17 replies to this topic

[skoughi]

Hahaha! I'm glad my reputation is being spoken about on the other side of the world!! I had a very interesting email relationship with Roger over the Ant, he was like a very keen child regarding that wee jeep. I was trying my best to keep her location a secret in case he came up to our small island and waved some cash at my cousin and took her away. My uncle now owns her and is hopefully going to be starting the rebuild on her shortly, secretly I'm hoping he gets fed up with it so I can buy her!. Regarding Kent, I bought this cam kit from someone on the scottish mini forum, it came with followers and the double spring set which even at the time I wondered why! So I just kept the standard ones and the engine has worked fine. I felt that I only needed a spring strong enough to do the job and nothing more. I have no experience with any other cams but I'm hoping to get another 1275 engine and gearbox to rebuild and hopefully make a better job of the one I'm using just now. I'll probably be looking to a cam from someone else, maybe AC Dodd's ones. I read somewhere that Kent does Swiftunes ones, is this true?

[carbon]

I searched Kents website and couldn't find a +/- tolerance just the 36mm. There may have been a distance between coils spec as well but at that time I hadn't been as educated as what I am now! I've actually driven her for the last year and a half on standard springs with no apparent problems. I to felt there was no need for double springs as seeing as the 266 was be touted as a "normal driving low revs torque" cam and I know that high revs means shorter engine life, plus it's my first engine build so it's not got the quality that an experienced builder can produce, remember the many messages that went back and forth between us a good while ago when I was seeking advice when I was putting the engine together? I had the intentions to take her no higher than 5k revs and have 99% stuck to that! Plus I felt that stronger springs means more wear. Anyway as I'm trying to actually have a proper go at doing the cylinder head I thought I'd fit these double springs that have been laying around doing nothing, though when I think about it then there probably is no need for them.

As Moke Spider says, the clearance between coils is really important. And as this depends on the amount of valve lift you have, it will depend on the details of your individual build, particularly the rockers.

 

The 266 does indeed behave like a 'normal driving low revs torque' cam in a 1275 when using valve lift of under 8mm. But if you run the 266 in a 1275 with over 10mm lift at the valve the driving experience is very different, and I would then suggest double valve springs are the right choice.

 

Kent produced a Megadyne leaflet many years back showing power profiles from 266, 276, and 286. An interesting comparison, particularly when looking at torque curves. But I have not seen this recently, must try to dig it out again.

[skoughi]

I fitted the outer spring onto the head and fitted it into my newly made Heath Robinson type jig for checking lift and rocker geometry, works quite well and I'm rather chuffed with myself! When I raised the pushrod side of the rockers to the maximum lift for the 266 then the gaps between the coils were quite large, far larger than 50 thou. I didn't write down the exact figure but will give it a another go tomorrow evening. Fitted spring height was showing that I'm needing a 10 thou shim. Does the double springs have larger gaps seeing as there's two of them so won't need so may coils for the length of spring? I didn't check what the standard single spring was like but will do that tomorrow. I'm going to be using a set of pressed steel rockers so should be getting somewhere about 8.5mm of lift on the inlets so may be best just to stick with the single springs? Also I've got a loan of some seat cutters to redo the seats once I drift in some new guides, I'm intending to cut all the seats to get the valve tips to the same height. I had a go on a spare head and the certainly work but I haven't tried them on a unleaded seat, I'm thinking these seats will be too hard  for a set of hand cutters? They're not carbide tip ones.