captinjohn

I would like too see a photo of the "new" head with a glow plug installed. That is of intrest ...right? Capt,n[:-]

CustomPC

If i get time i'll take the head off tonight and take a pic.

DarZeelon

Quote:

ORIGINAL: Sport_Pilot

There appears to be nothing in the way to cause it to bottom out, unless the thread is tapered.

Hugh,


The thread does not have to be tapered to cause this...
As you can see in CPC's quote below; the thread is too short and the hole continues, having too small a diameter, for the rest of the plug's thread to fit into it.

The hole is definitely not machined correctly...

Quote:

ORIGINAL: Sport_Pilot

Valves are canted in hemi or penthouse designs, flat in wedge designs.

Yes, but in a 'wedge' design, the valves are both tilted to one side... for their stems to be perpendicular to the angled top of the combustion chamber.
In this engine, they are 'in line' with the piston, because it is *not* a 'wedge' design.

Quote:

ORIGINAL: CustomPC

There are no threads exposed when the plug is inserted. The tip of an OS F sits flush.

It's the length of the threads which is the issue. The plug screws in until it reaches the end of the threads but that is not far enough to seat the copper washer and get an effective seal.

Noted, CPC.

CustomPC

Ok, here are the pics of the new head.

Pic 1 is with the glow plug and 1 copper washer

Pic 2 is with the glow plug and 2 copper washers. You can see the glow plug is the same depth.

Pic 3 is without the glow plug and you can see that the thread has not been cut the full depth of the hole.


I've found a local stockist of glow plug taps and one is one being expressed to me overnight. Hopefully i'll have it for the weekend and i can continue breaking in this engine.

If anyone wants to see some pics of the internals of the F-130S let me know and i'll try to take some before i get it back together.

estradajae

It´s always nice to see the guts of an engine! put some pics there!

Sport_Pilot

Which is what happens when you don't run the tap all the way through. The tap cuts metal, it is tapered and will leave a shallow thread on the tapered end. The new photos show very shallow threads near the combustion chamber

It would appear to me this is a wedge design, many have a flat squish area, most are not this large allowing valves to be placed in it. The glow plug is in front of the squish area which is correct.

DarZeelon

Quote:

ORIGINAL: CustomPC

I've found a local stockist of glow plug taps and one is one being expressed to me overnight.

CPC,


I do hope you did not over-pay for the glow-plug tap you had ordered...

Please read [link=http://www.rcuniverse.com/forum/m_8923459/tm.htm]this recent thread[/link] to understand what I mean by that.


A price of US$1.90 is enough for a reasonable quality tool.

RAYTELI

My Feedback: (113)

Just checked my TT 1.30. The plug will not seat. It gets tight, but the washer can still be moved. I removed the head and ran a 1/4 32 tap throught it. A suprisingly large amount of cuttings resulted. Cleaned everything up and reassembled. Everything is fine now. E-mailed Ace about this problem, but have had no respones from them yet.

cold_reboot

My Feedback: (20)

Hope they get this resolved, I'd like to have one of these.

CustomPC

I called the Australian importers and brought this thread and the issue to their attention.

I'll wait and see what elsy the have to say, but they have advised me to send the stripped head to their warranty repairer for a helicoil insert.

The person i spoke to said he has one of the first batch of engines and has no problems with his. He also said that Brian Winch has reviewed one and not seen the problem so perhaps it's only one batch of heads with the problem.

cold_reboot

My Feedback: (20)

lets hope! I had hopes for this engine going into a P47 or P40, let us know if you hear anything!

Waco

My Feedback: (265)

well I just bought one of these 2 weeks ago and so I went out and checked mine, I put the supplied glow plug and washer in and tightened it down, it snugs down nice and tight and the washer is not loose, so mine is oky, so not all of them is like yours.

CustomPC

Waco, that's good to hear.

I'd keep an eye on the area around your plug for any signs of oil pooling up there when you run it.

There's at least 3 heads with the problem so far. 2 of mine and the one belonging to Raytele

My Tap just arrived and i'll be able to fix mine tonight and do some more running over the weekend.

CustomPC

I've just finished re-assembling the engine after very carefully running the tap through the head. It was a slow process, going about a quarter to half a turn at a time, clean, test, repeat until i got the right depth.

You can see the end result in the pics below.

Pic 1. With glow plug tightened nice and snug.

Pic 2. The longest wall of the hole where the threads have been extended but not right to the end.

Pic 3. The shortest wall of the hole where the threads now go right to the end.

Pic 4. The original head with the stripped thread which i used for practice to determine just how far in i needed to run the tap. You can see i went just a little too far and now the hole has some jagged edges.

The litmus test was that i was able to screw a plug in fully without the copper washer. That let me know the threads were deep enough.

I can tell you that there is now a significant boost in the compression felt when the engine is rotated by hand. I hope to take it to the feild on Sunday and continue the break-in.

togatoga

My Feedback: (42)

I don't have any problems with both my engines, the plugs fit.Only thing is I used the OS type F plug, didn't try out the supplied redline plug though. The backfiring is an issue for me right now, its caused the demise of 2 plugs.

CustomPC

I've just finished testing my engine after the repairs and the engine runs much better and more consistant than the last time i ran it.

I did the whole break-in routine again, so as to bed the ring into the new cylinder.

After the first 3 tanks i peaked the needles and got 9,000rpm on both the 14x10 and 15x8 props.

The minimum reliable idle is slowly coming down. At first it wouldn't idle below 3,300 but it's now about 2,400rpm after I leaned the low needle a quarter turn from the factory setting. The idle is improving with each run.

I'm now satisfied with the engine enough to mount it onto my Venus II.

estradajae

Those are good news
I hope you enjoy your engine!

silver.kiwi

I purchase one of these engines back in July but have not attempted to run it yet. After reading these posts, I decided it would be a good idea to check mine out for the problems some of you have posted here. A visual inspection of the threads in the cylinder head appeared O.K. so I went ahead and carefully inserted the plug. It DID appear to stop short of going in fully but I backed it out and applied some more gun oil to the threads and on the second attempt it went in smoothly. I then filled the space around the plug with more oil and checked for air leaks. There were no bubbles so I'm happy to report that mine appears unaffected and I was able to get the supplied Red Line plug to tighten down nicely, or so it would appear before doing an actual test run. I also Emailed the distributor here in the U.S. (ThunderTiger 4U) to alert them to this forum so that they would have the opportunity to respond here as well. Cheers.

CustomPC

togatoga,

I was just pondering your backfiring problem and it occured to me that earlier in this thread you said you were using 20% fuel.

The compression on my engine is pretty high. Perhaps 20% is too much for such high a compression.

I would give 10-15% nitro a try to see if it relieves backfiring.

Sport_Pilot

Don't know about the 130, but 25% nitro was OK on the .91 TT.

gkamysz

My Feedback: (19)

The thread hole must be improperly designed or manufactured. Many OS engine have a hole that just clears the tip of the F plug making the end flush with the combustion chamber surface. With the Surpass 2 series engines the plug was made so the tip of the F plug protrudes into the cylinder.
The combustion chamber is typical for this type of engine, I don't see any issue with that.

captinjohn

High compression engines do better with less nitro...try that first to elimanate backfire or pinging. Capt,n

Sport_Pilot

The TT 91 is not a high compression engine. Most newer four strokes are not. OS surpass II is now used with 30% nitro in SPA pattern.

togatoga

My Feedback: (42)

I take it back.I removed the engine from the plane to do a thorough check of its condition after the backfiring and plug eating antics. I noticed some scoring of the plug threads and some fluff.I reckon its because the threads were not deep enough and as a result of the glow plug "making" new threads further in, it caused some of the gunk to be embedded in the threads as the plug was screwed out.


Custom PC was right, the threads are not deep enough, its just that because of a combination of ham fistedness and threads that thankfully did not give way, i did not notice anything amiss. Thing is that you might get a leak if a compressed or thinner washer is used which actually alerted me to the problem as I could hear whistling noises as i turned the prop over. A fix is needed or you might get a stripped thread eventually or inconsistent runs.

CustomPC

If i were you i'd strip the engine and make sure none of that gunk went through the engine.

My liner had a visible scratch which didn't look too deep but it could definately be felt with a finger.

I replaced the liner and tapped the thread with a 1/4-32 tap and it's working well now.


P.S. If you re-tap the thread, don't go all the way through as it will make the hole jagged (see my pics earlier in the thread). Run the tap through about 1/4 turn, test, repeat until the plug washer seats firmly.