wkilleffer
Jedi Knight
Offline
Anything to avoid doing homework...
Anyhow, my car's a 1974 MGB with an 18GK engine. The engine was rebuilt just over six years ago, and if I've counted correctly, it has less than 15k miles on it. The HS4 twin carbs were rebushed and shafted shortly thereafter.
In the last year, I've changed the manifold gasket, added insulation to the heat shield, put new jets and jet tubes on the carbs, and installed a Pertronix dizzy and matching coil. On the scale, the timing shows up right where it's supposed to. Any higher, and the car will knock some even with 93 octane.
The car seemed to be idling roughly the last few times I've had it out, so I decided to check a few things. The spark plug tips are grayish-white except one. If #1 cyl. is near the radiator, and #4 is by the bulkhead, #2 is the one I'm talking about. It seems to use more gas than it should. I can't get it to break 20mph city or highway, and people tell me that 23 mpg city isn't unusual even with spirited driving.
I've never done a compression check on it, so I was curious what would show up. I ran the car till the temp gauge was at NOT, and started with the #1. I didn't squirt oil into the cylinders or anything like that. Just a warmed-up engine. Here are the results:
#1 1st- 149lbs 2nd- 149
#2 1st- 145lbs 2nd- 145
#3 1st- 107lbs 2nd- 107
#4 1st- 130lbs 2nd- 130
Bentley says that an 18GK should be at 160lbs. Since the engine is rebuilt and not brand new, the 149lbs and 145 might be ok, but I really don't know.
Seems strange otherwise. I've always tried to adjust the valve lash correctly, but am willing to admit that may be a weak area for me. The rebuilder told me to use 10w40 oil in synthetic if possible, and I've always done that, or synthetic blend when I couldn't get full synth.
I've never abused nor raced the car, though I do like to go up to 3k between shifts if possible. The only thing that might be questionable is that I let the coolant stay in for two years one time.
Is this a blown head gasket or misadjusted valves? I've never seen coolant in the oil nor the other way around, but know that other things can happen. I'd hate to think that I've killed my baby.
Any advice or suggestions would be most appreciated.
Thank you,
-Bill
Anyhow, my car's a 1974 MGB with an 18GK engine. The engine was rebuilt just over six years ago, and if I've counted correctly, it has less than 15k miles on it. The HS4 twin carbs were rebushed and shafted shortly thereafter.
In the last year, I've changed the manifold gasket, added insulation to the heat shield, put new jets and jet tubes on the carbs, and installed a Pertronix dizzy and matching coil. On the scale, the timing shows up right where it's supposed to. Any higher, and the car will knock some even with 93 octane.
The car seemed to be idling roughly the last few times I've had it out, so I decided to check a few things. The spark plug tips are grayish-white except one. If #1 cyl. is near the radiator, and #4 is by the bulkhead, #2 is the one I'm talking about. It seems to use more gas than it should. I can't get it to break 20mph city or highway, and people tell me that 23 mpg city isn't unusual even with spirited driving.
I've never done a compression check on it, so I was curious what would show up. I ran the car till the temp gauge was at NOT, and started with the #1. I didn't squirt oil into the cylinders or anything like that. Just a warmed-up engine. Here are the results:
#1 1st- 149lbs 2nd- 149
#2 1st- 145lbs 2nd- 145
#3 1st- 107lbs 2nd- 107
#4 1st- 130lbs 2nd- 130
Bentley says that an 18GK should be at 160lbs. Since the engine is rebuilt and not brand new, the 149lbs and 145 might be ok, but I really don't know.
Seems strange otherwise. I've always tried to adjust the valve lash correctly, but am willing to admit that may be a weak area for me. The rebuilder told me to use 10w40 oil in synthetic if possible, and I've always done that, or synthetic blend when I couldn't get full synth.
I've never abused nor raced the car, though I do like to go up to 3k between shifts if possible. The only thing that might be questionable is that I let the coolant stay in for two years one time.
Is this a blown head gasket or misadjusted valves? I've never seen coolant in the oil nor the other way around, but know that other things can happen. I'd hate to think that I've killed my baby.
Any advice or suggestions would be most appreciated.
Thank you,
-Bill