Camshafts

[cjthorley]

Hi Guys,

I would like to renew my camshafts with sprint spec camshafts.

Where should I buy them from? Does anyone know who supplies QED?

Also I have been told its best to replace all cam followers when renewing camshafts is this correct? Should you just replace the cam followers since there are clearance considerations where the cam followers its in the head?

If this is not straight forward then maybe best to have the head taken off and rebuilt?

What do people think?

Thanks
Chris

 

[David Baldock]

If you go for hotter cams you should be aware that you might need to increase the size of the inlet valves, re-jet the 'carbs & upgrade your plugs. Your DCOE 40's are good for upto 155 bhp.

I went for the stage 1A head. That is Cosworth CPL2 cams, enlarged inlet valves (I think 1.56in.), re-jetted 40's & Ngk BP6ES plugs replaced BP7ES ones.

It's supposed to give about 5 bhp more than the special equipment head.

It starts well, idles nicely & go's quite well once it finds it's legs.

I had it done twenty years ago by Vulcan Eng who always did a good job but I don't know were to go now.

I don't see the point in changing the cam followers unless they're worn but I could be wrong there. A hotter cam will need re-adjusting anyway.

Hope this helps.

Dave B

 

[L2Man]

I have one car with Cosworth L2 cams in a +2s 130 big valve engine running Iridium BP7Ex's (Bp7ES equivalent) it is a docile as a standard car, was set up by an "era tuner rolling road" sanspeed and pulls from around 2,500 till you bottle out. This is great for road use.

I also have a rally car running a smirthwaite rally engine running a Newman Phase 5 inles and a JS1 special exhaust, running biggest valves possible. Once warm it pulls from 2500 with enough torque to drive Ok, but will bog down until up the rev range a bit. It comes alive at 4000 so much so that I cannot change gear quick enough (age thing) being 1760 helps with the tractability I would think.

I have been told by those that know (Nick Stagg and John Smirthwaite) that there are better cam profiles available now than I would go for as I like a bit of tradition! They both quoted BLF14's as the best for the road on the old profiles but latest qed and Newman ones are probably better when set up on a roller.

As for followers I think you throw them on a cam change when they wear on say a Xfloss or a Pre cross flow as you cannot adjust our the gap in the floower with twinks I think you can compensate for the follower wear by shimming adjustments. I would make sure not damaged and me more worried about age of springs and collets etc as a little let go and be a very big bill. That said in 37 years of ownership I have never had a head failure or indeed a water pump failure.

I use a traditional engine show in Rye for my heads if that suits you...they do a lot of racing jaguar stuff. When I asked about porting etc I was told to talk to Junior when he comes in. Junior lumpered in a Jaguar "D " type head he had done, was in a traditional blue apron and was not a day under 70!!

hope that helps


Brendan

 

[David Baldock]

Brendan, as a matter of interest, what bhp do you get with the rally car?

Dave B

 

[cjthorley]

Thanks everyone for the comments keep it going.......

Im really more interested in a standard sprint profile cam that is what my engine is designed for.

Where would you suggest I buy these from new?

Thanks

Chris

 

[L2Man]

Brendan, as a matter of interest, what bhp do you get with the rally car?

Dave B

In the years of ownership i believe all factory outputs are optimistic or bench dyno based.
My 130 l2'd engine gave 126 on a trusted roller. Some rollers have been known to just wind on the brake to give a higher reading as it keeps the punters coming back.

My rally engine has a bench dyno sheet from JS for 158@6750.

But i would expect a little less on a rolling road dyno.

Cheers


Brendan

 

[David Baldock]

Blimey! that must be about as far as you can go with carburettors.

Jolly good show.

Dave B

 

[Pete G]

Brendan, as a matter of interest, what bhp do you get with the rally car?

Dave B

In the years of ownership i believe all factory outputs are optimistic or bench dyno based.
My 130 l2'd engine gave 126 on a trusted roller. Some rollers have been known to just wind on the brake to give a higher reading as it keeps the punters coming back.

My rally engine has a bench dyno sheet from JS for 158@6750.

But i would expect a little less on a rolling road dyno.

We have ben here before,- I haven't had my LC on a dyno yet but have had other cars on one.
They only measure wheel bhp and extrapolate the data to get a flywheel figure, so it depends on what 'fiddle factors' are programmed in to the machine that convert the wheel bhp to estimated flywheel bhp.
A manufacturer's published bhp figure is at the flywheel because they put their engines on a test bench dyno machine, but testing a car on a rolling road dyno is measuring wheel bhp only.
Estimates of the losses down the drive train vary but 20% is not uncommon, so 100 at the wheels could be 120 at the flywheel, etc.

Brendan, was that 126 given as engine bhp (flywheel) or at the wheels?
If it is wheel bhp your doing well!

Pete

 

[L2Man]

Brendan, as a matter of interest, what bhp do you get with the rally car?

Dave B

Brendan, was that 126 given as engine bhp (flywheel) or at the wheels?
If it is wheel bhp your doing well!

Pete

I wish Pete! was 126 est at flywheel albeit with a tired
Drivetrain and lsd.

Cheers

 

[Brian c]

Hi Guys,

I would like to renew my camshafts with sprint spec camshafts.

Where should I buy them from? Does anyone know who supplies QED?

Also I have been told its best to replace all cam followers when renewing camshafts is this correct? Should you just replace the cam followers since there are clearance considerations where the cam followers its in the head?

If this is not straight forward then maybe best to have the head taken off and rebuilt?

What do people think?

Thanks
Chris

Standard head/valves are fine for sprint spec cams (CPL2) i would personaly change the followers with the cam as the new cam will need to be run in. You could ask about getting your current cams reground to sprint spec which does work out alot cheaper but still needs running in as with a new cam. With People like QED or Burtons you can just take your complete head in and they'll change the cams/ followers and re-shim the head so all you'll need to do is refit the head, but labour does workout expensive.

 

[David Baldock]

There seems to be some confusion these days on the various cams used for tuning our engines so I'd like to quote a few things from my bible (Tuning Twin Cam Fords by David Vizard). First published in 1969 he gives very clear procedures for the various stages of tuning & they are as follows:
The first stage above standard is to fit the 'Lotus special-equipment cams'. These will give a gain of 8-10 bhp over the standard items. This, in conjunction with a stage 1 head, will take the power output to about 113bhp. He then goes on to say that in practice, when all driven auxiliaries & the silencer are taken into account this is likely to be closer to 105bhp.
Next he suggests the Cosworth CP L2 cams which he says will give a further increase of power of 5 bhp over the special-equipment cams, with practically no drop in flexability. This means a genuine 118bhp with a motor which is still tractable enough for rush hour driving, and has enough at the top end to make open road driving more than interesting. Don't forget we are talking 1969 rush hours here!
Above this we enter 'Nielsjuke/L2man' country with Cosworth L2's, L1's & Vegatune FLB's. That's a step too far for me.

If they're still available I would thoroughly recommend this book to anyone considering tuning their twin cam.

Hope this is of interest.

Dave B

 

[Brian c]

Worth noting that twincam development has come along way since 1969 thanks to guys like QED ect... The more modern cam profiles are more road usable and have alot more low down to mid-range torque. In my experience L2 and L1 cams are not suited to road use.

 

[cjthorley]

Standard head/valves are fine for sprint spec cams (CPL2) i would personaly change the followers with the cam as the new cam will need to be run in. You could ask about getting your current cams reground to sprint spec which does work out alot cheaper but still needs running in as with a new cam. With People like QED or Burtons you can just take your complete head in and they'll change the cams/ followers and re-shim the head so all you'll need to do is refit the head, but labour does workout expensive.

Thanks for this. I did think about getting the existing cams reground but not familiar with the procedure and worry taking metal off the already warn lobes also worry the cost of shipping around and if there are problems with the reground for whatever reason may cost me more alot in the long run.

So replacing the followers would you say is a straight swap out. I understood followers to be made to match where they fit. Is this just a matter of finer detail or would new follows with no machining cause issues?

Im fine to take the cams out and re-shim no problem just worry about replacing the followers.

Thanks

Chris

 

[Brian c]

The followers are a straight forward swap, you'll need a valve grinding rubber sucker to pull them out and just swap them with new ones and re-shim. On re-assembley use camlube or graphogen to help moving parts bed in. Burtons sell followers at £14.95 each, QED are normally a bit cheaper.
Also i had some old cams re-ground at Burtons (Kentcams do the regrinding) and they came back like new. As long as the bearing surface is good you'll have no problems.

 

[cjthorley]

Can the cam bearing just be swapped out aswell?

 

[Brian c]

Can the cam bearing just be swapped out aswell?

Yes, about £100 a set.

 

[Rick]

I too used to use the Vizard books as bibles but talking to people like QED and Burtons I have found that Vizard is not as clever as he thinks he is. using the SE cams you also need to re- jet the carbs making sure you lose the flat spot around 3000rpm. Some of the QED profiles give a lot more power and torque over SE, Sprint CPL2 etc and remain tractable for road use.

Cam followers are availible in oversize, if you don't know the full history of your engine then check each one with a micrometer to determine its size, mark up each one with its postion, you can't swap the cam bearings around if you are reusing them, again mark the postion of each shell.

If having your cams reground to a different profile be prepared to have some large shims ready to take up the slack.

accurate cam timing will give you the best power / torque and a smoother running engine, a good 360 degree timing wheel and a dial gauge with a mag base I would say are essential items along with vernier timing wheels, you can use offset dowles but the verniers save so much time well woth the investment.

 

[David Baldock]

If I could just jump to Mr Vizards defence, he does say in chapter 7 of my book that "Any modifications to the engine, however, will require the carburetters to be recalibrated to suit".

I understand that QED's 'bottom of the range' set up will now give 135bhp yet stay tractable enough for a trip to Tesco's in the rush hour. I accept this a commendable engineering achievement but as an old timer I still like a little bit of cough & splutter.

Dave B

 

[L2Man]

If I could just jump to Mr Vizards defence, he does say in chapter 7 of my book that "Any modifications to the engine, however, will require the carburetters to be recalibrated to suit".

I understand that QED's 'bottom of the range' set up will now give 135bhp yet stay tractable enough for a trip to Tesco's in the rush hour. I accept this a commendable engineering achievement but as an old timer I still like a little bit of cough & splutter.

Dave B

Imho 135 on cams and weber re-jet will be a big ask, unless you totally trust your rolling road i would tell him you engine is bog std and let him overachieve!
If you tell him you expect 135bhp by smoke and mirrors or use of the clutch on the rollers he will always hit it.
Cynical i know but twin cam outputs have always been exaggerated. I love them to bits but a crossflow on 40's hits similar power to a tuned twink, i have driven both and the difference is marginal, except the crossflow is always rated at 115bhp and the lotus at 130bhp.
At the end of the day as long as you are happy with the performance you get the numbers do not matter apart from pub talk!!

 

[David Baldock]

Wise words Brendan. Many's the time I've been embarrassed at the hands of a hot GT.

Dave B