Lotus Elan

Camshafts marked IWR 141

PostPost by: mart2elan » Sat Mar 03, 2018 4:50 pm

Hello,
I have a set camshafts marked with IWR141. I bought them about 8 years ago in lot of spare parts. The only thing i know is that IWR could stand for Ian Walker Racing but i'm not sure about this. Does anyone know the specifications of these camshafts?
My TC is a Weber SE with the standard C (SE) cams. Because of a major oil leak at the rear crackshaft seal (thirth time since rebuild in 10 years :oops: ) i have to take the engine out and want to do some more jobs on the engine. A good moment to check the valve train and put these camchafts in when they give some more power.
I did some measuring on the cams but this gives only a very global indication.
Marten.
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PostPost by: RonR » Sun Mar 04, 2018 11:13 am

It's a bit of a long shot, but you could try contacting FAI auto https://faiauto.com/about/history-2/, they took over what was left of Ian Walker Racing around 1970. Perhaps they still have some documentation from that era.
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PostPost by: elated » Sun Mar 04, 2018 2:24 pm

I have a note that they were designated "Race Rally", 135 bhp contended for, 0.350" lift and had a 270 degree overlap. Inlet clearance 5 to 7 thou / exhaust 9 to 11 thou.
I cannot guarantee accuracy of above.
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PostPost by: nmauduit » Sun Mar 04, 2018 3:08 pm

mart2elan wrote:Hello,
I have a set camshafts marked with IWR141. I bought them about 8 years ago in lot of spare parts. The only thing i know is that IWR could stand for Ian Walker Racing but i'm not sure about this. Does anyone know the specifications of these camshafts?
My TC is a Weber SE with the standard C (SE) cams. Because of a major oil leak at the rear crackshaft seal (thirth time since rebuild in 10 years :oops: ) i have to take the engine out and want to do some more jobs on the engine. A good moment to check the valve train and put these camchafts in when they give some more power.
I did some measuring on the cams but this gives only a very global indication.
Marten.


I'm not sure what the rationale might be for using camshafts of quasi unclear characteristics :
- if for historical or sentimental reasons, I could understand, but then their characteristics and settings should be known
- if for performance seeking while on a very tight budget, care should be exercised to measure as accurately as possible the profile (a stamping does not warranty that the cams have not been reground, so lift and duration should at least be assessed, would it only be for clearance issues), as timing them will obviously will get on the table with a lot of trial and errors, and that is likely to be very time consuming - if tuning is to be done on a rolling road, the cost of that session alone is likely to balance favorably to get them reground to a known profile instead
- in any other case, I would start with a known profile : it is lengthy enough to get the best of a know cam

good luck !
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PostPost by: mart2elan » Mon Mar 05, 2018 6:22 pm

Thanks Ron. I will contact Fai auto.
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PostPost by: mart2elan » Mon Mar 05, 2018 7:18 pm

Gordon The numbers you mention for the lift are the same i measured. The lift is easiest to do so i' m pretty sure that 0,350 is correct. The overlap i found was some were arround 315 (-38TDC / 97BDC inlet) degrees and MOP 119 degrees. In comparison with the standard C cam (1 grove) with lift 0,345 ; MOP 110 ; 272 (-26TDC / 66BDC inlet) there is a big difference. I don't know if these numbers are in the range of what is possible in practice for a TC and if so what kind of powerband it will give.
I hope to find some more information at FIA auto on that.
The cams are in a really perfect condition and the still have there 1 inch (25,4 mm) base diameter in the lobe so i don't think the are regrinded.
I'm not looking for extreem power but on the other hand when i have to take out the engine and have to do some work on the valve train i can take these cams as well.
Regards Marten
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PostPost by: rgh0 » Mon Mar 05, 2018 7:49 pm

Sounds like a classic long duration low lift race cam of the 60's. Not really good for much these days as to long a duration for road use and not enough lift for a modern performance cam.

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PostPost by: mart2elan » Mon Mar 05, 2018 8:39 pm

Thanks Rohan. I use the car for 2 track days a year for fun and the rest of the year for the road and like to be the fastest at traffic lights. I understand that the long duration and low lift isn't the best combination then.
What would you advice as a good bhp+ cam without the need of changing valves (length) and valve springs. What is possible within the standard valve train.
By the way: i' m still very happy with your Weber main and idle jets. They work perfect.
Regards Marten
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PostPost by: Craven » Mon Mar 05, 2018 8:46 pm

A popular upgrade of the era was to fit a L2 camshaft it provided an increase in top end power but at the cost of low end torque.
L2 46/70/70/46
Duration 296 deg
Lift 0.345 believe this is valve lift based on 0.010 valve clearance.
Inlet fully open 102 ATDC
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PostPost by: rgh0 » Tue Mar 06, 2018 10:19 am

mart2elan wrote:Thanks Rohan. I use the car for 2 track days a year for fun and the rest of the year for the road and like to be the fastest at traffic lights. I understand that the long duration and low lift isn't the best combination then.
What would you advice as a good bhp+ cam without the need of changing valves (length) and valve springs. What is possible within the standard valve train.
By the way: i' m still very happy with your Weber main and idle jets. They work perfect.
Regards Marten


It is hard to beat the standard sprint cam of 0.360 lobe lift and 272 degrees valve duration seat to seat in a road and occasional track day car if you dont want to go to higher lift valve train.

The standard valve train could take around 0.370 to 0.380 lift before coil bind on the springs and that varied from engine to engine depending on the details of the tolerances in the valve train assembly. Given that engines have all be rebuilt and the detail of the springs or the valve seat locations may have changed it is hard to know exactly how much lift your current valves could accommodate. I have seen "improved performance cams" with around 0.370 lobe lift versus the sprints 0.360 and slightly longer duration of around 280 degrees versus 272 of the sprint cam that are aimed at pushing the limits of the standard valve train without loss of torque and without pushing the power peak above the 6500 rpm limit of the standard block assembly. However the performance gains of these style cams are marginal at best and probably not worth the effort versus standard sprint spec cams.
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PostPost by: mart2elan » Wed Mar 07, 2018 8:32 pm

Thanks for the advice Rohan.
It's clearly that these IWR141 cams are not the one's oppropriate to the way i use the car.
Regards Marten
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