A87 Head Chamber Volume

General Discussion about the Datsun PL510
HP 510
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A87 Head Chamber Volume

Postby HP 510 » 24 Mar 2017 16:35

Is there a large chamber version of the A87 head? I have an A87 closed chamber cylinder head and the combustion chamber measures 55cc, all the information I've been able to find says the chamber volume should be in the 41-45cc range. Does anyone know what this head is from? The chambers are not modified.

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okayfine
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Re: A87 Head Chamber Volume

Postby okayfine » 25 Mar 2017 16:39

Open A87s are typically 45.3cc. Post pictures of your head's combustion chambers?
Because when you spend a silly amount of money on a silly, trivial thing that will help you not one jot, you are demonstrating that you have a soul and a heart and that you are the sort of person who has no time for Which? magazine. – Jeremy Clarkson

datzenmike
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Re: A87 Head Chamber Volume

Postby datzenmike » 25 Mar 2017 19:28

Raise the valves up off their seats and rub a little grease on the faces to help seal them. No way its 55cc. Only thing I can see is you are allowing the surface tension to bulge up and above the head surface.

I used a plastic CD case with a small hole near the edge. Run a little grease around the combustion chamber to seal the case against it with the hole near the edge and press flat. To measure cc's I used a child's plastic liquid medicine 'syringe' that holds 10cc. Pharmacist gave it to me when I told him what it was for. Four full 10cc squirts and tilt the head slightly to allow air bubbles out the hole. finish filling. An unshaved closed chamber head should be 41cc and open chamber 45.3cc.
"Nissan 'shit the bed' when they made these, plain and simple." McShagger510 on flattop SUs

HP 510
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Location: NEPA

Re: A87 Head Chamber Volume

Postby HP 510 » 26 Mar 2017 06:39

I used a 1/4" thick piece of acrylic with 2 small holes, one to fill one to vent, a 100ml lab burette and sealed the plate to the head and the valves with white grease. I also checked the burette calibration against a syringe. I'm sure I must be doing something wrong because I got a similar inaccurate reading when I tried to cc the dome on the piston. How much of an effect will the fluid used have? I used RV antifreeze (mostly for the color).
I'll try to get some pictures later when I go out to the shop.

datzenmike
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Re: A87 Head Chamber Volume

Postby datzenmike » 26 Mar 2017 08:52

Mine was repeatable, did Z20, Z22 and Z24 heads twice, all were 57cc. The dose syringe is graduated in 1/10ths and available at WallMart or any pharmacy for a buck or two. The best of all, this low tech total cost was zero.
"Nissan 'shit the bed' when they made these, plain and simple." McShagger510 on flattop SUs

HP 510
Posts: 8
Joined: 05 Jul 2016 07:56
Location: NEPA

Re: A87 Head Chamber Volume

Postby HP 510 » 31 Mar 2017 06:24

Found the problem, a brand new in the box burette that was calibrated wrong. I need to recheck but the first try with a small syringe gave a chamber volume of 43.2 cc. Thanks for the replies.


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