I'm picking up a 91 Rodeo doner this weekend with the GM 3.1. As soon as I confirm it has the larger valves (same as the crate motor) I'll pick up a low mileage LG8 3400, ditch the al heads (head gasket issues), rebuild and bolt on the iron 3.1 heads, intake, TBI and injectors (swapped from a 4.3), plug in the ecu and rock and roll.
Shawn
Shawn, the heads on the Rodeo 3.1 are identical to those of the Goodwrench HT 3.4 crate motor. As are the heads of a 2.8 Trooper.
The HT 3.4 does have upgraded valve springs and valve spring retainers, to go with the HT's upgraded cam.
The HT's cam/springs/retainers would be a highly-recommended upgrade for a 3.1/3.4 build (only of course if using a RWD block; FWD blocks will have probably have roller lifters/cam for which there aren't many options).
BTW if you intend on bolting RWD cast-iron heads to the FWD block, you'll also need to change the pistons. FWD pistons have a large dish (which corresponds to the much smaller squish area of the FWD aluminum heads). If you used dished pistons with cast-iron heads the compression ratio will be quite low.
You'll want to use RWD 3.1 pistons and the only applications for those are Rodeo/P'up, Camaro/Firebird, and '90's vintage GM FWD minivans which used the iron-headed TBI motor.
Sealed-Power carries some very nice pistons with teflon coating on the piston skirts. This helps with the 3.1's infamous Dreaded Piston Slap Syndrome. I used them in an '89 Trooper 2.8-to-3.1 'stroker' project and they are SWEET ! <img src="/forums/images/graemlins/smile.gif" alt="" />
You might find this Fiero message thread interesting:
http://www.fiero.nl/cgi-bin/fiero/s...mp;thread=081409&style=printableCheers..........ed
p.s. don't forget if you use one of the newer FWD 3400's you'll also have to deal with the issue of the cast-aluminum oil pan. You can't use the 4WD stamped-steel pan on these motors; the main bearings are cross-bolted thru the pan.
