Burnt Valve ? '78 620

[Draker]

Take picture of the drive spindle without the dizzy attached. Typically if the dizzy is turned that much, you are a tooth off. Easy to spot by the drive spindle.

[Sh00bs]

I was ! Dropped the oil pump,  spun what I believed to be 1 tooth and put it back in. Wouldn't start dead on the lines. I retarded it (CW) the dizzy a little and she fired right up

Idles perfect

Gonna get the radiator and lines all back in with fluid tomorrow and use a timing light to really dial it in, we're pretty close

Anyone know what timing degree is at idle? A 240 buddy said L24/26 are ~8 or 9 ° he thinks

 

[datzenmike]

L20B

12 degrees BTDC. Hot engine, idle below 800.

[Sh00bs]

8 hours ago, datzenmike said:

L20B

12 degrees BTDC. Hot engine, idle below 800.

thank you!

[banzai510(hainz)]

If one lines up the notches on the oil pump it usually goes in but can catch the gear too soon and make it a tooth off.

 

as for lining up the to TDC , Just open the valve cover cap. tap the starter till the cam lobe right there looking in the hole is about at the 9 o clock position to the left. then turn the crank to the right till the Timing mark is at zero  keep the tension all the way up to zero You can do this by hand.   The crank zero never changes  everything is based off this.

 

Nice to hear a stock datsun exhaust.  Next time Im going back to a stock type muffler maybe just increase the size

[Sh00bs]

4 hours ago, banzai510(hainz) said:

If one lines up the notches on the oil pump it usually goes in but can catch the gear too soon and make it a tooth off.

 

as for lining up the to TDC , Just open the valve cover cap. tap the starter till the cam lobe right there looking in the hole is about at the 9 o clock position to the left. then turn the crank to the right till the Timing mark is at zero  keep the tension all the way up to zero You can do this by hand.   The crank zero never changes  everything is based off this.

 

Nice to hear a stock datsun exhaust.  Next time Im going back to a stock type muffler maybe just increase the size

Your videos were great! Much thanks

[Sh00bs]

So everything was going smooth, I have the radiator back in, fan hooked up, new rad coolant lines 

Im pouring in coolant and she's just about full, then coolant starts dripping on the floor..

 Seems like from the middle of the engine on the driver side 

Almost like it's coming from under the headers 

 

I did take a few of the head bolts out when I pulled the cam

Ughhggghfjgh wtf 

 

Head gasket ? 

I wish I could post videos here without having to upload to YouTube

I did get under the back of the driver side front wheel and look up, I can see a drop on the bottom of the headers - this is after it stopped dripping. Sigh

[banzai510(hainz)]

15 minutes ago, Sh00bs said:

I did take a few of the head bolts out when I pulled the cam

why?????????????  anytime you take a cam tower out one risk poulling the threads out of the head. I dont know why they are so ez to ruin but I did it myself.

I kinda know this was a non no  when you posted it earlier loosing the head bolts

 

 

did you take the intake off at anytime???? If not then the headgasket is most likely compromised. I guess you can retorq it down but I myself will never loosen all those head bolts and then retorq them down.I my self I tear the whole fucking thing apart and put a new gasket as the gasket is crushed to it size already.  and then being a 10-20 30 year old gasket who knows how close to being worn around the water jacket areas

Edited May 27, 2021 by banzai510(hainz)

[Sh00bs]

1 minute ago, banzai510(hainz) said:

why?????????????  anytime you take a cam tower out one risk poulling the threads out of the head. I dont know why they are so ez to ruin but I did it myself.

I kinda know this was a non no  when you posted it earlier loosing the head bolts

 

 

did you take the intake off at anytime???? If not then the headgasket is most likely compromised. I guess you can retorq it down but I myself will never loosen all those head bolts and then retorq them down.I my self I tear the whole fucking thing apart and put a new gasket as the gasket is crushed to it size already.  sand then being a 10-20 30 year old gaskt who knows how close to being worn around the water jacket areas

I took the head bolts out that held the cam down 

I thought that was the only way to get the cam out 

 

What's the over under on torqung down ~5ft lbs over oem specs ? Long shot but whats there to lose at this point 

[banzai510(hainz)]

17 minutes ago, Sh00bs said:

thought that was the only way to get the cam out

that is a short cut to redo the whole head and pull it out now.

 

I would try 5 -7pounds over  but once a leak they usually never stop leaking.

Im not a head gasket expert if I do loosen or retorq it would be on a new gasket.

 

 

I would never pull a cam from the top out and then put a new one down as you dont know if the cam toweres are really on there straight and cam freely spinning.

You have to pull all the rockers off then pull the sprocket then slide the cam out but then even get that far you have to keep the chain on till all rockers off so you dont hit a piston ec.....  You might have went 3 steps backwards   Keeping in mind to reset motor back to TDC before removing the sprocket and crank on Zero

 

 

this is why I kinda always on my theme dont fuck with stuff thinking your going to make it better for 3 extra HP.

Edited May 27, 2021 by banzai510(hainz)

[Sh00bs]

Yeah I mean when I got the truck a rocker was off already 

It damaged a rocker and the cam 

I got a new (used, undamaged) rocker on without taking the cam off to replace the one that came off

 

Since it damaged the cam too when it came off, I now had a MEAN tick 

Hence the cam job... please don't think I was just like hey I wanna put a cam on this 100% stock motor 

 

I'm not trying to come off like a dick, just frustrated as shit. Not having a good time so far as a datsun owner... sigh. Shoulda just left her keep running on 3cyl's lol 

 

Re torqued to 66ft lbs 

Added coolant. Almost immediately started coming out again

 

Can you see the puddle on the intake runner ? This shot is looking in between the thermostat housing and the intake filter housing 

 

 

[banzai510(hainz)]

like i said if you DID NOT have the intake and exhaust manifold off then you know its not the intake gasket as they can give the same leak if it has a water passage for the heated intake manifold. I cant tell which type you have unless I see a whole photo or if its a exhaust heated type manifold.

Really the later L20 are full of emmsions and I hate then as its hard to get to the bolts nuts ect....

 

 

You can get the cam out by pulling thru the cam towers removing the rockers and turning the can and doing each rock . its time consuming but alot ezer than taking the head off now with all the emmssion crap and not breaking a 40yr old bolt soemwhere.

 

 

maybe you can take the head off with the intake and exhause manifold together but Datzenmike or maybe someone else and guide you thru this as I dont know beside unbolt the exhaust flange and pull the whole motor now, Cause getting those intake exhaust manifold botls out is a mofo with a emmssions intake

[Sh00bs]

So I was going to pressurize the system and look for the leak to confirm HG

I took the blue intake housing off the carb for a better view and low and behold ! Torn hose

Fingers crossed my HG is okay. Will let you all know 

 

Appreciate the quick replies Hainz!

[datzenmike]

A 78 is a W58 head an they have the water cooled/warmed intake. As shown by the broken hose above. I think the outlet on the intake is larger than the by pass metal line so that's why that replacement hose looks so crushed by the hose clamp. I would wrap the metal pipe with electrical tape then slip the larger hose on and clamp it.

[Sh00bs]

4 minutes ago, datzenmike said:

A 78 is a W58 head an they have the water cooled/warmed intake. As shown by the broken hose above. I think the outlet on the intake is larger than the by pass metal line so that's why that replacement hose looks so crushed by the hose clamp. I would wrap the metal pipe with electrical tape then slip the larger hose on and clamp it.

 

 

Will do! Thanks sir

 

Looks like I gotta take the carb off though to get to the hose clamp to get her off... still easier than a HG

[datzenmike]

 

You sure? Should be just out from under.

 

Carburetor removal is a bitch. So fix right the first time.

 

I sacrificed a 12mm spanner, shortening it so it would clear all the crap in the way

 

 

 

[banzai510(hainz)]

i would try not to take carb off as then the gaskets most like will rip

[bilzbobaggins]

cant just nip the clamps and replace them?  Use a good set of dikes?

[banzai510(hainz)]

carb is most likely off already!!!!!!!!!!!!  he needs to wait to get more infor from people before doing

[Sh00bs]

Aha no its not off .... ill try to get the clamp and hose off before pulling the carb tomorrow 

[Sh00bs]

Good news / bad news

Timing light is VERY old, took a shit on me... gonna grab another tomorrow or Monday 

She fires right up and runs great! Idles perfect, bleed the coolant system, took it out for a drive. Started missing a little 

Turned around to come back (never left the community), really didn't want to stay running under load 

She's about fully warm now 

I can keep her running when not under load 

Limped back 

 

Shut off. She fires right back up fine but only runs for 3-4 seconds on her own before dying 

 

Sigh. I can't win 

 

On the plus side, when it was still warming up it drove great for the first minute or so haha no more tick! Old cam was definitely the culprit 

[A guy named Rick]

On 4/27/2021 at 12:02 AM, wayno said:

I burnt an intake valve once over 300 miles from home, it started back firing thru the carb, I had to get home so I removed the spark plug wire from the bad cylinder and drove home on 3 cylinders, it was gutless but it got me home.

I expect if it had been an exhaust valve it would have just missed, but it may have back fired thru the exhaust, I had a exhaust valve go tight on my in my work truck 4 or 5 years ago and all it did was miss, I was close to home(within 2 miles) so I drove it home and fixed it without any continuing issues.

 

You do not want un-burnt fuel going into your exhaust so if you have a bad exhaust valve and it is just missing you should still remove the spark plug from that cylinder, otherwise bad stuff can happen like this.

 

But I fixed it and it looks like this to this day, the explosion was indescribable.

 

 

Damn, i wish i had the pic of my muffler on the 240z that i blew up. I kept trying to get it started, having issues with the distributor and the carbs. idk what happened, but i sucked enough fuel down and it finally sparked and boom. blew the muffler up and scared the shit out of the neighbors. it was a turbo muffler, and it blew it open and folded up around the lower rear corner of the quarter panel.

[datzenmike]

Gasoline contains just over 10 times the energy of a similar weight ot TNT. Not that you could properly mix and perfectly burn it but 10 times is a scary amount of energy in your tank. One gram of gas would lift your 2,700 pound car over 13 feet. TNT would be 1.1 foot.

[Sh00bs]

I bypassed the filter and ran the hose from the pump into a gas container to confirm it wasn't a clogged filter 

I can put my finger I've the hose and feel the pump sucking 

Same thing though, starts and runs for a few seconds and dies

[datzenmike]

Pull the coil wire off so it won't start. Pull the hose off the fuel pump outlet and direct into a pail. Crank the engine over with the starter. What you should see is strong surges of fuel shooting out of the pump.

 

 

Start it up and look at the glass window on the front of the carburetor. Gas should be at the half way mark. Is it?????