W58 closed chamber head... removing exhaust sleeves???

[distributorguy]

So I have a 1980 head with 1800 miles on it, closed chamber, figured its a good candidate for the spare Bonneville motor - to straighten out chassis issues with maybe 10 - 11:1 compression and the big Weber carbs.  

My question - is there an easy way to get the sleeves out of the exhaust ports???  I suspect I'll have to remove the valve guides and start cutting until I can get them to collapse.  If there's a way to do it without removing the guides, I'm all ears.  This head has a legitimate 1800 miles on it.  Sat at Brainerd International Raceway since they broke the diff catching air.   :thumbup:

I'm not in the mood to die grind the sleeves until they fall apart - at least not tonight.  Ugh.   But this head has a lot of potential and I'd like to make the most of it.  

[Stoffregen Motorsports]

When I worked for Rebello we gave this head a few tries, and even with the sleeves out, the juice wasn't worth the squeeze.

 

Are square port heads getting that hard to find?

[datzenmike]

Taking the guides out doesn't remove the cast lump around the base anyway. I just removed the valve and cut, twisted and bent it over them and out. Hammer, 6" chisel and vice grips, slit lengthwise in at least two places and bend pry into the middle of the port and out. 45 min for the first one, and 15 for the last. There are raised bumps cast into the port to support the liner away from contact so it glows red hot. I ground these away and put a square port gasket on, marked it and gasket matched it. Shrug, I was curious. It also was an closed chamber import head used on a 200sx.

[distributorguy]

Square port closed chamber heads are getting harder to find.  We are building 2 of them as full race heads.  I have this head as a spare, so I'm using it for an old motor that we can make the truck mobile with, and it may end up in our leftover truck carcass.  Looking at what's under the sleeves, I know its not going to flow very well.  Gas will expand after passing the seat, which will allow the head to absorb more of that heat as velocity drops.  I'll likely need to hog out the intake ports to keep intake to exhaust flow ratios even close to appropriate - guessing in the 90% range?  But really, this engine is being built to get the truck balance correct, test the brakes, set the alignment, finish the wiring, etc...  

Thanks guys.  I'll report back.  

[datzenmike]

Without the sleeve it will be the same as the earlier U67 heads, other that the port to intake shape. With the sleeves, less heat will transfer to the ports.

 

 

If just for making the truck mobile it isn't worth the bother.

[distributorguy]

Well, 35 minutes for the first one, 8 for the last.  Now I wish I had a couple more heads to pull them from.  Easy once you get a game plan.  I split the sleeve on the short side of the port through the runner by thinning it with a coarse die grinder.  Then I did the same to the long side of the bowl behind the guide.  From there you could fold the "tube" in on itself and peel back the dish behind the bowl and curl it in on itself, above the guide.  That final curl gave you something to hit and pound it out the hole.  So far I'm in about 75 minutes, and the basic port work is done as well.  Ready to cut the seats, then do a final smoothing in a few areas and put it all back together after a final cleaning.  

 

Once the truck is mobile, it needs to run well enough to do some ice testing on a local lake once we have a solid foot or so.  The total lack of traction will be good driving experience for the salt, so if we can make 120 hp instead of 100, that would be great.   :thumbup:   Half of what we hope for on the salt.  

[G-Duax]

With the sleeves, less heat will transfer to the ports.

 

That is what ceramic coatings are for :)

[datzenmike]

True, but I was referring to this comment...

 

Gas will expand after passing the seat, which will allow the head to absorb more of that heat as velocity drops.

Without liners it's just a U67 head.... and it didn't suffer from excessive heat transfer.

[distributorguy]

This head has more material missing below the seats than a normal U67.  Now, when air passes the valve head, there's a large dead space on the back side of the guide, under the seat.  Pre-"smog" versions don't have this material missing, at least not the ones I have seen.  That recession under the seat is going to create some turbulence and a dead spot in that area directly under the valve on the long side of the port.  Eventually it'd build up with carbon.  If it wasn't for that issue, I'd weld up the ports so they are "square port" instead of round but its essentially a waste of time.  

[datzenmike]

Never noticed but makes sense they would make more room for the sleeves under the seat. You need to remove material to make it square.

[distributorguy]

If I removed enough material to make it square, I'd run out of room for valves within the cylinder walls.  The good news is that I can minimize turbulence.  If this were the intakes, It'd be a junk head.  

[datzenmike]

   If it wasn't for that issue, I'd weld up the ports so they are "square port" instead of round but its essentially a waste of time.  

 

 

  You need to remove material to make it square.

 

 

If I removed enough material to make it square, I'd run out of room for valves within the cylinder walls.  The good news is that I can minimize turbulence.  If this were the intakes, It'd be a junk head.  

 

Not following. Just gasket match it to the intake. No welding required. How would you run out of room for the valves. I missed something here.

[distributorguy]

The area in question is UNDER the valve seat, in the bowl.  In the middle of the 90 degree airflow directional change.  That's where the biggest issue with turbulence lies.  If you can't get air to pass by the valve in some kind of orderly fashion, its also not going to want to head down the pipe.  Turbulence acts like a shield of air, blocking other air from flowing through the port.  Since this issue below the seat exists, there's no use in spending a ton of time porting this as anything more than a street head.  

Gasket matching is what it is - a mess in this instance.   

[wayno]

If it is a street head, then why bother removing the liners, unless that is how you found out about the issue(dead spot) as the liners were in the way of seeing the issue(dead spot).

 

I have always been of the opinion that a W58 head is an alright head for street use because no normal driver would run the engine RPM up to the point where the liners would ever become an issue while driving on the street.

[G-Duax]

Not a street engine, and he's just throwing a head together to do a little testing on everything else.

If I had never seen the inside of a sleeved head, I would have cut it out just to see what was there also.

That is what hot-rodders do.

[datzenmike]

For stock with or without it will flow fine. Specially exhaust, it wants out. Intake only has about 15 PSI pushing the air in so good flow is vital. It's not a racing head.

 

I had one years ago and took the sleeves out, don't remember the exhaust ports

[Stoffregen Motorsports]

If it is a street head, then why bother removing the liners, unless that is how you found out about the issue(dead spot) as the liners were in the way of seeing the issue(dead spot).

 

I have always been of the opinion that a W58 head is an alright head for street use because no normal driver would run the engine RPM up to the point where the liners would ever become an issue while driving on the street.

Because Datsun.

[wayno]

Because Datsun.

 

Because Datsun Owner :lol:

[distributorguy]

Because race truck.  

All this is being done in the effort to win the production mini truck class record at Bonneville.  Datsun should own that record, and I'll do my best to make it happen.  

 

One of the differences between me and many others who will rip liners out of a head is that I have a flow bench to test what I'm doing to prove it works or it doesn't.  Just having a "big enough" port usually isn't the answer, and exhaust doesn't typically just "let itself out" unless everything is set up properly.  Typical intake to exhaust flow ratio is around 85% in an L20b head.  I'm running an enormous exhaust header, no pipe or muffler, and Weber 50's.  We need rpm to set a record, and you get into higher revs partially by opening up the exhaust to closer to 95% Intake/exhaust flow if you can get there.  And retard the cam timing.  While this motor is simply a test motor to set up the chassis, I'm putting it together in a way that will replicate (on a smaller scale) how the race motor will run using techniques that can be reversed without much effort.  Port the exhaust, not the intake so flow can be balanced later for a street engine.  Use a stock cam, retarded for hp.  Use a closed chamber head with a zero-decked block and dished pistons.  Its nothing special, but set u pin a way that allows me to use the Webers enough to dial them in, get fuel and ignition set up, then swap to the race motor and move forward efficiently.