Just bought a 521

[Stoffregen Motorsports]

Yes, very few pickups interchange with other pans. They are almost always a matched pair.

[mainer311]

So, the L20b short block that I bought came with a 200mm 30lb flywheel. Based on that clue, I would say the engine came out of a sedan of some sort. Does that sound right?

 

The kid gave me an oil pickup tube with it, but I have no idea what it’s from:

 

[banzai510(hainz)]

L20b with 200mm is a car/seden

I think a truck would be a 225mm when its nearly 30pounds

[d.p]

my l20b came out of a 610 and I used the pickup tube from a a 521 that I got from Wayno (along with a pan).  

[datzenmike]

dp, How much larger are both valves and did you change the seats?

[mainer311]

10 minutes ago, datzenmike said:

dp, How much larger are both valves and did you change the seats?

 

This is my thread, not DP's. 

 

43mm intake (1mm bigger than stock)

 

35mm exhaust (stock size)

 

No seat change required. I cut the intake seats larger. 

[mainer311]

1 hour ago, banzai510(hainz) said:

L20b with 200mm is a car/seden

I think a truck would be a 225mm when its nearly 30pounds

 

It's 30lbs and 200mm. I measured and weighed it. 

[datzenmike]

Sorry, oldtimers disease.

 

I put the valves in an electric drill and rounded that edge like trumpets on ITBs by holding them against emery paper.

[banzai510(hainz)]

1 minute ago, mainer311 said:

 

It's 30lbs and 200mm. I measured and weighed it. 

Don't know!!!!!

 

I have a lighten(like 11 pounds I think) stock 200mm with the back side cut,but scared to run it as it might explode. I give it too you just give send me the money back for shipping

[mainer311]

1 minute ago, banzai510(hainz) said:

Don't know!!!!!

 

I have a lighten(like 11 pounds I think) stock 200mm with the back side cut,but scared to run it as it might explode. I give it too you just give send me the money back for shipping

 

I'm good. I plan on running a Z flywheel with the 240mm disc. 

[datzenmike]

Get the D21 Hardbody KA pressure plate AKA the White Bunny clutch. 30210-86G00... with 450 Kg clamping

 

With a 240mm wheel you can also go with the pressure plate from...

 

'82-'83 280zx turbo and non turbo 300zx.... 30210-P9510 rated at 550 Kg clamping

 

or even the '84-'85 300zx turbo ................... 30210-P9600 rated at 600 kg clamping

 

 

[mainer311]

Yeah, early 80’s flywheels are still available, so I may go that route.

[Stoffregen Motorsports]

That 200mm flywheel is worth hanging on to. Roadster clutch is a common upgrade for the 200mm. Less inertial mass than a large clutch and can handle tons of HP.

[mainer311]

1 hour ago, Stoffregen Motorsports said:

That 200mm flywheel is worth hanging on to. Roadster clutch is a common upgrade for the 200mm. Less inertial mass than a large clutch and can handle tons of HP.

 

I'm thinking about it. Looks like an SRL clutch is 600kg. 

[Stoffregen Motorsports]

Anybody with a lathe can lighten it, but it should be balanced afterward.

[Charlie69]

5 hours ago, mainer311 said:

 

I'm thinking about it. Looks like an SRL clutch is 600kg. 

I do not get this line of thought, you want all this clutch pressure and you have a 110 hp engine.  Makes no sense to me.

Edited January 12, 2021 by Charlie69

[mainer311]

1 hour ago, Charlie69 said:

I do not get this line of thought, you want all this clutch presseure and you have a 110 hp engine.  Makes no sense to me.

 

110hp? A roadster U20 with side-drafts was advertised at 150hp. 

 

It is my hope that my L20b gets somewhere close to that. My goal is 130. And so what if the clutch grabs harder?

-mild cam

-bigger intake valves, and worked head

-bored to 86.5mm

-flat tops bringing compression to >10:1

-dual Weber DCOE40's

 

I don't think it's that far fetched.

Edited January 12, 2021 by mainer311

[mainer311]

1 hour ago, Stoffregen Motorsports said:

Anybody with a lathe can lighten it, but it should be balanced afterward.

 

I've seen the CAD drawings, and I just don't want to bother with it. I'd rather just get a flywheel as-manufactured and not worry about it coming apart.

[Stoffregen Motorsports]

1 hour ago, Charlie69 said:

I do not get this line of thought, you want all this clutch presseure and you have a 110 hp engine.  Makes no sense to me.

I have run them in just about every 510 I have ever owned or built. The pedal pressure is not bad. It actually feels perfect.

1 minute ago, mainer311 said:

 

I've seen the CAD drawings, and I just don't want to bother with it. I'd rather just get a flywheel as-manufactured and not worry about it coming apart.

Come apart? Guys have been doing this for years. You lighten it to resemble the stock light flywheel. Was that in a 240Z? I don't remember.

[mainer311]

Just now, Stoffregen Motorsports said:

I have run them in just about every 510 I have ever owned or built. The pedal pressure is not bad. It actually feels perfect.

Come apart? Guys have been doing this for years. You lighten it to resemble the stock light flywheel. Was that in a 240Z? I don't remember.

 

Yes. According to Mike, around 21lbs to account for the extra weight of the I6 crank.

[Stoffregen Motorsports]

I thought 21 lbs sounded right. Thanks for confirming that.

[demo243]

1 hour ago, mainer311 said:

 

110hp? A roadster U20 with side-drafts was advertised at 150hp. 

 

It is my hope that my L20b gets somewhere close to that. My goal is 130. And so what if the clutch grabs harder?

-mild cam

-bigger intake valves, and worked head

-bored to 86.5mm

-flat tops bringing compression to >10:1

-dual Weber DCOE40's

 

I don't think it's that far fetched.

With all that in mind you may want to bump up to Weber 45s. I ran Mikuni 44s on my L20b after talking with the late Todd Walrich of Wolf Creek. His reasoning was you can easily choke down the 44s and its helps in the actual usable power range of these engines. Once you start messing with Cams and compression 40's end up running out as the revs go up. Per Todd, for a stock L20b crusing around 40s are fine, but for anything modified or with the intent of more spirited driving 44(45 webers) are better.  

Just something to think about. 

[mainer311]

7 minutes ago, demo243 said:

With all that in mind you may want to bump up to Weber 45s. I ran Mikuni 44s on my L20b after talking with the late Todd Walrich of Wolf Creek. His reasoning was you can easily choke down the 44s and its helps in the actual usable power range of these engines. Once you start messing with Cams and compression 40's end up running out as the revs go up. Per Todd, for a stock L20b crusing around 40s are fine, but for anything modified or with the intent of more spirited driving 44(45 webers) are better.  

Just something to think about. 

 

I'm not completely sure. If you look at the Weber charts, a displacement of 500cc per cylinder at 6k RPM requires a choke of 36mm. Wouldn't 40's be enough at that point?

[demo243]

34 minutes ago, mainer311 said:

 

I'm not completely sure. If you look at the Weber charts, a displacement of 500cc per cylinder at 6k RPM requires a choke of 36mm. Wouldn't 40's be enough at that point?

 

Keep in mind though that a 36mm choke is the largest choke you can run on a 40. Where as a 36mm choke is smack in the middle of the range for a 45.

Here is what I ran in my Mikuni 44s per Todd's recommendation. Ill have to do some digging on what cam I was running. CR was unknown , but running some dished Ross Pistons and a w58 head --- edit looking back at old posts, the head was decked and ported.
 

 

 

Just something to think about

 

Edited January 12, 2021 by demo243

[datzenmike]

4 hours ago, Stoffregen Motorsports said:

That 200mm flywheel is worth hanging on to. Roadster clutch is a common upgrade for the 200mm. Less inertial mass than a large clutch and can handle tons of HP.

 

The 200mm Roadster clutch is TALL. I have a 240mm pressure plate out back and should weigh it. It's THIN!!! I'd be curious to their weights.

 

Agree a larger diameter clutch does have a larger moment of inertia.

 

OK Z24 4x4 240mm pressure plate is 14.4 pounds