Nemett Jaguar--Canadian style

[gus]

While Paul and Gus and Jim are still slogging at the Nemett-Lynx Engine,Brian is about done with Jaguar.th_wav

 

[Brian Rupnow]

No Gus, far from it. I have to make the cams, the sump, the gear cover, the pushrods, and the ignition cam yet.

 

[Brian Rupnow]

This is step #1 in my cam making operation. I am going to cut both cams at the same time, then separate them afterwards. The material I am using is an oil hardening tool steel, 1/2" diameter. It was left full size in the area where the two cams will be and reduced to 0.236" diameter in the area which will be adjacent to each side of the cam lobes. All turning was done at 550 RPM with the .093" cut -off tool you see in the picture. The parts were drilled and reamed to 4 mm diameter to a depth sufficient to pass through both cams and the lands on each side of them. I will now shorten the material to approx 3" long and mount it in the 3 jaw chuck mounted to my rotary table.

 

[Brian Rupnow]

Okay--Part is in 3 jaw mounted on rotary table. Long "X" axis of part is centered under the quill. Rotary table is set on 300. Digital vernier has been zeroed on the top surface of the 1/2" round rod which will become the cam. Table stops are set so that I can only move the rotary table within a predetermined distance, which means I don't have to constantly watch my travel in X axis. 3/8" 4 flute end mill being used to make the cuts. Wish me luck!!!

 

[Brian Rupnow]

It appears that the cam program works okay. What it wasn't clear about is the fact that when you are finished all the milling, it looks like this. The lobe portion of the cam appears to be fine. However the base circle of the cam is still based on the 1/2" diameter rod that I started with. This base circle has to be brought down to 8mm or .314". I can't do it in the lathe without cutting away the lobe of the cam. I guess my next step is over to the rotary table to finish cutting away the base circle.---More to follow.

 

[nowramfg]

Brian, why did you set the rotary table to 300? I am needing to make some new cams also for the Lister and its sister. Also what increments ,in degrees, did you use?

 

[Jasonb]

Brian, top of page 653 says once the offsets have been cut to do the rest of the increments at the zero lift setting which gives the base circle.

Cam has 120deg of duration with the highpoint at zero degrees you start to form the lobe 60deg before that so 360-60 = 300 and the cam is rotated through 120deg ending at 60deg with no lift. 60-299 are cut at zero.

 

[Brian Rupnow]

Jason--Having not cut a cam this way before, I didn't understand that I was to leave the blank in the rotary table and continue cutting at zero change in the depth of cut until I had went completely around the rest of the cam. However, the blank is out of the rotary table now, and setting on the end of my desk. Odds are very slim of putting the part back into the rotary table chuck at this time and carrying on. I would never get it back in exactly the right position in a thousand years.--But wait---The tricky part of the cams is cut, and all is well. If I flip the rotary table 90 degrees and put the part back into the chuck so it is setting vertically, then use the side of an end mill to finish cutting the unmachined portion of the cam to the correct .157" (4mm) radius, would that not achieve exactly the same end result?

 

[Brian Rupnow]

Against all odds, I was able to return the unfinished cam to my rotary table set-up (which I thankfully hadn't torn down) and as far as I can see, hit it "spot on"!!! I was able to finish milling the profile in the original manner it was intended to be finished in. The cams turned out perfect, as near as I can tell.--That was more good luck than good management, believe me!!! Now I have to separate the cams from the parent stock and from each other, and heat treat them with my oxy acetylene torch and an oil quench. ---And I REALLY REALLY hope that they don't change shape or tighten up in the bore, or anything weird!!!

 

[Brian Rupnow]

So, there we have it---two cams, finish machined and heat treated. That shaft they are setting on is the cam shaft, but their final resting place will be inside the crankcase. I just tried them on that shaft to make sure the bores hadn't shrunk when they were heat treated.

 

[ShopShoe]

Brian,

Thanks for showing the trials and tribulations of your cam-milling attempt. You inspire confidence for future learning of new skills. In some ways cams look more scary than gears when one hasn't done it yet.

Regards,

--ShopShoe

 

[doubletop]

Brian I've been a bit slow in finding this thread. As I saw somebody pointed it looks like Jaguar, Bobcat and Lynx are the engines of the moment. I now need to go and find Chucks thread. Then I can sit back and watch the fun having already done the Bobcat and Lynx. Pete

 

[Brian Rupnow]

Today was just too beautiful outside to spend the whole day in my shop. It was 86 degrees F and all sunshine today. I did however sneak in for a couple of hours this afternoon and Loctited the first cam to the camshaft---a messy, nasty business, and Damn, I hope I got it in the right place. There isn't much room to work inside that crankcase, even with the crankshaft removed. I also managed to finish the intake manifold, bolt it in place, and install a Chuck Fellows carburetor on it. I'm not sure of the proportions---It looked okay on the solid model, but it kind of looks like a long necked goose in person. Perhaps when I get the rest of the engine back together things will look better proportion wise. I may have to put a spacer under my rocker arm support--the rocker arms are running uphill on quite a pronounced angle. I am going to be very tight for room between the intake pushrod and the head of the capscrew holding the intake manifold on. I may have to do a little creative counterboring there, although I'm not sure yet. Tomorrow, after the Loctite is thoroughly set up on the first cam, I have to position the second cam rotationally and Loctite it to the shaft.

 

[Jasonb]

Brian, it looks like you have the hole for the rocker pivot and that for 3mm bearing on the same centreline rather than the bearing being offset upwards, this would account for your sloping rockers.

 

[gus]

Today was just too beautiful outside to spend the whole day in my shop. It was 86 degrees F and all sunshine today. I did however sneak in for a couple of hours this afternoon and Loctited the first cam to the camshaft---a messy, nasty business, and Damn, I hope I got it in the right place. There isn't much room to work inside that crankcase, even with the crankshaft removed. I also managed to finish the intake manifold, bolt it in place, and install a Chuck Fellows carburetor on it. I'm not sure of the proportions---It looked okay on the solid model, but it kind of looks like a long necked goose in person. Perhaps when I get the rest of the engine back together things will look better proportion wise. I may have to put a spacer under my rocker arm support--the rocker arms are running uphill on quite a pronounced angle. I am going to be very tight for room between the intake pushrod and the head of the capscrew holding the intake manifold on. I may have to do a little creative counterboring there, although I'm not sure yet. Tomorrow, after the Loctite is thoroughly set up on the first cam, I have to position the second cam rotationally and Loctite it to the shaft.

This one engine I must build. I am crazy about push rods and rocker arms.
Seen my dad adjusting the tappet clearance as a young lad of 12. Dad had no time to explain why the clearance is so important.

 

[Brian Rupnow]

Jason--nothing the matter with the part.--However (embarrassment)---I had them mounted upside down!!!---Brian

 

[Brian Rupnow]

Well, for better or worse---The cams are both attached to the camshaft. I agonized all morning about just how they went on there.--The angles just weren't working out. After just about pulling my remaining hair out, I found that the value I had entered for the ratio between the gears was entered incorrectly, giving me a ratio of 1.91:1 instead of 2:1 for the ratio. Once I got that dragon slayed, things made a great deal more sense. Part of my problem also, is the fact that I want this engine to run in the opposite rotation to what old Malcolm had intended. I also whittled out a pair of counterweights for the crankshaft while I was waiting for the camshaft Loctite to set up firmly. I am actually down to only 4 or 5 parts remaining to be made. Of course, one of them parts is the gear cover, which isn't exactly simple.

 

[Swifty]

Hi Brian, are you confident that the loctite will be enough to hold the cams in operation. I know that Malcolm used loctite, it's just that I'm a bit cautious about using it on rotating parts.

Paul.

 

[gus]

Hi Brian, are you confident that the loctite will be enough to hold the cams in operation. I know that Malcolm used loctite, it's just that I'm a bit cautious about using it on rotating parts.

Paul.

Me too. I come from WW ll when Loctite if on hand would have been scoffed by
my neighbourhood maestros who believed in keys,dowel pins etc.:rant:

Will watch and see. No offence. Gus is too conservative. And fear of the unknown.But I am open minded on Loctite.

7.45am Singapore time.Will clock in at 8:00 am to work on Con-Rod.Will do it smarter this time. The last two Con-Rods barely passed Q.C. for Webbie and Rupnow H&M Engines.:hDe:

 

[Brian Rupnow]

Properly applied and cured Loctite is very powerful stuff. Am I confident of its holding ability in this condition?--Hell No!!! But then again, maybe it will work fine. Any problems I have had with Loctite not holding in the past was more a case of my impatience than of Loctites holding ability. I cleaned both parts to be Loctited with "hot" paint thinners, which will degrease anything. I sanded the shaft with light sandpaper to abrade it to give something for the Loctite to grip. I set the Loctited parts up under a 60 watt lightbulb for 12 hours to speed up the curing time. I am a bit concerned about the strength of the valve springs I used---(0.025" diameter wire). This is a case of being between Devil and deep blue sea. A good strong spring will help avoid valve leakage problems. However, that same strength may make the Loctite let go. i will try it and see. If (worst case scenario) the Loctite lets go, I will carbide a 1mm hole through the shaft and the cam shoulder and put in a dowel pin.