Chiphead

iTrader: (2)

You guys might remember that I built a Gen III 5.3L with a small cam motion cam and high compression for my '04 ECSB 2wd. I've had it in the truck for about a month now and I figured I'd give an update.

5.3L with flattops, 241 heads milled .020", .040" cometic, 10.2:1 compression. LS7 lifters, CM 205/210 .510 lift 115+4. 7.35" pushrods. PAC 1211X springs. trunnion upgrade. Melling high pressure pump. All new sensors. heat sink style coils.

Stock everything else. 3.42 gears.

Initial drivability was great. Engine was much more responsive to small throttle inputs. Pulled pretty hard at 1/2 throttle. Slight bog right off idle was gone.

However, after a few days, it became obvious that the stock computer can't really handle the cam and compression changes. The shift points are off, and the engine surges during accel. Sometimes the truck refuses to move out of its own way when rolling into the throttle from a dead stop. It stays in 2nd gear and will barely move. Engine is more octane sensitive. 89 and 93 octane performance is about the same. 87 octane results in pinging and refusal to shift and run with any power.

I used 7.35" pushrods based on measuring with length checker. The engine has some sewing machine noise but not terrible. I will triple check pushrod length when I have time. Oil pressure with 5W30 oil is 40 hot idle and 60 at cruise.

I have ordered a BB mail order PCM and I'll post back when I get that installed and the CASE relearn done.

Atomic

iTrader: (42)

You absolutely must retune the computer when making any internal changes to the engine. I would say you needed a tune from day 1. I would not suggest ever using 87. By wanting higher compression, you signed up for always getting 91 or better.

Vortec350ss

iTrader: (20)

What he said.

I'm really surprised you tried to make it work without a tune for so long...

1FastBrick

iTrader: (17)

What size is your tire? Those 3.42's are hurting as well.

53bowtie

iTrader: (6)

Well at least you know the knock sensor work.......

Chiphead

iTrader: (2)

Yes, I totally agree that the engine needs a custom tune. I did not order the PCM beforehand because I wanted to be sure of the end combination first. I had exchanged emails with Justin at BB and he said it would run on the stock PCM, just not optimally. I expected (and he predicted) that the engine would want at least 89 even with the stock timing table and fuel maps.

I had put 93 in the truck just before the engine swap, but when I burned through that I stopped and got gas. I've been putting 87 in the truck for 11 years, so I brain farted and used 87 out of habit. I immediately knew I screwed up, but hey what can one do? I ran it easy for a few days and put a half tank of 93 in it to get the octane back up to 89. The bucking and farting immediately stopped.

The goal for the truck is to make more power for towing and DD while not hurting gas mileage or reliability. So that means I can't put a big stall and 3.73 gears in it. It's a challenge to make the truck faster without having to spin it to the moon.

1FastBrick

iTrader: (17)

3.73 won't affect gas milage and will make it a better tow rig. You don't really need a stall.

I have 3.42's in my old DD and I absolutely hate driving it now. I'm so accustomed to the 3.73 in my new DD and especially with towing I would never, ever go back. They make a huge difference especially for towing.

I am in the 31-32 in tire range on both trucks. Both 2wd, both ex cab with 5.3L, both basically bone stock. Old one is 3:42 the new is 3.73 and both are factory gears.

Chiphead

iTrader: (2)

Just got the BB PCM installed last night. Had to do the security relearn, that's 45 minutes of my life I'll never get back. However, once that was done it started right up. No CASE relearn light yet.

Idle speed is about 100 RPM higher than the old PCM. Idle quality is noticably better. The stock PCM always had a slight tremble when engine was idling, this is dead smooth. It's nice, smooth and heavy sounding.

Light throttle driving is smoother than it ever was. No surging during accel. Rolling into the throttle results in smooth accel and quick upshifts. Truck is more responsive everywhere. I keep holding my breath expecting it to do something stupid or go into KR but nothing yet. I ran it up to 4500RPM and it was really pulling hard in second and wanting to freaking go. I got off the pedal and let it upshift. I have not really run the truck hard, the engine only has 900 miles on it and I still need to swap in the shorter pushrods.

Its really hot here in South Carolina this time of year, afternoon temps are expected to be 101F. I'll see how it runs in the heat with 89 octane gas, that's the real acid test of the combination.

Chiphead

iTrader: (2)

Got the pushrods installed last night. Now have .075" preload on the lifters. The tapping has been reduced to an even sewing machine noise. I can't hear it unless I turn the radio off and listen hard for it. Motor still runs strong and holding 40 PSI at idle. No signs of KR in the heat yesterday afternoon.

What is typical redline on stock-rod/stock piston engine with ARP rod bolts?

Atomic

iTrader: (42)

I wouldnt push it past 6500 or so