4L60 Re-Rebuild for my C20

[LTZ C20]

JMHO but your cam appears to be a little radical for a towing low torque producing engine. The LSA of 110 degrees is passing a lot of fuel mixture in and out until rpm rise makes everything catch up. The lumpity lump sounds great but kills low end

I understand what your saying. It's not that lope sounding anyway, it's actually a pretty smooth idle just with a nice muscle sound. The truck also has aluminum heads and a block bored 40 over. It makes good power at low end. I've had relatively easy time in past being able to pass some slow poke while towing a load trailer. I just think it could be better with a better converter. Almost everything I have put into the engine has been recommended by Summit's Tech Support with full knowledge of my current specs and intentions. The 110 lobe separation is because it's fuel injected. I love the current engine, it does everything I need it too.

[LTZ C20]

I still haven't made a decision on this yet. Opinions?

[bd]

Candidly, your indecision stems from no personal (seat of the pants) experience with the real world effects of altering converter stall RPM.  Realistically, your truck is dual purposed: 1) impressive, quick launches versus 2) towing/hauling, fuel economy, and drivetrain life.  The two purposes conflict.  To complicate matters, add the facts that since you're not tuning to win races based on quantitative data, nor are you using the truck to generate revenue, your focus for selecting a converter is somewhat arbitrary and stall RPM becomes personal preference - in other words the "feel" of one stall compared to the other.  Lower RPM stalls engage quicker (over a narrower RPM range) that higher RPM stalls.  They 'feel' different.  You haven't enjoyed the opportunity to experience that difference.

I run a 355 with 10:1 compression, 202°/212° @ 0.050", 0.560"/0.560" valve lift, 113° LSA, 109° ICL retro-roller, AFR 1041 heads, Edelbrock retro 600 CFM MPFI, and Crane HI-6 ignition, twisting a 3.42 axle ratio and 31" tall tires through a beefy 4L60.  The primary difference in our trucks outside of curb weight is engine RPM vs MPH road speed.  I ran a higher stall Hughes converter for a couple of years with no problems... then switched back to an OE stall, because I prefer the 'feel' of a more positive engagement. 

[LTZ C20]

I agree. I don't have much in the way of non stock converters. So basically, which one would be best? Stock or aftermarket. Everything you listed for #2 of the dual purpose is what I care about. I'm not in high school anymore, quick launches only get you exhibition of speed tickets lol.

[Irish_Alley]

if it was mine i would go for the low stall or stock and from what ive read the reason theres a gap on the ranges like 1400-1600 is because the stall depends on the engine tq. so a 6 banger with that stall might stall at 1400 while a 454 might stall at 1600.

[bd]

I agree Irish.  Under the circumstances I would lean toward the heavy duty PDQ converter recommended by LTZ's transmission tech.  A 1200 - 1600 stall range should effectively work out to slightly proud of 1400 based on the torque his engine is producing.  I think the quicker engagement of a 1400+ converter would be ideal for his circumstances.

LTZ - I'm sorry to say you will always second guess and wonder, "But, what if I had used the other converter?"  The only way to actually "know" is to try the other converter.  Only then will you have sufficient experience to confidently apply your own judgement without second guessing.  It's agonizing!

Nonetheless, it seems the general consensus on this forum is to use the lower stall converter, in spite of Hughes' recommendation.

[LTZ C20]

I agree Irish.  Under the circumstances I would lean toward the heavy duty PDQ converter recommended by LTZ's transmission tech.  A 1200 - 1600 stall range should effectively work out to slightly proud of 1400 based on the torque his engine is producing.  I think the quicker engagement of a 1400+ converter would be ideal for his circumstances.

LTZ - I'm sorry to say you will always second guess and wonder, "But, what if I had used the other converter?"  The only way to actually "know" is to try the other converter.  Only then will you have sufficient experience to confidently apply your own judgement without second guessing.  It's agonizing!

Nonetheless, it seems the general consensus on this forum is to use the lower stall converter, in spite of Hughes' recommendation.

WONDERFUL! Thank you all. I'll get the PDQ converter. I'm more than happy to wonder about "what if" I used the Hughes converter but I'm not going to spend $100 on a PDQ and then $425 on a Hughes and R&R the trans a few times just to play with converters to "feel" somethings slightly different. For $525 that slightly different feel ain't worth the trouble! I'll experience it when required on a different machine.

Thank you all again. On the plus, the PDQ is cheap so I might be able to swing it with the other stuff on the next paycheck and I won't have to wait another 2 weeks to drive my truck again.

Thanks to all again!

[bd]

I figured you would see the light, as well as the silliness in second guessing.  You just needed a little encouragement.      I think you'll be very satisfied with the outcome... especially at 1/5 the cost!   

[LTZ C20]

I figured you would see the light, as well as the silliness in second guessing.  You just needed a little encouragement.      I think you'll be very satisfied with the outcome... especially at 1/5 the cost!   

Darn skippy. I just don't want to do something twice for relatively the same outcome and one way be x amount of dollars and the other way be xxxxx amount. I'm trying to get hired with local law enforcement agencies, I don't really have the time to be dilly dallying around with my transmission. This whole second rebuild is already a giant PITA.

[bd]

Welcome to the world of high performance, partner.  Unfortunately, I gained my experience the hard way with no one to nudge me in the right direction.  It figures I'd begin with the expensive option and work backward.  lol   Oh well, you know what they say about hindsight....

[LTZ C20]

Thanks. I don't mind experimenting, just not on my DD and when I don't have the lettuce to make the salad. You know what I mean?

[bd]

I do.

[LTZ C20]

Hey since I got you guys here. I have another question.

The dipstick tube for the trans is the one that goes with the 89 truck the trans came out of. The tab welded to the tube for the bell housing bolt broke off so it's got 3 little holes in it and nothing to anchor it. I have the dip stick and tube from my old TH350. I measured the 350 tube using a piece of string to follow the bends and then used a tape measure to find the length of the string straightened out. It's 30 inches long. I measured the 700 tube the same way, it's 29 3/4 inches. I then measured both dipsticks and they are both 33 inches long and laid next to each other they are the same  and their hot and cold marks line up with each other.

So I should be able to cut a 1/4 inch off the end of the 350 tube and use it right? It's properly shaped to the body of the truck and it's mounting tab isn't broken off.

[Irish_Alley]

what matters is the base of the dip stick tube and stick. put the sticks in their tubes, then measure from the end of the dip stick to the shoulder of the tube. thats what matters 

[LTZ C20]

If I'm following you, those are the same. I'll double check when I get home.