Help needed to ID FOX engine

Can someone please tell me what model this FOX combat special is?
IT has steel piston/cyl, one piece head (no button) and high backplate.

Thanks

Charlie

Charlie,
It appears to be a Mark III Combat Special. I think that they
came out around 1975 or 1976.

Best regards,

Richard Ferrell

Yes - MK III Don't get too crazy with the nitro and don't get too small with the prop or you will have a paper weight with a busted crank. I run mine on 5% and an 8/8 prop or so.

>Charlie,
> It appears to be a Mark III Combat Special. I think
>that they
>came out around 1975 or 1976.

Then what was mine? I bought what I thought was the MK III CS in early 1980 but it had a button head and the red annodized drive washer. I ran it once on the bench but never flew it - wound up selling it to Richie Salter.

I also had the .29 and .36 versions of the MK V sport engine with single BB, tall back door and button head. It was designed to run on suction for slow combat. I flew it on a Combat Flite Streak and a scratch built Eagle slow design.

Man that is one short shaft! I guess the Fox 35 isn't much longer. No wonder it's so easy to rap your knuckles on the back of the prop when adjusting the needle.

That is the best of the Fox Combat Specials, at least until the last aluminum-piston engines. I still use Mark IIIs, although with a lot of after-market parts. Replace the shaft with a Brasher-McFadden shaft if you can find one. Replace the bearing with a plastic-retainer R-8.

I read someplace that, MK 3s dont run well on suction, so i would dare to say to run er on a bladder. I could be wrong, but what else is new! < Paul

>I read someplace that, MK 3s dont run well on suction, so i
>would dare to say to run er on a bladder. I could be wrong,
>but what else is new! < Paul
Hi,
These motors don't suck.

If you make an insert similar to the one in the mark 6 pictured here:

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=5900791468&ssPageName=STRK:MEWA:IT

It should run well on suction. I ran these engines back in the 70's with a bladder and never did manage to wring a shaft off any of them. I originally had about a dozen of the Baldies (Mark 1 & 2s) that proceed this engine and they were very powerful but the shaft kept failing. I talked to the factory and wanted to replace them under warrantee. They said if I sent the engine back they would only charge me half price for the newer tall back door mark III engine. I said nope-just replace these. I ended up with a dozen Mark III engines and didn't pay a dime more. I just got done selling the last one on ebay. The ones I kept the box for went for between 90 to 125 bucks, turned out to be a fairly good investment. I still have one baldies, brand new, never been used, with the piston stuck tighter than a drum. I have it soaking in oil now. I'll get back to it one of these days. Since I got back into modeling recently I found that I couldn't use the engines I used to run and found some good buys on OS engines.

Thanks for the tips chaps. This one goes like the clappers, but eats plugs like I was getting them for free (which over here they definitely are not). I have only been using 5% nitro fuel in a bladder and turning a 9 x 6 Taipan prop. Is there any way of reducing it's plug consumption?

>That is the best of the Fox Combat Specials, at least until
>the last aluminum-piston engines. I still use Mark IIIs,
>although with a lot of after-market parts. Replace the
>shaft with a Brasher-McFadden shaft if you can find one.
>Replace the bearing with a plastic-retainer R-8.

>Thanks for the tips chaps. This one goes like the clappers,
>but eats plugs like I was getting them for free (which over
>here they definitely are not). I have only been using 5%
>nitro fuel in a bladder and turning a 9 x 6 Taipan prop. Is
>there any way of reducing it's plug consumption?

That was one scary engine when I first fired it up. I used a baby pacifier force fed with a 9/7 Tornado prop on a short boom Voodoo and
let's just say I hit an adrenalin high every time it flew. Beat the ST G21 .35.
I recall it eating plugs but I remember thinking it was the price I paid for going that fast. I think the hottest fuel I put through it was 15%. Zooom.
I still have the engine.

Lots of plugs now have .005" diameter wire. Find one with .008" wire. OPS and Rossi plugs have pretty heavy wire, as do some of the Ohlsson plugs available in the US.

I won the Slow combat event at the 1979 Nationals with a MK III on suction. 15 % nitro and 22% oil 9X6 Rev-Up props and K&B 1L plugs. Almost never blowing plugs. And, after the First one that broke a shaft in fast, I modified the thrust washer and never broke another shaft. In fast, I ran 35% nitro and 22% oil. These engines like to burn plugs until they get really broken in good. If you run too much oil, they will knock plugs out. They don't burn out, but the elements break by the oil droplets pounding them. Howard always ran 5% more nitro than ANYBODY!!!! His stuff REALLY went FAST!!!.
Howard's advise for the R-8 bearing is good, although I never used them. I changed my bearings every season of flying and always used factory bearings. I did have a couple that failed during the season though. That engine pictured IS a MK III and it DOES have a head button and clamp ring. The Red anodized thrust washer versions are "usually" MK IVs and have a cast head clamp ring rather than the machined one on the MK III

Bigiron

By-the-Way, The engine that I won the Nats with was "Bone stock" other than the suction venturi insert. I had three of them in planes at the Nats and flew all of them during the course of the event.
Big

I use pistons and cylinders made by Australian Andy Kerr 20 years ago. They are great and still going strong. If you know Andy, please give him my regards.

Norm in post# 9 got it right when he said, "these engines suck". Mine sucked enough streamers and string to win the '78 NATS which may have been the last year of single elimination combat. It also sucked up more of said streamer and string to the tune of 2 Bladder Grabber wins and a Northwest Regional win or two. In fact if memory serves me correctly it sucked up a whole bunch of Rush Puppy tail!

Unfortunately, I have just recently been relegated to DingBat and umbrellas. DingBat is truly a strange scary place fraught with Combat Dereliction. I have now begun therapy and request your prayers for a full recovery.

PTG was that (78 Nats) the one where your competitor for 1st/2nd place kept trying to make a lawn dart out of his plane?? I believe his initials were MT.

HMMMM.

>Is there any way of reducing its plug consumption?

Add a head shim to reduce compression?