3900 headgasket on 3400 head and other lz9 info

[The Dark Side of Will]

Well?

Hole in the ground... deep subject.

I have the brackets and even an extra cradle and transmission... but not an engine.

[Shaun41178(2)]

I didnt take any picyures but the oil pans between the lx9 3500 and the newer gen 4 LZ motors are different. They have different bolt patterns.

Also the timing cover bolts are different. On the lz engines all the timing cover bolts are the same thread and pitch. The lx9 and earlier engines have different sized bolts in several locations.

You can probably use a lx9 timing cover on an lz but you would have tonuse the lz bolts

[ericjon262]

I didnt take any picyures but the oil pans between the lx9 3500 and the newer gen 4 LZ motors are different. They have different bolt patterns.

Also the timing cover bolts are different. On the lz engines all the timing cover bolts are the same thread and pitch. The lx9 and earlier engines have different sized bolts in several locations.

You can probably use a lx9 timing cover on an lz but you would have tonuse the lz bolts

early timing cover will almost definitely interfere with the water manifold, the waterpump volute is almost right against the head.

[RacerX]

Well?

Hole in the ground... deep subject.

I have the brackets and even an extra cradle and transmission... but not an engine.

I know this discussion is a year old but did you determine which bracket would be the best starting point for the 3900 Fiero install? I have a fiero that has been sitting without a motor for 10+ years and decided the 3900 NA is the way I want to go.

[Shaun41178(2)]

I know this discussion is a year old but did you determine which bracket would be the best starting point for the 3900 Fiero install? I have a fiero that has been sitting without a motor for 10+ years and decided the 3900 NA is the way I want to go.

If you have an 88 the stock front bracket can be modified to work. Quick breakdown.

3900 block is missing a boss on the left side of the timing cover when looking at the front of the engine. This boss on the 2.8 blocks is there. The front engine mount bracket uses two bosses on the block to bolt the front engine mount bracket and the alternator bracket to the block. This top boss is missing on the 3900.

So you would only have one boss location if using the 85-87 front engine bracket. Not sufficient.

However the 88 bracket uses the same as the 85-87 but also has a third on the right side of the timing cover. The 3900 block shares this same boss as the old 2.8 blocks.

With a bit of grinding you can use the 88 bracket.

Now if you have an 85-87 cradle or year car, then you have two options. Get the factory style front bracket that is oem for the 3900 and modify it to fit the front rubber mount bolts. Or two, get an 88 bracket and modify it.

I suggest if you have an 85-87 you get the oem front bracket for the 3900 and modify it to fit the bolt hole locations of the 85-87 rubber front mount.

I did a video of this and put it on YouTube. Not sure how useful it might be.

https://youtu.be/aYgi9fFln-s

[The Dark Side of Will]

I know this discussion is a year old but did you determine which bracket would be the best starting point for the 3900 Fiero install? I have a fiero that has been sitting without a motor for 10+ years and decided the 3900 NA is the way I want to go.

You inspired me, Shaun.

Based on your pics of your oil pan in your turbo system thread, I looked up the PN for the engine mount bracket that goes with the LZ4/LZ9 (and LX9?) oil pan.
Here it is:





It *LOOKS LIKE* it might just drop onto the stock Fiero mount with little to no modification. I don't know if it would place the engine higher or lower than what you have now, though. I guess I'll have to quick jaw jacking and find out.

I did a little more follow up on the mount bracket.

The Buick Rendezvous was available with both the High Value and High Feature V6's in the same year. Both engines used the same rubber mount. The 10216970 bracket shown before is for the pushrod, but there are two different versions of the bracket for the 3.6: 10334474 & 10331334. I have one of each on the way for investigation. Depending on how difficult these are to adapt to the Fiero cradle, this could be a nearly bolt-in mount bracket for a high feature V6.

10216970 2005-2007 3.4/3.5
10334474 2005-2006 AWD 3.6
10331334 2004 AWD 3.6

I forgot to look over this weekend, but I have one of the alternate brackets. The one pictured is probably the best bet.

[Shaun41178(2)]

There was a thread on 60 degree a while back talking about using an lnj camshaft in an lz4 or lz9 as a drop in replacement.

I figured I would buy the cam. I bought from GM parts direct. About 200 bucks. #12596567 I have an extra 3.9 lz9 engine on an engine stand. I can confirm the lnj cam from an 08 equinox fits without using cam bearing spacers. The lnj cam has the larger cam journal diameter.

Lnj cam I measured at .269 lobe lift on int and exh. I have not done duration events yet.

The cam is in the block right now. I bought melling timing set 3-700sc and I believe this will work as its the timing chian set used on the lnj. GM doesnt appear to sell this anymore but I could be wrong.

Also I couldnt find the 3 bolts for the cam gear so I took some measurements and ordered some arp bolts. I'll see if this all works this weekend. The lx9 uses a single center bolt but lz and lnj use a 3 bolt cam.

Total cost about 300 bucks

received_153305930011706.jpeg (102.85 KiB) Viewed 7736 times

[ericjon262]

Interesting... but just to be clear the LX9 cam is still a small journal cam, and will require you to use bearing spacers.

[Shaun41178(2)]

Correct

[The Dark Side of Will]

What's the LZ9 lobe lift?

[Shaun41178(2)]

What's the LZ9 lobe lift?

GM says its .271. I think I measured .270 a long time ago. I posted it somewhere. Its the same lift as all the stock 3x00 cams.

I did measure two different durations on 3900 engines. I measured an lz9 and an lgd and the lifts were same but durations were different

[Shaun41178(2)]

20210408_194115~2-1.jpg (652 KiB) Viewed 7702 times

20210408_194041-1.jpg (582.89 KiB) Viewed 7702 times

20210408_194108-1.jpg (577.16 KiB) Viewed 7702 times

[The Dark Side of Will]

Awesome sauce. Is the waterpump incorporated into the front cover as it is with the earlier generations?

//

Eric mentioned that the Lucerne 3.9's have the alternator mounted on the front and lower than the rear mount on the normal engines. Since the rear/high mount interferes with the decklid the Lucerne accessory drive might be the ticket for popping the engine in without any interference problems.

The Lucerne also uses the same crossover type single-outlet exhaust manifold setup that the minivans use, which should make it relatively easy to pack into a Fiero.

[Shaun41178(2)]

Water pump is incorporated but the LZ timing cover is longer because of the vvt mechanism. The point of using this cam is to use an lx9 cover or earlier 3x00 covers or the fiero cover and ditch the lz timing cover

[The Dark Side of Will]

Does the original 3900 accessory drive not fit in the Fiero engine bay?

[Shaun41178(2)]

It fits just fine

[ericjon262]

accessory drive fits fine, here's a friend's 88 with an LZ9 (LZ4 intake). he's running an E67 PCM, and the stock getrag 5 speed.



here's how he routed his accessories.



and here's a shot of a Lucerne alternator setup in a Fiero. I don't know who's car it is, or have any other info at all. it looks like it would require hinge box mods, but I haven't seen it in person, or any other pictures.

[Shaun41178(2)]

Thats a clean install in that 88.

[The Dark Side of Will]

It fits just fine

accessory drive fits fine, here's a friend's 88 with an LZ9 (LZ4 intake). he's running an E67 PCM, and the stock getrag 5 speed.

I was really just going to raz Shaun about doing a VVT delete.

Thats a clean install in that 88.

Dam Str8. Attention to detail pays off.

[The Dark Side of Will]

and here's a shot of a Lucerne alternator setup in a Fiero. I don't know who's car it is, or have any other info at all. it looks like it would require hinge box mods, but I haven't seen it in person, or any other pictures.

I'm not so sure it would interfere... I think there's a fair amount of space between the battery and belt and the hinge box may just drop right into it.