Cam Timing Notes

20th Mar 2018

**Disclaimer: This information has been compiled by a resource independent of The Bonneville Shop. Please conduct your own research and verify that the information is correct before utilizing any of the information in this post.**


Cam timing notes

Note that cam lift numbers are sometimes specified at the valve, and sometimes at the lifter (follower/tappet), which will be the same as the lobe height. Triumph rockers generally (as far as I know) have around a 1:1.1 ratio. This means that the valve lift does not equal the lobe height - lift at the valve will be higher than the lift at the lifter.

Cam timing is sometimes quoted at 0.020" of valve clearance, sometimes with 0.040" of valve clearance, and sometimes at 0.050". 0.020 is the older way, but 0.040 is used because that's almost exactly 1mm, and modern (IE metric) cam timings are specified with 1mm of clearance.

Triumph part number conversion:

Factory cam timing numbers

These numbers are from various shop manuals (Triumph, Haynes, Clymer, etc), which most likely originally come from the Triumph manuals. I think the lift numbers quoted are measured at the tappet (IE the cam lobe height), but it's not explicitly stated.

intakeexhaust
openclosesopensclosesliftmeasured
clearance
tappet
radius
btdcabdcbbdcatdcintakeexhaust
650cc 345555340.002
6T DU.101 on255260170.3050.3050.020
TR6 DU.101 to DU.44393345548270.3140.2960.020
T120 DU.101 to DU.24874345548270.3140.2960.0200.750 (STD)
T120 DU.24875 to DU.44393345555340.3140.3140.020
T100S345548270.2960.0200.750 (STD)
T100T 405261310.3140.3140.0201.125 (R)
5TA to H.49833344448270.020
TR5T345548270.0200.750 (STD)
T100R405261310.0201.125 (R)
TRIUMPH 750 SHORT ROD
26.569.561.535.50.3500.3500.0201.125 ? What Cam ?
TRIUMPH 750 INTAKE (T-75)
40740.3450.0201.125 Matches M20416 T140E intake
JOMO 15
437474430.3550.3550.0201.125 (R)

Note: Megacycle says "When 'R' followers are specified, you can also use STD, which will produce more low RPM power".


Notes on the legendary Triumph E3134 "Q" cam

The E3134 cam wasn't (always) a specific cam, it was a cam profile that was used on many cams for many years. There may have been a cam with the part number E3134, but there were many other cams that used the E3134 profile.

To make things more confusing, there were two E3134 cams - Tricor and Factory. The Tricor profile (34/55 55/34) is the most common.

The E3134 may have been the hot thing many years ago, but it's no longer considered a high performance profile.

This is the E3134 profile:

intakeexhaust
openclosesopensclosesliftmeasured
clearance
tappet
radius
btdcabdcbbdcatdcintakeexhaust
Tricor "Q" E3134
345555340.3140.3140.0201.125 (R)
Factory "Q" E3134
345858340.3100.3100.0201.124 (R)

Group 1 - High Performance - E3134 "Q" Cam Form

Intake opens: 34 BTDC - Intake closes: 55 ABDC

Exhaust opens: 55 BBDC - Exhaust closes: 34 ATDC

Part #
CodeCasting #Intake/Exhaust
E3134E3134
E4819XE3134Inlet
E5047YCPE5048Exhaust
E5162XCPE4602Inlet
E10040XNE10040Inlet
E10041YNE10041Exhaust
E4038SGE3838Inlet
E4039E3838Exhaust
E4678E4679Inlet
E5044YCPE5045Exhaust
E5047Y*Exhaust
E5163CPE4679Inlet
E6965YE6642Exhaust
E10043NE10043Inlet
E10047E10050Exhaust
E11063N71-0040Inlet
E11064N71-0043Inlet
E9983YN71-9986Exhaust
E9984YN70-9987Exhaust
E9989YN70-9990Exhaust

Note: 1. Running clearance .002 in. intake and .004" exhaust.

2. Take readings at .020 in. follower lift with "std" radius (3/4 in.) followers

3. Lobe Center 100.5°

4. Duration 269 °

5. Lift .314 in.

Group 2 - High speed touring - E3325 Cam Form

IO 27 BTDC - IC 48 ABDC - EO 48 - BBDC - EC 27 ATDC Inlet or Exhaust

Part #
Code
Casting #Intake/Exhaust
E3325E3325
E4818XE4997Inlet
E4848YE4560Exhaust
E4855YE4561Exhaust
E4931Inlet
E4022SGE3838Inlet
E4023E4679Exhaust
E4786YE4679Exhaust
E10046YNE10049Exhaust

Note: 1. Running clearance .002 in. intake and .004" exhaust.

2. Take readings at .020" follower lift with "std" radius (3/4 in.) followers

3. Lobe center 100.5°

4. duration 255°

5. Lift .296 in.

Group 3 - Ramp cam form (standard) - Quieting ramps

Intake opens: 26.5 BTDC - Intake closes: 69.5 ABDC

Exhaust opens: 61.5 BBDC - Exhaust closes: 35.5 ATDC

Part #
CodeCasting #Intake/Exhaust
E3275E3265
E3838SGE3838Inlet
E3839E3838Exhaust
E5341YE5342Exhaust

Note: 1. Running clearance .010 in Intake and Exhaust.

2. Take readings at .020" follower lift using “std” followers.

Group 4 - Modified ramp form (racing)

Thruxton Bonneville

Part #
CodeCasting #Timing
E4220E4220Valve lift at TDC with nil clearance 0.195/0.175" Intake
E6267E4220Valve lift at TDC with nil clearance 0.205/0.215" Intake
E6147YE6146Valve lift at TDC with nil clearance 0.165/0.175" Exhaust

Note: 1. Running clearance E4220 .008 in. E6267 & E6147 .013 in.

2. Valve timing taken in inches of VALVE lift at T.D.C. with valves set at nil clearance for checking.

3. E6267 and E6147 must be used with 3" radius cam followers and special guide blocks.

Key to Codes: X = Breather Y = Contact breaker

CP = Copper plated SG = Spiral gear (distributor drive)

n = nitrited


"specs for Stock Triumph 750 short rod:"

Intake: 26.5* - 69.5* 111.5* lobe center

Exhaust: 61.5* - 35.5* 103.0* lobe center

measured @ .020" tappet lift

running clearance .010" intake and exhaust

valve lift: .350" 278* duration

Random cam numbers I've run across:

M20416 - 71-288? casting - 750 intake

M20360 - 750 exhaust

E5048 - T120 exhuast - E3134 profile - use R followers

E3059R - "R" follower

E1485 in/ex 1938/9 5T

E3275 in/ex 1953-8 5T

E3325 in/ex 1955-8 TR5

E4819 - Bonneville E3134 profile intake

E4855 - Bonneville E3134 profile exhaust.

70-7016 - T140 intake

70-7017 - T140 exhaust cam

70-9990 - T120 exhaust, mate to 71-1063?

70-9986 - 1970 T100C exhaust cam

70-9989 - 67-72 T120 exhuast cam

70-9989 - 650 Exhuast cam

70-9989 - T120 exhaust cam late unit

70-9989 - Exhuast cam, half race

71-0040 - Cam, intake

71-0041 - Cam, exhaust

71-0043 - Forging blank for 71-1064, 70-9986

71-0046 - Cam, T100, exhuast

71-0046 - T100C exhaust cam

71-0049 - T100 ex cam 68 on

71-1063 - T120 intake - Nitrided E3134 profile - use R followers

71-1063 - Cam, '70 and later

71-1063 - 70-72 T120 intake cam

71-1064 - 1970 T100C intake cam

71-3011 - T140 intake - up to 1975.

71-3012 - T140 exhaust - up to 1975.

71-7016 - T140 intake cam

71-7017R - T140 spitfire exhaust cam

71-7182 - T140 exhaust cam

70-3059 - 'S' cam follower

70-3059R - 'R' cam follower

70-8801 - cam follower

71-7008 - cam follower

70-8801 - 650/750 exhaust follower oil feed

71-2297 - B50 cam


Cam forging blank numbers

These are not cam numbers, they are the part number for a blank that a cam profile is ground onto. A single blank will often be used for a number of different cam grinds, so this number doesn't actually tell you what cam you have. The forging number should have raised numbers, the cam grind number should be stamped in. Either number is sometimes omitted.

71-0040 - Forging blank for 71-1063

71-0042 - Forging blank for 71-9990

71-2887 - Forging blank for 71-3011

71-0042 - Forging blank for 71-3012

71-3012 - Forging blank for 71-3012 (really)


Someone recommends "put a T140 inlet in the exhaust using a modified

rev counter nut/drive to spin a one off Boyer rotor. FWIW, I clocked

up the cam and it's almost identical to Nourish's Z cam, so I used his

timings of 102 degrees."

TRICOR "Q" intake cam is also named E3134-E4819:

intake 34-55 deg, exhaust 55-34 deg

cam lift .314"

duration 269

lobe center 100.5 deg

vs FACTORY "Q" E3134-E4819:

intake 34-58 deg, exhaust 58-34 deg

cam lift .310"

duration 269

lobe center 102.5 deg



Megacycle cam grinds

Triumph 650/750 twins:

CAM
NUMBER
LOBE
HEIGHT
DURATION
AT .020"
LOBE
CENTERS
TAPPET
STYLE
DESCRIPTION
AND APPLICATION
Intake:open/close
Exhaust:open/close
RUNNING
CLEARANCE
510-05.348"
.348"
282
282
100
102
"R"Best for low-end and some mid-range increase. Street / road performance 2500 R.P.M. to 7000 R.P.M. Should clear pistons. Check clearance. Uses stock springs.41 btc/61 abc
63 bbc/39 atc
.010"
.010"
510-15.355"
.355"
297
297
105.5
105.5
"R"The legendary Kenny Harman #15 grind. (Also known as JOMO 15). TT, flat track, all around use. Must use modified springs.43 btc/74 abc
74 bbc/43 atc
.007"
.009"
510-xl.401"
.401"
308
308
102
106
"STD"
only
Reproduction of Sifton 460. Racing use. Mid-range to top-end power.52 btc/76 abc
80 bbc/48 atc
.008"
.010"
510-65.355"
.355"
TDC lift
292
295
101
104.5
.163" in
.150" ex
"R"For 650 or 750. Best all around street and road cam. Broad power band, mid-range and top-end. TT style performance. Use modified springs. (Recommended by Motorcyclist Magazine)45 btc/67 abc
72 bbc/43 atc
.010"
.010"
510-75.400"
.400"
TDC lift
326
326
102
105
102LC=.159"
105LC=.146"
"STD" only
Racing use only. Must remove material from tappet guide blocks to install this cam. High R.P.M. power. Must use racing springs and pistons. Check clearance.61 btc/85 abc
88 bbc/58 atc
.008"
.008"
510-x2
.375"
.375"
296.5
296.5
103
105
"R"New race profile. Best all around road-race. Best peak performance. May need to trim flywheel clearance. Use racing pistons and springs.
TDC lift in = .174" @ 1.1 rocker ratio/with lash
Base circle diameter=.812"
ex=.153"
510-95.400"
.400"
340
340
108
108
"STD" onlyFull race only. All racing components required. High R.P.M. drag race, grass track, competition.62 btc/98 abc
98 bbc/62 atc
.008"-.014"
.008"-.014"
Stock
650
.322"
.322"
272
272


.322"     278
.322"     278
Stock for your reference.
750 short rod









Triumph 500 twins:

All cams listed below will work with "R" or "STD" tappets

CAM
NUMBER
LOBE
HEIGHT
DURATION
AT .020"
LOBE
CENTERS
DESCRIPTION AND APPLICATIONIntake:open/close
Exhaust:open/close
Running
Clearance
512-05.348"
.348"
282
282
100
102
Designed for stock pistons and springs. Good throttle response/all around performance.41 btc/61 abc
63 bbc/39 atc
.010"
.010"
512-65.355"
.355"
292
295
101
104.5
Best all around street/road race profile.42 btc/67 abc
72 bbc/43 atc
.010"
.010"
512-x5.293"296.51938 Triumph 500 Twin stock reproduction.
512-x8.375"
.375"
296.5
296.5
103 on "R"
105 on "R"
Best competition road-race profile. Maximum peak horsepower and throttle response. Must use racing pistons and valve springs. Trim flywheel for clearance.44.5 btc/71 abc
73.5 bbc43 atc
.008"
.010"
Triumph and BSA triples:
CAM
NUMBER
LOBE
HEIGHT
DURATION
AT .040"
LOBE
CENTERS
TAPPET
STYLE
DESCRIPTION AND APPLICATIONIntake:open/close
Exhaust:open/close
RUNNING
CLEARANCE
511-05.345"
.345"
282
282
98
102
"STD"Best all around profile, road and touring. Use modified pistons and springs. This was the factory road race profile used by Dick Mann at Daytona. Smooth power band.
43 btc/59 abc
63 bbc/39 atc
.005"
.007"
511-x5.375"
.375"
287
287
104.5
107.5
"STD"Road race profile. Strong mid-range, top-end. All out racing. Use modified pistons and valve springs.
39 btc/68 abc
71 bbc/36 atc
.008"
.010"
511-35.346"
.346"
268
268
104
104
"STD"Short road race where throttle response is most important. Less top-end than the 511-00. Very strong mid-range.
30 btc/58 abc
58 bbc/30 atc
.008"
.010"
511-75.400"
.400"
274
274
108
108
"STD"Full race. Must trim tappet guide blocks. High R.P.M. race application. Race components.
29 btc/65 abc
65 bbc/29 atc
.008"
.010"
511-95.400"
.400"
288
288
100
100
Special application race profile.
44 btc/64 abc
64 bbc/44 atc
Stock.328"262For reference.

Johnson Cam Grinds

T100R Daytona

LIFTCENTERLASHTAPPETDUR'NOPENCLOSEAT
INTAKER2724052.020
EXHAUSTR2726131.020

T120 "E3134"

LIFTCENTERLASHTAPPETDUR'NOPENCLOSEAT
INTAKE.3142693455.020
EXHAUST2695534.020

Triumph 750 short rod

LIFTCENTERLASHTAPPETDUR'NOPENCLOSEAT
INTAKE.350111.5.01027826.569.5.020
EXHAUST.350103.01027861.535.50.020

Q cam

Factory speed kit grind for 500's of the 50's, also used in the 650 TT

Specials of the 60's.

LIFTCENTERLASHTAPPETDUR'NOPENCLOSEAT
INTAKE.316105.002R2713160.020
INTAKE.316105.002R2512150.040
EXHAUST.316105.004R2716130.020
EXHAUST.316105.004R2515120.040

Jomo TT Cam

A little more duration than the Q cam, gives a little more top end power.

LIFTCENTERLASHTAPPETDUR'NOPENCLOSEAT
INTAKE.310105.002R2763365.020
INTAKE.310105.002R2552153.040
EXHAUST.310105.004R2766235.020
EXHAUST.310105.004R2555223.040

Harmon&Collins 7054 Cam

A little more lift than the Q cam. For more mid-range torque.

LIFTCENTERLASHTAPPETDUR'NOPENCLOSEAT
INTAKE.326105.002R2673156.020
INTAKE.326105.002R2462046.040
EXHAUST.326105.004R2676126.020
EXHAUST.326105.004R2465016.040

Connely #1 Cam

Lots of torque off tight corners. Tight TT, short Motocross, not good

at high rpm.

LIFTCENTERLASHTAPPET
DUR'NOPENCLOSEAT
INTAKE.353105.002R2803169.020
INTAKE.353105.002R2612159.040
EXHAUST.353105.004R2806139.020
EXHAUST.353105.004R2615129.040

Johnson J360/264 Cam

Johnson designed for 750 Triple Road racing, and by coincidence is a

modern version of the TH6.

LIFTCENTERLASHTAPPETDUR'NOPENCLOSEAT
INTAKE.353102.006R3055173.020
INTAKE.353102.006R2777360.040
EXHAUST.353110.006R3058341.020
EXHAUST.353110.006R2776929.040

Triumph T-3 Cam

Stock 750 triple cam. Has always been hard to beat and works well in

500 twins also.

LIFTCENTERLASHTAPPETDUR'NOPENCLOSEAT
INTAKE.328102.006R3934469.020
INTAKE.328102.006R2643054.040
EXHAUST.328105.008R2937241.020
EXHAUST.328105.008R2645727.040

Triumph T-65 Cam

Between a Q and a Jomo 15. Good for hot street, short track, and TT in

650 and 750 twins.

LIFTCENTERLASHTAPPETDUR'NOPENCLOSEAT
INTAKE.344105.008R2803664.020
INTAKE.344105.008R2552352.040
EXHAUST.344105.010R2806635.020
EXHAUST.344105.010R2555322.040

Triumph T-75 Cam

Stock 750 twin intake. Use in exhaust also, for hot street motors and

racing, where endurance means more than the last HP. Good to 7000rpm

with stock springs. Similiar to Nourish Z.

LIFTCENTERLASHTAPPETDUR'NOPENCLOSEAT
INTAKE.345105.010S2944074.020
INTAKE.345105.010S2702961.040
EXHAUST.345105.010S2947144.020
EXHAUST.345105.010S2705932.040

Jomo 15 Cam

This cam has long been considered the classic "all around" racing cam

for the Triumph 650 and 750 twins.

LIFTCENTERLASHTAPPETDUR'NOPENCLOSEAT
INTAKE.354106.006R2893772.020
INTAKE.354106.006R2672860.040
EXHAUST.354106.008R2896939.020
EXHAUST.354106.008R2675929.040

Sifton 390 Cam

This grind is an improved version of the Jomo 15. With less seat to

seat timing the motor makes more torque, and runs "crisper" down low.

LIFTCENTERLASHTAPPETDUR'NOPENCLOSEAT
INTAKE.352105.008S2903971.020
INTAKE.352105.008S2672858.040
EXHAUST.352105.008S2906941.020
EXHAUST.352105.008S2675828.040

Triumph TH6 Cam

Developed by Doug Hele for the factory 500 twin road racers of the

late 60's, also used in the 750 triples of the 70's.

LIFTCENTERLASHTAPPETDUR'NOPENCLOSEAT
INTAKE.350105.006R3054977.020
INTAKE.350105.006R2743361.040
EXHAUST.350105.008R3057947.020
EXHAUST.350105.008R2746331.040

Sifton 460 Cam

For 1/2 mile and mile flat track and real racers. NOT FOR THE FAINT OF

HEART!. Must trim flywheel and tappet blocks.

LIFTCENTERLASHTAPPETDUR'NOPENCLOSEAT
INTAKE.400105.008S3064977.020
INTAKE.400105.008S2833765.040
EXHAUST.400105.010S3067947.020
EXHAUST.400105.010S2836735.040

Johnson J 46

Johnson Design for a smoother, modern version of the Sifton 460

cam. This grind was developed to be easier on springs, tappets,

etc. Must trim flywheel and tappet blocks.

LIFTCENTERLASHTAPPETDUR'NOPENCLOSEAT
INTAKE.410102.008S3035073.020
INTAKE.410102.008S2793861.040
EXHAUST.410110.008S3038241.020
EXHAUST.410110.008S2797029.040

Johnson J481 Cam

Johnson design drag race cam. It is not recommended for anything other

than drag racing. Must trim flywheel and tappet blocks.

LIFTCENTERLASHTAPPETDUR'NOPENCLOSEAT
INTAKE.443102.008S3165779.020
INTAKE.443102.008S2904466.040
EXHAUST.443110.008S3168947.020
EXHAUST.443110.008S2907635.040