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AP .061 engine porting

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AP .061 engine porting

Old 10-31-2011, 06:44 AM
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Nikolas K
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Default AP .061 engine porting

Hi all!

As far as I know, the AP Wasp .061 engine is a clone of the Norvel Big Mig .061 engine, which means there are prospects of tuning up the small AP to the Norvel AME .061 standards, i.e. more power.
I would like to do the experimet and port that little engine. Is there any previous experience in this? Are there any chances to find the Norvel AME's exhaust and transfer port areas and timing in order to start porting?

Many thanks,
Nikolas
Old 10-31-2011, 12:33 PM
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digital_trucker
 
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Default RE: AP .061 engine porting

Search through this forum. Port timing diagrams have been posted for both the Norvel and AP's. You can Norvel performance out of an AP, if you get a good AP.
Old 10-31-2011, 03:59 PM
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Default RE: AP .061 engine porting

Having an old, worn out AME in your hand that you can copy is worth 100 times more than all the reading you can do on this subject.

There are also a couple ideas you can get from studying an old Cox KillerBee.

Toad published one of the best AME mods ever, where he removes material from the piston skirt and from the counterweight on the crank to allow an unobstructed path for gasses to travel up the transfer port.
Old 11-01-2011, 09:46 AM
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DeviousDave
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Default RE: AP .061 engine porting

I sure wish I could find Toad's mod page, I saved it and lost it in a hard drive crash/transplant and couldn't find it when I went to replace it.[]
Old 11-01-2011, 10:04 AM
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Default RE: AP .061 engine porting

His old website was a dead link, but it looks like he has a new location: http://www.solmachine.com/
Old 11-03-2011, 09:26 AM
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Max_Power
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Default RE: AP .061 engine porting

I recently did a bit of a experiment on one of the AP .061's . I had tried to get it running on diesel a year or two ago and only managed to waste a day or 2 fiddling. I recently pulled it back out and mounted a green 5x3-ish combat prop and pet a few tanks through it set up glow fuel. I actually got it to run pretty good although I don't remember the rpm #'s I'm thinking It was around 24k on 35% nitro Although not amazing for such a small prop I felt it sounded and throttled, started well. It of course about this time was beginning to get the loose crank fit that these guys develop and I started thinking about what could be done to correct it. I was contemplating a new brass sleeve for the crank, bit was scared off as the factory one is SO thin walled? Seemed like it might be difficult to turn one and press it in, I figured I'd have to press in a solid then bore the hole with the whole case in the lathe. Being lazy, and knowing I had a few of these engines and wouldnt be wasting a precious artifact, I took out the crank and polished it as smooth as I could get. Then I cleaned the case really good and heated it up with a propane torch and "tinned" the brass bushing with some lead solder. I let it cool down and did a bit of deburring ...suprisingly the crank fit pretty much right back in with only a slightly snug fit. I put some time in just spinning it with a drill and some oil till it loosened up and felt right. Well see how long it lasts, But I did finally get it to run on diesel yesterday (I still need to up compression a bit and add some A.N. to the fuel I think) !! YAY[8D] !! http://www.youtube.com/watch?v=K9r6JbN_Eg8 I put about 4 ounces through it and the crank fit still seems the same so maybe it will last a while. Maybe I'll mod my test stand to allow a muffler and go fiddle with it a bit more later. I wober if the solder could be a viable semi-permanent fix? Todd
Old 11-03-2011, 01:04 PM
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Default RE: AP .061 engine porting

I'm not sure what the material was, but old time engine mechanics poured molten metal into the engine blocks to form the bearings. They were called babbit style bearings. It had to be pretty soft, low temp stuff. After the stuff cooled off, the babbits got shaved by the mechanics freehand until they could cram all the parts back together and I'm sure that the break in process was a "nail biter" unless you were really experienced at it.

The Ford Model A engine was considered fairly low maintenance back then and they recommended a complete tear down with new rings, babbits, valve work, etc., every 10,000 miles.
Old 11-03-2011, 01:15 PM
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Default RE: AP .061 engine porting

ORIGINAL: Max_Power

Then I cleaned the case really good and heated it up with a propane torch and ''tinned'' the brass bushing with some lead solder. I let it cool down and did a bit of deburring ...suprisingly the crank fit pretty much right back in with only a slightly snug fit. I put some time in just spinning it with a drill and some oil till it loosened up and felt right. ................<snip>........... I wober if the solder could be a viable semi-permanent fix?
Babbitt bearings have been in use for almost as long as shafts have been running in pillow blocks and they were used in the automotive industry until the mid-fifties. There are a number of compounds used in poured babbitt bearings, but lead/tin compounds were among them. Solder with a high tin percentage should work satisfactorily. Many of the babbitt metals included antimony and copper for added hardness, but 60/40 solder might work OK. You will just need to ensure that your fuel has sufficient oil and that the engine doesn't get a hot lean run that might soften the bearing material.

Unlike bronze or brass bearings, the surface of a babbitt bearing is soft and easily scratched.

Edit: Whoops, looks like CP beat me to the punch on babbitt bearings.
Old 11-03-2011, 04:43 PM
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Default RE: AP .061 engine porting

The running surface of Clevite 77 (current production automotive insert bearings) is babbitt.

You can easily scratch the surface of babbitt with your fingernail, yet with constant lubrication and tight clearance it will last for hundreds of thousands of miles.

There are many formulas of babbitt, but most contain about 90% tin, alloyed with lesser amounts of antimony, copper and lead. The melting points are in the 400 degree Fahrenheit range.
Old 11-03-2011, 05:25 PM
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Default RE: AP .061 engine porting

My Dad (born in 1927) tells stories of replacing crankshaft bearings in Model T's with leather sliced from his belt.
Old 11-03-2011, 07:24 PM
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Default RE: AP .061 engine porting

Some of the really early Chevrolet 235 inline 6 cylinders the ENTIRE conrod bearing is poured Babbitt I think? I got to rebuild the 2-range "hydromatic "trans in a I think 1951 "duece-an-a half" military truck and got to check out the lower end when my co-worker was slappin a pan gasket on it. Weirdest thing I remember it had two driveshafts going to the tandem rear axles instead of a "power divider". One driveshaft was diagonal and came from above to get to the rearmost diff[:-] I popped said AP engine apart tonight and so far it looks "good to go" I know,I know...pictures maybe I'll pop it apart again soon after I get some more diesel runs on it. If I can get it to draw fuel a bit better it might just be a ok engine CP funny 10,000 miles probably seems really short nowadays...Even so..when I look at a engine it amazes me any of them last 5 minutes with those metal pieces sliding around at god knows how fast[X(] mind boggling some diesel engines go a million miles between overhauls, but a good metal file can knock off .010 in one stroke in cast iron or aluminum.Todd
Old 11-03-2011, 07:43 PM
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Default RE: AP .061 engine porting

ORIGINAL: digital_trucker

My Dad (born in 1927) tells stories of replacing crankshaft bearings in Model T's with leather sliced from his belt.
Yeah, a piece of belt leather will work OK, but bacon rind usually lasts longer.
Old 06-20-2012, 05:49 AM
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Default RE: AP .061 engine porting

Just in case anyone was curious as to how the case re-bearing I had spoken about on the AP is lasting I thought I'd post a follow up.

I yanked said engine off a model it had been flying for another 10-20 runs in flight and on ground (on 25% glow) to power up the model. That and I think I tweaked the rod, even with my hornet starter....These AP rods seem really weak. I'm thinking next one will be 2043t3 if anyone has center-to-center measurements on the holes I'd love to have em.

Anyway, The crank fit is still great...judging by trying to push and pull on a prop tip with the prop at 12 and 6 to look for radial slop or "teetering" of the crank in the case. I took some pictures, which honestly make the surface look like moon rocks (They are actually pretty smooth rinning a push-pin across them), But the photos show the lead filling low spots with the only brass visible peeking out at high spots. If anything it felt like the fit was a bit tight still. So I smeared a tiny bit of thinned down anti-sieze and put the engine on my new case fitting machine for a few hours while I dealt with some excess fermented liquids around the house [8D]. I'm betting I can probably buy a nice sharp reamer from enco that fits for $4 so I may try that next time.

I'll try to follow up here if I make a conrod... I know I probably wont get any more zing out of these APs, but perhaps I can make a few last a bit longer? Todd
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Old 06-20-2012, 07:36 AM
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Default RE: AP .061 engine porting


ORIGINAL: Max_Power

<snip> .....................So I smeared a tiny bit of thinned down anti-sieze and put the engine on my new case fitting machine for a few hours while I dealt with some excess fermented liquids around the house [8D].

Good choice in both cases.

I've read that the AP Wasp has been discontinued, so if you need parts, you should probably get them while they can still be found.

andrew

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