• Hi Guest! Being a Paying Supporter is NOT a requirement to participate at BCF. However, subscribing will help ensure we can continue to serve the LBC community for years to come. If you enjoy BCF and find our forum a useful resource...Please consider supporting us by **Upgrading**
    (PS: Subscribers don't see this banner)
Tips
Tips

TR2/3/3A Compression testing again...

karls59tr

Darth Vader
Country flag
Online
Just did this with my friends compression tester. Car was run for awhile but not up to operating temperature.We got 170 in all four cylinders? Did he read the gauge wrong? Seems a bit high seeing as how it was mentioned that 150 was normal. We did let the engine crank more than four revolutions maybe until it stopped going up?....it was four revolutions for the test was it not? Also we did not have the choke out...was it supposed to be out. I think I remember that when doing compression tests on American cars the carb throttle valve was supposed to be wide open?
 

Geo Hahn

Yoda
Country flag
Offline
Yes, you want the throttle plates wide open (to be able to suck in enough air to compress). Gauges vary quite a bit so 170 may or may not be the exact figure, but it sounds good to me.
 

CJD

Yoda
Country flag
Offline
An SU choke doesn't affect the reading, as it is not a blade type choke. Blocking the throttle open may help to get a quicker rise. You are looking for the highest attainable, regardless of cranking time...but if it takes a large number of strokes then that may say something too.

High compression would indicate:

Carbon build up on a completely stock motor.
Shaved head giving higher compression ratio.
Short duration cam or a cam advanced from stock index.
 
OP
K

karls59tr

Darth Vader
Country flag
Online
The motor has sat for 15 years. If there was carbon build up would there be black smoke from the tail pipe? The car does not smoke at all. I don't know the history of the motor. The compression readings are all the same so that's a good thing. Would a rebuilt motor account for the high readings?
 

CJD

Yoda
Country flag
Offline
It depends. Fresh carbon, from say a carb that started running rich will cause smoke. That "carbon" is really unburned hydrocarbons, which are light and do not affect compression. Carbon that is baked onto the head, valves, and pistons is what is left after everything that can burn is burned. It is hard as rock and does not cause any smoke. It can also glow read hot and cause pre-ignition.

The rebuild itself has no factor, but, again, if the head is shaved it will raise compression. Also if the cam is short duration or advanced from straight up.
 
Similar threads
Thread starter Title Forum Replies Date
MadRiver Testing Compression MG 1
W Compression Testing Triumph 4
tahoe healey compression testing Austin Healey 32
J compression testing Austin Healey 15
B TR4/4A Finding compression stroke Triumph 7
M TR6 High Compression in One Cylinder Triumph 28
AUSMHLY Compression test results Austin Healey 17
S TR2/3/3A Compression Triumph 8
J TR2/3/3A Figure of Eight Gasket Compression - Copper vs. Steel Triumph 8
NutmegCT Variable compression? Other Cars 22
T Even but low compression on 3.8 - timing slightly off? Jaguar 7
edkap2002 TR6 fuel line compression fittings....how to remove Triumph 3
R TR2/3/3A Good Compression Triumph 1
3798j Fastronix Battery Compression Ends Restoration & Tools 4
F TR2/3/3A Compression Test Triumph 13
HighAltitudeTR3 TR2/3/3A Compression Question Triumph 10
warwick-steve High compression head identification Austin Healey 16
Tinkerman TR2/3/3A 1960 TR3A engine compression question. Triumph 7
Jim_Gruber Bugsy IV and Engine Compression :[ Spridgets 11
Martinld123 Compression check 1956 BN2 Austin Healey 7
2 TR2/3/3A compression numbers Triumph 1
P TR6 Latest compression test Triumph 11
MY66AH Compression woes Spridgets 11
S Unexpected Compression Readings Austin Healey 14
Gliderman8 TR6 Compression help in one cylinder Triumph 7
tinman58 TR2/3/3A Surprise on compression. Triumph 9
K TR2/3/3A Cylinder Head and Compression Ratio Triumph 0
T TR6 TR6 compression test Triumph 12
B TR6 Fuel tank to line compression fitting Triumph 1
tinman58 TR5/TR250 Compression # Triumph 9
R TR4/4A Need Advice as to what to do regarding Engine Compression Problems Triumph 26
M Compression test results Austin Healey 11
R TR2/3/3A Steering, stator tube compression sleeve? Triumph 4
Kleykamp TR2/3/3A compression numbers & smoking engine Triumph 20
S Bugeye 948cc Compression Spridgets 7
L 1275 Compression, Camshaft, et al Spridgets 16
me61ic Compression results - Worth Rebuiding? Austin Healey 13
D Compression #'s Triumph 13
Tinkerman TR2/3/3A 60 TR3A Compression test Triumph 15
D Austin Healey 100-6 Compression Austin Healey 1
P TR6 1971 TR6 compression Triumph 2
T TR6 TR6 fuel line / mechanical fuel pump compression? Triumph 5
T Milling a head on a Stock 1275 for compression? Spridgets 13
RichBall For us 1500 guys, high compression head up on Ebay Spridgets 10
M TR4/4A TR4 Optimal Compression - 91 Octane Pump Gas Triumph 13
pkmh Compression Test Results for BJ8 Austin Healey 14
TulsaFred 1275 compression ratios and horsepower Spridgets 29
R TR4/4A TR4a engine compression Triumph 6
R Spitfire Lbs of compression Spec for 1979 Spitfire. Triumph 3
BN6_2197 Question on Engine Compression Austin Healey 9

Similar threads

Top