L16 Bottom End Paired to A87 Peanut Head

[BrianE]

Wondering if anyone in the community has or is running with the above combination. Pros/con's? Suitable as a street"+" config? Ability to reasonably climb a mountain road or is this a pairing better suited to flat and level? Thanks in advance.

[datzenmike]

Compression will drop from 8.5 to 8.21 from the larger A87 combustion chamber, so you might want to mill it slightly. 0.020" or 0.5mm should get you close to the original 210 head compression. You can cc the chambers aiming for 38.5 I believe.

This will work just fine and with larger valves and ports and the A87 head usually being equipped with an L20B cam which is basically very close to the L16SSS cam, breath a little better too. Better breathing, you might consider a 32/36 Weber now.

It should be mentioned here that although a closed chamber head, you don't get the benefits of a closed chamber head. To take advantage of the peanut head you really would need flattop pistons like the L16SSS has. Flattops at TDC have only the gasket thickness between them and the lower head surface. Any air compressed in this area is violently pinched out into the combustion chamber generating beneficial turbulence. That's hard to do with dished pistons.

[BrianE]

Thank you. To your comment "breath a little better too. Better breathing, you might consider a 32/36 Weber now"..., or a pair of SU's I suspect?

[BrianE]

My reason(s) for asking is I will have an opportunity to preview / make an offer on a 510 here shortly with this very setup (L16/A87/SU's). It's a setup that I have not had any experience with previously but am excited at the prospects....

[datzenmike]

How do you know it's a closed chamber head??? We did get A87 heads on all the L18s we got. ('74 620 and 710 and the '73 610 ((L18)) and '74 610 L20B) For emissions purposed, these were all open chamber in North America.

There are closed chamber A87 heads but these were probably off engines imported in the late '70s or '80s. It was cheaper to install a low mileage import head that to rebuild them.

If you do have an open chamber A87, the compression will be a terrible 7.72 down from the stock 8.5.

[BrianE]

Thanks for the A87 history/insight.
"How do you know it's a closed chamber head???" No evidence other than word of mouth by the seller at this point. I'm asking for and hoping they can provide a document trail but who knows. I suspect an engine with a 7.7 CR will barely give a Ford Pinto from back in the day a decent run for it's money....

[yenpit]

It should be mentioned here that although a closed chamber head, you don't get the benefits of a closed chamber head. To take advantage of the peanut head you really would need flattop pistons like the L16SSS has. Flattops at TDC have only the gasket thickness between them and the lower head surface. Any air compressed in this area is violently pinched out into the combustion chamber generating beneficial turbulence. That's hard to do with dished pistons.

JUst read thru more posts...........already answered, but here was my reply regardless............Not all A87's are closed/peanut chamber & not all A87's are big port, big valve. We see the same confusing issue with the USA spec Z car E88 cyl heads..........three different cc sizes!! Ugh!! I'm guessing that the limited production USA spec A87 on the L18's in the 620's were the ones that were open chamber, small port, small valve & the JDM A87's (many imported here in the 1980's) were often closed/peanut chamber, big port, big valve. I have had BOTH in my hands, so I am confident in this myth, that all were closed/peanut chamber!