Don't laugh at my Flat Tops...Yet

[Bruce Palmer]

Cap'n,

The shop on the weekend is usually abuzz with Datsun owners of all sorts. The sooner you can get by and get aquainted, the shorter your learning curve will be. Everybody started at square one sometime. Call me if you'd like to make arrangements to stop by.

[Mike B]

Too bad I don't have a way to play this yet. I think it may be a betamax tape, since it says Sony on the side.

-Mike

Edited April 13, 2010 by Mike B

[JonnyRock]

That's awesome Mike!

[sblake01]

Too bad I don't have a way to play this yet. I think it may be a betamax tape, since it says Sony on the side.

-Mike

I'd take that to someone with the equipment and have them transferred to DVD.

[motorman7]

I have been driving the '73 daily now for the last two months and they seem to be doing just fine. They do prefer the warm weather and run very smooth when warm. They also work well during acceleration

The only 'issue', though not a big deal, is that the engine is a little weak when cold. I have to run the revs up during the first 2 or 3 minutes of operation when starting up from the stop signs on my block. I should hook-up the hose that goes from the manifold cover to the air cleaner. That would probably help the cold start issue some. Once my engine temp moves over 120, everything runs fine.

Also, regarding the cold: when its cold, seems like a little more cranking time, maybe 5 seconds till start. Also could be cause I am not running the electric pump (which I will replace some day). On warm days it starts of in less than a second.

So, pretty happy with the flat tops so far. No plan on changing anything except the adding the hose and electric pump eventually.

Thanks for all the input.

Rich

[MikeW]

I've never understood the hose from the manifold to the air cleaner for winter use. If the engine is completely cold it doesn't seem like it would help one bit when starting the car. If the engine has been turned off for a short enough time that it's still warm it should crank back up instantly. For performance cold air is better than warm so it doesn't seem like you'd want to drive around with hot air coming from the manifold once the engine is hot anyway.

I seem to recall making this statement in the past and someone explained it to me but I've already forgotten the answer.

Regarding the the power loss when the engine is cold it could be choke related. While I can't offer any advice with the flap tops I have to assume that the choke principle is the same when cold starting the engine. Especially in cold weather it's often necessary to leave the choke on until the engine has reached operating temperature.

[Zedrally]

Carbie heat is applied to prevent carbie icing, possibly better known a phenomena in aviation, it's just that the land based condition isn't as deadly!

[MikeW]

Thanks for the explanation. I was aware of icing in aircraft engines but never considered that possibility in cars that weren't in extremely cold environments. After researching it a bit online I learned that it doesn't even need to be cold outside to cause icing. With humid air the venturi effect inside the carburetor lowers pressure enough that it's possible to freeze the humidity in the air and cause it to build up on the butterfly valve.

[motorman7]

I've never understood the hose from the manifold to the air cleaner for winter use. If the engine is completely cold it doesn't seem like it would help one bit when starting the car.

Thought about that after I wrote it. Seeing as how the Exhaust manifold is thick cast iron, I am sure it takes at least a couple minutes before it heats up.

Also, if I am not mistaken, there is a vaccuum operated valve on the air cleaner that closes that path from the exhaust manifold once the engine is warmed up.

Which, leads to the issue most likely being the choke. I will have to go back and check the adjustment.

Rich