Questoin about the 4AC...

[T-Bone]

I was wondering what the difference was between the 4AC with the straight valve cover and the curved valve cover. i saw some sale thing on ebay. here is the link.

http://cgi.ebay.com/ebaymotors/Toyota-C ... 4739QQrdZ1

Also, what parts can be swaped from the 4AC to the 3AC. like can the pistons from the 4AC be installed into the 3AC and stuff.

[GTSSportCoupe]

I was wondering what the difference was between the 4AC with the straight valve cover and the curved valve cover. i saw some sale thing on ebay. here is the link.

http://cgi.ebay.com/ebaymotors/Toyota-C ... 4739QQrdZ1

Also, what parts can be swaped from the 4AC to the 3AC. like can the pistons from the 4AC be installed into the 3AC and stuff.

Thats interesting...I never knew there was a difference. Before buying one, check yours to make sure you buy the right type. I'd say Toyota probably changed the head design of the 4AC somewhere along the line. Maybe there is an early and late revision?

AFAIK most parts can be swapped from 4AC to 3AC. Pistons can NOT be swapped though. The bore is the main difference between the two engines.

[T-Bone]

do you know is there is a diff between the 3AC and 4AC carb/inlet manifold? from what I have read about them they are both the same.

[GTSSportCoupe]

do you know is there is a diff between the 3AC and 4AC carb/inlet manifold? from what I have read about them they are both the same.

From what I know, the rwd 4ac has the same manifold/carb design as the tercel 4wd 3ac. But I have not verified this personally. The fwd versions of the 4ac are likely slightly different.

[neonsport]

The wavy head design was used on 4ACs from 86-on. THe engines are identical except for the shape of the head and valve cover. I don't know what the reason for the change was, but I'd suspect it has something to do with oil drainback.

BTW, the 2 3A-SCVs I've seen both had the wavy valve covers as well.

[raybbaby]

So I'm wondering if the 4ac head will fit onto a 3ac block. I've read it will but I may need to remove some metal via milling. I can't find out the specifics of this proposition though. Any help?

[T-Bone]

does anyone know if the 4AC head is ported out more then the 3AC head or something, maybe diff cam? I know the 4AC has a bigger displacement. I think the 4AC head should bolt up to the 3AC block because you can bolt the 3AC head on to the 4AC block.