which head?

[moparvwfreak]

alright. heres what i am up against. i have to check the A87 off the old motor, but as i am yanking the head off the L20 i figured i should ask. either way its going to have the stock L20 cam and pads so thats not an issue. so heres the question....

 

A87 off my L16, or the W58 off my L20? either way its getting new valve seals and all other gaskets (bought a whole motor gasket set) but which would be better for my daily drivinghauling needs???

Edited October 9, 2009 by moparvwfreak
f'd up the numbers.

[MicroMachinery]

I think if they're the closed chamber(kidney bean shaped combustion chamber), then they're the same, unless the other head has those pesky metal liners in the exhaust ports.. did you mean w53 or w58? I'm pretty sure there's not a w52... I'd go w/ the A87; it's the stock L18 head, and w/ a little modification to the intake ports(porting to 1.5" from 1.25"), it's the same as the SSS head. I think by just adding the head, it gives you a comp. ratio of almost .5:1 higher. Definitely more umph to your L-series. I don't believe you have to run higher than regular octane, either; but that's just going off how my L18 behaves. I advanced the hell out of it, and couldn''t get it to spark knock. Same w/ my L16 in my truck. I advanced it until it started running slower, and it never pinged on me. Anyhow, all that to say, I'd use the A87.

[datzenmike]

The A-87 could be open or closed, won't know until you remove it. It has small intake ports and square exhaust ports.

 

The only possible advantage of using the A-87 on the larger displacement L20B is if it's a closed chamber (pea-nut) head. This would bump the L20B compression from 8.40 to 8.90 and also provide detonation resistance at the same time. The smaller intake port will increase air flow speed which is a good thing for efficient cylinder filling in the low/mid range, but becomes a choke point for the needed air volume as the revs go up. Yes, the port can be opened up but, it needs to be opened up all the way to the valve pocket and not just a small gasket matching job to the intake.

 

A disadvantage is the square ports on the exhaust. You will need an L16/18 exhaust manifold and down pipe if using it on your '78 truck. If this A-87 is an open chamber I wouldn't even bother with it.

 

 

The stock '78-'80 truck head was a W-58 open chamber with emission reducing liners in round exhaust ports.

 

This head has a larger intake port size better matched to the larger L20B needs. It has round exhaust ports that already match your '78 exhaust manifold. Somewhat of a disadvantage is that it's open chamber, although there are closed W-58 heads. I did have a pea nut W-58 from an S-10, but it may have been a dealer replacement head under warranty as I can find no evidence they were ever installed at the factory. The W-58 is considered a 'smog head', and avoided because of the exhaust liners, but with some small effort the liners can be removed. So much for 'smog head'. I've done this and recommend doing so.

 

 

 

So stock W-58 maybe with liners removed, OR.... A-87 IF close chamber and with L16 exhaust manifold added. Optional: open up the intake ports.

[moparvwfreak]

well the A87 is off the truck, but i dont know enough about the heads to tell if its open or closed. how do you tell??? also the W58 has the liners... i could post a pic or two as i have no idea on how to tell.

[datzenmike]

This is an open chamber W-58 head. It is circular and there is open space above all of the piston top when at TDC.

 

http://i138.photobucket.com/albums/q251/datzenmike/L%20Z%20Heads%20and%20Motors/motorW-58openL20B78620.jpg[/img]"]

 

This is a closed chamber (peanut) W-58 head. It is roughly heart shaped and there are some areas where the piston is only the 1.2mm gasket thickness from the head surface. This is called the quench or pinch areas.

 

http://i138.photobucket.com/albums/q251/datzenmike/L%20Z%20Heads%20and%20Motors/01300019.jpg[/img]"]

 

 

 

Here is an A-87 closed head:

 

http://i138.photobucket.com/albums/q251/datzenmike/L%20Z%20Heads%20and%20Motors/motorheaadA-87closed.jpg[/img]"]

[datsunaholic]

If the A87 is the ORIGINAL 1973 L16 head, it's open, AND it likely has the smaller (1.30") exhaust valves vs the 1.38" valves. But you won't know without measuring (the difference is less than 1/10 of an inch, and in either case you have to have the head off.

[moparvwfreak]

alright. it seems that both are open, so i will most likely use the W58 head. i just got done yanking the head to do all new gaskets and they look to be about hte same. :( to bad i dont have the cool stuff. hopefully tomorrow or later tonight, i can get some parts cleaned and starting to go together.

[MicroMachinery]

Bummer man, I'd try and find a closed chamber head, if you can hold out. It'd be worth it. You can find them semi-easily; guaranteed on this forum.

[moparvwfreak]

if i had the time to wait, i would try to find a closed head. but i cant afford to keep driving my 'yota everyday. its eating me out of house and home in fuel.