• The Roadster Factory Recovery Fund - Friends, as you may have heard, The Roadster Factory, a respected British Car Parts business in PA, suffered a total loss in a fire on Christmas Day. Read about it, discuss or ask questions >> HERE. The Triumph Register of America is sponsoring a fund raiser to help TRF get back on their feet. If you can help, vist >> their GoFundMe page.
  • Hey there Guest!
    If you enjoy BCF and find our forum a useful resource, if you appreciate not having ads pop up all over the place and you want to ensure we can stay online - Please consider supporting with an "optional" low-cost annual subscription.
    **Upgrade Now**
    (PS: Subscribers don't see this UGLY banner)
Tips
Tips

Compression Test for 1600

Michael Oritt

Yoda
Gold
Country flag
Offline
What readings (warm) should I hope to find when doing a compression test on an MG 1600 and what %age variation between cylinders is acceptable?
 

jcatnite

Jedi Knight
Offline
What cranking pressures you would find depends on the engine. Type of cam, timing, etc. I can't really say what they should be. The one thing that is pretty important is that they should all be withing 10% or so of each other. As the engine wears the cranking pressure will be a bit lower or it might take 4 or 5 cycles to get it up to full pressure. A new engine would build most of the pressure in the first cycle maybe 2/3's or so and then come up to maximum in the next couple of cycles.
JC
 
OP
Michael Oritt

Michael Oritt

Yoda
Gold
Country flag
Offline
[ QUOTE ]
What cranking pressures you would find depends on the engine. Type of cam, timing, etc. JC

[/ QUOTE ]

I don't have any information on the cam but the compression ratio has been boosted to 11:1. Let's assume for the sake of the discussion that the engine has recently been redone and that bearings, etc. are in good shape--what is normal in an MG 1600 w/stock compression and what might raising the ratio do to compression readings?
 

jcatnite

Jedi Knight
Offline
I've read that you should expect between 17-20 times the compression ratio but you really can't rely on that. The intake valve has a great deal to do with it. The compression ratio that you are listing is 11:1 but that would be at running speed. Cranking rpm's are significantly lower and that would lead to lower cranking pressures. With that being said, I guess what I'm saying is it is extremely difficult to say what you should see for cranking pressure. I would guess that I would expect somewhere between 185 to 200ish? Like I said, it is more important that they all are within 10% of one another.
JC
 
Similar threads
Thread starter Title Forum Replies Date
petnatcar Compression Test Record Form Austin Healey 0
kodpkd Compression Test Results Austin Healey 1
AUSMHLY Compression test results Austin Healey 17
F TR2/3/3A Compression Test Triumph 13
P TR6 Latest compression test Triumph 11
T TR6 TR6 compression test Triumph 12
M Compression test results Austin Healey 11
Tinkerman TR2/3/3A 60 TR3A Compression test Triumph 15
pkmh Compression Test Results for BJ8 Austin Healey 14
M Compression test Triumph 25
eschneider TR2/3/3A follow up - TR3 broken pushrod &compression test Triumph 1
R compression test procedure on 1500 midget Spridgets 5
F Compression test: What does it tell me Spridgets 6
bighealeysource What is a good compression test number for a BJ8 ? Austin Healey 6
pjsmetana Spitfire Compression Test - Spit 1500 Triumph 34
J 145 - 130 - 155 - 160 warm compression test Triumph 10
Michael Oritt Compression test questions Racing 13
Michael Oritt Compression test questions MG 4
wkilleffer MGB Worrisome compression test results on my MGB 18GK MG 69
N Prpoer way to do compression test. Triumph 13
bmurphy7369 Compression test on 4.2 XK engine Jaguar 11
Creatrixx Compression test results British Motor Corp 6
eschneider need help with compression test readings...... Other Cars 7
Morris Compression test diagnosis??? Spridgets 12
Ralph_Y used car compression test question MG 1
Mark Jones Compression test - how to Triumph 5
kindofblue Compression Test Results Triumph 14
S Compression Test BJ7 Austin Healey 8
B Compression Test Results BT7 Austin Healey 3
E 948? Compression Test Austin Healey 8
W Cylinder compression Hillman super minx Other British Cars 15
Donald1107 TR2/3/3A low cylinder compression Triumph 12
Patrick67BJ8 Cylinder Compression Checks Austin Healey 30
B TR4/4A Finding compression stroke Triumph 7
M TR6 High Compression in One Cylinder Triumph 28
S TR2/3/3A Compression Triumph 8
J TR2/3/3A Figure of Eight Gasket Compression - Copper vs. Steel Triumph 18
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
K TR2/3/3A Compression testing again... Triumph 4
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
MY66AH Compression woes Spridgets 11

Similar threads

Top