Thread: Rebuilding a 3800

As seen in my XPZ vs XP/Nitrous thread (btw, I'm going with the XP/Nitrous option), I mentioned that I was rebuilding a junkyard motor. I pulled a L36 motor out of a 1997 GT for $150. I've already torn it down and had it inspected by my machinist. I was concerned about the rings and bearings. The rings were toast, but the cylinder walls and bearings are fine.

My original plan was to replace the bearings/rings and just reuse the L36 rods and pistons, but apparently they're not great for higher horsepower builds. I was also going to use ARP Rod Bolts, Main Studs, and Head Studs.

I knew about the align boring for the main studs, and the head studs apparently aren't a big deal to install. The problems arose when I was informed the the rod bolts will give me a huge problem. Even though there are two sets out there...one for the Series II and one for the Series III motors, the rods still need to be machined to make the bolts work. I'm still not clear on what needs to be done for those to work.

I want to build this block properly the first time, so I don't have to worry about it again for a few years. I want my DD to be as reliable as it currently is...I know that's almost impossible, but as close to stock reliability is good enough.

Here is the list of parts that I have so far:

- 3800 Block
- 3800 Crank
- 3800 Mains w/ stock bolts
- L36 Rods & Pistons w/ stock bolts
- ARP L36/L67 Rod Bolts
- L32 Rods w/ stock bolts
- Assembled Ported Heads w/ 105# springs
- XP Cam
- LS7 Lifters
- Stock Pushrods
- Stock Rockers (I may get roller rockers, just not sure yet)

and what I need to order:

- Main Bearings
- Rod Bearings
- Cam Bearings
- Piston Rings
- Head Gaskets
- ARP Head Studs
- ARP Main Studs
- Valve Seals
- Double Roller Timing Chain
- 130# Springs

Here is the list I have for the machinist:

- Resize rods for new bolts and bearings
- Increase ring gap...was suggested to increase by about twice OE specs
- Align bore for the main studs
- Machine crank timing gear from double chain to match the stock gear
- Machine .020" off of the pump side of the oil pump cover
- Plug balance shaft oiling hole
- Assemble long block

Questions I have...

- Should I just go ahead and buy some L67 pistons (there is a set on my local Craigslist) and use the L32 rods instead of the L36 Rods/Pistons. I wanted the bump in compression, but if it's going to cause me too much trouble and possibly a damaged motor, I might as well go with what works.
- Are stock rod bolts reusable? They don't look like they're TTY. I'm not quite sure I want to use the ARP Rod Bolts just because of all of the problems associated with them.

What do you guys think? Is there anything I missed?

Sorry for asking so many questions in my last thread and this one...I just want to get this right the first time, and you guys are really knowledgeable and know what to do and what not to do with these motors...I apparently failed on just using a stock short block

Once everything is figured out, I'll do a write-up

It appears you have a great handle on what needs to be done and how you should do it.

I'd say you likely know the answers about the pistons and rods. On the bolts, they are TTY and according to the FSM should not be reused.

One thing I'm not sure of the answer on: resizing cracked rods.

Some have said its not possible.

Others have said its possible, yet difficult.

Might want to talk to your machinist regarding that if you're considering L32 rods and ARP bolts.

I didn't think you could mis-match the high compression pistons with low compression rods...don't mind me if you can...I thought the wrist pins were different...oh well.

Regardless, like Bill said...seems like you've got everything laid out, ready to go...now get at it.

id have the machinist open the oil galley holes to 3/8 or 5/16 at least. thats your restrictions. and the filter neck hole needs to be opened up more too.





very restrictive

before drilling the galley holes larger?

Originally Posted by deangtp

Eagle makes a rod for these cars, wonder if they're any good

Woohoo for cheap rods...I bet they're weaker than stockers.

Originally Posted by Moar Cats In Muh Trailer

id have the machinist open the oil galley holes to 3/8 or 5/16 at least. thats your restrictions. and the filter neck hole needs to be opened up more too.

very restrictive

Which holes in the filler neck? I can't tell from the pic.

I spoke with my machinist yesterday afternoon. He says it's not usually normal to resize cracked rods, but he is going to install them, torque them down, then measure to make sure everything checks out.

You gonna keep the balance shaft?

If not, you'll need the oil port that runs to drilled and tapped...and plugged as well.

Originally Posted by ls1camino

Woohoo for cheap rods...I bet they're weaker than stockers.



Which holes in the filler neck? I can't tell from the pic.

lemme put the picture in paint then ill circle the hole

now lemme get a pic of the l32 oil passage, youll see how much it can be hogged out