Just bought a 521

[mrbigtanker]

13 hours ago, mainer311 said:

Won’t work. I’m already at +.040”. Plus, no way I’m paying that for old stock pistons. I’ve read that the ITM pistons from Rock Auto are actually very good, but the rings they include aren’t. I can get 6 pistons for about $225. 

That is correct. ITM is pretty good stuff.

[d.p]

13 hours ago, mainer311 said:

Won’t work. I’m already at +.040”. Plus, no way I’m paying that for old stock pistons. I’ve read that the ITM pistons from Rock Auto are actually very good, but the rings they include aren’t. I can get 6 pistons for about $225. 

 

Why do you need 6 pistons?  

[banzai510(hainz)]

they come in a set of six as its for a Z car set

Edited November 6, 2020 by banzai510(hainz)

[d.p]

Ahh ok.  

[mainer311]

@datzenmike @banzai510(hainz)

 

I have a W58 round port exhaust head coming from Washington, but someone else just offered up a U67 to me. In terms of compression ratio, valve diameter, etc., which one has more potential on a L20b? Probably keeping the head stock, but replacing the valve seats. My plans (and we all know how those go) are flat tops, a mild cam, and dual sidedrafts. Might also take a few lbs out of the flywheel. 

 

So, U67, or W58? (Both are open chamber.)

Edited November 12, 2020 by mainer311

[Crashtd420]

I'd say the u67 would be better, w58 is what they refer to as the smog head....

 

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

 

I know you've seen this but has the comparison info you probably want to look at.... 

Also you may not have to actually change the valve seats,  so check what the material is first, my w53 head had the hardened valve seats in it already..

[mainer311]

Thanks for the heads up. Would be nice not to have to deal with it.

[banzai510(hainz)]

Yes the later head might have the unleaded gas seats in already  which would be both models mentioned

[greenthumb]

That’s a super helpful article to help wade through the myriad of head options for the L. 
This should be a sticky

[mainer311]

1 hour ago, greenthumb said:

That’s a super helpful article to help wade through the myriad of head options for the L. 
This should be a sticky

 

I've read it a few times, but it's lacking bits of info here and there to be able to make direct comparisons between heads. Like, it doesn't mention the valve sizes for the W58 "smog" head. I really don't want to bother with round exhaust ports, but will if I have to. 

[Charlie69]

For my purposes which is mainly drive-ability I have always run the U67 heads.  I ran an A87 peanut a while back and it was ok but I did not see any performance difference worth seeking out the A87 head.  Also had to run premium gas with the A87.   That is not a problem to me as I run premium gas  in all my vehicles.

 

 

Edited November 19, 2020 by Charlie69

[datzenmike]

Identical but the W58 has the obvious round exhaust ports which don't really match a square header or the desirable L16 cast iron header. (although you can use them)The W58 also has steel exhaust 'liners'. These are metal pipes held away from the port walls by 'bumps that are cast in. This prevents heat transfer so that the liners glow red hot and burn off any hydrocarbons in the exhaust. I guess there might be some slight restriction from this. Last, the W58 is drilled for use with the coolant cooled/warmed intake manifolds. This is, in my opinion, far superior to the U67 that uses a heat riser and forces hot exhaust up onto the underside of the intake to warm it. They always rust in place and either don't work or over heat the intake. The water intakes warm in cold weather and cool in hot. They draw away heat radiated from the exhaust manifold just inches away. Only the '75-'77 L20Bs had this all L16/18 and '78 and up L20Bs used coolant in the intake. If you have a coolant intake it's easy enough to drill two 3/8" holes in a U67 head, I did this.

[mainer311]

Yeah, I run premium in my L16 w/ 210 head. I also run premium in my R16. I figure the performance loss (from less ignitability) isn't as important as the "safety factor" from pinging and detonation. 

[mainer311]

So if the valves are the same between the W58 and U67, I guess I don't mind just running the W58. My plan is to run a sidedraft manifold, and as far as I know, most of them don't have the coolant circuit. If that is the case, I may actually plug the holes up so that they don't leak. If the manifold does have the circuit, then I'll run it. 

[Charlie69]

I have run both water cooled intake and non water cooled manifolds. the 1980 720 trucks I have owned always pinged in the summer time here in Phoenix. The intake manifold on the 1980 720s were married to the exhaust manifolds.  I also had a 15^o increase in operating temperature in the summer with the married manifolds here in the Phoenix area on 110^o to 128^o days.  I always run 180^o thermostats in my vehicles.  I believe that divorced manifolds are the way to go on the L motor.

 

Water cooled manifolds did not make the engine run better in hot ambient temperatures this is why I do not bother to run them.  Now in a colder climate I can see that the water cooled manifolds would help in the winter time.  I feel that the married manifolds were completely flawed engineering.

[Crashtd420]

I dont think any of the side draft manifolds have coolant ports....

[datzenmike]

2 hours ago, mainer311 said:

So if the valves are the same between the W58 and U67, I guess I don't mind just running the W58. My plan is to run a sidedraft manifold, and as far as I know, most of them don't have the coolant circuit. If that is the case, I may actually plug the holes up so that they don't leak. If the manifold does have the circuit, then I'll run it. 

 

You don't ever have to plug the holes. The intake gasket has way over an inch all the way round any hole to seal and they do.... after all all W58s have these holes and they don't leak. I now have a home made intake and the holes on my U67 head that I drilled out are covered and I never give them a thought. There is another advantage to the coolant ports. They also circulate coolant from two points on the head  on the manifold side rather than it having to work it's way forward to the thermostat to get out.

 

2 hours ago, Charlie69 said:

I have run both water cooled intake and non water cooled manifolds. the 1980 720 trucks I have owned always pinged in the summer time here in Phoenix. The intake manifold on the 1980 720s were married to the exhaust manifolds.  I also had a 15^o increase in operating temperature in the summer with the married manifolds here in the Phoenix area on 110^o to 128^o days.  I always run 180^o thermostats in my vehicles.  I believe that divorced manifolds are the way to go on the L motor.

 

Water cooled manifolds did not make the engine run better in hot ambient temperatures this is why I do not bother to run them.  Now in a colder climate I can see that the water cooled manifolds would help in the winter time.  I feel that the married manifolds were completely flawed engineering.

 

That's odd because all '78 and up engines had the W58 head with coolant flow intakes unless someone swapped them. If it had the married intake to exhaust this was from a '75-'77 L20B . The co-joined ones would get hot because of exhaust but also because they are bolted together. The W58 intakes have a heat shield to reduce radiant heat.

 

1 hour ago, Crashtd420 said:

I dont think any of the side draft manifolds have coolant ports....

 

Only the stock Hitachi SU intakes had coolant use. All Weber intakes probably don't because... race engine and cold weather/hot weather stop/go driving isn't a concern.

[mainer311]

My Offy dual-plane manifold has a coolant circuit, and I used it. Got all snazzy with some heating oil copper line to route it back to the water inlet on the front cover.

 

 

 

Edited November 12, 2020 by mainer311

[MikeRL411]

3 hours ago, mainer311 said:

Yeah, I run premium in my L16 w/ 210 head. I also run premium in my R16. I figure the performance loss (from less ignitability) isn't as important as the "safety factor" from pinging and detonation. 

 

The R16 requires premium gasoline.

[mainer311]

5 minutes ago, MikeRL411 said:

 

The R16 requires premium gasoline.

 

I don't know what the compression is, but I know it has domes.

[datzenmike]

3 hours ago, mainer311 said:

Yeah, I run premium in my L16 w/ 210 head. I also run premium in my R16. I figure the performance loss (from less ignitability) isn't as important as the "safety factor" from pinging and detonation. 

 

All octane does is reduce the compressed gas and air from auto ignition before the spark plug fires. High octane gas works exactly the same as low octane when lit by a spark plug. You could run 114 octane aviation fuel if you want. Gasoline will auto ignite at 536F. Octane additives will raise this point. A spark plug fires at over 8,500F so no amount of octane will prevent ignition.

[MikeRL411]

2 hours ago, mainer311 said:

 

I don't know what the compression is, but I know it has domes.

 

Would you believe the piston are flat topped ?  Because they are.  Compression is just below 10 : 1 requiring premium gas.

[mainer311]

6 minutes ago, MikeRL411 said:

 

Would you believe the piston are flat topped ?  Because they are.  Compression is just below 10 : 1 requiring premium gas.

I already told you, pistons are domed. According to the roadster forums, the stock R16, which it is, is 9:1.

Edited November 12, 2020 by mainer311

[MikeRL411]

9 minutes ago, mainer311 said:

I already told you, pistons are domed. According to the roadster forums, the stock R16, which it is, is 9:1.

 

I own a RL411.  Since new.  I rebuilt the engine many years ago.  The bore had so little wear that I reused the factory pistons.  The original and true replacement pistons are flat topped.  See if the pistons in your engine are numbered on top signifying factory matching to the actual bore diameter.  Replacement pistons are likely unnumbered pistons.\\

 

If your existing pistons are domed I would say they are replacement, not factory originals.

 

[mainer311]

4 minutes ago, MikeRL411 said:

 

I own a RL411.  Since new.  I rebuilt the engine many years ago.  The bore had so little wear that I reused the factory pistons.  The original and true replacement pistons are flat topped.  See if the pistons in your engine are numbered on top signifying factory matching to the actual bore diameter.  Replacement pistons are likely unnumbered pistons.\\

 

If your existing pistons are domed I would say they are replacement, not factory originals.

 

 

Factory pistons are domed. Engine was original. I rebuilt it with...new domes. The RL411 may have used flat tops, but the SP311 used domes.

Edited November 12, 2020 by mainer311