Lotus Elan and Lotus Elan Plus 2 Forums

Does anyone have lift, duration and timing specs at full lift specs for BRM Phase IV and RF450 camshafts? I have a head that was supplied with these and just going through rebuild, want to compare to say Mcoy 450's or QED 450/460's

Cheers

Vaughan

I don't know the specs of those specific cams but you will generally find that older cam profiles will have a lower lift at the same duration or a longer duration at the same lift as modern cams.

cheers Rohan

Hi Vaughan,
You could send the cams to Malcolm at Camtech, Alfred rd, Chipping Norton and he should be able to read them for you.

Alan P.

Thanks Rohan, Alan,

I've emailed TTR and Racing Fabrications, TTR arranged for the head to be prepared by them for me. I'm really more interested in QED or McCoy cams as in my Alfa I used high light short duration cams to great effect, and as Rohan points out the Twin Cams responds well to them, I suspect better than an alfa as the head an valve angles are better for flame propagation than the Alfa.

If I get stuck with the email, I'll definitely send them out to be profiled.

cheers

V

Hi,
No help with cam details, but you may be interested in a spec of a BRM engine using their Phase IV cam. An engine for Group 5 & Formula B Race.
Capacity--------1594cc
Compression Ratio----------11.5 : 1
Crankshaft-------Forged Steel
Pistons & Rods-------Forged Slipper & steel Rods
Carburation------45 DCOE or Lucas Injection

Min Power 165 BHP 45 DCOE
Min Power 175 BHP Injection.
Resonating Exhaust system.
Unfortunately NO RPM given but with basically an all steel engine and the included note ?Resonating exhaust? indicates to me it?s a bit of a peaky cam, but you guys will know more about race engines than me.
For what It?s worth
Ron.

Hi Ron, thanks for the data, my dyno sheets are 10 years old or more and the print has faded away so cant give details other than ~178bhp ~120 ftlbs but looks high up rev range

Cheers

V

Hi Vaughan
I spoke to George Wadsworth this morning.
He says the RF450 is basically a BRM phase 4 cam with same timings and duration.
Cheers
Dave Hughes

http://www.newman-cams.com/pdf/lotus.pdf

This provides details of the of the BRM phase IV cam - 320 degrees and .452 lift. These days you can get that lift from a 280 degree cam ( Newman does one see the page above) or you can get up around .5 lift from that duration

The web site is pretty informative on the technical side of cam manufacture with such things as material selection and hardness. His information on how to fit high lift cams into twin cams is dated as he still talks about spring pocket deepening which is not needed any more if you use the right valve lengths and springs and follower thickness and cam base circle

cheers
Rohan

Thanks Dave and Rohan,

Feedback and links all appreciated. Its a little bizarre that the head RF refurbished for me via TTR has two cams noted on invoice, inlet RF450 exhaust BRM Phase IV, mind you both set at 102 with different clearances inlet to exhaust, suggested they were different, I've not asked until now as I've driven the 26R with its original Cosworth engine, cams etc and its lovely but peaky, torque comes in relatively high up the rev range which means to get the best out of it I'll be changing diff's for each circuit and revving it hard, two diff's I'm ok with but 3 or 4 diff's! This is worsened due to the large rolling diameter of the Dunlop CR65 tyres.

I've been down the short duration high lift cam route previously with my Sb Alfa and it worked a treat, torque power and the engine lasted, so I'm keen to explore that route for the 26R. I've had a few exchanges with John McCoy who is very switched on with LTC's and is actively developing both heads as you've pointed out in some of your posts on this forum Rohan, and cam/spring/valve retainer sets.

I've two options, I'm getting the existing head flowed and measured so I can send John the details to see if its in the ball park, or I've a few virgin heads one of which I may send over to have the full job done on it.

Only wish I'd have thought of this a year ago as the A$ has lost ground to US$.

Cheers

V

It was good when the A dollar was high - got myself a couple more spare heads done by John so I am set for a while now

Yes, im kicking myself. Did you use new heads or good original ones Rohan? Cheers V

I used good Stromberg heads that I had here or purchased in the USA and had them converted by John. John can also source good Stromberg heads from time to time for you if your lucky and it saves on freight costs. This is the cheapest way and the result is as good as any other approach if not better. This is acceptable for group S ( you are allowed to machine metal off the head and allowed to replace the inlet manifold). I don't know how acceptable it is for cars covered by a Certificate of Description you would need to talk to the relevant eligibility officer.

cheers
Rohan

Hi Rohan, for road definitely, im a liitle surprised about Sb as id have though primary casting can have removal, but seems like its stretching it, regardless its obviously accepted as you've been in the class for years which is good to know.
The 26R would need to be a Weber head both here and if it goes to europe due to CoD or FIA papers for a holiday one summer. Im keen to run it in France and UK at end of a contract in a couple of years,
Id be interested in stromberg coversion for a long term rosd car project i will get to one day.

I have discussed with the eligibility officers for Sb and yes it complies. The regulations specify head machining is allowed and manifold replacement with a period style manifold is allowed the conversion just combines those 2 allowed actions. Johns replacement manifold is of identical style to the original including its surface finish and in an Elan you are hard pressed to tell the difference unless you know what your looking for.

They are more "original" in my opinion than the new SAS heads or new big inlet tract QED heads as the main head casting itself is still original

cheers
Rohan