Differences in Cylinder Heads between 5speed and A/T models.

TL;DR - what is possible difference between head on AT and 5 speed, if visually same porting, valvetrain, bolts, ect?


I am rebuilding my 1982 accord lx 3 door, particularly the EK1 engine. I overworked that puppy for many years on many roadtrips, and now im rebuilding her due to bad compression. Upon opening up the engine, I discovered a cracked head, and a broken piston (the part between the top 2 rings was cracked and broken).

I'm having the block machined with some oversized pistons, and I'm putting all new bearings in the lower end, so I have that covered. I need to get a new head somewhere though....

I ordered one from american cyl head but they sent me the wrong one, and now they're out of stock. everywhere else i find that says they have it, I call and find out they are gonna order from american cyl head and send it to me, but i already know ACH doesn't actually have it.

I found one on ebay that seems right but says it's for Automatic transmission. I am wondering what the differences in the cylinder heads could be for a/t vs 5 speed.

I made sure it has the same valve arrangement, same port arrangement, same bolt patterns on the manifolds, same looking cvcc bs, and the same PC1 casting mark. what else could be different? Please help I need to get this car running ASAP

No differences in the castings, valves, rockers as far as I know. I do believe the autos had a slightly different cam profile. So if you're buying a full assembly, that might be the difference.

The big thing to look out for, make sure you get the same year. You can use heads from 82-83 only. 81 and earlier are different.

thanks for the reply! I ended buying it because it was so cheap - It is the same year, and everything lines up. I got the full assembly - rockers/valves/cam ect. visually the only difference I can see is the cam pulley is a different part, but it has the same diameter and the same number of teeth, so i think it should be fine.

I was planning on using the cam i received with the head, as it is in better condition than my original one. I can swap the pulley over, although i think they are functionally the same part, just look a little different for some reason. Do you think that would work, or would it be a bad idea? do you know how, specifically, the cams profiles differ? like does the auto have the valves open longer/shorter, ect? what timing differences are the with it?

thanks!

I am not a EK 1 specialist,but i would use the old camshaft,or have the new AT one reshaped to manual specs if possible, or get a new manual camshaft. There is a reason why it is different,your engine will run different,might not be a huge difference but nevertheless. You would also be able to use your own timing etc.
Maybe there are other opinions about this issue,but i would prefer a manual cam.

Auke.

Yeah, I see your logic and agree for the most part, but now im just interested in what that difference is.
like what if it's a more aggressive cam put in to compensate for some of the power loss of the auto? then I would prefer to run that.

I thought Auto's had slightly less power in favor of more torque.