What fox engine is this?

getback wrote:Welcome to the forum James !! take a look at this site at 1961  http://www.clcombat.info/foxhistory.html  I am not an authority on Fox but maybe this will help . getback

Thanks getback.I have read thru that site.

You have the late 50's plain bushing Rocket but the cylinder head is incorrect for that engine. That cylinder head could be from the .29 or .36 from the 70's. Ken

You gotta love it! Old Duke certainly kept people guessing. He never gave too much away with his engine markings and you've done well to even get the "Rocket" inscription/logo. Some engines you don't even get "Fox" let alone a size.

Ken Cook wrote:           You have the late 50's plain bushing Rocket but the cylinder head is incorrect for that engine. That cylinder head could be from the .29 or .36 from the 70's. Ken

Ken since reading, i believe it to be the one built in 61 with the wrong head.This engine does have the the removable insert in the venturi.that's why i think now that is the fox 40 rat race rocket engine.It has the brass brushing.i have torn it down and 5 of the cylinder head screws, the heads just broke right off.Do you know what the proper oreintation of the piston liner is to the case?How the case is supposed to be installed?

n 1961 Fox introduced the new Fox .40 Rat Race engine, 1st type. It used the same crankcase as the 2nd type .35 Red Head "Rocket" with a rocket on the bypass and four lugs on the crankcase front. It had a larger intake with insert, boss for pressure fitting on the rear cover. It had the same .800" bore as the .35 engines, but it had a longer stroke. The .35 engines have a .700" stroke and the .40 has a .790" stroke which means the cylinder liner on the .40 is .090" longer than the .35 liner. Thus the .40 engine has a .090" gap between the head and the cylinder top fin and it has the wristpin hole in the rear of the crankcase. The Fox .40 R/C engine was also introduced in 1961.

I think i found a picture of the engine type i have on ebay.It has the correct head.

http://www.ebay.com/itm/Vintage-Rc-Model-Airplane-Plane-Engine-Motor-Fox-Rocket-cl-ff-r-c-/181961102304

The rat race engine was easy to identify due to the thick liner rim where the cylinder seated on the case. When the head was installed it held the cylinder head way up. Of the rat race engines I know of, they had no casting symbols but rather a sticker. Andre Ming was a Fox employee back in the late 60's early 70's. I met Andre this past Sept. He had mentioned some other one off engines where the .40 piston sleeves were machined into cases that were smaller mills. One of these engines were present at the Garden State Circle Burners vintage combat meet.


                As far as piston orientation, the baffle of the piston opposes the exhaust side of the case. The cylinder head will have a groove on the underside to accept this piston baffle. As for the cylinder, of the two cutouts, you will see that one of them is higher in the liner than the other. The higher cutout is the exhaust cutout. As you just found out, taking these engines apart can be detrimental to them due to the fact that nothing indexes the cylinder. Not a good practice to take these engines apart. You can have a hard time realigning the cylinder to the piston's exact position. Another problems with these engines is the castings. They're very thin and will distort. When assembling, it's a must to do it dry and with the plug out. While tightening, check for binds when tightening the screws down in a criss cross pattern. There's the magic screw that if tightened will egg the cylinder and cause a bind. This is more apparent in the Fox .35 stunt as the cylinder head is much thinner as well as the case. The Rocket shared the same case as the Fox Blackhead Combat special.


Do you have intentions of using the engine ? If you do run it, I wouldn't run too high of nitro just due to it's age and no parts supply. While I'm not a big castor oil fan, I would keep the castor content high on this one. Ken

Ken Cook wrote:The rat race engine was easy to identify due to the thick liner rim where the cylinder seated on the case. When the head was installed it held the cylinder head way up. Of the rat race engines I know of, they had no casting symbols but rather a sticker. Andre Ming was a Fox employee back in the late 60's early 70's. I met Andre this past Sept. He had mentioned some other one off engines where the .40 piston sleeves were machined into cases that were smaller mills. One of these engines were present at the Garden State Circle Burners vintage combat meet.


                As far as piston orientation, the baffle of the piston opposes the exhaust side of the case. The cylinder head will have a groove on the underside to accept this piston baffle. As for the cylinder, of the two cutouts, you will see that one of them is higher in the liner than the other. The higher cutout is the exhaust cutout. As you just found out, taking these engines apart can be detrimental to them due to the fact that nothing indexes the cylinder. Not a good practice to take these engines apart. You can have a hard time realigning the cylinder to the piston's exact position. Another problems with these engines is the castings. They're very thin and will distort. When assembling, it's a must to do it dry and with the plug out. While tightening, check for binds when tightening the screws down in a criss cross pattern. There's the magic screw that if tightened will egg the cylinder and cause a bind. This is more apparent in the Fox .35 stunt as the cylinder head is much thinner as well as the case. The Rocket shared the same case as the Fox Blackhead Combat special.


                 Do you have intentions of using the engine ? If you do run it, I wouldn't run too high of nitro just due to it's age and no parts supply. While I'm not a big castor oil fan, I would keep the castor content high on this one. Ken

Thanks Ken, for posting that info, sorry for not posting back earlier, have had trouble here with trying to log back into the forum.Ok so the liner was installed wrong according to your advice, and there was a bind when turning the engine over before i took it apart and reassembled it back together, i installed all new head screws.engine now turns over smoothly, and with the plug installed has plenty of compression.I will now balance a couple of props and set out to do a breakin on this engine.I do plan on trying to use this engine, with 15 % nitro, with plenty of caster.Thanks again.

You have to admit that Fox castings were awfully rough, particularly when you had the actual engine in your hand and perused the M.A.N. advertisement portraying the engine as a gleaming jewel. Thinking of both my Fox 0.09 and Fox 0.15.