different cam shafts timing

[lotusbzz]

Hallo da Bella Italia!
I?m in trouble with the cam timing now!

I?ve bought the car dismantled and right now I?ve realized that the two cam shafts are different each other.
The duration that I?ve find with accurate measurements is completely out of the range that I?ve seen on line for such part.
Following the guidelines of the Twin-cam bible, I?ve found the following figures:

That has noting to do with the cam-shafts that you can see on line, race, rally, standard fast track etc etc, none matched to my figures:
1. Inlet-duration 315
2. Exhaust duration 284
The above data have been set following as much as possible the valves-clearance reported in the TC-bible, anyway the valve clearance is within the tolerance.
Te clearance has been carefully set through the spacers between the valve-stem and the cam-followers
The lobe-lift is:
8.65 mm = 0.34 inch exhaust
8.00 mm = 0.31 inch inlet

The two shafts are stamped with the following marks

EXHAUST : MC22929 B255Z6
INLET : B255Z6

Now the Hamlet?s doubt is the following:
Do I go on with these unknown cams shafts
or
throw them away and go for well known parts with written instruction including clearance of the valve and known open/lose point?

To be or not to be? The 600? extra charge is the question!!!

If I accept the challenge to go on with these silly cam-shafts, have anybody an idea where set the opening of the inlet and the opening of the exhaust?
The sprockets are standard, they have no vernier for continuous adjustment
Watching the marks on the shafts, do you know who could be the manufacturer or where can I get a good advice to set them in decent way?

I know that probably the 600? is the easiest way to solve the problem, but before giving up, I?m a bit fascinated by the challenge to go on with the silly cams.

THANKS FOR THE GOOD ADVICES
HAVE YOU ALL A NICE WEEK END!!!

[rgh0]

The cams you have appear to be very strange

Standard cam valve lift is 0.35 inch lift for a sprint cam so you cams have a lower lift than standard at 0.31 and 0.34 inch.

However you have much longer durations than standard at 315 degrees and 284 degrees. Cams with these durations typically are used on competition motors and have a much higher valve lift in the 0.41 to 0.49 inch type range. A combination of a 315 degree inlet and 284 degree exhaust is used to build a high revving race motor (9000 rpm) with improved mid range torque, especially in something like an Elan where the exhaust is more restrictive given the limited space.

I would not use these cams as the lift is to low to make them effective and the durations only really suited to competition motors and not at all suited to the Stromberg head you have.

Typical timings for a 315 degree cam is around 102 to 105 MOP and for a 284 degree cam is around 106 to 110, depending on the rest of the motor build details and application. I presume your using the valve timing chapter 5 in the Wilkins book for your calculation but you need to know the open and closing timing for a cam to calculate the MOP using his method. Where did you get the opening and closing timing you used as they appear to not be correct for your type of cams.

cheers
Rohan

[lotusbzz]

Ciao Rohan
Thanks for the quick replay!!!
I fully agree with you about throwing away this strange cams, but this problem is good to get some more experience in this matter.

Yes, of course the bible is the chapter 5 in the Wilkins book, I don?t know if there is any other literature about this matter, anyway I don?t think it makes any difference to fit this cams.

The data that I?ve report are the map/profile of each single cam, the problem is how to put them together i.e. the timing
The head has been delivered with the cams dismantled therefore I?ve assumed that they where part of the assembly , but now I?ve the doubt that they come from the rubbish bin of the ?clever? dealer that sold the car.

What about a cam like this (CPL2 Burton Power) ?
Power Band: 1500-6500rpm
Valve Lift: 0.350"
Duration: 270? inlet
Timing Figures: 25/65/65/25
Inlet/Exhaust Full Lift Position: 110? ATDC
Valve Clearances: .010" inlet/.010" exhaust

The engine fit new sleeves, piston, valves etc etc
The 0.35? lift is ok because I?ve double check before fit my strange cams
The duration/open/close seems to be normal without racing/rally features

Thanks again for your info.
Have a nice week end

Paolo

[Craven]

Hi,
UK spec Stromberg heads were fitted with Sprint cams 26/66/66/26 as OE.
Look into re-profiling your present cams to this spec. QED offer this service through, I think Kent Cams. Price is on their Web site around the ?200 mark all in. Check if you can the base circle diameter this will give you some info if your cams have already been got at. You will hope to find this dimension over 1 inch but this does not necessarily guarantee their suitability.
Ron.

[lotusbzz]

Hi Ron!
on-line there are no cams 26/66/66/26
BurtonPower offers Valve Lift: 0.350" , Duration: 270? inlet Timing Figures: 25/65/65/25 that should be ok for my S4 engine with Stromberg
the lift 0.350" is ok because I've checked this size
I do not want a race car but a nice convertible to enjoy the Italian sunny weather

ciao Paolo

[Craven]

Hi
If you want to buy NEW then the CPL2 offered by Burton is the only close equivalent to the Sprint cam I know, they are produced by Newman Cams.
http://www.newman-cams.co.uk/Newman-Cam ... _18901.jsp
Ron.

[rgh0]

The QED 360 cam is a Sprint cam equivalent. Dave Bean also does an equivalent.

cheers
Rohan