I just bought a mvvs .77 engine off **** for $100, it supposedly came direct from Morris hobbies in the summer of 2004.

I'm not sure if i'll get the manual with this purchase so I was wondering what glow plugs work best for this engine. Also what kind of fuel. I've heard 0-5% nitro but than I heard mention from on a post from Dar on possibly higher nitro percentage for mvvs engines into the u.s.????

The muffler that comes with it looks to be the cheaper 3255 side muffler. Would a better muffler be a good investment, recommendations and gains to be expected?

THanks,
Ryan

Ryan,


You did not mention is the engine is NIB, or used.

I must also know the 'model year', so to speak...
Does the carburettor on the engine have an elaborate intake 'trumpet', no idle stop screw, the idle needle has a full cross on its end and the prop driver is blue anodized?

...For most engines Morris offers the cheaper, extra shims "solution" to allow it it to use more readily available 10-15% nitro. Why don't you ask the original owner what he used, to get a better idea of what you are facing.

If the engine is 18 months old, or more, remove the head carefully (keep the sleeve aligned with the ports) and check if there is one head shim, or more.

Providing you can access 5% nitro fuel, one shim is all she wrote.


The original glow plug is/was a Novarossi 6. OS #8, Enya #3 and best of all K&B-1L will work great.

K&B is cheapest.

Dar,

Here is the pics from the auction page, it should come in the mail tomorrow. The seller said it was new in the summer of this year purchased right from the morris hobbies website. He said he ran 4 12oz tanks of fuel through it. I'm waiting for a responce from him on what kind of gas he ran. I'm guessing its unmodified as far as the shims and such but I'll ask.

I recieved my engine today. I also heard from the previous owner that he ran coolpower %15 !! Yikes. Could he have damaged it running that high of nitro on a brand new motor? He said it still has some breaking in to do. I've checked around and the 3 hobby shops nearby don't carry anything below 10% nitro so I guess i have to order it. What is the recommended gas to use?

I also didn't get a manual, is there one i can download online somewhere?

Ryan,


Running 15% Cool Power in this engine is analogous to running unleaded regular gasoline in your Ford Power-Stroke Diesel truck...
Need I say more?

Break-in MUST be done as described in [link=http://www.rcuniverse.com/forum/Tapered%2DBore_Engine_Break%2Din_%2D_Upgraded/m_1850473/tm.htm]this thread[/link].

The break-in is over by the time the engine has accumulated 15-20 minutes. That would mean about a 12 oz. tank and a half.
If not, he was trying to do a rich break-in. This is not good for this engine!

If the engine did run on 15%, the head is probably shimmed.

Find a source for 5% nitro, 20% oil fuel, out of which about half is Castor oil. If you order 4 gallon crates, the LHS will get it for you.

Cool Power is all synthetic. Again, this is not good for the engine!


Well, at least the carburettor seems to be the new model...


After removing the head to check out the shims, turn the engine over and see if the piston still 'catches' at TDC. It should.

I would not buy an engine from this source...

Well I was wondering what anyone thought of this. The first pic is when i pull the prop toward the front of the engine there is a gap between the prop driver and the case (see red arrow). In the second image, i pushed the shaft in toward the back. I believe that piece is called the prop driver, the driver is not moving on the shaft but the whole shaft is moving.

The driver actually snaps into the case as shown in pic 2 but it pops back out as in pic 1 when i pull the prop forward. Is this play normal? I measured the movement to be about 2mm or 5/64" with my caliper. Is the driver supposed to be pressed in the case harder to prevent the shaft from moving?

I ran the engine just for a 30 seconds or for the first time since i bought it used. It seemed fine during idle and low rpms, no wierd noises. I ran out of time so i'll play more tomorrow. I did notice the shaft moving out/forward (pic one) when it started.


Thanks,
Ryan

Ryan,


The crankshaft in MVVS engine is a push-fit into the bearings.
When disassembling the engine, after the con-rod is off the crank-pin, the shaft can usually be pushed back (out) with finger force.

The prop-driver sits on a split tapered collet. If this collet is not directly against the front bearing inner race, the crankshaft can move forward and back. The collet locks in place on the crankshaft when the prop-driver is pushed onto it, by the tightened prop.

You will probably see some scuffing on the backplate too.

When you buy a used engine, especially mail-order, you rarely know what you are actually getting...


Remove the back-plate and the prop-driver. Push the drive-collet back against the front bearing, while holding the crankshaft pushed forward (no need to remove the piston and the con-rod).

Now, reinstall the prop-driver and tighten the prop. Only the slight C3 bearing play should be evident. The shaft should have a very small (0.1-0.3 mm) free-play.


If the bearings are shot, this is a totally different ball-game...

Thanks for all your help Dar, I really appreciate it as I'm new to this and it's great to get help like this so fast online. I'll play with it today and get back to you.

Two more things, Ryan.

By the box the engine came in, it must be about three years old.
MVVS have since changed the design of the engine boxes twice...

Also, there is a very limited manual, with a short paragraph describing the break-in.

There is no more elaborate manual that I know of.

Thanks Dar, I'll check into how old this engine really is.

I ended up not being able to get rid of the play, i tried your suggestions to no avail. With the prop on tight there is still that same play in the crankshaft. You can watch my maiden video and listen to the engine here http://www.rcuniverse.com/forum/m_16...tm.htm#2270151 , .... let me know what you think.

Ryan

Ryan,


You must ascertain where the 'play' is!

"Nowhere" cannot be the right answer.

The crankshaft is one-piece, so the front cannot move separately from the rear (duh!).

The possibilities are:

1. The crankshaft is free to slip forward and back, in the bearings' inner races (for that I gave you a possible solution, in post #7, by verifying the front bearing's inner race, is held firmly between the 15 mm rear journal and the prop driver tapered collet.).

2. The bearings' outer race is held too loosely in the crankcase and is thus free to slip forward and back, with the crankshaft.

3. The bearings have too much free play, with the inner race moving excessively, with relation to the outer race.

4. A combination of the above three, or parts thereof.


When you engine is hot, does the amount of play decrease?

Hi Dar,

Is these statement apply to this particular engine only or all MVVS glow engines or all non-ringed engines ? what i know cool power fuel claimed to be the best suit for ringed engines..... and i stil hav 4 gals 15% Cool Power in box... [:-]

Thanks

at one point i tried cool power 10% in the mvvs .77 and it runs like Dar says(crap).
I get better performance with 80/20 . Last rpms checked
13.5*8 bolly @ 9500 (same rpm as MA 14*6, retired now)
13.5*6 bolly @ 10500
Engine is installed with 3267 muffler. It should sing a bit more with a standard 3255 muffler and be a monster with a pipe.

Idik,


I do not recommend (and neither do most fuel manufacturers) using fuel with all synthetic oil, in any ring-less, tapered bore engine. The exception is YS.

The MVVS .77 is an ABC engine, of the discussed class, so the recommended fuel must contain some Castor oil (I recommend 10%, although others may settle for less).

I am running the same engine (old type of casting) with a 3267 in cowl muffler .
The engine does not like cool power fuel at all and I have gone back to running 80/20 fuel because it is offers more cooling (more oil, castor). An enya #3 plug is good.

some rpms i get with a 13.5*8 bolly @ 9500, bolly 13.5*6 bolly @ 10500, MA 14*6 @9500 .

The engine will have better rpms with a 3255 silencer / tuned pipe.