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d.p

My 1971 521

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It's about the squishiest bump stop I have seen on a Datsun(figure 8 type), far better than anything after it, and cutting the bottom half of the lower section is like cutting it in half and it is self centering that way.

I am sure one will have a better ride when a quarter inch away from the figure 8 type bump stop than the ride you would have with a 720 bump stop and a quarter inch clearance, firm is not the description I would call it, but it is better than metal on metal contacts like I have in my 521 kingcab, I have learned my weight limits on that truck, still without the bump stops the ride is great, one day I will notch the frame on that one to.

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Anyone tell me where I can get piston rings for 40 over pistons?  Hastings doesn't have them.  Not trying to file them down either unless I can get the machine shop to do it?  

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9 minutes ago, d.p said:

Anyone tell me where I can get piston rings for 40 over pistons?  Hastings doesn't have them.  Not trying to file them down either unless I can get the machine shop to do it?  

40 over for which motor?

L16 or l20b.... I assume for the l20b.....

I would think you need to know what pistons you have to determine what rings you need but I'm not sure...

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Yeah 120b, how do I determine what kind of pistons I have ? They are stamped 100 on them and I think Mike said that meant they are .040 over.  Which I think equates to 86mm?  Fuck if I know though.  

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1 minute ago, d.p said:

Yeah 120b, how do I determine what kind of pistons I have ? They are stamped 100 on them and I think Mike said that meant they are .040 over.  Which I think equates to 86mm?  Fuck if I know though.  

Yes .... the 100 is probably 1mm... which is .03937 over.... so yes probably 86 mm bores.... 

Not sure how to determine brand or if it even matters..... 

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Fuck yeah thanks crash!  Going to have the machine shop measure them to confirm.   Oh and no idea if chrome is what I want either, any one have any comment on chrome vs whatever else is out there?  

Edited by d.p
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I know something was said about that somewhere.... 

Hopefully stroffgren or datsunmike can clarify.....

 

There where some measurements in that ebay ad.... I think they refer to the thickness of the ring.... maybe you could measure your old rings to be sure....

 

 

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Anyone know what size crush washer for the oil drain plug ?  Or a part number?

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11 minutes ago, DanielC said:

Your local Nissan dealer should have them.

 

Tried them but the guy couldn't go back past 1979 and without a part number I am SOL.  

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Part numbers...

 

WASHER-DRAIN PLUG
     11026-61000    

 

PLUG-DRAIN
     11128-69200

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New problem today.  Went to drive the fucker and the idle was super low, like 500 RPMS and the ignition light came on.  It usually idles right around 750-800 RPMS.  When I drive it around its fine in all gears and no ignition light, just when in neutral and at idle the RPMs drop and the ignition light either comes or flickers.  Alternator belt is tight with just a tiny bit of give but the bottom mounting bolt had backed out so I tightened that up but it didn't make any difference.   

 

I just changed the oil and topped off the coolant yesterday so not sure what changed between then and this morning.  Anyone know what could cause this?  I did put that new to me alternator in a couple weeks ago so it maybe dying?  Running voltage is right around 12 so maybe its my battery? 

Edited by d.p
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Idle speed is to low to spin the alternator fast enough to make a decent charge. This is normal. The idle speed may not be.

 

New oil thicker? It takes a long time to warm up engine oil, like half an hour while driving.

 

Change in the weather?

Check for loose or split vacuum line by pinching with pliers to see if RPMs go back up.

 

Turn the idle speed up. See if later it needs turning down. Maybe set the idle at 850 and it will be less affected.

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New oil is 15W-40 Rotella, was using 20W-50.  No change in temperature.  

 

Ill turn the idle up and see whats doing.  

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Most all alternators are designed to have a maximum rpm.  Because a Datsun L-engine can safely run up to 6,500 rpm, at any given engine rpm, the alternator is turning slower than the alternator on your typical V-8.

 

A sudden change in idle speed is commonly caused by a vacuum leak.

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Yeah same one.  I turned the idle up and it hovered right around 750 where it was before and seems to be OK. 

 

Changing out the alternator is a bitch so I am just going to run it until it dies.  In the meantime does anyone have trick or tip to getting that bottom alt bolt in the back tightened up?  Tried from below and above and there is no easy way.  

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Whattttttt from underneath. My truck is a bitch I have to pull the turbo crap out just to remove. Go from under. It helps though if you jack it up first. 

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If your at 12 volts running that is a issue . What is the voltage when lights and heater on at say 2 k rpm? 

when I start running at low rpm I always check the distributor timing , maybe advance it more, check the idle speed screw. Sometimes the idle jet might be getting dirty.

Be honest I think that alternator is a time bomb waiting to happen. I went with a new PowerSelect small 35 amp alternator  from Rockaito and have 2 yrs good luck so far as the o Riley autozone 35$ units wasn’t lasting more than 8 months. They are made in China but I have good luck so  far but are about 80$ now

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On 9/18/2019 at 7:57 AM, d.p said:

Fuck yeah thanks crash!  Going to have the machine shop measure them to confirm.   Oh and no idea if chrome is what I want either, any one have any comment on chrome vs whatever else is out there?  

For low budget rebuilds, I like Hastings sprayed chrome rings. Because of their construction, they break in quick. The Sealed Power rings you showed appear to also have a sprayed chrome top ring.

 

Technology has changed over just the past couple years and it may be worth reading up on. Here are two good articles -

https://www.hastingspistonrings.com/tech-tips-faqs/hastings-piston-ring-set-composition-recommendations

 

http://blog.jepistons.com/piston-ring-materials-explained

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30 minutes ago, banzai510(hainz) said:

If your at 12 volts running that is a issue . What is the voltage when lights and heater on at say 2 k rpm? 

when I start running at low rpm I always check the distributor timing , maybe advance it more, check the idle speed screw. Sometimes the idle jet might be getting dirty.

Be honest I think that alternator is a time bomb waiting to happen. I went with a new PowerSelect small 35 amp alternator  from Rockaito and have 2 yrs good luck so far as the o Riley autozone 35$ units wasn’t lasting more than 8 months. They are made in China but I have good luck so  far but are about 80$ now


11.8 or so IIRC. 

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41 minutes ago, Stoffregen Motorsports said:

For low budget rebuilds, I like Hastings sprayed chrome rings. Because of their construction, they break in quick. The Sealed Power rings you showed appear to also have a sprayed chrome top ring.

 

Technology has changed over just the past couple years and it may be worth reading up on. Here are two good articles -

https://www.hastingspistonrings.com/tech-tips-faqs/hastings-piston-ring-set-composition-recommendations

 

http://blog.jepistons.com/piston-ring-materials-explained

 

 

 

 

This would of course assume a perfect cylindrical, machined and honed cylinder wall. I've done a couple of quick hone and ring jobs on an L16 and L20B in the 70s using chrome rings because they were the 'best.' It reduced the oil burning but it was not at all 'like new' and within a year I was back where I started. I now know I should have spent time measuring the bore wear and maybe just used plain cast iron rings for a better break in seal.

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Nissan used high quality materials in their engine blocks, so cylinder wear is not always an issue. Only a couple times in my life have I ever seen an L block with the (common to Chevy and Ford) ridge at the top of the bore.

 

Out of round cylinders are more common, but again, not always an issue. The Hastings rings are quick to break in and last a good amount of time and are perfect for someone on a budget. Not because they are cheap, but because they allow you to ignore the cylinder wear. Ultimately, I would have the machine shop help in the decision making process. Have them measure and give their $.02 on the rings.

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DP 

i use a cig light voltmeter while running so I can monitor the voltage. You should be getting near 14 volts esp with everything off when driving. You might be driving off the battery.

 

Rings I have seen fancy TotalSeal type chrome rings that have almost 100% seal. But cheap cast rings seem to work fine. My engine builder said he puts them in dry and they seal faster. Long as the oil pump is primed and oil flows pretty quick

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