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Head swap...any input?


DRIVEN

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Bought a replacement head for my A15. Thinking about swapping it in before Canby. It looked very clean and had a recent resurfacing. Plugs were brand new. Here's my question -- Since it was pulled from an F10 (FWD) A14 (tag said 80HP), Is there any differences that will not allow this to work. The only things I noticed were the thermal vacuum switch at the rear (will be driver's side in my car) of the head. I will plug this. Also a air? port next to thermostat housing. Can I just plug that also? Note; thermostat housing was swiped from a different car.

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The car was a 1978 F10 with A14 manual transmission and head is H72. Since it was half price day it only cost $22.45 + $5 core. Figured I couldn't go wrong. You guys wanna set me straight before I do something stupid?

Edited by DRIVEN
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Just wondering if there's any weird, seldom heard secret pertaining to the FWD version of the A14. The job itself is not going to be a problem.:cool:

well theres that thing, involving that one thing that connects to the other thing...naa you can figure it out.......:lol:

nope, nothing wierd about it. just plug up your unnecessary crap and you should be good to go!

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So I thought I was going to Just swap out the heads and toss this engine back in for Canby. Pulled the old head off on Monday to find a pencil eraser sized hole in #4 exhaust valve. No surprise, right? Well the thing that was a surprise was the huge difference in combustion chamber size. The replacement head (H72) had an open chamber that looked about twice the size of the original (H89). When coupled with my stock dished pistons I figured my compression ratio should be a dishwater friendly 3.7:1 or so :mad:. So I did some reading on 1200.com and it looks looks like most A-series heads can take around .080 mill and still be safe. I called my machinist and checked his lead time. Rushed both heads down to him and told him to use his best judgment. He called back and said they both basically need everything. So I guess I won't be needing that replacement head after all. I spent the morning re-ringing the bottom end so that when he calls tomorrow I can rush over and pick it up, assemble the engine and swap it into my car again. SHEESH!! The things I do to keep you guys entertained.:rolleyes:

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It will work, the compression will only be about 0.25 lower.

 

In 1981 the A15 changed: Larger combustion chamber (with quench) and smaller dish in piston.

 

The 1980 A15 used the round-port head. 1981 is oval port.

Edited by ggzilla
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Aside from the quarter point lower is there any difference? Valves and ports were the same size. I guess now I have a spare:D. My machinist said he might have it done yesterday afternoon or this morning. I'm literally standing in my shop waiting for the phone to ring.

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Interesting pistons and rods. The dish is to the one side. Do you know the diameter of the main bearing? The rod length from center of main to center of piston pin? And do you know the distance from center of pin to the piston top?

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Just to finish up the thread...

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Fresh valve grind, seals and surface.

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Got the head back and started bolting it on at 1:15 Friday afternoon. Had an appointment at 5:30 so I had to at least have it in by 4:30. Had the engine in and everything bolted up by 4:40. Went to fire it and the battery was weak. Got up the next morning and Got it running. Since I had run this combo before there wasn't much tuning to do beyond setting the timing. Ran it around town a bit and started cleaning it up. Made it to Canby for Sunday's festivities. Mission accomplished.

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Just to finish up the thread...

001-9.jpg[/img]

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Fresh valve grind, seals and surface.

003-10.jpg[/img]

Got the head back and started bolting it on at 1:15 Friday afternoon. Had an appointment at 5:30 so I had to at least have it in by 4:30. Had the engine in and everything bolted up by 4:40. Went to fire it and the battery was weak. Got up the next morning and Got it running. Since I had run this combo before there wasn't much tuning to do beyond setting the timing. Ran it around town a bit and started cleaning it up. Made it to Canby for Sunday's festivities. Mission accomplished.

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holly shit dude, i didn't know you were doing this. very cool. what kind of carbs are those? how does it rev? how did you build the manifold to mount those carbs? more pics man , more pics. and details.

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The carbs are '02 Katana 600. Supposed to be same as earlier GSXR. The manifold was made from left over tubing from a sandrail frame I built. The I.D. just happened to be the same as the throttle plates (44mm). The flange was some 3/8" plate that I had. The runners were pie-cut and welded -- about 6 times per runner, if I remember right. It runs pretty good but I'm sure if I spent more time perfecting the jetting, it could be improved. Throttle response is great. Mid-range is really good. It probably could benefit from more cam. Drops off at about 5500RPM. The sound is incredible. I have never heard another A motor growl like this -- not with Hitachis or Webers! It is intoxicating. The worst part of the whole project was clearing the brake master. I have heard people talk shit about the runner angles, but it was unavoidable and still a smoother transition than a stock intake. These are shots of mock-up before final welding.

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