Lotus Elan

Camshafts?

PostPost by: Davidb » Fri Jan 27, 2017 6:20 pm

After examining the cams in my engine I have concluded that they are the standard 'B' cam as described in Miles Wilkins book. What intrigues me is that Wilkins states the cam lift as 0.375" whilst he states the Sprint cams are 0.360". Is this a misprint? Should the numbers for the 'B' cam be 0.355"? It seems odd that the Sprint should have lower lift.

I have read as much as I can on cams on the forum and I am aware of the benefits of high lift/short duration cams-I used these on the last engine I rebuilt (Aston Martin) with good results.

I am on a budget with this rebuild though-the valves and seats are in good shape and the valves are the 1.56". I have read comments by the Australian members saying the Wade 205 grind is good-this is .373" lift and 30/70-70/30 timing. If the "B" cam is indeed .375" lift then it is very close to the Wade 205.

What have I missed?
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PostPost by: rgh0 » Sat Jan 28, 2017 12:21 am

Wilkins is wrong ( sorry God for my blasphemy :shock: )

I believe the confusion arises from the FIA homologation papers submitted by Lotus where valve lobe lift on the standard cam B cam of .350 was confused with the valve lift at coil bind of .375 inch ( maybe deliberately to allow use of a higher lift cam ???)

The Wade 205 cam was to give a longer duration and to fit in the highest lift cam you can as a bolt in replacement without changing the rest of the valve train. It has more top end power than a sprint cam but looses a little mid-range torque with its long duration timing. When fitting a Wade 205 in an other wise standard engine you always need to check for valve coil bind as you are very close to the limits and given the variation in head machining they may not fit.

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PostPost by: Davidb » Sat Jan 28, 2017 4:30 am

Many thanks Rohan.

So what cam grind is best given my present specs-Standard cams, 1.56 valves and no wish to spend money on deepening the valve spring pockets?
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PostPost by: rgh0 » Sat Jan 28, 2017 5:16 am

You dont need to spend money deepening the valve pockets to fit high lift short duration cams these days. But you will need to to fit new valves, spring set and followers.

The cheapest and best option for a road car if you don't want to touch the rest of the valve gear is to fit Sprint cams or their equivalent. This combined with the other sprint modifications give a significant HP and Torque boost over a standard B cam car.

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PostPost by: Davidb » Sat Jan 28, 2017 9:49 am

Thanks Rohan, I was still a little confused about that.
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PostPost by: Davidb » Sun Jan 29, 2017 4:17 am

After more consideration and reading page after page on this forum, I think I will try Sprint cams. My racing days are over but I drive in 'enthusiastic' style in the mountains around here so lots of torque is what I need.

Anybody have any good condition Sprint cams they want to part with? :)
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PostPost by: Davidb » Sun Jan 29, 2017 8:20 pm

I spent some time searching for more cams and found the Burton BLH46 which provides .380" lift and 280 deg duration-that doesn't seem too wild.

I noted Rohan's concern that since this is at the limit of lift for use with standard valve train components all of the fits and clearances must be very carefully checked.

My engine is 1720cc.

Anyone using this cam who would care to comment on it?

http://www.burtonpower.com/fast-road-ca ... 6-ltc.html
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PostPost by: Craven » Sun Jan 29, 2017 8:53 pm

Hi,
I think these are the closest new cams available to the sprint spec, their version of a CPL2.
Ron.
http://www.newman-cams.co.uk/Newman-Cam ... _18901.jsp
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PostPost by: Davidb » Mon Jan 30, 2017 4:08 am

Thanks Craven. I am hoping to find a cam that with a little more lift than a Sprint but without having to replace the valve train components. Newman make a cam very similar to the Wade 205 and the Burton I mentioned above:

http://www.newman-cams.co.uk/Newman-Cam ... _18901.jsp

The Newman and the Wade are both 30/70 but the Burton is 34/66--I wonder if that would be noticeable?

Edit: I just realised that the cams are the same but the setting of the MOP is different-so either the Newman or Burton cams above could be adjusted to give the same timing--am I right Rohan?
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