perpetual plug fouling...pissing me off!!!!!!!

[datsunfish]

So I cannot seem to get any plugs in my 620 to last longer than 15 minutes before they foul out and run like shit.So here is the run down so we are all aware of where I am at.

A few months back I shattered my timing chain guides and opted to just swap out the block since I had one.L18s.When I put in the new motor I went with the 210 head from my 510 since it was nice and supposedly rebuilt at one time.Not my choice of heads but I figured it better than the beat up w58 that did not match the exhaust mani.Ran ok for a while then would foul out plugs like mad.At first I was running the msd and 8mm's with ngk irridiums.I was planning to sell it so I threw on a points and super stock coil and that also ran like shit.I took the new wires,cap and coil from my 521 and put them on there.I have used the stock hitachi carb from my 510,a holley 32/36 carb and my weber dfav all with the same results.Gradually every attempt to stop plug fouling had failed.

At this time it was my determination that since I was running a larger ported intake mani on the small 210 head it must be a matter of the fuel puddling up and going in not atomized.

I swapped out the mani and ran into some electrical problems and decided to tear out the harness and go through it.I fixed her up and got it started using the stock hitachi,stock size mani and good wires,coil and cap with pertronics.Ran like crap so off to the parts store for some new plugs.Popped them in and she ran good.Needed a little tinkering to get it dialed in but I got it to run great,for a while.Let it idle while cleaning it out and when i went to park it wouldnt you know it,FOULED ASS FUCKING PLUGS!!!!!:mad::mad::mad::mad::mad::mad::mad::mad::mad:

I took them all out and the front 2 were black and sooty while the rear were clean and whitish.Cleaned them up and she ran good for about a minute.

Sorry for the longwindedness of this but I figured I should tell all about it so nobody suggests I go buy new plugs.

Is the 210 head insufficient for the l18?I cant see how.Mechanically it seems ok.No clacking.No smoke other than fuel.No water in the oil.

My next shot is to change out the stupid fucking head.I am tired of trying to get this thing to run right just to sell it.I have 2 others that desperately need work.First $600 takes it.Unless some one can help.Thanks.

[hang_510]

valve adjustment?

[datsunaholic]

Done a compression test?

[datzenmike]

Three different carbs? How about fuel pressure? too high? factory pump or electric? When running, is the fuel level in the center of the sight glass?

 

Two different manifolds? Is the vacuum port for the power brake booster sealed tight or if using is the hose leaking?A whitish plug means that the 2 cylinders are running lean. Both rear cylinders would seem like the rear half of the intake is leaking vacuum.

[banzai510(hainz)]

is the ballast resistor still installed with the Accel Superstock coil? Not the Super Coil. If Super Coil then a added ballast must be added to the stock ballast resistor.

 

a superstock is close to same resisitance as the stock coil of 1.4-1.6 ohms

But is still needed with a ballast if running a Pertronix or points.

 

If the pertronix or points was run w/o the stock ballast it will FRY the points FAST and could fry the Pertronix

[datsunfish]

I gots dem der uh,,prtranix.I have an exide select coil with stock resistor installed the super stock was only another part to throw around.Brand new ngk's.

I have tried every setup available except for swaping the head.I had a hard time getting the 510 going good until I swapped in the w53.Probably because this is the head I replaced.

[73super]

Did you shave your hooks? This can cause the rest of your truck to go downhill very fast.... Just a reminder for you kids out there thinking of doing the same thing! :lol:

[banzai510(hainz)]

I have an exide select coil with stock resistor installed the super stock was only another part to throw around

 

Now Im more confused.

 

If you have too much resisitance maybe you dont have enough spark al make sure the pertronix the + side has the full 12 volts

 

all those heads cant be bad? they work or dont

 

mayb the carb float is to high causing flooded condition?

[datzenmike]

He said he tried three carbs... hi fuel pressure??? Why only two cylinders black??? Compression test them?

[banzai510(hainz)]

a mechanical fuel pump will go limp once the carb is full if no return line.

 

I have never seen a mech pump have High pressure. But I guess it could happen.

[Phlebmaster]

Ha Ha!! Leave them hooks alone!!:D

 

Mine runs better after I wash it.....weird.:lol:

 

Did you shave your hooks? This can cause the rest of your truck to go downhill very fast.... Just a reminder for you kids out there thinking of doing the same thing! :lol:

[datsunfish]

I dont know whats so confusing.This head on this block is the only I have used.I have tried 3 carbs,ported and unported manifolds and 3 different coils all setup correct.I run a resistor on everything other than a matchbox with msd.Runs perfect until the plugs foul out.

I ran a comp check and it wasnt great but fairly even.i am going to check the booster.

[datsunfish]

I think the manifold was a big issue here.Also I think that my carbs sitting for a while with gas in them didnt help either.

I rebuilt the dfav weber and got it to run pretty good.The only true test now is to drive it on the highway for half an hour.Friday I will do that and then I can go get my z24 motor in lacey.I never realized how much I need a pickup until only having a 510 to drive.

Thanks for all your replies.This has truly been a confusing battle.I will keep you posted.

[datsunfish]

I went out and fired her off and let it idle for a bit.No fouling yet but what I did find is that at low idle if I hold the brake down or turn the lights it will step down a bit.This should suggest an electrical issue.I have had nothing but problems with the old hacked up harnesses.I suppose I will replace them and wire new relays to throw ground through the switches rather than power.

[datsunaholic]

Even mine does that... turning on the lights loads the alternator, and at idle it's enough to put a noticeable load on the engine.

 

Switching the ground vs the positive power side through a switch won't make a difference. It's the same current. But using a relay is a good idea, since less current through the switches is a good thing.

[Hirns]

Had a similar problem with a different vehical years ago. Turn headlights on, extra load, did not like, Brake aplication, did not like! Rear two plugs lean, front okay. Solution IN MY case was a leaking diaphagm on the brake booster master. Fuel air mix was first sucked off the rear cylinders, leaning the mix, foward cylinders were better.

 

Second bet, do the comp test, these heads can have cracks/warps and leak between cylinders.

 

 

But I must say, if it makes you feel any better you have posed a good riddle.

 

Hirns(Aussie)

[dat521gatherer]

around a year ago my l16 was was fouling out plugs every week. i swear the oil was dripping right off the valves. so i had bought a weber dgv from evilbay for around $100 and finally decided to try it out and low and behold i'v not had any plugs foul out since. and thats with a stock ignition. still burned oil like hell though.i would love to try my matchbox but i dont have a pedalstal:( i think hainz said i could use a c-clamp just to try it out.:)

[banzai510(hainz)]

dat gather

try my matchbox but i dont have a pedalstal i think hainz said i could use a c-clamp just to try it out.

__________________

 

Yeah just bolt it in there set to #1 and where it lines up just clamp the timming plate down somehow.

[]2eDeYe]

Although your idle should go down when you depress the brake, I think Hirns could be on to something.

 

Depressing the brack pulls vaccum from the manifold, which cause the idle to drop. If it's leaking it could create a bad vaccum problem. If it is bad the power from the vaccum assist will wear off. You might not notice it with a manual transmission and drum brakes unless your on a steep incline.

[datzenmike]

Two different manifolds? Is the vacuum port for the power brake booster sealed tight or if using is the hose leaking?A whitish plug means that the 2 cylinders are running lean. Both rear cylinders would seem like the rear half of the intake is leaking vacuum.

 

Was this checked????????

[DanielC]

This is a way off base guess. If you have an automatic transmission in your Datsun, there is a thing called a vacuum modulator that helps control the transmission. It has a diaphram in it, and hooks up to manifold vacuum. If the diaphram gets a leak, the engine sucks ATF from the transmission and dumps in into the cylinders.