George's Engine Build

[GeorgeS]

After enjoying various build threads I thought I'd post some photos of my own work. I've got plenty of motivation and knowledge from what's on this forum and Zappers build was great to follow, so like him I got busy with the camera.

What I have so far is a pair of NOS cases (2 stud), a DRT 53/105 crank (from Mathias), 27/69 (from Wayne) and a 25mm Dellorto & Manifold (from Hank). The barrel is a malossi 135 and the cases have been matched to it & the inlet opened up. On the shopping list is a Franz pipe (as everyone seems to have good things to say about them), a DRT runner with short 4th and probably vespatronic electrics. It will go in to my Primavera.

What I want is something that I can do 60mph on without kicking the arse out of it, plus a bit extra for overtaking if needed.

My old man is a bit of a whizz on the metal work front, so yesterday we had a bit of fun machining the cases for the crank to fit. His passion is building working model steam trains & as part of his kit he has a CNC milling machine. This is a mill he's owned maybe since the 80's and in recent years converted it to CNC.

Here's the machine:



Here's the 53/105 DRT crank, along side an old standard 51/97 (handy for measuring & comparisons). The DRT number looks great, I'm well pleased with it.



So first up we use a tool to find the centre position of where the crank it. The mill has a function that does a left/right, up/down movement & we ran this on the fly-side bearing seat.



We also checked the centre tool was good with a dial gauge...



Once we had that sorted, we used a program called 'CamBam' to draw the circle which we want to cut. This is the standard crank web size +2mm. You enter the tool width and depth & the program will run a kind of spiral downwards as it cuts over something like 3 or 4 revolutions. The last revolution is all at full depth.



To be sure, we ran the program on a piece of old insulation as a fuck up would have probably ruined the cases.





All good, so we went full the real deal:



Here you can see where the cut is being made, slowly making its way to full depth. At first we thought we where off centre as the bottom of the web was not being cut, but after looking at it afterwards its just a shallow point on the casting. The mill sounds great when its in action, a kind of siren type sound as the stepper motors are speeding up & down to make the circle shape.



Here's the finished cut:



After this we realised that the stepped-in 'lip' of the web, or whatever you'd call it, also needed taking out (seems obvious once you think about it). The crank would fit but the bottom of the conrod was very close to the wall. So the job was repeated taking that part out too.

Here's a couple of shots of the completed work & the shallow part of the casting is very clear to see. Nothing to worry about I think.





Next job was to make up a couple of dummy bearings:






Here's the cases together. The stepped part of the case now feels exactly in line with the drive side.



A bit of loose assembly and self-congratulating. All things considered the work went very well and there was minimal swearing. I can't take any credit, the old man is well and truly the chief here, and he even made the lunch!



So the next job on the list for me is to do a bit of searching & learning on port timings. What we did do is make up some 8mm 'sleeves' for the barrel to sit on (the conrod is 8mm longer than a standard stroke). I think this should at least give me something to work with & find out how much I need to pack the barrel up by etc. In this picture you can see the sleeves on the barrel studs.



The old man has the Malossi base gasket and will be making up a packer. He has some 12mm aluminium sheet for this & we'll trim it down if needed. We also made up a 2mm spacer that I'll need for the conversion bearing.

So I think I need to invest in a dial gauge with magnet base & a decent degree disk for the next part. The piston deck also seems very high, the side of the piston is maybe a whisker below the barrel edge (I'll take a picture over the weekend), but I suppose I've only packed it up by 8mm and the stroke will be +1 to standard at TDC.

I'd be very glad to hear of any advice, comments etc to help me along the way. I'll post more as the work continues. I'm interested to hear if anyone would recommend a GS piston from the outset or the MMW head (I have the old-style non O-ring head which I've read are a bit shite).

All the best,
George.

[jeanshorts]

You might deck the case to get more surface to seal and so as not to have to back to it in the future should you want to go bigger. I decked mine a tad for height adjustment but wish I had just gone the full 1-1.5mm now.

[nick121170]

loving this thread

[Wayne Miller]

Nice thread George, we like engine builds

[jude]

Looking like a good thread already.
Oh, to have access to all those toys

[a4tlo]

Nice one George I will try and keep up. as this is all a bit above me.

[eean]

Great work George you're very lucky to have a dad that can do that but also the machinery :-)
Watch for that 2mm spacer you've made for the conversion bearing over closing the lube hole in the casing you may need to just use a drive side circlip and leave the opening of it under the hole to let it do its job ;-)

[GeorgeS]

I had a couple of attempts at measuring port timing over the weekend and realised it really had no idea what I was doing. With some more reading and thinking, I think I understand it now - it's not about when things happen (as in, when on the timing disk) its about duration, right? Also, setting things up accurately with just digital callipers was a real pain in the arse and hopefully I'll have a dial gauge in a day or so to make things easier.

jeanshorts, I'll probably not deck the cases as they're already matched to the barrel and I wasn't planning on doing much at all to the inlets, but I'll certainly keep it in mind as things progress.

eean you're spot on about the spacer covering the oil hole, it cuts right across the middle. Whilst there's still space either side of the spacer I guess you really wouldn't want anything to reduce the amount of flow, so I'll probably cut a section out of the spacer & fix it with something (I suppose it could move with vibration or during fitting?).

There was a recent thread on conversion bearings and after reading it a few times I can't see what comes out as preferred in terms of either ball or roller. I'm thinking roller as you'd get any lateral expansion movement without putting load on the outer race & therefore the spacer wouldn't be given the opportunity to move?

[eean]

Either bearing is good, its your personal choice, I would use the drive circlip as the tension will stop it moving around and blocking the hole up ;-).

[GeorgeS]

So here's what I have on the port timings, I'd be glad of some advice here, firstly if they look like what you'd expect of a Malossi barrel out-of-the-box.

With barrel packed 9.4mm
Exhaust          Open:269   Close:90     = 179 Duration
Left Transfer   Open:243   Close:116   = 126 Duration
Right Transfer Open:244   Close:115   = 129 Duration

(is that a blow-down of 26?)

With barrel packed 8.0mm

Exhaust          Open:267   Close:94      = 173 Duration
Left Transfer   Open:240   Close:121    = 119 Duration
Right Transfer Open:241   Close:120    = 121 Duration
(is that a blow-down of 27?)

My inlet timing is around 190 with the case inlet port fully opened up.

I'm targeting 190-192 on the exhaust (for Franz) and 125 on the transfers, so that's going to be somewhere between the above two, is that right?

Thanks for the advice,

George.

[GeorgeS]

Just a small update, the old man has made the packer and I'll pick that up at the weekend. Been trying a few different high combinations out and plenty of measurements and I think I know where it's heading.



Whilst waiting I've started work on the inlet side. The inside has been taken out to the very limit, hope it's not too far



On the manifold side I made a template and there's a little bit still to be taken off from the top of case. On the manifold I need to take some from the bottom, but very nearly there now.



These arrived today!


All the best,
George.

[smallframetony]

thats not much sealing surface left on the inlet, by the looks of it there is no sealing surface left on the bottom. Might have gone too far there

[potatopl]

I've done almost the same to mine, it's very easy to fuck up the bottom edge of the pad during porting as it's much less perpendicular to the intake wall than other sides. It's good to pait the sealing pad with a black permanent marker before starting to work on it, makes it more visible how much sealing surface we have left.

[nicsar]

Looks to be a bit too far.. hope its only an optical thing. You want to break through the casing on the bottom of the inlet, try to make a straight line all theh way through.

[jeanshorts]

Looks like you've gone one step beyond there on the sealing pad as others have noted. In retrospect I wish I had just gone reed and may do just that at some point. My filter needs wringing out between rides from back sputter is my main complaint. That and I wasn't able to get a respectable inlet timing without going at the crank. That with a short inlet pad, came out circa 170.

[GeorgeS]

Yes, it really is right on the edge. The photo makes it look worse than reality, here's another shot where which is slightly better, you can see there still is a wall at the bottom, but its extremely close.



It not my work I must say, it was done by Graham at Kegra sometime in the mid 90's when I first got these cases and barrel (and before 'life' got in the way...). Hopefully I'll just about get away with it, we'll see....

Is there anything I could do to build up that edge? JB Weld or something? Having never used the stuff I don't know how well small bits would stick and if it came loose it would make a right mess.

Thanks,
George.

[potatopl]

I've recently repaired a two deep crevices in the sealing pad with liquid metal. Then I started to work on the pad with dremel and the repair was very sturdy, nothing had chipped off.

I'd put some JB Weld between the edge of the pad and the inner surface of the crankcase. When it's half-dried the liquid metal becomes plastic, but not sticky anymore. I'd take a crank then and press it to the repaired area to form a new sealing pad.

Remember to grind out the surface and clean with acetone a moment before applying the liquid metal.

[briggsy]

hi George, great thread - I think you will get away with that sealing pad, the last photo shows some of the seal present, im guessing but it looks to be around 0.5mm?

[Tommy]

Feb 23, 2014 19:08:34 GMT eean said:

Great work George you're very lucky to have a dad that can do that but also the machinery :-)
Watch for that 2mm spacer you've made for the conversion bearing over closing the lube hole in the casing you may need to just use a drive side circlip and leave the opening of it under the hole to let it do its job ;-)

Is this common practice to install a driveside circlip when using the 6005 conversion bearing?

[eean]

Mar 5, 2014 22:50:43 GMT Tommy said:

Feb 23, 2014 19:08:34 GMT eean said:

Great work George you're very lucky to have a dad that can do that but also the machinery :-)
Watch for that 2mm spacer you've made for the conversion bearing over closing the lube hole in the casing you may need to just use a drive side circlip and leave the opening of it under the hole to let it do its job ;-)

Is this common practice to install a driveside circlip when using the 6005 conversion bearing?

Its a good solution if your crank has not been made with a 2mm lip to consider the bearing only being 12mm instead of 14mm, its a case of measuring and trying :-) My falc crank has the 2mm lip so didnt need it