Fully built 3.4 vs 3.8sc

[Kohburn]

spark plugs are easier to do on this engine than the stock 2.8

[crzyone]

spark plugs are easier to do on this engine than the stock 2.8

Totally, just like I said a couple posts ago. I don't think Bookster has ever actually seen a 3.4dohc.

[bookster]

Nice photo I see you cut the timing belt.
And yes I do know and have seen tdc.
you wants some parts. I use them for paper weights.
tore down they get a nice chunk of change for the alloy.
Oh lets see what Al data says on the replacement time for head gasket.

Well it pays 11.5 hr for both why do 1 for 7.5hr
and the 3.8 pays 5.5 on both and 4.0 for one.

Oh and the spark plugs. you still have the stock plug wire holders in place they hold the boot and the wire sort of a T handle you can not!!!!!!! pull it out at all no mater what with out lowering the sub frame........!!!!!!!!!!
ok now to pull the plugs. you drop in a socket hope it don't crack the oracle then you drop in a 3 in extension and another and then if you have room a ratchet align all the tools loosen it up. and pull them out piece at a time.
oh now lets put it back in drop the plug in and hope it don't bend the electrode then the socket and the rest tighten it up. pull the tools out 1 at a time. God forbid you left the rubber plug retainer in your socket unless you have locking extensions you will leave the socket on the plug.

Have I got this right?? I am sure I do I have only done it more times than you have seen the engine.

Ok you remove the T handle from the plug boot.
hope you use very very good epoxy to keep the plug wire on the plug boot oh and installing it correctly that's fun to make sure it is on the plug and seated. Yes you can use dialectic grease makes a little easier.

As for NOS I don't mean holley brand I mean nitrous oxide in general
is a violent performance additive, and requires you check plugs often.

Now for the tool that thinks the 3.4TDC is so easy to work on. Grow up.
As for it being a good swap? Yes it is in stock form not upgraded as this thred is about.

as for the timing belt I could change 10 3.8 in the time you could do 1 3.4 TDC.

[bookster]

2.8 plugs are easy as 3.8
I could do it in no time.
on the 3.4TDC try an hour easy per head

[The Dark Side of Will]

[Cleaned up.
Mind your manners, gentlemen. As Aaron was kind enough to remind you, this is Tech, not AG. Thanks for behaving yourself, Aaron, even if it was in retrospect.

Do you guys have surveilance on me or something? I don't have to moderate anything for a few weeks and then the day I'm busy pulling and tearing down engines I come back and find a pile of dirty diapers in the recent posts.]

[The Dark Side of Will]

Continuing from tearing down engines...

I pulled apart the rebuildable TDC long block that's been on my engine stand for months. The rod bearings were in pretty much uniformly good shape, except for #6. That one had perceptible play and the junk in the bearing to prove it. The mains looked pristine except that the wear pattern in #4 was offset favoring #6 rod... the effects of the shock from excessive rod bearing clearance.

When I first got the engine, it was seized. I pulled the heads and sprayed a puddle of WD-40 into each cylinder then tucked the engine in the corner for a while. A couple of months later when I went back to pull the crank pulley bolt, the engine wasn't seized anymore and I had to put some bolts in the back of the crank to hold with a prybar.

The TDC oil pump is BIIIIG. It's easily twice the size of the stock pump from my 3.1 Gen II.

While the DOHC implementation from a pushrod architecture is cool (or at least was in the early '90's), I see how relatively primitive this engine is. It's testament to GM's philosophy in the early '90's. Comparing the two, it's hard to believe that the Northstar debuted about the same time this engine did.

[crzyone]

While the DOHC implementation from a pushrod architecture is cool (or at least was in the early '90's), I see how relatively primitive this engine is. It's testament to GM's philosophy in the early '90's. Comparing the two, it's hard to believe that the Northstar debuted about the same time this engine did.

The first time I took apart a 3.4dohc I was surprised that GM would even put that motor in production. A timing chain turning a dummy cam which turns the other 4 cams via belt. On top of that the cam carriers are also primitive. Why not make proper heads with cams attached via the N*? Bad oil drainback, a very long oiling system. Heavy engine.... the list goes on.

Its a very strong running engine, and it felt really good in the fiero but the engine its self is a strange design.

[whipped]

Has anyone seen inside the 3.5? Are they built with a split case/mains girdles like the N*?

[Aaron]

The mains looked pristine except that the wear pattern in #4 was offset favoring #6 rod... the effects of the shock from excessive rod bearing clearance.

That doesn't surprise me, #4 is the most problamatic, and the one that always spins.

The TDC oil pump is BIIIIG. It's easily twice the size of the stock pump from my 3.1 Gen II.

I didn't know there was a difference externally, though I know they flow a lot more. This, mixed with other "flaws," are responsible for the oiling issues.

While the DOHC implementation from a pushrod architecture is cool (or at least was in the early '90's), I see how relatively primitive this engine is. It's testament to GM's philosophy in the early '90's. Comparing the two, it's hard to believe that the Northstar debuted about the same time this engine did.

As bad as this design is compared to the N* and other newer DOHC motors, it works. Yes it weighs a lot, and makes it slightly harder to modify (Cams), but other than these I can really see no other significant downside. And as if it needed to be said, the flow advantage more than makes up for the problems in my opinion.

Has anyone seen inside the 3.5? Are they built with a split case/mains girdles like the N*?

Well IIRC it is basically a N* with 2 cylinders cut off (Thus the term ShortStar), sort of like the 4.3 is to the 5.7. So in theory, if I'm right, it probably has near identical design of the N*.

Thanks Will

[Kohburn]

2.8 plugs are easy as 3.8
I could do it in no time.
on the 3.4TDC try an hour easy per head

BWAAHAHAHA

dude - i can and HAVE changed the plugs in about 20 minutes on my 3.4dohc - yes i still have the stock plastic boot covers

use a telescoping magnet to carefully place the plug into the front holes and to pull it back out - I use 2 short extennsitons and a universal joint to get into the front holes.. easy as pie - no need to tear my arm up getting to the front plugs like on the 2.8

[The Dark Side of Will]

The mains looked pristine except that the wear pattern in #4 was offset favoring #6 rod... the effects of the shock from excessive rod bearing clearance.

That doesn't surprise me, #4 is the most problamatic, and the one that always spins.

Reread... The #4 MAIN...

As bad as this design is compared to the N* and other newer DOHC motors, it works. Yes it weighs a lot, and makes it slightly harder to modify (Cams), but other than these I can really see no other significant downside. And as if it needed to be said, the flow advantage more than makes up for the problems in my opinion.

As bad as the design of the small Chevy is compared to the LS1 and other newer pushrod engines, it works. Yes it weighs a lot...

The TDC is just a primitive engine. It IS possible to like something while accepting its flaws.

[Kohburn]

It IS possible to like something while accepting its flaws.

hell we are on a FIERO forum.. :thumbleft:

[Mach10]

I'd like to note that ANYTHING the shop manuals say for doing anything to a 3.4 absolutely, completely, and positively DO NOT APPLY in a Fiero.

Once the motor is in the car, EVERYTHING is accessible using nothing but jackstands once you pick up the rear.

Case in point; the alternator in a Z34 requires you to pull all sorts of shit apart to get at it... In the Fiero, it drops right out (you do have to rotate it 90º... But if you have opposing thumbs it shouldn't be a problem).

What've I done in-car on this motor?
-Intake manifold
-AC compressor
-Timing belt
-Exhaust manifolds
-cam carrier (front, FTW)
-Power Steering
-Alternator
-Waterpump.

It's no biggie. And in case of extreme emergency, as long as you are careful to undo everything, you can always drag the whole subframe out within about 2.5hrs.

The 3.4TDC has definitely got some quirks. Mad head design (for the time) but a primitive bottom end.

It's a nice motor, perhaps on the heavy side, but I find that I like it despite of it's faults. It's easy to work on, reasonably tough (as long as you aren't a retard with it), and if the specs that GM gives you are any indication, reasonably idiot-proof in terms of tear-down/rebuild. :thumbleft:

Once it's in, I feel that the motor suits--perfectly I might add--the personality of the Fiero, and literally shows what the car SHOULD have been.

Are there faster, stronger swaps? Yep.

Do I care? Nope. :thumbleft:

[The Dark Side of Will]

The 3.4TDC has definitely got some quirks. Mad head design (for the time) but a primitive bottom end.

I'm going to disagree slightly and say good *port* design. I think the whole head/cam carrier thing was a bad idea. The insert-from-the-front pushrod style cams are MUCH heavier and have MUCH higher bearing surface speeds than conventional OHC small journal saddle & cap cams. The design of the cams meant that the lifters had to be installed from the bottom... which meant that the heads and cam carriers had to be separate. Having the heads and cam carriers separate adds weight, complexity and potential leak paths, as well as making maintenance more difficult (keeping track of lifters when removing a cam carrier).

It looks to me like somebody wanted to save money or time or tooling costs or something by using that style of cam. That decision forced the design of certain aspects of the rest of the top end of the engine in an unfavorable direction. It's classic GM design by committee at its finest.

If they'd done it right from the get go, and used small journal cams in caps & saddles, then they could have done the heads right, saved weight, reduced complexity and might still be using the engine today.

But as it is, it's a fine example of compromised GM design. It obviously works reasonably well... it just could have been done a lot better. It's a good example of decent engineering turned loose on a bad idea.

[Mach10]

I don't know enough about cam geometry or head engineering to comment about the valvetrain layout, so I didn't really mean to include it into my definition of head design.

I was talking more in terms of good port design.

The motor doesn't have much trouble breathing right out of the box. To me, that shows that someone put at least a little thought into it, rather than casting a couple of holes in front of a valve.

[Fastback86]

I always found the cam carrier design amusing when talking to Steven about his engine. You have to take the carriers off the engine to get the cams out, and try not to lose all the lifters in the process. Why are the carriers 1 piece? Even Ford makes their OHC engines so that the cam is held down by a couple of caps that can be unbolted. I just don't see why they thought the massive carrier thing was a good idea.

[The Dark Side of Will]

As I said above, I bet it's because somebody thought he could save money or complexity by using pushrod style cams (large journals). This may or may not have saved anything... it may have allowed the cams to be cut on the same tooling as the pushrod cams, but it required its own blank to be cast, for instance.

Anyway, somebody got a wild hare up his ass and ended up compromising the rest of the design around his idea (IMNSHO).

[Shaun41178(2)]

Well I am bringing this back to see how goatnipples dual tb project is coming along. Its been 2 months now. So you should be done now right?

FYi, this is the same dude who had the idea of injecting nitrous into his fuel rail.

[Blue Shift]

Well I am bringing this back to see how goatnipples dual tb project is coming along. Its been 2 months now. So you should be done now right?

FYi, this is the same dude who had the idea of injecting nitrous into his fuel rail.

*Mortal Kombat Announcer Voice* HUMILIATION!!

[Aaron]

*Mortal Kombat Announcer Voice* HUMILIATION!!

Wasn't that from Quake 3?