2.5 Engine... will an 85 cyl head fit an 87 engine? (Page 1/2)
82-T/A [At Work] JUN 22, 11:33 AM
Hey guys, quick question... will the cyl head from a 1985 engine fit properly on a 1987 engine? Both motors are from a Fiero.


Thanks!
Dukesterpro JUN 22, 11:53 AM
As far as I know the later model duke heads are different and use a different intake manifold. They will bolt to the block, but you will need the whole enchilada (intake, rockers, pushrods etc)


PS. (Later model referring to the 87 and 88 DIS dukes and not the 84-86 distributor dukes)

[This message has been edited by Dukesterpro (edited 06-22-2023).]

82-T/A [At Work] JUN 22, 12:11 PM

quote
Originally posted by Dukesterpro:

As far as I know the later model duke heads are different and use a different intake manifold. They will bolt to the block, but you will need the whole enchilada (intake, rockers, pushrods etc)


PS. (Later model referring to the 87 and 88 DIS dukes and not the 84-86 distributor dukes)





Thanks Dukester, this is kind of what I'm questioning.

I'm interested in buying an 87 block, but then using the 85 cyl head, intake, and exhaust... and then making use of DIS and the accessories of the 87 (serpentine belt and new A/C compressor style), with an aftermarket ECM.
sleek fiero JUN 22, 07:37 PM
Todd you are like me .Lets see if we can do something different than everybody else even if it takes a lot more effort. love you buddy .you are creative and willing to try different solutions to a satisfying end. If i could I would help you more on your duke .Like I said the only dukes I worked on were marine. keep working on this as I know you will make this combination work. sleek
82-T/A [At Work] JUN 23, 07:34 PM

quote
Originally posted by sleek fiero:

Todd you are like me .Lets see if we can do something different than everybody else even if it takes a lot more effort. love you buddy .you are creative and willing to try different solutions to a satisfying end. If i could I would help you more on your duke .Like I said the only dukes I worked on were marine. keep working on this as I know you will make this combination work. sleek




Haha, thanks Sleek, I appreciate it. For my daughter's car, I just wonder if I can't get the benefit of the modern belt system with A/C, DIS, and then the old-school intake and exhuast... would be kind of neat. At least more reliable for her too...
Patrick JUN 23, 08:34 PM

quote
Originally posted by 82-T/A [At Work]:

For my daughter's car, I just wonder if I can't get the benefit of the modern belt system with A/C, DIS, and then the old-school intake and exhuast... would be kind of neat. At least more reliable for her too...



Is there something superior in your opinion to the '84-'86 duke's "old-school intake and exhaust"? If you wish to have the "modern belt system with A/C, DIS", why not just swap an entire '87 or '88 duke into your daughter's '85 Fiero? I'm sorry, but I'm just not understanding your modus operandi here.
David Hambleton JUN 23, 08:53 PM
I replaced my '86 2.5L with an '87 2.5L in 2013.
There are several changes from the '86 2.5L to the '87 2.5L: fuel delivery is on the opposite side of the throttle body injection system; the air intake system is a different configuration; the distributor style ignition system is replaced with a direct ignition system; vacuum & heater hose connections are altered, the '87 ECM has a different mounting bracket (wish I'd realized that & kept the '87 bracket!). Mostly, though it's a plug & play swap.
Patrick JUN 24, 12:57 AM

quote
Originally posted by David Hambleton:

I replaced my '86 2.5L with an '87 2.5L in 2013.



Full disclosure... My first Fiero was a 2.5L '87, and I hated that engine, so it's not like I'm promoting an '87 duke. But I just don't understand why anyone would go through the trouble of trying to mate the head/intake/exhaust from an '85 duke onto an '87 block when it seems a complete engine swap is relatively simple/straightforward.
82-T/A [At Work] JUN 26, 10:12 AM

quote
Originally posted by Patrick:

Full disclosure... My first Fiero was a 2.5L '87, and I hated that engine, so it's not like I'm promoting an '87 duke. But I just don't understand why anyone would go through the trouble of trying to mate the head/intake/exhaust from an '85 duke onto an '87 block when it seems a complete engine swap is relatively simple/straightforward.




Long and short... (edit: lol, this is an unintended pun!) ... there is a brand new 1987 Fiero 2.5 short block. Totally brand new NOS GM... it's $1,895 w/ $450 shipping. There's also a complete 1988 Fiero engine for sale with EVERYTHING on it... for $800. All minus tax of course.

I could get both for $3,500. Then, I could buy the MicroSquirt for $350


What my daughter would be left with is a relatively stock looking Tech-4 that had DIS (with crank and cam sensor), the factory intake and TBI for that year, modern computer control, and the serpentine belt system with the new HVAC compressor (which is more reliable, less heavy, and more compact).

All of that would equal a more efficient running engine, a more reliable engine (conceivably), and something my daughter would have a bit more fun with.


I just have to grapple with whether or not it's worth ~$4,000 bucks to have a basically "new" engine and improved belt system with DIS and computer.

versus...

Rebuilding exactly what I have (which already has the roller cam), and whatever that would cost.


I say it's not about the money... but after a certain point, I do have to be a bit more reasonable on how much I want to spend on my daughter's first car... especially when I have all the rest of the car to go through with her, and... she would miss-out on a lot of the bottom-end work.

[This message has been edited by 82-T/A [At Work] (edited 06-26-2023).]

Patrick JUN 26, 01:32 PM

quote
Originally posted by 82-T/A [At Work]:

I just have to grapple with whether or not it's worth ~$4,000 bucks to have a basically "new" engine...



Yeah, $4000 for a new duke. Wouldn't be what I'd spend that kind of money on.