series8217

The timing chain and belt design is indeed ------- ridiculous, but it works. I wouldn't call the block a piece of ----, considering that they haven't been broken even with reasonable amounts of power put through them. There are a few 400+ whp DOHCs running around, one I know has 60,000+ miles on it boosted, with no problems, another something like 20,000 (weekend car, didn't get driven much, the drivetrain is now getting put in another customer's car). There are 3 other massively boosted DOHC 3.4 Fieros in the works right now that will start testing the strength of the block beyond the current 413 whp (highest documented).

Umm... like a BMW... like a Cadillac Northstar.. like a VW.. like a Volvo... like a Ferrari.. it's actually pretty common on performance OHC engines. Have you really never been inside another OHC engine or what?
Anyway, when I said you were wrong about them being "firefly lifters" I was referring to the fact that it doesn't have the same lifters as the Firefly. The parts are different. Sorry, I didn't realize you actually didn't know much about OHC engines. Spekter was right.

Actually, they are apparently a giant piece of ---- in the cars they came in, perhaps also because of the poor quality control by GM in the motor assembly process. I have heard plenty of horror stories. I've also seen a lot in junkyards... with overheated engines. None with parts failures; it was mostly poor maintenance.
However, my motor along with the other DOHCs that I know of in Fieros (I can think of ten off the top of my head) that were rebuilt properly or just thoroughly inspected before they were installed have put on many miles with no problems at all, some of them even running more than 400whp turbocharged. I think GM's build quality is partly to blame, and the fact that 95% of them came with awful automatic transmissions. Even the crate motors I know of in Fieros are running strong and reliably. Maybe better taken care of? It's a million times easier to do proper maintenance while its in a Fiero, since you can get to everything. It could also be that the ones that are still around today just don't have the unspecific problems you haven't mentioned yet.

Anyway, the main reason I picked this motor is because its the only motor I could put in a Fiero with a manual transmission that makes more than 200 hp. I live in California, land of the smog *****. The rules are VERY strict here on drivetrain swaps. My choices were a 180hp Quad-4 that cracks heads, or this DOHC with its infamous reputation of unspecific reliability problems. I'm totally happy with my reliable 220 whp and a flat torque curve from 2200 to 5500 RPM, and it doesn't get impounded if I get pulled over and the cops take a look. 20,000 miles on my swap with no probs.

And what unspecified reason is that, besides the cars being shitboxes regardless of the drivetrain that was in them? You know even those same cars with the other engine options are piling up in junkyards faster than people can pull parts off 'em.


Hey, if you guys don't want to hear about my projects, that's fine. I only started posting here because I thought my knowledge would be helpful and appreciated.

Tom-Guy

Hey, it's a nightmare engine with a lot of problems. You mention DOHC 3.4 in this forum and there are a handful of guys who've run up against them that shudder in horror. If you think we're ganging up on you and don't want to hear about your car projects, all I can say is search my post history for what I think of the engine - I give very specific lists of what goes wrong, all that overheating ---- is from how the engines jump time, you know - and it's pretty obvious I *haven't* reamed you for owning one out of some respect for what you do, and what you know.

series8217

Thanks Joseph.
My qualms mostly lie with highroller's "hahahaha you dumb ------- ****" comment. Totally uncalled for.


BTW I can definitely see this motor being able to jump cam timing, due to the small cam sprockets, but I've never had it happen.. I shift at 7150 rpm anytime I've got the pedal down. I've done this for 20,000 miles. I downshift with glee. I hold the revs up high in the turns. I drive the **** out of the damn thing. That sound like a nightmare engine? I don't think so.
It also hasn't happened to any of the 10 Fiero swaps I know of with hundreds of thousands of miles of combined driving... so the problems still sound like poor maintenance from shitbox W-body owners to me. I've never heard of cam timing causing overheating either. Not like spark timing does, at least. The Fiero guys, including myself, have experimented with all sorts of different cam timing on this motor and never had overheating problems. Sure sounds wicked at idle with a lot of overlap though. One of the Fiero guys had a special tool made so we can degree the cams easily. The sprockets are infinitely adjustable.
I think what the Fiero guys (myself included ) are doing with the damn thing is pretty impressive. It really just doesn't work out stuffed in a small engine bay of a 3500 lb car with a slushbox. I guess we take care of our motors better too.

darkhorizon

Are you kids done?

The 3400dohc is a nice motor, its dirt cheap in junkyards, and you have UNLIMITED options as to what ECU you can run on it, and it comes with the manual trans option. It is a very obvious swap into a fiero, because even stock you can run 13's with them.

Just because something has "rumored" unreliability, does not mean its true for all motors in all situations... If fieros burned down as much as people think they do, then I most likely would have the last one left by now.

Tom-Guy

Welcome to HMT, we roll like that.



Welcome to HMT, we may not be. :P

idiot-stick

Sweet ride and fabbing. Just looking at it makes me claustrophobic. I'm pleased any time I see something other than a Honda on HMT....you dumb ------- ****.

con

relax princess I'm just ------- with you, its true I dont like the dohc fail motor but I do like the fact that you built and swaped something. Look at my truck its a fail 6.0 ford that most people hate and I haven't had a problem either.

I've been in almost every motor ever made

Your still a dumb ****,





































welcome to the club, OK.

stenseltizm

My first car was a fiero. I literally caught it on fire 3 times and the ****** was never even registered I just blasted around backroads etc.









just don't ask how many of those times was the fault of a 14yo self learning mechanic :P

darkhorizon

Its people like you that keep this stupid fire rumor going....

Fieros are VERY roomy inside, they are really great for odd shaped people compared to EVERY other 2seater out there, I have been in most, and the fiero is night and day. One of my clients was a bigger guy, 400lb+, and he loved the fiero because he fit so well in it.

I anorexic looking, but 6'4" and I fit great, I even move the seat up 3 clicks or so.