1984 2.5 to 1986 Fiero (Page 1/2) Drake_wake APR 24, 03:03 PM I bought a 1986 2m4 it was a barn find hasn’t ran in 15+ years. She’s got rod knock. Anyone know if a duke out of an 84 can go in an 86 I assume some modifications will have to be made im pretty new to Fiero’s. cartercarbaficionado APR 24, 04:30 PM quote Originally posted by Drake_wake: I bought a 1986 2m4 it was a barn find hasn’t ran in 15+ years. She’s got rod knock. Anyone know if a duke out of an 84 can go in an 86 I assume some modifications will have to be made im pretty new to Fiero’s. Just change the sensors from the 84 to the 86 stuff, like everything good off of the 86 has to go in the 84 engine, probably swap intakes and exhaust as well, are you going to be pulling from the top or dropping the subframe? you can do either but only on the i4 will it properly fit out of the top with the deck lid removed olejoedad APR 24, 05:48 PM quote Originally posted by cartercarbaficionado: Just change the sensors from the 84 to the 86 stuff, like everything good off of the 86 has to go in the 84 engine, probably swap intakes and exhaust as well, are you going to be pulling from the top or dropping the subframe? you can do either but only on the i4 will it properly fit out of the top with the deck lid removed There is a LOT more to it than that..... Different wiring harness... Different ignition system... Different computer... But! If you just use the long block from the 84, and swap the ignition system and wiring harness, intake and FI unit, it should be pretty easy. cartercarbaficionado APR 24, 09:04 PM quote Originally posted by olejoedad: There is a LOT more to it than that..... Different wiring harness... Different ignition system... Different computer... But! If you just use the long block from the 84, and swap the ignition system and wiring harness, intake and FI unit, it should be pretty easy. hence the everything off the 86 onto the 85 engine. I'm putting a 86 long block into an 84 currently so I'm actually dealing with these issues just like the g-swap honda I finished up a few weeks ago, I mean if he really wanted to he could go get a random fwd iron duke and throw the parts on and put it in 82-T/A [At Work] APR 25, 11:33 AM quote Originally posted by Drake_wake: I bought a 1986 2m4 it was a barn find hasn’t ran in 15+ years. She’s got rod knock. Anyone know if a duke out of an 84 can go in an 86 I assume some modifications will have to be made im pretty new to Fiero’s. To be fair, there isn't a whole lot of difference between those years (unless we're being nit-picky). BUT, so long as you use *everything* from the 1986, the long block from the 1984 will work JUST fine. You should use nothing at all from the 84, other than the engine itself. Meaning, literally strip it down to just the bare block and use the brackets, sensors, everything from the 1986. The only thing that I think bums me out a little bit though, is that the 1986 has some slight advancements that the 84 engine doesn't have. The most pronounced improvement is the use of a roller cam in mid-1985+. Ideally, if you can find a 1985-1986 engine to replace the one you have, is probably your best bet. The 84 engine has a solid lifter cam, FYI. Patrick APR 25, 02:47 PM quote Originally posted by 82-T/A [At Work]: The 84 engine has a solid lifter cam, FYI. Correction... the '84 duke originally came with flat tappet hydraulic lifters. 82-T/A [At Work] APR 25, 03:05 PM quote Originally posted by Patrick: Correction... the '84 duke originally came with flat tappet hydraulic lifters. LOL, sorry... my VW Bus has solid lifters. I meant flat-tappet. What I mean is, you no longer get "roller lifters," so it can be noisier, and more prone to wear. olejoedad APR 25, 06:11 PM Hmmm, just thought of this potential wrinkle... Are the intakes interchangeable, and if they are not, do the two engines use the same TPI unit? And, if the intakes and TPI issues require putting the 86 head on the 84 block, are the heads interchangeable? At some point, one the cylinder head bolt holes were moved slightly and the intake ports were reconfigured, but I am unclear when that happened. Does anyone have info about these potential wrinkles? 82-T/A [At Work] APR 26, 08:24 AM quote Originally posted by olejoedad: Hmmm, just thought of this potential wrinkle... Are the intakes interchangeable, and if they are not, do the two engines use the same TPI unit? And, if the intakes and TPI issues require putting the 86 head on the 84 block, are the heads interchangeable? At some point, one the cylinder head bolt holes were moved slightly and the intake ports were reconfigured, but I am unclear when that happened. Does anyone have info about these potential wrinkles? The intakes and TBI units all changed in 1987. But 84-86 are all interchangeable... same head too. cartercarbaficionado APR 26, 08:32 AM quote Originally posted by olejoedad: Hmmm, just thought of this potential wrinkle... Are the intakes interchangeable, and if they are not, do the two engines use the same TPI unit? And, if the intakes and TPI issues require putting the 86 head on the 84 block, are the heads interchangeable? At some point, one the cylinder head bolt holes were moved slightly and the intake ports were reconfigured, but I am unclear when that happened. Does anyone have info about these potential wrinkles? can 2nd TA's statement of the pre 87 intakes all interchanging as I have an 84 intake with a 85 tbi and 85 Block with 86 head apparently the builder liked Legos lol as for the heads its apparently late 1986 models that come with a 87 engine that have the different head