would apply- cut a slot. Then replace ALL the screws with properly hardened types. There's no way to damage the heads of properly-hardened screws by removing them with a correct driver; you'll break the screw before it strips the head.

     Brett

    If there's a grip issue, I would suggest the usual Gamma Gauze tennis racket grip like you use on control handles.
   As it turns out, the JIS drivers work pretty good in real Phillips screws but not the other way around. The shallower angle makes the JIS screwdrivers ride on the "cross" part of a Phillips. The Phillips drivers in the JIS scres bottom out and you don't get full engagement of the cross. The "driver-drill" type bits are not Phillips, either, they are "posi-drive" and intended not to "cam out" at excess torque. Phillips screws are intended to cam out of the slot so you can't over-torque the screw. Of course it also means that you can't get them loose easily if they are stuck, which is why we all hate them.
 
     Brett

I use a large tap handle on my screwdriver and this works really good if you have the small handled screwdriver that fits these screws. It also has a hex shaft that you can use a wrench on to loosen these screws. I also like the idea of using  different screws on these engines because it is just easier to put head gaskets in or new piston and sleve in.

I think the problem with rounded out Allen heads is using the wrong driver.  The driver I use for 4-40's almost fits the metric screws on a Tower 40, but is a hair small.  I bought a cheap folding metric driver at the hardware store and it works fine.  I use it to break or tighten the metric screws, and then screw them in or out with my easier to use 4-40 driver.

      I think the one you are looking for is a 2.5MM driver. That's what the screws on a 40VF are. I have  T-handle wrench from Harry Higley that is long enough and heavy enough that you can spin it loose, and you can find ball drivers in that size, I think. The 4-40 driver will turn it if it's very free, but as you say, it won't apply any torque to speak of.

     Brett

Hi Brett,

 . . .  I have not used (or even messed with) any of my LA engines yet, and I have a couple .46s and a .25 which I want to swap out the screws on BEFORE I use them.

So far, I have not had any problems with tearing down the FP engines. ()

Thanks!
Bill

Bill --

I dunno. I was going to do the same as you are, but Brett's "sales pitch" for the JIS drivers changed my mind. If the JIS drivers work "as well as advertised", there is no reason to swap out the screws. 

I'm not sure how the cost of the JIS drivers ($17.99 plus shipping, a one time fixed cost) compare to the hassle + cost (per engine) of a complete bolt swap * "some number of engines", current and future. Part of my decision was based on a couple of LAs with some time on them (potentially stuck bolts), and I might need the JIS drivers just to loosen the old bolts. In that case, the $17.99 drivers are an additional expense to the bolt swap. In your case, with new engines, you shouldn't need the JIS drivers at all (using a blunted Phillips for disassembly).

Anyway, I ordered the JIS drivers today, before ruining any of the "Phillips" heads with the wrong tool.

Nice, informative, thread 

       Larry Fulwider

Myself I have never like phillips head screws(US or Japanese) and told that to my son many times.  Could never torque down the screws without stripping them.   

   Use the right screwdriver and it's a non-issue - they are at least as secure and tight at Allen screws.

     Brett

     The screw size is 3x11 mm for the cylinder head. Ken

The head screws are 3mm x .5mm (pitch) x 12mm long...at least, that's the length I bought and use. It's probably cheaper to replace the screws than to buy the JIS screwdriver. They should last the life of the engine, but if they don't, they'll be a lot cheaper to replace with more, than with an OS screw set. The 25LA has 2.5mm backplate screws, but I dunno what the pitch is...maybe .6mm. 

As with SAE threads, there's a fine and coarse pitch, and the coarse is always recommended for threads into aluminum.  Also, FYI, I tried tapping the holes deeper on one of the LA's, and the hole was not excessively deep, so I wasn't able to tap deeper. My SOP for LA's is to replace the backplate with an aluminum one, and replace all the screws with socket heads. I have less trouble with them, because torque is easier to judge, since it's not a push and twist, but just an easy twist. I suggest using a standard, short arm hex wrench, not the T-handles, long handles, or the screwdriver sort. Thumb on the bend in the wrench, index finger tip on the end of the arm, turn about 1/4 turn past snug...done deal. Don't bend the wrench!  Steve