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Identifying “Peanut” Heads for L Series


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5 hours ago, Soundline said:

Im utterly unfamiliar with the SU’s. My tentative research lead me to Weber DCOE 40’s side draft. Admittedly I’ve not done my homework so I didn’t wanna speak out of turn. I TRY not to ask totally stupid questions.

 

You should look into them. Similar performance to DCOEs on anything but a "race" motor, better mileage, and way better driveability. Also infinitely easier to tune. 

 

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As for Cams Keith suggested Isky which, appears to only have one grind, that appears to have been used since the 80’s. 

 

I believe Competition Cams still offers a few?

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42 minutes ago, datsunfreak said:

 

He is full of beans. A U67 head is in no way identical to a 219 head. 😄


I personally don’t have a dog in the fight, I’m just quoting the source.  I see this particular book referenced as the Bible of tuning our rigs. So it’s interesting to see it be just another source. 

 

38 minutes ago, datsunfreak said:

 

You should look into them. Similar performance to DCOEs on anything but a "race" motor, better mileage, and way better driveability. Also infinitely easier to tune. 

 

 

I believe Competition Cams still offers a few?


Interesting. I sourced a U67 head tonight and I’ll keep chipping away at research until I’m comfortable with moving forward with a new thread. I prefer to make myself as educated as reasonable before opening up and proving my ignorance.

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10 hours ago, Soundline said:

I see this particular book referenced as the Bible of tuning our rigs. So it’s interesting to see it be just another source. 

 

It was a handy book in 1975. Most of it is very outdated now.

 

Also, a lot of it was building to a specific racing class, which did not allow you certain modifications. These days it's really only good for someone trying to build a 2.5 Trans Am or B/Sedan replica.

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I have a L16 bored out to a 18 with a Jap W53 import closed chamber match ported to a Mikuni 1.5 intake 40mm mikinis and I run regular gas 89 with no pinging.

Im not sure on a Longer stroke L20 but I would be fine with a closed chamber on a stock bottom end. as a daily runner... I would matchport intake, your fine

the closed chamber head the benifits are more for the anti detonation than the compression.

 

If somebody want HIGH Compression put L18 4cc dish pistons or flattops on a closed chamber head.  But if falttop piston on a open chamber head I would not run as it going to detonate unless one has 93/94 gas floating around I siuspect

 

 

210 head from l16 are best just to get the motor running. Nothing more. most get thrown away or used for parts or trouble shooting

100_0500.JPG

Edited by banzai510(hainz)
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I will ck again will a light but swaer I had like like 12-14 on this motor.

 

my 521 I got L16 with flattops and U67 openhead and I got to run SUPER otherwise it pings on a hot day or going up hill but I dont have the common dieseling when key shut off. I ran a 3 core(160deg stat) and replaced with another dist and doesnt do it anymore

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17 hours ago, Soundline said:

One of these days I’m gonna drive up to Canada so you can drink beer and tell me all the stupid things I need to fix. 
 

I let this slip by in the earlier conversation, and I’m sure someone can address this.  From Honsowetz:

73EC7539-7C2D-4121-B97B-A342799A64B6.jpeg

 

Wasn't implying anything just tidying it up. I'm more OCD on other people's stuff.

 

 

1/ The U67 is my favorite but the intake ports are only 1.375" the 219/912 SSS head is 1.5". None of the L series intake manifolds are 1.5" to match the SSS head anyway. The SSS SU intakes are. I would 'gasket match' and port the intake out and blend so it transitions smoothly. 

 

2/ The U67 does not have the coolant holes for the intake where the SSS head does. (you CAN drill them out)

 

The intake and exhaust valve sizes are the same.

The L20B cam is considered to be so close as to be identical to the SSS cam. 

 

4 hours ago, datsunfreak said:

 

It was a handy book in 1975. Most of it is very outdated now.

 

 

And the L20B was barely a year old then.

 

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3 hours ago, banzai510(hainz) said:

I have a L16 bored out to a 18 with a Jap W53 import closed chamber match ported to a Mikuni 1.5 intake 40mm mikinis and I run regular gas 89 with no pinging.

Im not sure on a Longer stroke L20 but I would be fine with a closed chamber on a stock bottom end. as a daily runner... I would matchport intake, your fine

the closed chamber head the benifits are more for the anti detonation than the compression.

 

If somebody want HIGH Compression put L18 4cc dish pistons or flattops on a closed chamber head.  But if falttop piston on a open chamber head I would not run as it going to detonate unless one has 93/94 gas floating around I siuspect

 

 

210 head from l16 are best just to get the motor running. Nothing more. most get thrown away or used for parts or trouble shooting

100_0500.JPG


That’s a great looking engine bay.  You have a wonderful rig brother. 

 

4 hours ago, datsunfreak said:

 

It was a handy book in 1975. Most of it is very outdated now.

 

Also, a lot of it was building to a specific racing class, which did not allow you certain modifications. These days it's really only good for someone trying to build a 2.5 Trans Am or B/Sedan replica.


Also good to know. Proper tool for the proper job. 

 

7 minutes ago, datzenmike said:

 

Wasn't implying anything just tidying it up. I'm more OCD on other people's stuff.

 

 

1/ The U67 is my favorite but the intake ports are only 1.375" the 219/912 SSS head is 1.5". None of the L series intake manifolds are 1.5" to match the SSS head anyway. The SSS SU intakes are. I would 'gasket match' and port the intake out and blend so it transitions smoothly. 

 

2/ The U67 does not have the coolant holes for the intake where the SSS head does. (you CAN drill them out)

 

The intake and exhaust valve sizes are the same.

The L20B cam is considered to be so close as to be identical to the SSS cam. 

 

 

And the L20B was barely a year old then.

 


Actually I’m glad you caught it. I’d be happy to sit down and have a drink and a burger with all of you. I’ve learned more in this thread than I’d pieced together on my own in months.

 

I’ll be putting together an L20b with a U67, with a cam and side drafts. I’ll figure out the specifics on them as I get closer.  Can I put the larger valves into a U67 that’s been machined out or do you think that’s a waste?

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The larger the valve the more will go through it without altering the cam specs. Upgrading the cam will probably be enough as the U67 has pretty good breathing anyway and hard to improve on. If the valves and seats are shit anyway and it needs to be rebuilt then YES it would cost the same to put larger ones in. If the valves are good already hard to justify the entire replacement cost for any improvement over stock.

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18 minutes ago, Soundline said:

Can I put the larger valves into a U67 that’s been machined out?

 

The money-to-horsepower ratio might be off, but yes.    😁

 

This is the sort of thing where if you have a machinist you trust, take his advice, not ours. 

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DatzenMike and Freak pretty much got it!!!

 

The U67 head if you running sidedraft webers or Mikunis dont need the water holes so your good there. as those manifolds dont use them anyways. Its better and not have to deal with leaks!!!!

 

now key is the sidedraft manifold size. I had a Cannon type and those are 1.25in and cannot be HOGGED out to 1.5   with out weaken the casting on the manifold. 

 

as for the valves the U67 I believe had hardened seats and would just get a valve job and make sure the guy gets it same across the board so when you get a Cam you can get close to one size on the lash pads.  I only say this as its getting harder to explain this to machinist and sometimes the valves seats fall out cause it wasnt done right.  The early Datsun heads had the softer seats and would sink over time and cause a valve not to CLOSE (usually a exhaust due to the heat)  go to adjust the post down on the rocker arm your out of adjustment and you dont1156840786_HPIM0285(2).JPG.4f5280889c755bbab9a67f5367d4484a.JPG fire on that cyl.  Most time when one loose a cylinder a lash pad falls out of retainer.

Mainer 311 got some lash pads from Australia that can use the stock valve retainers but one needs to mock it up and get close w/o trying to buy all the sizes needed.( bought all my sets 150-200) then got the alum valve retainers. But that was before I seen the Aussie set up.  As like I said the machinist had the tip the valve stems and seat hight to make it perfect. If not perfect it still ok but one just needs various size lash pads.

 

let us know who still makes Cams!!!!!

 

 

cannonnismointakesize.jpg

Edited by banzai510(hainz)
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15 hours ago, banzai510(hainz) said:

as for the valves the U67 I believe had hardened seats... The early Datsun heads had the softer seats and would sink over time and cause a valve not to CLOSE (usually a exhaust due to the heat)  go to adjust the post down on the rocker arm your out of adjustment...

 

U67 does indeed have hardened seats. Anything past '74 should have them. 

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fLTUVOI.jpg

 

This one was a give away at a Canby. No history but look at the color of the intake seats. Kind of bronze color. This is what I suspect it is. As I hear it, the bronze seats rely on the anti knock tetra ethyl lead in the old gas to lubricate them and prevent wear.

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On 4/7/2021 at 8:14 AM, datzenmike said:

No history but look at the color of the intake seats. Kind of bronze color. This is what I suspect it is. As I hear it, the bronze seats rely on the anti knock tetra ethyl lead in

the old gas to lubricate them and prevent wear.

 

They are indeed made of bronze, and should be removed immediately. Mechanics used to call that the "Datsun bomb". A car would come in with a ticking from the head that you couldn't find because it was the seat falling out, then it gets knocked back in, then falls out again, etc. 

 

It was usually okay until the one time you stopped the engine with that valve open. Then next time you crank it up, boom. 😄

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Usually they fall out from poor work by shop replacing them, the other is the owner over heating the engine.

 

This is a throw away head I'm using on an LZ24 I put together. That's why the pockets around the valves from unshrouding them.

 

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