RockChucker
Well-Known Member
- Location
- Highland
Close to 5 years ago, I picked up an LQ4 out of a GMC savannah with 205k on the clock. The van had been rolled, but I did hear the engine run, since I had to turn the van around in order to pull the motor. The effort was worth it and I snagged the motor and 4L80 attached to it for $550. I sold the 4L80 for $200 and voila, $350 LQ4 ready to play with.
And there it sat on a stand for years. I had always intended on building the motor. At the very least tearing it down to inspect bearings, replace the rings, etc. 205k is a lot of miles and I didn’t want to worry about the motor. Plus I felt I had a little room to put some money into the motor since I got it for about 1/4 the price of the going rate for a 6.0 at the time.
The scheming and research began. And I quickly realized how little I knew about engines and the nuances of building an engine to accomplish what I wanted it to be able to.
My list was as follows:
1. Smooth idle. Sure. The chop from a clearly cam swapped engine is cool. But not practical when you are trying to gingerly work through a technical obstacle.
2. Maintain vacuum so my brake booster still works. I didn’t want to deal with hydroboost and manual brakes suck. I like having power brakes. Call me spoiled.
3. 500ish horsepower. Because why not? After having my suspension tuned, I quickly realized I was running out of horsepower to drive as aggressively as the suspension will allow. Plus hill climbs and sand dunes.
Now how to get there...here’s the recipe I came up with.
1. A “moderate” cam. Comp Cams #54-424-11. Nice wide lobe separation angle of 115° to meet the requirements of 1&2 and put it well on the way of getting to number 3. This cam is optimum from about 1800-6700 rpm if I remember correctly. Been a minute since I chose. Ok like 4 years haha.
2. L92/LS3 heads. Casting number 823 or 5364. Scored a set on eBay for $500. I did have to replace all the intake valves. But I couldn’t complain. These are the best factory flowing heads aside from LS7 heads. I did install aftermarket beehive valve springs that are capable of the taller lift from the cam.
3. Gen IV truck intake. Because L92 heads have rectangle ports instead of cathedral ports. Along with an OEM 90mm ACDelco throttle body. Should breathe easy.
Now to the what I’ll call the consequential parts from looking inside the motor. After tearing it down, I found the cross hatching of the cylinder walls was all but gone. And there was a slight lip at the top. Bummer. Couldn’t get away with just a hone. Deeper inspection after taking the block all the way down to bear indicated that everything else was in ok shape. I told myself that if it was ok, I’d draw the line and not stroke it. That would have happened if the crank was done. But amazingly it looked good. No sludge buildup in the motor either. This motor had clearly been maintained pretty well. The cam bearings were toasted though.
I dropped the block and crank off at clegg’s in Orem. They did great head work on my duramax when I did head gaskets. I didn’t see any reason to not use them again.
The cylinder bores were no longer cylindrical. They thought they could clean it up with a .020” overbore, but I chose a .030” overbore for more common (cheaper/more plentiful) piston options. They also had to take .006” off the deck to square up the deck to the crank centerline.
I went with a flat top piston and aftermarket 4130 I beam connecting rods. I have it written down somewhere. But with the machined deck and piston heights available, the pistons come out of the hole a fair amount. The quench height is close to zero and the static compression ratio will come in a shave under 10.5:1. Pretty high. But the dynamic CR is under 9:1 with the cam I have selected.
Clegg also balanced the rotating assembly. Initial read showed the crank 1200# out of balance at 10k rpm. Not terribly surprising since the crank was balanced for the stock rods and pistons. After balancing, it is now only 11# out of balance at 10k rpm and only 3# out at 6000 rpm. Should make for a reliable motor.
I spent a small fortune on gaskets, new hydraulic lifters (a few of the original ones were cracked oddly enough) and the other parts to assemble the motor.
As of right now, it is a bare block with cam bearings installed. I applied a few coats of engine enamel last night while the block is still bare. As soon as my micrometer arrives, it’s time to get down to business and start assembling this bad boy. Should be fun. First time I’ve built a motor.
Plan is to have Matt Snell at Pauls auto and 4x4 tune it when it is all done. In addition to making the stand alone 6L90 shift like magic as well. More to come....
And there it sat on a stand for years. I had always intended on building the motor. At the very least tearing it down to inspect bearings, replace the rings, etc. 205k is a lot of miles and I didn’t want to worry about the motor. Plus I felt I had a little room to put some money into the motor since I got it for about 1/4 the price of the going rate for a 6.0 at the time.
The scheming and research began. And I quickly realized how little I knew about engines and the nuances of building an engine to accomplish what I wanted it to be able to.
My list was as follows:
1. Smooth idle. Sure. The chop from a clearly cam swapped engine is cool. But not practical when you are trying to gingerly work through a technical obstacle.
2. Maintain vacuum so my brake booster still works. I didn’t want to deal with hydroboost and manual brakes suck. I like having power brakes. Call me spoiled.
3. 500ish horsepower. Because why not? After having my suspension tuned, I quickly realized I was running out of horsepower to drive as aggressively as the suspension will allow. Plus hill climbs and sand dunes.
Now how to get there...here’s the recipe I came up with.
1. A “moderate” cam. Comp Cams #54-424-11. Nice wide lobe separation angle of 115° to meet the requirements of 1&2 and put it well on the way of getting to number 3. This cam is optimum from about 1800-6700 rpm if I remember correctly. Been a minute since I chose. Ok like 4 years haha.
2. L92/LS3 heads. Casting number 823 or 5364. Scored a set on eBay for $500. I did have to replace all the intake valves. But I couldn’t complain. These are the best factory flowing heads aside from LS7 heads. I did install aftermarket beehive valve springs that are capable of the taller lift from the cam.
3. Gen IV truck intake. Because L92 heads have rectangle ports instead of cathedral ports. Along with an OEM 90mm ACDelco throttle body. Should breathe easy.
Now to the what I’ll call the consequential parts from looking inside the motor. After tearing it down, I found the cross hatching of the cylinder walls was all but gone. And there was a slight lip at the top. Bummer. Couldn’t get away with just a hone. Deeper inspection after taking the block all the way down to bear indicated that everything else was in ok shape. I told myself that if it was ok, I’d draw the line and not stroke it. That would have happened if the crank was done. But amazingly it looked good. No sludge buildup in the motor either. This motor had clearly been maintained pretty well. The cam bearings were toasted though.
I dropped the block and crank off at clegg’s in Orem. They did great head work on my duramax when I did head gaskets. I didn’t see any reason to not use them again.
The cylinder bores were no longer cylindrical. They thought they could clean it up with a .020” overbore, but I chose a .030” overbore for more common (cheaper/more plentiful) piston options. They also had to take .006” off the deck to square up the deck to the crank centerline.
I went with a flat top piston and aftermarket 4130 I beam connecting rods. I have it written down somewhere. But with the machined deck and piston heights available, the pistons come out of the hole a fair amount. The quench height is close to zero and the static compression ratio will come in a shave under 10.5:1. Pretty high. But the dynamic CR is under 9:1 with the cam I have selected.
Clegg also balanced the rotating assembly. Initial read showed the crank 1200# out of balance at 10k rpm. Not terribly surprising since the crank was balanced for the stock rods and pistons. After balancing, it is now only 11# out of balance at 10k rpm and only 3# out at 6000 rpm. Should make for a reliable motor.
I spent a small fortune on gaskets, new hydraulic lifters (a few of the original ones were cracked oddly enough) and the other parts to assemble the motor.
As of right now, it is a bare block with cam bearings installed. I applied a few coats of engine enamel last night while the block is still bare. As soon as my micrometer arrives, it’s time to get down to business and start assembling this bad boy. Should be fun. First time I’ve built a motor.
Plan is to have Matt Snell at Pauls auto and 4x4 tune it when it is all done. In addition to making the stand alone 6L90 shift like magic as well. More to come....