U67 head question

[john510]

Im building an l20b and im putting the A87 peanut head on it .The A87 is on my L18 right now.I want to swap the A87 from the L18 and put the U67 on the L18 so i can drive the car as im building the L20b.The U67 does not have water passages for the intake manifold.Im using SU carbs.What will happen without water getting to the intake manifold?is it ok to just run it like that? thanks ,john

[izzo]

yeah its fine running it like that...

[datzenmike]

If the intake has holes for water and you have the return hoses and hard line down to the lower rad inlet then just drill the holes out and run with it..

 

 

The water is to warm the manifold and aid evaporation of the fuel. This increases efficiency. The U-67 head used an intake and exhaust manifold that were bolted together and used hot exhaust to do the same thing.

 

 

Without it the throttle response will be poorer when the engine is warming up and also in cold weather. Mileage would be better with it working.

[john510]

Thanks for the answers guys,i did consider drilling holes but im concerned about how deep and what angle to drill,i dont want to ruin a good head.You can definitely see where the holes need to be from where the gasket left marks.Im wondering if there is a hollow cavity or passage like the A87 head or would it be solid aluminum all the way through? thanks again,john

[Braden]

honestly i wouldnt mess with drilling it, slap your manifold on there, i honestly doubt you are gonna be able to tell a difference other than possible cooler carb temps and like mike (hey isnt that a movie?) said maybe a loss of fuel mileage but hey whats a 32nd of a mpg gonna really hurt? honestly if i had the holes (which i did) i would put a 1/4 inch npt allen head pipe plug in them, i my existing holes needed no drilling juts a simple tap and some plugs and threadlocker. i have heard of people having problems sometimes running the manifolds with the water passages, the intake gasket leaks and water comes out the exhaust causing the illusion of a blown head gasket.

[datzenmike]

You can't hurt anything drilling them out. Nissan used one form or another to warm the intake manifold on all L and Z motors. Trust the design.

[banzai510(hainz)]

if you think your going to put sidedrafts on there one day then DONT drill them out.

 

then plug the water line from the water outlet by the fuel pump. (put a bolt in the small hose).

If you really need to drill it out I just use a 1/4 drill bit and use a intake gasket and put the hole in the center.

 

If you live where ist freezes the water line help warm up the gas to prevent the carb from icing up.

[Braden]

drill at a 90 degree angle from the manifold mating surface.

[Z-train]

You can't hurt anything drilling them out. Nissan used one form or another to warm the intake manifold on all L and Z motors. Trust the design.

The design was for driveability during warm-up & emissions.Once up to temp the water in the manifold is completely redundant.

[hang_510]

If you live where ist freezes the water line help warm up the gas to prevent the carb from icing up.

unless ^^^ you do, no need for any more holes in your head ;)

 

 

on my 2 U67's, 1 has the holes 1 doesnt...

[john510]

Alright thanks for all the input guys ,i think i will pass on drilling holes in a perfectly good head.It doesnt really freeze here in san diego,freezing here is frost on the grass.Not cold enough to freeze an engine up.That head wont be in the car very long anyway,i hope.thanks again,john

[datzenmike]

Without it the intake air would vary in temperature too much and tuning would be problematic. The engine will run better overall if it runs at the same temp year round. On hot days the radiant heat from the exhaust manifold will scorch the underside of the intake and the water in the runners will actually help draw the heat away preventing the gas boiling in the cab.

[john510]

I drilled them out,it was pretty easy there wasnt as much metal there as i thought there would be, maybe 3/16 of an inch.I drilled them because years ago i was running the SU carbs without water going thruogh the manifold,in the summer when it was real hot 100-105 where i live it would run like shit especially after sitting at idle for a few minutes.I took it to my datsun guy he recomended hooking the manifold up into the cooling system.Problem gone.Datzenmike your last post reminded me of that,thanks.Hainz how do you block off those water holes if you run sidedrafts? just curious.

[izzo]

John, not sure if this would work for you, but on heads that already have holes, people just put freeze plugs in there. Might find a head that already has the holes there, drill yours to match and do the same?

[hang_510]

how do you block off those water holes if you run sidedrafts?

my manifold covers them.

didnt do anything, just be sure the gasket is of good quality ;)

[wayno]

I agree with datzenmike, I have been running dual SUs for over 10 years, when I had the head built(W53) it had no holes for the water jacket, the machine shop drilled them for me using the gasket as the template and I have never had a leak, or any other water related issues. The only issue the truck has, is the driver beating the crap out of it everyday. :lol: wayno

[mr68gts]

Mines been without holes and SU's since 76. Only time it's affected anything is when trying to warm up. It's a cold blooded son of a bitch, but as far as drive ability goes, never had an issue once warm. Now this may change now that I'm in a lot colder climate and at 7000 ft altitude. (quite the change from San Diego and Palm Desert)

Paul

[datzenmike]

Here's my SSS intake and flattops. You can see the PCV hose in the middle and way over on the far right an outlet pipe for the water passages. This would be connected to the thermostat housing return to the bottom rad hose inlet to the block. Water would flow from the head through the runners (to warm and air fuel vaporization) out the front of the manifold and down to the lower rad hose and be recirculated.

 

 

Myself, I would drill the head out using the gasket to locate the holes. You will need the return hose, or you may already have it there with a bolt in the hose end.

 

 

Here's the lower rad hose inlet. It has a T with the heater hose and manifold hot water return connections on it...

 

[john510]

Yes, thats how the A87 head was plumbed for water to the intake and now the U67 is the same.Its all put back together now after removing the front cover because i couldnt get enough slack in the timing chain.The A87 head must have been shaved a little and U67 wasnt.I tried and tried but could not get the cam sprocket back on,so i took the cover off and put new chain guides and tensioner in while i had it apart.It runs better now with the U67 head even with less compression.It turns out the A87 head had a stock L-16 cam in it.The U67 has a cam with roughly a .430 lift,what a difference it makes.