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Topic: lather, rinse, repeat.
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Oly_Lowlife
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bullet Topic: lather, rinse, repeat.
    Posted: 08 December 2005 at 12:44am
So i used the search feature, and checked out some other boards, and I have this question for all you guys with the years under your belts. I have a L20 I want to use for a daily driver in my 620, I want it to be cool, and be practical. I've taken a lot of different ideas into consideration and a heavily moded l20 dosent make sense when you can swap a ka24 or whatever for similar cost. I'm not adverse to having machine work done, I just want to know from experience best bang for the buck on a L20. I already have a lightened 280z 6 hole flywheel, cylinders need to be bored out as it is, and I have that 5 speed too. keep that in mind.

Z22 crank worth a daily driver? quite a bit of mony involved in sidedrafts, so still on the fence on that one. How does that 32/36 compare to a sidedraft car? turbo oil pump-ok.   exhaust would need to be changed from the l16 style....

by the way, my L16 is running great! thanks again for all the pointers.
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datsunaholic
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bullet Posted: 08 December 2005 at 8:39am
If you use a square-port L20B head you can still use the L16 exhaust. The L20B exhaust is either the heat-riser type manifold that requires use of the stock intake (since they're mated) or the round-port smog type.

The Z22 crank gets you 2.1L in a L20B bore, but as mentioned elsewhere yoc can't use stock parts to do it. The Z22 used a different piston-pin height than the L20B so the L20B pistons would "pop out" of the block if used. Can't use Z22 pistons without boring the L20B to Z22 specs- at that point, might as well use the Z22 block too. Once you've put the L-series head and timing cover on it, there's no difference. The price to rebore the L20B to Z22 specs costs more than a good Z22 short block from a junkyard. Unless you got the Z22 crank and rods for one heck of a deal. Or have your own machine shop.

Carbs- Sidedrafts are a whole other beast, and only come alive with head work. The 32/36 compares to stock, slightly different feel but nothing radical.
'64 320
'68 520
'72 521 V6
'74,75,79 620s
'76,78 4X4
'76 KC
'72 510 Wgn
'78 B210
'78,81 510 Wgn
2X '78 510 Coupes
'83 720 KC

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Bleach
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bullet Posted: 08 December 2005 at 11:02am
32/36 with intake manifold porting works great. Mild cam, stock 280Z dished pistons (86mm bore), and call it good.
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Oly_Lowlife
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bullet Posted: 09 December 2005 at 12:10am
Very helpful guys. Sounds like that crank swap is way out of the question. Is there any cam in particular you would recomend for what I'm trying to do? and where would I find one? would the compression ratio be the same with 280 pistons? My pistons will need to be oversized due to a slight taper in the cylinder wall anyways.

I do have a w58 head with the round exhaust ports and the secondary air ports welded shut in the manifold. I've been very carefully grinding on those inserts in the exhaust ports, trying to remove them. Kind of unsure as to how that will affect low end power by enlargeing them that much. is this a mistake or no?

I start getting out there in the clouds, but bleach is probly right to keep it simple.

I talked to a local machine shop about prices, quoted me about $100 for me to brig him the pre hot tanked parts, with the head stripped bare, and then he fly cuts my head flat and bores the block. how does that sound?
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Bleach
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bullet Posted: 09 December 2005 at 11:27am

Oh, how about a closed chambered A87 head. Good quench, slightly higher compression, slightly smaller valves though. Hainz may have experience with L16 style valves.

If crane cams still makes a can for the L-series, get the Stage 2. They have 3 stages of cams last I checked.

I ordered mine from Honest Performance in Federal Way, WA

Stock 280Z pistons will be a 1mm overbore in the L20b. The dish is ever so slightly less, so you will gain a very small amount of compression. Maybe not though. The 280ZX (same size) piston comes in flat tops as well. Too high of compression for most people.

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Ryan in Seattle
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bullet Posted: 09 December 2005 at 6:05pm

l20b block with l18 pistons, bore .030 over, Offenhauser intake manifold, Weber 32/36,electric fuel pump, u67 head w/ early L16 exhaust manifold,2" exhaust, 1968 "1600" valve cover,single groove l16 pulley, 280zx turbo starter, oil pump, head bolts, water pump (with the stamped not cast wheel) & pulley, 200mm flywheel from 510 L20b so as to utilize the roadster clutch, (thanks Hainz)........1979 e.i distributor w/ Msd coil............and a billet oil dipstick.

Fairly cheap, too.

1973 620 "Prerunner"
L20B,A87,5spd.Lynx,40dcoe,
header,cammed & bored.
zx oil pump,starter,headbolts
& water pump/pulley.
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Ryan in Seattle
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bullet Posted: 09 December 2005 at 6:07pm
Yes, a billet oil dipstick, and what? huh?
1973 620 "Prerunner"
L20B,A87,5spd.Lynx,40dcoe,
header,cammed & bored.
zx oil pump,starter,headbolts
& water pump/pulley.
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datsunaholic
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bullet Posted: 09 December 2005 at 6:12pm
Ooh, a stamped-steel crap water pump. Trying to make that heater hotter?
'64 320
'68 520
'72 521 V6
'74,75,79 620s
'76,78 4X4
'76 KC
'72 510 Wgn
'78 B210
'78,81 510 Wgn
2X '78 510 Coupes
'83 720 KC

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Ryan in Seattle
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bullet Posted: 09 December 2005 at 6:24pm
no, faster water, c'mon silly.
1973 620 "Prerunner"
L20B,A87,5spd.Lynx,40dcoe,
header,cammed & bored.
zx oil pump,starter,headbolts
& water pump/pulley.
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datsunaholic
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bullet Posted: 09 December 2005 at 7:11pm
Faster water?

Not. They cavitate too much. Stamped-steel impellers aren't the correct design for fast flow. It's why my jet boat uses a cast impeller. Don't believe the pump maker's claims that the stamped-steel is a better design- the sole reason they make them is they are far cheaper to produce.

That's not to say they don't work. They do, at least sufficiently, but I won't use them. I've had a few. I've opened up several pumps once the seal went to find the car had a stamped-steel, though most were cast. But the only one I've ever had blow up (taking out the timing cover in the process) was a stamped-steel one where the aluminum casting was half as thick as the OEM type. Crappy pump didn't even give a warning before the shaft bearing failed, twisting the shaft, pulley, and impeller sideways and gouging a large gash in the timing cover's water pump face.
'64 320
'68 520
'72 521 V6
'74,75,79 620s
'76,78 4X4
'76 KC
'72 510 Wgn
'78 B210
'78,81 510 Wgn
2X '78 510 Coupes
'83 720 KC

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Hainz
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bullet Posted: 10 December 2005 at 9:17am
Datsuaholic is right
Use the stock Atsugi type pump with the curve in there.

We think that the GNB pump cause more cavitation and helped ruin my front cover. Well I sand blasted it and maybe slightly pitted already but I know it wasnt taht bad when I put this motor together. 2yrs later it look like termites went thru it. only to find a pinhole in the cover which let water in my pan

I have had good luck(GMB) with the pumps themselves. lasting about 5 yrs if I dont over tighten the belt(Ive done this) But the the stock cast curved impellers type
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Ryan in Seattle
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bullet Posted: 10 December 2005 at 12:52pm

I hear you guys, maybe I sould rethink that then, I do want longegevity.

is that spelled correctly?

1973 620 "Prerunner"
L20B,A87,5spd.Lynx,40dcoe,
header,cammed & bored.
zx oil pump,starter,headbolts
& water pump/pulley.
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defdes
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bullet Posted: 10 December 2005 at 1:32pm
no.
'72 LZ22 510
'71 L16 510 Vintage CS Racer
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Ryan in Seattle
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bullet Posted: 10 December 2005 at 4:48pm
longevity?
1973 620 "Prerunner"
L20B,A87,5spd.Lynx,40dcoe,
header,cammed & bored.
zx oil pump,starter,headbolts
& water pump/pulley.
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Oly_Lowlife
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bullet Posted: 10 December 2005 at 6:01pm
Why l18 pistons? whats the difference between those, l20, and 280z pistons?
Do you have a picture of that Offenhauser intake?
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Ryan in Seattle
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bullet Posted: 10 December 2005 at 6:35pm

l18 pistons have the same bore as the l20 pistons, (85mm)except a smaller dish ,meaning higher compression, but not as extreme as a flattop. the only reason I did the small overbore is because I fuc ked up my cylinder from not building the engine correctly before.

here are two older pics of the offy.....

the weber bolts right up to it.

1973 620 "Prerunner"
L20B,A87,5spd.Lynx,40dcoe,
header,cammed & bored.
zx oil pump,starter,headbolts
& water pump/pulley.
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]2eDeYe
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bullet Posted: 11 December 2005 at 11:58pm
mmmmmmmm offy...
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Labdork
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bullet Posted: 12 December 2005 at 12:24pm
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Ryan in Seattle
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bullet Posted: 12 December 2005 at 6:04pm
I already got some like those, but cheaper price, and better design than the last ones I had.
1973 620 "Prerunner"
L20B,A87,5spd.Lynx,40dcoe,
header,cammed & bored.
zx oil pump,starter,headbolts
& water pump/pulley.
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Hainz
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bullet Posted: 13 December 2005 at 8:44am
those are DEEP dish pistons Looks like L20(85mm) 11.36cc dishs.
The L18 ones barely have a dish.
Ck Rockauto.com under 73 Datsun 610

ck this below these is a L20b dished piston. Looks like the same dish size to me.
http://kb-silvolite.com/spistons.php?action=details&S_id=365
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