L31 towing cam upgrade

[L31MaxExpress]

Yikes! When I worked at a boat shop, we always tack welded the pickup tubes for this very reason.

It was a Goodwrench 350 with like 35K on it, I might have knocked the pickup loose re-installing the pan after the cam swap or may have just fallen off after the fact. I now use big block pumps with bolt-on pickups that mount in the very center of the pan.

 

[kylenautique]

To keep the cost down on this project, I think I'm going to go with the Summit Racing camshaft. Thank you so much for the recommendation L31MaxExpress! I reached out to Summit and they said both camshafts will work great with noticeable gains over stock, but I would only notice a difference between the two on a Dyno, not in the seat.

 

[Road Trip]

Think of the harmonics from the crank that's getting those twisting
power pulses every 90°? And this is being coupled directly to the
oil pump bolted to the #5 main cap? No wonder sometimes a pickup
(that's just pressed in at the factory) sometimes ends up loose in the
pan?

As for the #1 rod bearing going first, that almost makes sense too -- it's
the last one in line to get the magic juice...

 

[L31MaxExpress]

To keep the cost down on this project, I think I'm going to go with the Summit Racing camshaft. Thank you so much for the recommendation L31MaxExpress! I reached out to Summit and they said both camshafts will work great with noticeable gains over stock, but I would only notice a difference between the two on a Dyno, not in the seat.

The 6395 would keep costs even lower, albeit less gain on top-end. The Summit cam will carry decent power to 5,500 rpm and beyond if your short block is up to it, you have a decent air intake, headers and exhaust and you fix the ignition coil minimum dwell setting in the PCM that acts like a rev-limiter around 5,800-6,000 rpm. Advancing 4° will bring the powerband down ~300 rpm.

As I mentioned earlier, I would get a new roller timing set. The Cloyes 9-1157 is 3 way adjustable. Advance the Summit cam 4° to bring its powerband down to work better with the stock intake manifold. This is especially important if you still have exhaust manifolds and stock exhaust. Advancing the cam will also help keep the idle vacuum closer to stock which should allow it to run better with less tuning headache.

Summit has an advertised powerband of 1,500-6,000 on the 8800. Advancing it 4° will lower that to about 1,200-5,700 which is perfect for the 5,800 rpm fuel kill. Stock shift points are at 5,000-5,100. If the engine is solid and not strangled by the stock exhaust manifolds, I would not hesitate spinning it 5,500-5,700 rpm although HP flat lines around 5,200 rpm with a stock intake manifold and it just carries the same HP higher with more cam. When I had the stock cam I actually shifted mine early at 4,800 rpm.

 

[L31MaxExpress]

Think of the harmonics from the crank that's getting those twisting
power pulses every 90°? And this is being coupled directly to the
oil pump bolted to the #5 main cap? No wonder sometimes a pickup
(that's just pressed in at the factory) sometimes ends up loose in the
pan?

As for the #1 rod bearing going first, that almost makes sense too -- it's
the last one in line to get the magic juice...

Yep you will almost always see #1 or #2 or BOTH spun on an engine that was run until the oiling became a big enough problem to kill it.

 

[kylenautique]

The 6395 would keep costs even lower, albeit less gain on top-end. The Summit cam will carry decent power to 5,500 rpm and beyond if your short block is up to it, you have a decent air intake, headers and exhaust and you fix the ignition coil minimum dwell setting in the PCM that acts like a rev-limiter around 5,800-6,000 rpm. Advancing 4° will bring the powerband down ~300 rpm.

As I mentioned earlier, I would get a new roller timing set. The Cloyes 9-1157 is 3 way adjustable. Advance the Summit cam 4° to bring its powerband down to work better with the stock intake manifold. This is especially important if you still have exhaust manifolds and stock exhaust. Advancing the cam will also help keep the idle vacuum closer to stock which should allow it to run better with less tuning headache.

Summit has an advertised powerband of 1,500-6,000 on the 8800. Advancing it 4° will lower that to about 1,200-5,700 which is perfect for the 5,800 rpm fuel kill. Stock shift points are at 5,000-5,100. If the engine is solid and not strangled by the stock exhaust manifolds, I would not hesitate spinning it 5,500-5,700 rpm although HP flat lines around 5,200 rpm with a stock intake manifold and it just carries the same HP higher with more cam. When I had the stock cam I actually shifted mine early at 4,800 rpm.

Cool! I emailed Justin at Black Bear (I know, your favorite person... haha!) on how we should approach this. He should be able to advance the base timing on the ECM, or we can do it mechanically. I may get the truck tuned on a dyno by a different local person, Wongs Performance Engineering here in Vancouver WA. He is really good. Either way, this should be a good replacement on my stock engine. I'm running stock exhaust manifolds and stock exhaust, but I've removed the cat, so it flows better now.

The old girl runs fine with decent power until it gets put under a heavy load, like towing my boat. It doesn't have the power it had last summer, and its eating a little more oil than it used to.

 

[L31MaxExpress]

Cool! I emailed Justin at Black Bear (I know, your favorite person... haha!) on how we should approach this. He should be able to advance the base timing on the ECM, or we can do it mechanically. I may get the truck tuned on a dyno by a different local person, Wongs Performance Engineering here in Vancouver WA. He is really good. Either way, this should be a good replacement on my stock engine. I'm running stock exhaust manifolds and stock exhaust, but I've removed the cat, so it flows better now.

The old girl runs fine with decent power until it gets put under a heavy load, like towing my boat. It doesn't have the power it had last summer, and its eating a little more oil than it used to.

My only real problem with the man is he needs to really play around with one of these hands on while datalogging everything to understand what the torque management does when he ZEROs commanded shift times. I have seen him do it multiple times on multiple trucks when people have requested stock torque management and firmer shifts. Zeroing the shift times disables the upshift torque management which then leads to 4L60Es failing. It is a flawed old way of doing things before people understood what it did and in just about every tuning writeup out there. I wish that bad information would just go away and people might actually keep their 4L60E in one piece. I have not had a single 4L60E (save for the one in the Tahoe that was already wounded from the servo cover popping off and running out of fluid) fail that I have tuned since I stopped zeroing shift times, set them to 0.300 or 0.250 msec and started actually adding more torque reduction during the shifts.

 

[kylenautique]

My only real problem with the man is he needs to really play around with one of these hands on while datalogging everything to understand what the torque management does when he ZEROs commanded shift times. I have seen him do it multiple times on multiple trucks when people have requested stock torque management and firmer shifts. Zeroing the shift times disables the upshift torque management which then leads to 4L60Es failing. It is a flawed old way of doing things before people understood what it did and in just about every tuning writeup out there. I wish that bad information would just go away and people might actually keep their 4L60E in one piece.

I should send you my tune and see what you think. I made some adjustments on my own to add in TQ management at specific places.

 

[kylenautique]

I've decided to go with the Comp Cam 08-049-8. It doesn't require head modification to make it work on a stock vortec, which will keep the cost of this project down. And, I feel better about using this over the summit cam. Nice that we have some real life butt dyno data too! Looking forward to making it more of a stump puller.

 

[kylenautique]

Well.. here we go! I got all my parts back from the machine shop. Slowly starting to assemble. The block came from a 98 Suburban 2500 with 80k miles. Didn't even have a ridge on the cylinder walls. We were able to just hone the cylinders and leave the bore stock. Polished the crank, new cam bearings, rebuilt the heads. Only issue was the replacement timing chain was super sloppy (cam install not shown in photos). I ended up buying a race version. Problem solved.

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