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+--- Thread: Speed quandry (/showthread.php?tid=7568)
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Speed quandry - Vancevr - 29-05-2022
I was driving down the main street in my town which has a 40 mph limit. And when I got to third gear it no longer excelerates it goes to about 35 down a steep hill but thats it. If I move the advance lever it only makes the car run worse. So I downshift and now the engine is running really high. I am at 6300 ft in elevation but I should get a little more out of the car. Any thoughts
RE: Speed quandry - Bob Culver - 29-05-2022
In their day, before possessed by youths in the mid 1950s, ordinary Sevens would very rarely be taken to 30 mph in 2nd (of 3) gears. Cranks stresses are high on a closed throttle and increase with revs squared. Not conducive to long crank life. What speed does it reach in nuetral?
Apart from crank considerations, the usual down hill speed limiter is driver terror.
Is it really downhill or is it some optical illusion?
RE: Speed quandry - squeak - 29-05-2022
ignition timing , butterfly not fully open, rats nest in the muffler
RE: Speed quandry - Mike Costigan - 29-05-2022
Is this the first time you've driven the car, or has something changed from last outing?
RE: Speed quandry - Colin Reed - 29-05-2022
Hi,
At that Altitude you will lose between 2.5 and 2.9 PSI Atmospheric Pressure ,
Which Translates to about a Fifth of of the Engine HP, fitting a High Compression Head would help.
Colin
NZ
RE: Speed quandry - Mike Costigan - 29-05-2022
A 20% loss of power is a very depressing thought when you've only got 10bhp to start with!
RE: Speed quandry - Reckless Rat - 29-05-2022
I think verifying that the engine is operating at optimum first is a good starting point, for example, cylinder compression test, valve/tappet clearances, ignition settings etc. I get the impression Vance, that you really don't know what you're doing with this car...
RE: Speed quandry - robert regan - 29-05-2022
I just checked and here in Blackwood south wales it says that we are 564 ft above sea level and my 1926 chummy easily does 50mph along the flat it is in standard form, I am terrified when its going at that speed and there is only me in the car, if there was a passenger with me there is a fair chance that they would beat me with a big stick when we stopped Regards to all Rob.
RE: Speed quandry - AustinWood - 29-05-2022
If 50mph is terrifying I suspect you need to increase the castor of the front axle.
RE: Speed quandry - robert regan - 29-05-2022
it goes where I point it and handles as well as any seven could but that does not take away how vulnerable you feel in such a tiny open car ! does it not worry you regards Rob.