Datsun Roadster Forum-311s.org

the rear carb is leaking fuel into the venturi when sitting..and the car isn't running right at all..missing on the #3 cylinder and such.
Does it need a rebuild?

thanks
steve

Most likely not. You need to check to see if the float is sunk. If not, then the float valve has crap on it, or the level is set wrong. PM me your number and I will see if I can help.

ok took it apart..looks good cleaned it out, but...

if you pull the #3 plug off it doesn't effect the engine...but all of the other ones do..so why is this?

all the valve lash is correct...manifold tightend down..im lost!!

steve

Hmmm... Tough to say without being there, but try swapping plug wires. You may have a wire with a bad end or something that is not firing once it is connected. If you swap it and the condition follows the plug wire, then you will know the answer to that question.

It seems like I have had this problem in the past, I can't remember what I did to fix it. Check to see if your dizzy driveshaft is bent. Also see if your cap is seated completely.

Will

One way to check is to pull the plug wire a little bit off the plug with the engine running, USE INSULATED PLIERS about 1/4 inch and see if you hear it arcing to the plug or if the miss goes away.
You can also just put a spare spark plug in the suspect wire and ground the body of the plug and see if there is spark. If you solder a piece of wite to the plug body and add a clip to ground it, you get a great tester to keep in the emergency kit in the trunk

i traded wires, plugs..and it shocked the hell out of me..and it is arcing...

i did a compression check..but the gauge is old, but it matched the other cylinders...
But tomorrow im getting a better guage just to make sure..checked all the valve lashes to make sure a valve is hanging open..the cam lobe isn't wiped out..

and the head and tail lights don't turn on niether do the turn signals..the brake lights work tho'...argh!!

thanks guys
steve

You can buy a pair of spark plug wire pliers, made of insulating materiel, or make something out of wood. Before you start, pop the plug boots loose and push back almost tight. If the plug wires Zapped you while both ends are connected, they are bad, no question.

I bet that when it overheated, it baked the wires. Ditch them and buy some new ones. Most shops don't list the roadsters anymore. I am told that if you buy a wire set for an early 80's Datsun 210, you will get a set that will fit. Or you can buy a universal set and roll your own. (I did that with a V8 set - I got two sets of wires!) Replace the wires, check the cap/rotor/plugs to ensure that they are good (may want to just replace the plugs - they are cheap and if one cracked, you will go nuts trying to figure it out) and try again.

What was the issue with the carb? Adjustment?

Oh, a neighbor kid may have a Volvo turbo lying about. I sold him one a while back and he may still have it. Want me to check on it? I doubt that he will use it...

i switched the wires around..changed brand of plugs and switched from diff cylinders!!!

the adjustment on the bottom of the carb (from the bowl to the carb itself) was unscrewed more on the back one than the front one, basically the front was almost tight and the rear one was loosend a bit more.

replaced all the carb and spacer gaskets as to make sure on air leak thing...still happening..the #3 spark plug is black..and the others good color. but it still running on 3 cyl.so its getting fuel...but not the right amount of air...atleast thats what im told..

so tomorrow ill be checking the compression

yes intrested in the turbo!!!! still thinking about the placement..need to find another rad. maybe one that has the bottom hose on the left instead of the right. to get it away from the turbo. maybe it won't be in the way..won't know until i get a turbo...

thanks
steve

yup it has enough compression...any other ideas?

steve

Damn, talk about gremlins!

Let me get this straight: even if you switch plug wires and/or plugs, #3 cylinder refuses to fire? And you have good compression?

The only piece in this puzzle not touched is the distributor cap, right? Hmmmm.......

Can't wait to hear the solution on this.

yup...#3 cylinder has 175 #1 225 and the others are at 200...it should run...the cap looks new. i don't see how it would go bad from sitting for acoupple of years.im going to try even differnt plugs to see what happens

steve

Check a few things...
1 the cap and rotor, cause it's easy to check.
2 check the point gap on all 4 lobes of the distributor cam to see if they are equal and if the shaft wobbles
3 do a wet compression test. 1/2 teaspoon of engine oil in the spark plug hole and test as usual. It should be higher because the oil "super seals" the rings, but if #3 gains alot more than the others, rings are suspect.

4 cylinder leakage test. This is tougher, but definative. This is from memory, so someone correct me if I'm wrong (20 years since school)
A. take out all 4 plugs, ground coil high voltage wire to dist cap. Get #3 to top dead center, (both valves closed) put the car in top gear, parking brake on. If you are not at exactly TDC, the motor will turn and the car can move forward, so be careful. Make sure there is room to go forward just in case.
B. Take off oil cap, aircleaner and radiator cap.
C. SLOWLY Apply about 100 pounds of air pressure into the spark plug hole and if the car doesnt move go to step D. If it moves, go back to A and start again.
D. with the air pressure applied, listen at exhaust pipe and carburetors for air escaping. Thats a leaky intake or exhaust valve. Check coolant for bubbling and listen at cylinder #2 and#4 for air leakage. That would be head gasket. Listen at oil cap hole, that would be rings. It will always leak some past the rings, so you can do another cylinder for comparison.

5 Last thought, was the plug on #3 wet and black, or dry and black. Dry is rich, wet is lack of ignition.

6. I'm assuming no coolant in the oil, no oil in the coolant and no unusual smoke or steam from the exhaust.

If all else fails, roll an engine hoist toward the car, they sometimes respond to threats.

it was dry and black..ill have to try that

Thanks!

steve