Thread: 3.9 cam lift

The lift at the cam is .390inches.
I don't know how you could measure at the rocker as the hydraulic lifter would leak down if raised slowly. You could measure at the pushrod top but the same problem would exist.
The only real way would be to measure from the lobe.
As a guide my 196KK 3.9 cam had 0.5MM difference from back of cam to lobe tip vs new, so the differences between a worn cam and new are quite small.
And that resulted in (subjectively) quite a loss in high end performance .
Regards Philip A

never do it at 100ks,,
at 2k revs the hp and twist just aint there for 2t of car,,

the same hill at 2500 rpm would just dissappear though,,,

oops

Sorry PhillipA , if it was .390 at the cam . that would shove the caps through the top of the valve guides
.390 times a rocker ratio of 1.5 would be .539 at the valve , very funny !
Try .260 , times 1.5 , that gives a total lift at the valves of .390 , a typical puny rover type lift . Considering the power comes from the Average lift , not the total , with its severe Port choking , it easy to see why the RV8 makes poor power !!
your run of the Mill type cam (Crow grind )
Part Number370771 Lobe Separation 111
Inlet Valve Lift .409
Inlet Opens22 B.T.D.C
.Inlet Closes56 A.B.D.C.
Exhaust Valve Lift .422
Exhaust Opens66 B.B.D.C.
Exhaust Closes16 A.T.D.C.
Inlet Duration 200 at 0.050
258 Advertised Exhaust Duration
205 at 0.050 262 Advertised

Lobe centers too wide
Lift too Low
To much overlap !!!

oops again !!

what would you suggest 400hpongas?

OK you are correct with teh oops!
I didn't really take much notice.
I got the specs from here.

Ok, I've spent the evening reading and then spread sheeting the numbers and finally think I'm starting to understand correctly.... I hope.

Also, I was just looking at the Rover SD1 site.
They have some excellent cam info and a cam timing calculator. (Increasing Capacity). Dan, I plugged in your cam info and the numbers jived, except it says the cam is only 2 degrees advanced, not 4, when installed straight up. Any idea why the difference?

So, if I got it straight, in general:

1. The earlier the IO, the smaller the LSA, and the greater the OL -> the greater the power, but narrower the power band.

2. A later IO, wide LSA and small OL will give lots of torque over a wide power band, but less overall power.

3. In general the earlier the IO, the wider the duration.

4. The 50% duration numbers indicate the shape of the lobe, which in turn indicates how fast the valve opens and the ramp loading. A higher 50% number means the valve is open higher, longer so more fuel/waste get through.

5. The following numbers I assembled and/or calculated from the various posts I read (Thank you all!) and manufacturer info. It's comma deliminated and can be sucked into excel fairly easily.

Make,Number,IO,IC,EO,EC,Dur,LSA,OL,Valve lift ,Ret(+) Adv(-),RPM Range,Class ,Comments ,
Crane,H-194,10,54,59,15,244/254,112,25,.400/.430,2.5,,Road ,Economy cam only. Not to be used with comp. ratio over 8.75:1 ,
Rover,ERR5250,14,70,64,20,267/264,115,34,0.416,3.0,,Production ,4.6-litre - Hi Torque Cam,
Crane,H-204,15,59,65,21,254/266,112,36,.430/.456,3.0,,Mild Road ,Improvement over standard cam. Can be straight swap. ,
JE,JE101,20,65,65,20,265/265,112,40,0.430,0.0,,Road ,,
Kent,H200,20,64,69,25,264/274,112,45,.435/.460,2.5,,Mild Road ,For pre-SD1. Also good for automatics. ,
Isky,621262,21,61,61,21,262/262,110,42,0.445,0.0,2000 - 5000,Mild Road ,,
TA Perf,TA212,21,64,69,31,265/280,110,52,0.473/.485,5.0,1900 - 4900,,,
Crane,H-216,21,65,71,27,266/278,112,48,.456/.480,3.0,,Road ,Excellent all rounder. Good power increase across rev. range. ,
Piper,HR270,22,62,64,28,264/272,109,50,421/.439,3.0,,Road ,Flexible with good mid and top end improvement. ,
Crower,50230,22,58,69,17,260/266,112,39,0.446/.451,-2.5,1500 - 4000,Mild Road ,,
V8Tuner,AS-H180,23,59,59,23,262/262,108,46,0.441,0.0,1000 - 4500,Mild Road ,Hi torque,
Isky,621270,26,64,64,26,270/270,109,52,0.470,0.0,2000 - 6000,Fast Road ,,
Piper,V8BP270i,26,66,66,26,272/272,110,56,0.420/0.420,0.0,1500 - 6000,Fast Road ,Hi Torque EFI +22hp,
Crower,50231,27,63,74,22,270/276,112,49,0.451/.477,-2.5,1800 - 4500,Mild Road ,,
Piper,V8BP270,28,64,64,28,272/272,108,56,0.420/0.420,0.0,1500 - 6000,Fast Road ,for Carbs +24hp,
Kent,H180,28,64,64,28,272/272,108,56,0.439,0.0,1000 - 4500,Mild Road ,Good for automatics ,
Rover,ERR3720,28,77,66,39,285/285,109,67,0.390,5.5,,Production ,4.0-litre,
Woody’s ,RV10/RV15,28,72,76,32,288/280,112,60,0.448/.461,2.0,,,,
Rover,ERR5924??,30,75,67,37,285/285,109,67,0.390,3.5,800 - 4000,Production ,3.9-litre - use with CAMSHAFT THRUST PLATE ERR5926,
Rover,ERC2003,30,75,68,37,285/285,109,67,.390/.385,3.5,,Production ,3.5-litre SD1 / TR8,
Crower,50232,30,66,76,24,276/280,112,54,0.488/.490,-3.0,1800 - 4500,Fast Road ,D&D's Ulitmate Road Cam,
Kent,H214,31,73,80,34,284/294,112,65,.469/.494,1.5,1500 - 5000,Fast Road ,Very flexible. Good road camshaft. ,
SD1Web,,31.5,60.5,78.5,23.5,272/282,111,55,0.55,-4.0,1000-4500,Torque,,
Rover,ETC8686,32,73,70,35,285/285,109,67,0.390,1.5,800 - 3600,Production ,3.9-litre 36D 38D,
Woody’s ,RV10/RV15-2,33,67,79,29,280/288,111,62,0.448/.461,-2.0,1500 - 5000,Fast Road ,,
SD1Web,,34,63,81,26,277/287,111,60,0.55,-4.0,1500-5000 ,Torque,,
Kent,H224,36,78,85,39,294/304,112,75,.494/.520,1.5,2000 - 5500,Road Rally ,Slight loss of flexibility.,
SD1Web,,37,64,80,31,281/291,109,68,0.55,-3.0,1500-5000 ,T&P,,
Kent,H234,38,80,87,41,298/308,112,79,.520 /.542,1.5,,Rally ,Poor low end but improves mid and top end power. ,
SD1Web,,40,70,80,40,290/300,108,80,0.55,0.0,2000-5500 ,Power,,
SD1Web,,40,66,83,33,286/296,109,73,0.55,-3.5,2000-5500 ,P&T,,
Piper,V8BP285,41,75,75,41,276/276,107,82,0.420/0.420,0.0,1500 - 6000,Fast Road ,Ultimate road cam. +30hp,
JE,JE102,43,79,79,43,302/302,108,86,0.500,0.0,3000 - 6500,Rally ,Good high end power. Peak torque 5000 rpm ,
SD1Web,,43.25,76.75,81.75,43.25,300/305,108,86.5,0.55,0.0,2500-6000,Power,,
Piper,HR285,44,72,72,44,296/296,104,88,0.439,0.0,2000 - 6500,Fast Road ,Ultimate road cam. Tractable but slightly lumpy tickover. ,
Kent,GPA,44,76,76,44,300/300,106,88,0.390,0.0,,Rally ,"Same valve lift as standard engine (.390"") ",
Oselli,RV8500,46,82,82,46,308/308,108,92,0.542,0.0,4000 - 7000,Race ,Ultimate hyd. camshaft.,

It was an entry from a poster on Triumph TR8/TR7/Rover V8 Forum :: Index
However my comments stand that you cannot really measure it at the rocker unless you inserted a solid lifter, and were sure the rocker ratio is correct. You would soon find out the .390 is at the valve.
Regards Philip A

Piper,HR285,44,72,72,44,296/296,104,88,0.439,0.0,2000 - 6500,Fast Road ,Ultimate road cam. Tractable but slightly lumpy tickover.

Now thats more like it , stick this one it at 6 degrees advanced , that will pull the power back 1500 RPM , so its suitable to luh around in a 2.5 ton car !!

Alas , all these cams really wont do anything much without Headwork .Me mate ports even the early heads out to over 300hp Flow potential .
Yep 200kw out of 3.5 , streetable engine . Easily done , but not cheap !!