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1973 620 - yellow turd


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well as usual i am having trouble getting the new l20 to run and fire. I have 130 psi compression in all four cylinders, and i have fuel in the Weber. i popped off the valve cover to find my timing is out, i think. I could have swore i set it all perfectly but now i dont know. the crank is a TDC on the number one, the cams are 2 and 10 and the No. 1 is up, but the "bright" link is off a tooth :(

Im also not sure about the oil pump/distributor drive

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Ok it was out a bit.

 

Um so when 1 is at TDC and its 0 degrees on the timing plate the chain marks line up and the cam sprocket is up and when you look through the cam sprocket to the cam align plate there is a indent that aligns with a notch on the cam sprocket right??

 

And then I align the two dots on the oil pump, stick it up through the front cover and it should be 5 deg off the bolt holes for the distributor with the small part to the front of the engine yes??

 

The why the fuck now is the NO 1 cylinder at the back of then engine on the distributor cap? I thought it was at the front??

 

It fires and runs like a turd, no power even at full throttle but oil light finally went out after 30 crank overs.

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If the chain is on correctly.

 

1: yes. looking thru the cam sprocket there is a notch that should be slightly out of alignment with a mark on the cam plate. (stolen pic off net) you want yours to look like the one on the right.

 

0900c1528004f2b5.gif

 

 

2: yes small half forward. not sure about the "dot thing". I've always just stabbed the shaft thru making sure I have it small side forward at 11:25 (stole this pic off the net)

 

motordistributortiming.jpg

 

 

3: honestly it doesn't truly matter where #1 is .... AS LONG as you set the firing order at 1, 3, 4, 2 (counter clockwise) 

 

 

It should be running like a turd because the cylinders are firing in some weird out of timing/sequence pattern it sounds like.

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So that first picture was in my Haynes but it was such poor quality I couldn't make it out.

 

There is a pin hole on the oil pump and on the drive shaft. Its stupid because it just moves anyways.

 

I'm still not sure about the chain, I swore I got it right but I think I was actually two teeth off on the oil pump. Sigh I didn't really enjoy pulling the accessory case off.

 

Anyways my coworker (used to work at Nissan and race 510s) said it sounded like an oil pump tooth being out.

 

Long story short it runs!! But has a exhaust leak at the head and I still have to fill the transmission and swap out the clutch slave. And set the timing and the carb. But it runs. Finally. Whoo!

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Glad its running. 

 

In a sense your coworker is right. If the chain is off a tooth or two then the oil pump shaft is off as well. It just makes timing everything a giant guess. 

 

I know its a pain in the ass but making sure the chain is on correctly lessens any future chance for confusion if you have an issue with something. You can double check the timing chain without pulling the cover by only removing the bottom crank pulley bolt & washer along with the valve cover cover....... You just set your engine at top dead center (zero) pull the bolt & washer to make sure the key way is on top at the 12:00 position & then check your cam sprocket & chain links... done. 

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Sigh I didn't really enjoy pulling the accessory case off. unless you drop chain and tensioer fall out.

 

YOu dont have too.

Marks in cahin are for intial set up. you can just pull the cam sprocket after you know the crank is at Zero. the move the cam sprocket(using the wedge) and do a adjustment there and just use the crank Zero mark the the cam sprocket V and - mark behind sprocket

 

 

after you spin the motor a few times the marks dont line up again untill a certain number of rotation. usually I just go by the crank TDC mark then look thru the cam and see if right on or slightly advanced

 

as in the AFTER ADJUSTMENT diagram

 

 

cam off a tooth will still run fairly OK. oil pump off is worse

 

 

timming light would have caught this right away or the rotor on on TDC on cap. Usually between 1&3 on cap

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See that was my initial confusion. The crank pulley was 0 degrees, the keyways were up, the valves were 10 and 2 and everything seems like TDC but I couldn't get the "bright" link to land on the #1 dot. I hand cranked it 30 times, would hit the #2 and #3 but never #1 it was always a link out. And I thought the cam gear V notch had to line up with the mark on the cam plate, not be to either side so that also didn't help. :( it's not a very difficult task to line up the links so I'm still confused on that mater but I'm glad it runs. Now I just need to tune

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you most likely may never get it tuned to its potential....... I would set the engine at TDC on the #1 mark or as close as you can & then remove the cam bolt/washer/fuel pump lobe so that I could see which hole the cam shaft end-pin is in... it should be in the #1 hole..... if it is then your chain is off a tooth (or more) & you should do as banzai510 says above... lock the chain in place with a wedge & rotate the sprocket to the proper location.   

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just remeber soem taiwan chains dont have any brite links

 

long as you know TDC on crank and you have a jap sprocket with the V notch to ck with the dash youll be fine.

 

You can use #1 and #2 positions will no proplem. all this does is advance the can 4 degs. L20s they coem on nuumber 2 position. Should run fine

 

 

once the mechanical timming(motor) is set then you work on the electrical timming of the distributor/oil pump spindal.

 

 

Zero crank position is the reference. and so your distribotor spinal shoul be close to the 11/25 11/28 position looking at it from the side. Install the dist and the rotor will lock down and hopefull the dist is very close to pointing to a cap end(where plug wire will go to) then ck the timming plate and hopefull its in the middle of the slot movement. If not it can be adjusted on the under of the dist is a 8mm. I most times keep this loose. As once you start the dist will be need advance to 5 10 maybe even 20 to get started for the first time and carb adjust right but shoul be close to starting.

 

But if your this far already you already know this then.

 

Just to get best perfeormance motor needs to be timmed first. if crank is zero and you got the V on the dash or V slight right dash your GOOD

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Those bright links position are lost as soon as you crank or fire the engine up. They do not line up every TDC but perhaps every few hundred turns. I never worked this out.

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so what does one do for the shifter cover? conveniently if i flip in 180 degrees it still covers the shifter hole. do you guys just redrill the bolt pattern and use it as is?

 

I still think my oil pump/distributor timing is a tooth off. both the distributor plate and the pedestal are in the advanced spots (full clockwise on the plate, full counter-clockwise on the pedestal) I cannot retard the timing at all without the truck stalling and dying. i'm going wait till it cools of and check it again :/

 

other then that i think everything is good!

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