Performance Camshafts for the Triumph TR6

The following table is a list of cams that are available on the open market today. I've attempted to list all available specifications. There is not a lot of call for TR6 cams these days, and so they have been removed from their web-sites. However, if you called, eg, Isky, and asked them, all that information is still in their books. This is a living document and will be updated as the information comes to hand.

The following cams listed here is not an endorsement for any of the cams. It is intended as a starting point for the engine-builder to help decide upon a choice of cam for their needs.

For an article on interpreting two of the most critical specifications (duration and lobe center angle), with simulations showing the effects of changes in these specs, click here.

		Lobe Lift	Valve lift @ 1.46:1	Valve lift @ 1.55:1	Advertized Duration (I/E)	Duration @ 0.050"	Intake open (BBDC)	Intake close (ATDC)	Exhaust open (BTDC)	Exhaust close (ABDC)	Lobe Center Angle	RPM	Notes
Stock	PI (UK)	0.25	0.365	0.388	280		35	65	65	35	105		1969-1971
	PI (UK)	0.24	0.350	0.372	256		18	58	58	18	110		Post 1971
	Carb (USA)	0.22	0.321	0.341	240		10	50	50	10	110		Early TR6/GT6
	Carb (USA)	0.24	0.350	0.372	256		18	58	58	18	110	2000-5000	Post 1972
Ted Schumacher (TSI)	S2	0.279	0.407	0.432	282		31	71	71	31	110	3500-6000	Good for street
	S4	0.283	0.413	0.439	293		42	71	71	42	104.5	4200-6500	Marginal for street
	TSI275-6	0.293	0.428	0.454	275							3000-6500	Flat power curve
PRI (Performance Research Industries)	Stage 2	0.297	0.434	0.460	282
Ken Gillander (British Frame and Engine)	Profile #149	0.274	0.400	0.425	282						110		Good street racer, slight lope @ 800rpm
	Profile #150	0.274	0.400	0.425	292						110		Unsteady idle
	Profile #300	0.342	0.499	0.530	300		45	77	85	37	109		JK Jackson cam, too much with roller rockers
American Cams	M-26	0.31	0.453	0.4805	290		35	75	75	35	105		Very aggressive for street
TriumphTune	Road 83	0.288	0.420	0.446	266		30	56	74	28	104	2200-5200	max bhp @ 4750
	Fast Road 83	0.288	0.420	0.446	280		37	63	74	28	107.5	2500-6000	max bhp @ 5250
	Fast Road	0.270	0.394	0.419	280		30	70	70	30	110	2500-5500	max bhp @ 5500
	Fast Road 89	0.293	0.428	0.454	290		34	76	58	34	106	2750-6250	max bhp @ 5750
	Sprint 83	0.275	0.401	0.426	288		34	74	74	34	110	2700-5750	max bhp @ 5750
	Sprint	0.274	0.400	0.425	288		38	70	70	38	106	3000-6500	max bhp @ 5750
	Race	0.280	0.409	0.434	302		42	80	74	48	106	3500-6500	max bhp @ 6000
	Race 83	0.302	0.441	0.468	290		42	68	78	32	108	3300-6500	max bhp @ 6000
	Race 86	0.29	0.423	0.450	320		54	86	86	54	106	3400-7000	max bhp @ 6250
Richard Good (GoodParts)	GP2	0.258	0.377	0.400	278							2000-5500	No lope at idle
	GP3	0.282	0.412	0.437	288							2500-6000	Nice lope @ idle
Isky	Z-19	0.274	0.400	0.425	268		24	64	64	24	110		Road/race, regrind only
	Z-66+10	0.309	0.451	0.479	282		31	71	71	31	110		Competition, regrind only
Kent Cams	TH2-6	0.261	0.381	0.405	295		39	76	76	39	108	2500-6500	Sports "R", valve lash (I/E) 0.022/0.024
	TH5-6	0.281	0.423		280		37	63	73	27	103	2200-7000	Sports "R", valve lash (I/E) 0.022/0.024
	TH6-6	0.309	0.447		290		42	68	78	32	103	3000-7500	Supersport, valve lash (I/E) 0.022/0.024
	TH7-6	0.324	0.470		300		47	73	83	37	103	3750-8000	Race, valve lash (I/E) 0.022/0.024
Crower
Crane
Web Cams	#84	0.273	0.398	0.423	248	214							Good alround cam, broad power, for stock engines
	#7	0.288	0.420	0.446	260	232							Improved mid-range and top-end for hot streetb engines
	#1	0.298	0.435	0.462	290	252							Strong mid-range and top-end for racing engines
Elgin Cams	TR250	0.214	0.312	0.347	233	193							Stock replacement for TR250, very early TR6
	TR2	0.238/0.248			240/246	188/209							TR2 profile for TR6
	TR6	0.244/0.241			246/245	209/204							Stock replacement for late TR6
	64.5-12	0.251	0.366	0.389	258	204							Street performance
	TR3/TR4	0.262	0.383	0.406	264	217							TR3/TR4 profile for TR6, street performance
	TR5	0.255	0.372	0.395	269	226							Stock replacement for TR5
	67-18	0.289	0.422	0.448	268	222							Performance street, 9:1, springs
	70-9	0.262	0.383	0.406	280	228							Hot street, 9.5:1, max cam w/o bearings
	715-18	0.305	0.445	0.473	286	245							Hot street, headers, 10:1
	75-12	0.300	0.438	0.465	300	250							Full race, 12:1, head work
	77-9	0.312	0.455	0.484	308	256						5000+	Road race
APT Camshafts	TR26	0.256	0.374	0.397	278							2000-6000	Performance
	TR56	0.290	0.423	0.450	276							2500-6800	Hot street
	TR66	0.308	0.450	0.477	284							3200-7700	Vintage race
	TR76	0.324	0.473	0.502	295							3800-8000	Full race

Notes:

# Stock lift ratio on US (carb) cars is 1.46:1, and UK (PI) is 1.50:1.

Valve lift is given assuming stock US rockers (1.46:1) and 1.55:1 roller rockers.

Lobe center angle has been calculated, as it is generally not given. To do this, it is assumed that the lobes are symmetrical. Modern cams are often assymetrical, but it is likley that older grinds for the TR6 are probably symmetrical. Many thanks to Vance Navarrette of the 6-Pack mailing list for computing these numbers! To understand the importance of this critical (but rarely given) specification, click here.

Observations:

Notice how the British do not give any details on the cam grind, but rather use evocative name for description.

Finally, the specifications here are sadly incomplete. Information such as cam lift at various angles of rotation are necessary to determine the rates of acceleration on the leading and trailing flanks of the profile, lobe center angle, timing points at 0.050" rise off the base circle, etc. Cam profiles are perhaps the most complex part of a motor, and often this information is jealously guarded!

Last update: 27 December 2002.