8R vs 18R

[gunnut]

I just wanted to ask if anyone knows what the difference is between the 2 motors. Will all parts swampable? Or is it limited? If so, which parts?

I'm currently restoring a 70 Corona MKII with an 8RC motor. With that said, 8R parts are a bit hard to come by, and I have an opportunity to buy 2 18R motors for a decent price. Will I be able to swap parts between the 2 motors?

[Carlyn Dinkler]

The 8RC & 18RC engines used in the USA & Canada were similar engines that can be interchanged. The following table lists some information from the Toyota publication 00402-01632,0573.

-------------------8RC---------------18RC
displacement------1858cc/113.4ci--1968cc/120ci
Std piston dia------86mm-------------88.5mm
compression-------9.0-----------------8.5 (varied with head PN)
intake head dia----43mm-------------41mm
exhaust head dia---34mm-------------36mm

The crankshafts were manufactured differently and Toyota said not to interchange them, but most people did.

These engines were designed to use leaded gas, and some heads had hardened valve seats, some did not. If you run your engine hard (over 70mph on long trips) and you have to adjust the valves often, then you probably do not have hardened seats. When you run out of adjustment, pull the head, have hardened seats installed with stellite valves. Toyota did a big change-out of 18RC heads about 1975, and these new heads with valves (you see them on eBay) were designed for Leaded Gas (they have the good valves but not the hardened seats).

Most other parts are interchangeable between these engines. On some later engines the pan changed and so did the oil pump.

I have deep stock on most parts for these engines, so if you need parts or a complete engine, just ask. Carlyn Dinkler [e-mail]