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skubee

Hi from Houston

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Hi, I'm James and I've been lurking Ratsun off and on for the past year. Ya'll have a fine forum with many knowledgeable and helpful folks and I have learned or re-learned some very useful schtuff here. I've been clearing out my mini-storages in the past year and forgot I had stored so much Datsun stuff. We bought our first Datsuns in 1969...a 510 2dr for Dad and a 510 wagon for Mom and kids.We were an Air Force/vintage aircraft/Warbird/aviation industry family, so travel was always in the cards. We had many adventures from Texas to Virginia to New Jersey and back in the wagon moving the household or hotshot parts hauler for some sick airplane/helicopter. Many reliable fun miles in the Datsun's.. We were hooked and we've had many more Datsun/Nissan since. 510's, 240, 620, 720 4x4, Maxima, Pulsar, and sis's current Altima's.

 

After finishing my hitch in 1977 with the diesel submarine service in San Diego, I came back to Texas and eventually got into Sunbeam Alpines owning several. If your into Brit cars back then you needed something reliable to haul parts/tow Brit car/stuff. I got my Dad's hand-me-down '78 620 Kingcab truck and all was well. Morphed to MGB's from Alpines in the mid 80's. Along the way I also collected Datsun stuff  for a future 510 project. In the late 80's I bought '77 620 t-boned right at the drivers door/bed and parted it out. 1st to go was the front clip to get most of my bux back and I reduced the rest of the truck to shelved spares for my '78. I found a really clean '69 510 4dr for my road racer/streeter for $100 cheap so that project was now moved closer to the front burner. Then I was laid low with a dart injury. Darts can be a contact sport if you're not careful on who you play with. Recovery from a torn meniscus/ACL is a longer process than anticipated and the shop was getting hard to keep up with on crutches. A few months later, one of the local independent junkyards was getting ready to shut down and had a $100 sale..if you could carry it out it was yours for a hunert. I had already birdogged a 620 with a Weber 45DCOE/Cannon, Mallory dual point dizzy, header, and gambled on the head having a cam to match. 100 degree heat...complete head/header/intake with Weber assembly cushioned on a towel on my shoulder and the Mallory shoved into my BDU shorts pocket on crutches and 150 feet to go. There were many breaks.

 

To make an already too long story short(er). At dusk one evening in 1991, cruising in the Kingcab on an overpass an old guy looking into the sun pulled out in front of me and I t-boned him essentially killing my 620. I had moved and didn't have the tools with me or a place to repair the truck...and besides that...I could't afford a front clip!!!! Almost 30 years later I'm clearing out my storages and hadn't realized I had so much Datsun stuff and some of it is in very decent condition. Tho I want another 620 I've got to sell off my Datsun schtuff to make another coupla years to retirement/disablity. Got it all adverted in Houston Craigslist as '73-'79 620 Datsun parts. Anyway...Hi folks!

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At the top of every page just left of center below the RATSUN.NET logo is a link to our CLASSIFIEDS. Feel free to post up your parts there.

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Hi again, I ran outta room. I wanted to note something about my parts and ask a coupla questions I ran across in my parts stash. From the the '77 wreck, it turned out I had saved the tail light assemblies and parking/marker lights. 5/6ths of the parking and marker lights have rubber protective boots on them and I haven't seen them noted in the parts lists now available.

Cruising down the road a few years back I found an L16 in the weeds and ran home for the trailer and brought it back, Besides having a Weber 32/36 mounted on an Edelbrock intake, I found it had an A87 "peanut head". When I pulled the head the flat top pistons are stamped with a 3 and a 4 stamped at the "heel" of the 3. I'm guessing this has something to do with the size of the piston. Any youz folks know exactly what these marks mean? Ummm...and I forgot the second question...it'll come to me. Thanks for you time folks...

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At the top of every page just left of center below the RATSUN.NET logo is a link to our CLASSIFIEDS. Feel free to post up your parts there.

Ahhh..thanks Mike! is it OK to post some detail of the parts there with a link there to the Craigs ad ? I don't have a photo hosting site and being an analog guy I haven't learnt that yet.

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I guess so as long as it doesn't become an ad in itself with questions and offers.. 

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I guess so as long as it doesn't become an ad in itself with questions and offers.. 

I meant posted that way over in the classified section....

Thanks!

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Go for it.

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I guess so as long as it doesn't become an ad in itself with questions and offers.. 

OK Datzenmike. Any idea what the stamps on the flat top L16 pistons mean in the question I posed in my second post?

Anywho, here's the Craigslist link for now until I can post something in the Classifieds tonight or tomorrow. The 10% I save by not using Ebay I'll pass on to Ratsun members to go toward shipping. Paypal is good. Any queries please send a personal message.

https://houston.craigslist.org/pts/d/73-79-datsun-620-pickup-parts/6374731905.html

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Generally the piston has a clearance of 1 to 2 thousandths of an inch to the cylinder bore. That isn't much and trying to mill a bore to exactly 85.000mm for an L20B will almost certainly result in some being larger or smaller than intended and the same is true with the pistons. So to cut the waste and make mass production possible, cylinders and pistons are measured and given a number 1 to 4? Each number is a slight fraction over or under size. Now when the engine is being assembled, the block may have one or all cylinders over size and marked. The builder sees a 1 (which is only slightly over bore) and selects a number 1 piston from the #1 bin (which is also only slightly oversize) and the clearance is perfect. A much larger oversize #4 cylinder gets a a #4 very oversize piston but the clearance is still withing specification.

 

L20B pistons vary from 84.985mm to 85.035mm a range of 0.002"

 

L20B blocks vary from 85.000mm to 85.050mm a range of 0.0019 just under 2 thou.

 

If you take the smallest piston ( 84.985mm) and the largest bore (85.05mm) the side clearance would be 0.00256 well above the 0.001 to 0.0019" allowed. Hell the largest piston won't even fit the smallest bore! By grading the bores and pistons you can get the fit you want.

 

This is why if over boring your block you should discuss it with your machinist and supply the pistons so he can measure them and bore and hone as close to perfect as he can.

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So to cut the waste and make mass production possible, cylinders and pistons are measured and given a number 1 to 4?

Thanks for your explanation Mike. I figured it was some sizing reference. I noted your question mark. That set me to looking for stuff more pertinent to the L16. I imagine things changed over the years from what they used for the L16 and some kind of change by the time they got round to the L20B. The 3/4 stamp was on #1 and #4 piston. The next morning I cleaned the carbon from #2 and #3 and they were respectively stamped 3/4 and 4/5 :confused: . This not being a virgin engine I wasn't too surprised. There's no telling what this guy did until I get the mics out on teardown eventually. Weber 32/36, Edelbrock intake, and a "peanut" A87, but it had a bit of rust in 2 and 3 coz he reused the head gasket with blue silicone... :w00t: It's always sumpthin'....

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Well my opinion is those are used pistons from probably another L motor....

My guess would be from as l24 setup.. it's the 6cylinder but have the same bores as the L16..

The l16 should have stock dished pistons and a 210 head....

The a87 drops the compression into the low 8s... maybe even the high 7s on a l16.... the flat top pistons would raise the compression back up...

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Thanx Crash. I was under the impression that the closed chamber of the "peanut" A87 would raise the compression as well.

EDIT- I reckon the "Peanut" would actually be a semi-closed chamber.

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Thanx Crash. I was under the impression that the closed chamber of the "peanut" A87 would raise the compression as well.

EDIT- I reckon the "Peanut" would actually be a semi-closed chamber.

The L16 stock 210 head actually has a smaller combustion chamber... I believe 38.5cc... The peanut heads are 41cc...

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I had to look this up again.... the other open chambers heads that come on the l20b are 45.3cc... that's why people say it increases compression because in that senario it does....

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http://dimequarterly.blogspot.com/2012/02/tech-how-to-l-series-cylinder-head.html?m=1

 

Has all the different heads and shows the differences....

Thanks for the refresher Crash, it's been awhile since I had been there. That is one of the articles I ran into while re-aquanting myself with my Datsun stuff. Another handy one was www.davidcmurphy.com  for tech manuals and such....and of course the Ratsun forums. The fellow who eventually bought my peanut head A87, was telling me over the phone it was either a peanut head or an A87, but not both. That put me to searching the web and I ran into the Dime Quarterly article for confirmation. Some cylinder heads of different makers have very small peanut pockets and this Datsun one is kinda large comparatively...enough to be termed open or semi in some other makes.  One thing in the Dime Quarterly article I found fault with was the claim you have to remove the head to determine if you have a closed chamber or not if you don't have a borescope. With a stiff piece of wire bent to shape,  you start at the spark plug hole sliding it along the top of the chamber until you feel it stop or twist downward while noting the distance traveled. Graduation marks help. My endoscope couldn't make the corner from the spark plug hole so the wire trick told me to spend the time pulling the head because there was a reasonable expectation this was a closed chamber head. (The endoscope did find the rust in the right corner of #2 and #3 cylinder which told me I wasn't opening up an intact engine and wasting a head gasket. I'm glad it did... I'd hate to have sold someone an L16 long block with a "blue goo" head gasket and deal with that resultant mess, :sick: )

 

Oh by the way, Sunday I lowered some prices on my Craigslist ad.

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All  open chamber have a closed chamber shape around the valves but then a gradual slope out to the cylinder walls. Open chamber are all 45.2cc or less if milled.

 

Closed chamber heads are 41cc or less if milled. W58 and A87 heads (and others) can be closed chamber if imported back in the 70s-80s. Generally W58, U67 and A87 are open or the compression would be through the roof on engines that had to pass 70s emissions.

 

 

The 210 head for all L16 was 38.5cc and open but there have been some closed chamber 210s reported.

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