B20A top speed
 

What sort of top speed would be expected from a B20A with the M40 gearbox?

Realistically low 90's. Maybe 96 on a good day. I'm sure someone will say that they get over 100 but the original road tests don't say that.

Thanks Derek. Something to look into, very much doubt I would get 90.

what rpm are you doing when it wont go any faster?? The twin carbs had an overdrive for a reason:-)

Don't know rpm, it's a 142 with a B20A. I scored a M41 yesterday with a seized OD but have a spare OD I bought years ago off of something so a conversion is on the cards.

I've not as yet wound it out to see what it could do but doesn't have much top end.

I fitted an OD M41 gearbox to my dad's 1973 144S it made a useful difference .

If your engine produces its max power at say 5200 rpm and you are already doing that at around 85 mph it won't go any faster except down hill .

Doesn't really have much pull above 60 so really wondering would it be capable of winding out to that sort of speed or is their an issue.

there must be an issue , its unlikely to be a worn engine . it should do 70- 90 with little stress , the twin carb B20B would do 115 + mph

Thanks. Will go over things. Just pulled the air filter and it's filthy, no idea how long it's been on for. Has a new 123 dizzy, assume has been set up correctly.

To be honest you would be better off with the correct distributor , It will be accurate and more reliable if you use the genuine Bosch Points . The electronic is ok if programmed to the exact timing curve your engine needs and it will go on and on for a while until it fails stranding you . Has it got the vacuum advance unit ? The original Bosch Cap rotor and points were at the time the very best on the market and that's still true if you can find some. If i remember correctly the ignition timing is 17 to 19 degrees Before Top Dead Centre at 1500 rpm , with the vac pipe on the advance unit disconnected .