QuestionHi Howard
My son and I are doing an 80 B. It ran, but badly. In the course of the rebuild, the engine will be out. I did a compression test, it came in at 115, hot, across the board. The single carb is broken and the fuel mix is poor. I suspect the heads are pretty carboned up. I can't tell if the engine is high or low compression, the engine number is long gone. I have twin SUs, HS model to replace the old carb when we finish the body. I am unsure wheather to rebuild the bottom end or not. I am putting in a 4 speed with OD so I wonder if I should rebuild the engine to high compression? Can you also tell me if there is a difference in the length of the drive shaft from one tranny to the other. Is there any other way I can identify the engine? Thoughts please
Thanks
Chris
AnswerHi Chris,
The 115 compression test is not good but since it was across the board you may not have taken it correctly. You must hold the throttle wide open and be sure the engine turns over at least 5 or 6 revolutions for each cylinder tested. Then you should have done a "Wet" test. That is squirt several shots of engine oil into the cylinder to be tested and check the compression again. You should only see 15 or 20% difference between the dry test and the wet test. The dry test is for the general condition of the valves and rings and the wet test is for the rings only.
If you are installing an Overdrive box you will be able to use the "B" on todays expressways. Especially if you use the 4 speed differential as it is higher geared than the OD rear end. Many "B" owners make that conversion as I have too. I did several but for the life of me I can't remember if the driveshafts were a different length. I have a OD box and a 4 spd. but they are buried in a shed or I could measure them for you. I do remember the bolt patterns are the same but you will have to measure the length of the two boxes to see if you need an OD driveshaft or get a local driveshaft shop to correct the length.
With the engine out it would pay you to go all the way through the engine. If you need any tech advice along the way I will be glad to help. Also, be sure to do the clutch and release bearing too, as a higher gear ratio puts a higher strain on the clutch.
The single Stromberg carb was not a good setup for the "B" and the two SUs were good but if you don't have the "Twin SU exhaust manifold" you need to source one or a set of headers.
Without the engine number plate the only thing you can do is to confirm that it is at least a later engine by the 4 ports near the plugs and the engine was painted all black, bolts, nuts and all. There are a few things inside that may get you closer to which engine you have but basically they were close to the same on the later engines.
You may want to read some of my tech tips and my "Project" on my website. http://mg-tri-jag.net
let me know how your project progresses.
Howard
