Triumph Spitfire camshaft data Software: Microsoft Office
Software: Microsoft Office
from: Paul Geithner's Triumph Spitfire Links, References and Technical Information
(see explanatory notes below)
compiled by Paul Geithner on the web at: http://auskellian.com/paul/links_files/spitfire_cam_specs.htm
[email]
intake             exhaust            
rocker ratio = 1.50 rocker ratio = 1.50
manufacturer camshaft model BTDC
open		 ABDC
close		 duration cam
lift		 clearance valve
lift		 lobe peak
(ATDC)		 BBDC
open		 ATDC
close		 duration cam
lift		 clearance valve
lift		 lobe peak
(BTDC)		 overlap lobe
angle		 manufacturer's notes (RPM range is advertised power band)
Triumph (stock factory) 1147cc (mk1) 18 58 256 0.215 0.010 0.313 110 58 18 256 0.215 0.010 0.313 110 36 220 small journal, uses cam bearings
[from Haynes manual] 1147cc (mk2) 25 65 270 0.215 0.010 0.313 110 65 25 270 0.215 0.010 0.313 110 50 220 "
" 1296cc (low & high CR) 25 65 270 0.240 0.010 0.350 110 65 25 270 0.240 0.010 0.350 110 50 220 ", considered 'best' of the stock cams
" 1296cc (emission controlled) 10 50 240 0.220 0.010 0.320 110 50 10 240 0.220 0.010 0.320 110 20 220 large journal, no cam bearings
" 1493cc 18 58 256 0.240 0.010 0.350 110 58 18 256 0.240 0.010 0.350 110 36 220 "
Triumph Tune (Moss U.K.) road 83 30 56 266 0.288 0.016 0.416 103 74 28 282 0.288 0.016 0.416 113 58 216 mild profile for everyday use; 2200-5200, peak hp @ 4750
" fast road 83 37 63 280 0.288 0.022 0.410 103 74 28 282 0.288 0.024 0.408 113 65 216 very good all-around cam for fast road and traffic conditions; 2500-5500, peak hp @ 5250
" fast road 89 36 74 290 0.293 0.014 0.426 106 58 34 272 0.293 0.014 0.426 102 70 208 very good cam w/ more lift than f/r 83, better mid-range and top-end power; 2750-6250, peak hp @ 5750
" sprint 38 70 290 0.274 0.014 0.397 105 70 38 288 0.274 0.015 0.396 106 76 211 specifically designed for weekend sprint events, but still tractable for daily use
" sprint 90 39 71 290 0.302 0.014 0.439 110 81 29 290 0.302 0.015 0.438 116 68 226 tractable cam w/ very good mid- to top-end power; fuel injected only
" race 83 42 68 290 0.302 0.022 0.431 103 78 32 290 0.302 0.024 0.429 113 74 216 circuit car only, designed for max top end power
" race 86 51 79 310 0.290 0.018 0.417 104 79 51 310 0.290 0.022 0.413 104 102 208 circuit car only, designed for max top end power
Kent Cams TH12 31 59 270 0.287 0.016 0.420 104 67 23 270 0.287 0.018 0.418 113 54 217 high torque; 1500-6500
" TH2 39 76 295 0.261 0.014 0.382 108 76 39 295 0.261 0.018 0.378 113 78 221 fast road; 2500-6500
" TH3 34 70 284 0.282 0.016 0.412 108 70 34 284 0.282 0.016 0.412 113 68 221 rally; 3750-6800
" TH5 37 63 280 0.293 0.022 0.423 103 73 27 280 0.293 0.024 0.421 113 64 216 fast road; 2200-7000
" TH6 42 68 290 0.308 0.022 0.447 103 78 32 290 0.308 0.024 0.445 113 64 216 rally; 3000-7500
" TH7 47 73 300 0.324 0.022 0.470 103 83 37 300 0.324 0.024 0.468 113 64 216 race; 3750-8000
Newman Cams TRIS/260/375 PH1 20 60 260 0.250 0.014 0.375 110 60 20 260 0.250 0.016 0.375 110 40 220 road; ideal road cam for town use, good idle; 1500-6000
" TRIS/280/405 PH2 30 70 280 0.270 0.014 0.405 110 70 30 280 0.270 0.016 0.405 110 60 220 fast road/rally; good mid-range power; 3000-6500
" TRIS/300/435 PH4 40 80 300 0.290 0.014 0.435 110 80 40 300 0.290 0.016 0.435 110 80 220 race; powerful mid-range race cam; 4000-8000
Piper Cams TRBP255 17 55 252 0.268 0.022 0.380 109 55 17 252 0.269 0.024 0.380 113 34 222 mild road; 1500-5800
" TRBP270 26 62 268 0.284 0.012 0.414 108 62 26 268 0.284 0.014 0.412 113 52 221 fast road; 2000-6400
" TRBP285 36 68 284 0.284 0.012 0.414 106 68 36 284 0.285 0.014 0.414 113 72 219 ultimate road; 2800-6800
" TRBP300 44 76 300 0.309 0.018 0.445 106 76 44 300 0.309 0.018 0.445 113 88 219 race; 3500-7500
SpitBits "fast road profile" fast road; 2000-6500. Latest asymmetrical design profile using short duration opening, long duration
British Parts Northwest "BP270" closing inlet with long duration opening, short duration closing exhaust. Standard valve springs may
actually Piper HR270/2 22 70 272 0.285 0.012 0.415 112 62 28 270 0.276 0.014 0.400 106 50 218 be used. Up to 10 bhp can be gained with excellent bottom end and mid range power.
Isky Cams HR-8-003 13 53 250 0.245 0.012 0.356 112 53 13 250 0.245 0.012 0.356 108 26 220 stock refinish
" E4-58A 20 60 260 0.261 0.016 0.375 110 60 20 260 0.261 0.016 0.375 110 40 220 combination
" ZM-66 24 64 268 0.299 0.018 0.430 110 64 24 268 0.299 0.018 0.430 110 48 220 competition
" ZM-66-10 29 69 278 0.299 0.018 0.430 110 69 29 278 0.299 0.018 0.430 110 58 220 competition
" Z-307 40 80 300 0.339 0.028 0.480 110 80 40 300 0.339 0.028 0.480 110 80 220 super competition
Elgin Cams 64510-12 258 0.252 0.011 0.367 258 0.252 0.013 0.365 performance 1147, 1296 large tappet engines
" 6610-15 264 0.262 0.013 0.380 264 0.262 0.015 0.378 2 steps up, compression needs to be raised
" 7010-9 280 0.263 0.010 0.385 280 0.263 0.012 0.383 hot street; 9.5:1, springs, header
" 71508-18 286 0.305 0.019 0.439 286 0.305 0.021 0.437 autocross/race; 10:1, good head
" 7508-12 300 0.323 0.014 0.471 300 0.323 0.016 0.469 autocross/race; 11:1
" M7708-13 308 0.321 0.014 0.468 308 0.321 0.016 0.466 road race; 12:1, 5000-7500, must dyno tune
" 7708-12 308 0.348 0.016 0.506 308 0.348 0.018 0.504 road race; 5500-7500, must dyno tune
" 7806-14 312 0.328 0.017 0.475 312 0.328 0.019 0.473 GT3; 13:1
TSI Automotive B 33 67 280 0.282 0.014 0.409 107 73 27 280 0.283 0.016 0.409 113 60 220 Kastner/comp prep manual profile; good mid-range; 3500-6000
" TSI275-4 28 67 275 0.295 0.018 0.425 110 67 28 275 0.297 0.020 0.425 109.5 56 219.5 flat power curve; 3000-6500
" A-6 288 0.273 0.018 0.391 288 0.274 0.020 0.391 Kastner/comp prep manual profile; marginal for street; 4000-7000
" A-8 290 0.323 0.020 0.465 290 0.325 0.022 0.465 Kastner/comp prep manual profile; race only; 4500-7500
" TSI298-4 298 0.338 0.022 0.485 298 0.339 0.024 0.485 race only; 4500-8000
APT TH24 278 0.256 0.016 0.368 278 0.256 0.018 0.366 TR 1300/1500 performance; 9.0-9.5:1; 2000-6000; max rpm 6500
" TH54 276 0.290 0.022 0.413 276 0.290 0.024 0.411 TR 1300/1500 hot street; 9.0-9.6:1; 2500-6800; max rpm 7200
" TH64 284 0.308 0.022 0.440 284 0.308 0.024 0.438 TR 1300/1500 vintage race; 11.0-12.4:1; 3200-7500; max rpm 7800
" TH74 295 0.324 0.022 0.464 295 0.324 0.024 0.462 TR 1300/1500 full race; 11.5-13.0:1; 3800-7900; max rpm 8200
Integral Cams Stage 1 265 0.280 0.012 0.408 265 0.280 0.014 0.406
" Stage 2 272 0.295 0.016 0.427 272 0.295 0.018 0.425
" Stage 3 280 0.310 0.018 0.447 280 0.310 0.020 0.445
" Stage 4 290 0.325 0.020 0.468 290 0.325 0.022 0.466
" Stage 5 296 0.340 0.020 0.490 296 0.340 0.022 0.488
" Stage 5 Aggressive 296 0.340 0.020 0.490 296 0.340 0.022 0.488
" N7 Race 301 0.335 0.022 0.481 301 0.335 0.024 0.479
" Stage 6 304 0.343 0.022 0.493 304 0.343 0.024 0.491
NOTES:
values in BLUE = manufacturer's quoted values or measured values
values in italics = quoted values different than calculated results (quoted values shown)
values in BLACK = calculated (see equations below) cam profile diagram
values in GREY = guesses, unverified data or calcs based on such
BLANK = no data or insufficient data to calculate cam circle diagram
duration = opening+closing+180
valve lift = cam lift*rocker ratio - clearance
cam lift = (valve lift + clearance)/rocker ratio
lobe centers (for symmetrical lobes only):
intake lobe center ATDC = 0.5*duration - in. opening BTDC
exhaust lobe center BTDC = 180-(0.5*duration - ex. opening BBDC)
lobe angle (in crank degrees) = ex. lobe center BTDC + in. lobe center ATDC
overlap = intake opening BTDC + exhaust closing ATDC
ROUGH guides:
lift higher lift = additional power
(within limits of head to flow gases)
duration longer duration = more power at higher RPMs
but less torque at lower RPMs
overlap/lobe separation more overlap = better scavenging, more power
(small lobe angle means at higher RPMs but lower dynamic compression
tight/narrow lobe separation, and reduced torque at lower RPMs
typically more overlap) more unburnt gases at low RPMs
rougher idle
separation determines cam's RPM range;
wider separation = wider power band
but lower peak power
narrow separation = narrower power range
but higher peak power
timing advanced timing means earlier intake valve closing
increased low-RPM dynamic compression
more low-end torque
and peak power shifted down in RPM
marginal power decrease
retarded timing = less low RPM torque
and peak power shifted up in RPM
marginal power increase