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What needs to be done on a Penta 531 to work in a brick?

There seems to be a sensor and a plugged hole on the intake side of the head from the pictures. And the description says "Fourth cylinder ring already installed", could that be what you did?
 
I had mine welded and the port shaped so it looks like a standard 8v port. Well you reminded me of when I put the 405 on my turbo. The intake manifold may not clear the plug on the intake side port four. On mine I had to make a flat plug that was flush with the surface of the port so the gasket and manifold would work. I think it was a 14mm 1.5thread. I cut off the head of a bolt and cut slots int he remaining stud to make that.

Also had to drill and tap holes for a sensor or two.
 
So would you say it's worth it? It would be around $290 shipped and it already comes with a V cam, which I've read is a fair bit better than my B cam.
 
No he's saying take out the steel fourth cylinder ring and weld it up with aluminum, but you don't have to do that. Then on the intake side if you look there is only one sensor hole drilled and tapped for one temp sensor and the car heads have two, but maybe you could get by with only one. There is that plug also further back that the heater core hose usually hooks to in the cars also. You take that plug out and put the hose barb in there, it screws in, instead of the plug.

Other then that you don't have to do anything to run the boat heads if you don't want to.
 
Yes, as Simon points out if the iron ring and port are in good condition you don't have to mess with it. Mine was corroded so it needed work no matter what. If you want a good head for some performance a 531 is a good start. I've bought 405 and 531 heads and I've only used the 405 on my kjet turbo. It made a nice difference and the 405 has stock valves in it. Whether it is worth it is kind of a subjective opinion. For me it has been well worth it.
 
It seems that one of my spark plug holes is cross threaded (the plug is crooked compared to the other ones) and a couple of my valve cover holes are stripped. The previous owner beat the head up pretty bad. It seems like the 531 head in the ebay post is decently clean and leak free other than some visible corrosion.
 
That's another option, but then I'd have to swap the B cam to that head and shim it before installing it. Just weighing out what I should do. The better flow and cam seem nice for ~$290.
 
I would do a junkyard run over the weekend, but a 531 head with all seals replaced and a brand new stainless steel ring in cyl #4 for $290 seems like a good price.
 
I would certainly just grab a used 530. They are cheap and plentiful, and don’t require modification.

If you have a B cam that’s properly shimmed in your current head, you can just swap over the cam and all shims to the new junkyard head.


Spend the ~$100 and have the head resurfaced and hot tanked. I’ve never taken a lot of material off for performance reasons, only taken off minimum amount in order to make it flat. Last one I did was only .003".
 
Hot tanks kill valve stem seals too, so you might as well disassemble and lap the valves, then replace the seals once you get the head back. You’ll be lookin at around $200-$300 out the door if you disassemble and lap yourself.

530 is probably $70 or so
$100-$150 resurface
Lapping compound and tool is $15
Seals are maybe $2.50 a piece x 4
 
You'll have to drill and tap a hole for the ecu temp sensor on this. Other than that it bolts right up.
If you want gear you may have to drill the plugged hole out larger too, i forgot what all i had to do with that.
 
The 531 head and its ports are designed to work at high rpm. In a car application, they will have reduced torque, stock for stock, than a 530 head, for two reasons:

1. The intake ports flow more, but at the expense of velocity and low velocity is not good for lower rpm performance, efficiency or torque.

2. The combustion chamber has a larger volume so you would be lowering your compression ratio which is worse for torque(aka, what moves you) and efficiency. https://ozvolvo.org/discussion/8971/530-531-chamber-size-and-static-cr-measurements

For the port flow and velocity, it's not really worth installing a 531 or 405 head on a car unless you are planning on running a camshaft with at least 12mm or so of lift, as that's when you start really getting the benefit of the more advanced, and larger intake port design.

For the combustion chamber size difference and the loss of static compression, you can shave material off the head mating surface to bring it back up to, and beyond the 530's chamber size and effective static compression. That's no big deal, but you still are missing out on flow velocity and torque on what definitely sounds like a street car.

You should pull a 530 at the junkyard and call it day.
This, unless you're looking for performance above 4500rpm or so and are planning on using a camshaft more aggressive than the V.

That's another option, but then I'd have to swap the B cam to that head and shim it before installing it. Just weighing out what I should do. The better flow and cam seem nice for ~$290.
Swapping the B cam from one head to the other is the least of your worries...

Now I'm thinking of getting a decent 530 and milling off 0.040", bad idea for NA with B cam?
Good idea. You may need to run premium fuel and you might want to get an adjustable cam gear to move the powerband around to your liking. I would probably want to run it 2-4 degrees advanced in a non-turbo, automatic equipped car if that is what you're driving.

If you have a B cam that’s properly shimmed in your current head, you can just swap over the cam and all shims to the new junkyard head.
That is false. You may get lucky, but the valve stem heights of one head are not the same on all heads, especially with the varying amounts of wear. Swap just the camshaft over, then measure your valve clearances. If things are outside of .014-.020", you might want to adjust them. If they're within that, you will be "ok" to leave it as is. You might be able to mix and match with your shims from both heads to get things a little more even across the board, without getting a shim kit. If you want a smoother idle and more torque off idle, set everything on the looser side of specs, around .017-.018"(or so). If you want a little more top end pull at the expense of some idle quality and emissions, you can set the clearances tighter, around .014" or so.

Here are some misc. threads related to non-turbo performance I have saved over time, but it's by no means all of them.

http://forums.turbobricks.com/showthread.php?t=274989
http://forums.turbobricks.com/showthread.php?t=348598
http://forums.turbobricks.com/showthread.php?t=333776
http://forums.turbobricks.com/showthread.php?t=220554
http://forums.turbobricks.com/showthread.php?t=209648
http://forums.turbobricks.com/showthread.php?t=337311
http://forums.turbobricks.com/showthread.php?t=110700
http://forums.turbobricks.com/showthread.php?t=290198
http://forums.turbobricks.com/showthread.php?t=275416
http://forums.turbobricks.com/showthread.php?t=277707
http://forums.turbobricks.com/showthread.php?t=275133
http://forums.turbobricks.com/showthread.php?t=272196
http://forums.turbobricks.com/showthread.php?t=337956
http://forums.turbobricks.com/showthread.php?t=350635
http://forums.turbobricks.com/showthread.php?t=342490
http://forums.turbobricks.com/showthread.php?t=342456
http://forums.turbobricks.com/showthread.php?t=342098
http://forums.turbobricks.com/showthread.php?t=341814
http://forums.turbobricks.com/showthread.php?t=349476

And more.
 
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Kl, that’s a pretty good point I did not consider. That being said, most of the time I’ve swapped to other stock cams, everything is still within spec. So yes he may get lucky.
 
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