LZ4/Fiero Swap

[Guest]

Ti[: Wire it for the MS3, then make an adapter that combines the two plugs into the single no X MS3. I have done this with my Datsun, and plan to swap to my MS3X at some point soon.

[neophile_17]

That's a good plan. I had planned to make the injectors easy to split for sequential but hadn't thought to go so far as to make an adapter harness.

Anyone run a cam sensor with cam spacers on an LZ*? I was looking at the old VVT cam and a stock LA1 cam side by side on the bench and I'm a little concerned that sensor was offset inboard and the sensor won't see the tooth. Not sure it's a problem but it's a concern.

[neophile_17]

I did some testing on the crank and cam sensors last night to verify that I was on the right path with the input setup. They appear to be identical internally with only the physical housing being different to mount at the correct angle and bolt clocking.

Looking at the MS3Base documentation (clip below) for an LS motor the wire color lined up better with the LS1 than the LS2 even though the LZ4 has a 58X wheel like the LS2. I applied power to the sensor and looked at the voltage on the signal wire. What I got was 0V with the tip in open air, and 1.75V when next to an iron flag. This was the same with both sensors and input voltages at 4V, 5v, and 12V. I'm wondering if I should follow the current recommendations and attach the crank sensor to the VR circuit instead of the Opto In, or go to a smaller cap than originally speced.

[neophile_17]

I decided to go with the VR circuit for the crank sensor and the opto circuit for cam which seems to be the current recommendation for an LS1. I built the MS3 over the last week and did a little bench testing today. I can see the inputs in the log for both sensors which is promising. Now I need to get the motor cleaned up and back together.

[neophile_17]

So I've been thinking about a couple problems and can't seem to make up my mind.

Valve spring seats - Why did GM turn them into cups for the LZ4 and presumably LZ9? These are shown in the picture below. Is there any clocking required? I'll probably end up going to LS seats but I'm curious what made GM spend the extra $ on these.

Cam bearing holes - I opened up the cam bearing holes to match the spacers or 3/16". This started because I installed SBC bearings and I had to open up the second hole in the first bearing. But then I figured I should make all the holes line up. Now I'm concerned that I might have upset the oil flow balance and I'm considering a new set of bearings. Anyone care to chime in?

Thanks!

[neophile_17]

Just an FYI. This motor is getting pushed back into the corner so I can build a high compression 3400 for the race car. See you next year ;P

[1QUICKHATCH]

So I've been thinking about a couple problems and ca7n't seem to make up my mind.

Valve spring seats - Why did GM turn them into cups for the LZ4 and presumably LZ9? These are shown in the picture below. Is there any clocking required? I'll probably end up going to LS seats but I'm curious what made GM spend the extra $ on these.

Cam bearing holes - I opened up the cam bearing holes to match the spacers or 3/16". This started because I installed SBC bearings and I had to open up the second hole in the first bearing. But then I figured I should make all the holes line up. Now I'm concerned that I might have upset the oil flow balance and I'm considering a new set of bearings. Anyone care to chime in?

Thanks!

my 2009 lz9 has the buckets on the springs too. Not sure why they did this...

[neophile_17]

my 2009 lz9 has the buckets on the springs too. Not sure why they did this...

I actually think I've figured out the answer while I was researching springs. The buckets are actually dampers that reduce harmonics that increase spring fatigue. This is accomplished by the inner spring in a multi spring setup but it has the downside of adding heat and friction to the most highly stressed part of the spring- the inside. Because the cup dampens on the outside harmonics are reduced without adding additional stress to the inside of the spring. Pretty clever actually.

[ericjon262]

the buckets also probably allow oil to pool around the spring, which should help keep it cool. you driving this thing yet?

[neophile_17]

the buckets also probably allow oil to pool around the spring, which should help keep it cool. you driving this thing yet?

Unfortunately not. The racecar needs a motor first so this is going back in the corner. On the bright side I'll have to finally pull the bruised LX9 out so that I can use the crank and street tune the race motor. It's going to be a busy winter. But I have all the parts so I can build that next year while my wallet recovers from getting married.

[Guest]

I bought the wide bearings too. I ditched them as my machinist said once installed in the block the front bearing hung outside the block. He wasnt comfortable with it. I took his advice.

Once installed in the spacers and pressed into the block you will see what I mean.

Use the wide ones on other engines but not on lz engines with the spacers

[neophile_17]

Thanks! I'll have to pull the SBC bearings out- will be tricky but I think I have a way.

I just came across an interesting tidbit while doing research for my other build. The later LNJ 3400s have no VVT but do have the large cam journals. That would mean you could swap a LNJ cam into a LZ* motor and get 0.462 lift (assuming 0.272 of cam lift and LZ* 1.7 ratio rockers) without VVT or cam spacers. I wish I'd known that tidbit earlier!

[Guest]

If the spacers and bearing are already installed I wouldnt worry about pulling them back out except for maybe the number one bearing at the timing cover.

I would leave the rest to save the hassle. It was the first bearing my machinist took issue with poking out into the timing cover area.

Pretty sure the later 3400 does not share cam bore with the lz engines. Never ever heard of that before. Not one block I have seen is like that.

Please take pics and remeasure

The lx9 has the same bore size for the cam as the 3400. If GM had a larger bore for 3400 they would have transfered that to the lx9 too. No spec GM lists has it that way.

[neophile_17]

Thanks for the info!

Warning! This is all preliminary information based on an offhand comment I saw in a Enginebuilder article and some of my own digging.

The LNJ was the 3400 produced in China and it lasted until 2011 in some cars/SUVs. When GM switched to a 4X cam sensor they apparently upped the bore size of the cam journals. The LNJ didn't receive VVT but it did get the 4X sensor later on. The cam bearing part number is the same as the LZ4 but parts interchange is often wrong (I searched 2008 Equinox). I'd love to put my hands on one of these but it's not my top priority at the very moment. I'll update if I can track one down.

[1QUICKHATCH]

Thanks for the info!

Warning! This is all preliminary information based on an offhand comment I saw in a Enginebuilder article and some of my own digging.

The LNJ was the 3400 produced in China and it lasted until 2011 in some cars/SUVs. When GM switched to a 4X cam sensor they apparently upped the bore size of the cam journals. The LNJ didn't receive VVT but it did get the 4X sensor later on. The cam bearing part number is the same as the LZ4 but parts interchange is often wrong (I searched 2008 Equinox). I'd love to put my hands on one of these but it's not my top priority at the very moment. I'll update if I can track one down.

I believe that those 3400's also got the lx9 style PM rods... maybe they got a forged crank too! Lol