the33z33

I'm swapping my v6 out for an LM7 that I'm almost done building in the garage. Here's what it has:

1) 799 heads milled .030 with a new valve job and cleaning
2) nnbs intake and 36(ish) lb flex fuel injectors and stock 87mm TB
3) this TSP cam https://www.texas-speed.com/p-5072-t...-camshaft.aspx
4) PAC 1219 valve springs and hardened TSP pushrods
5) TSP 1 3/4 long tubes with 3 inch ORY

There's other little odds and ends like new oil pump and lifters with trays but that's all peace of mind stuff. That's actually the direction I'm going with this truck. I want a fun street truck that's reliable. Not really chasing huge HP numbers but I do like something that feels torquey.

The pursuit of reliability made me drive down to Houston today and pick up a 4l80. Everything will all be going in at the same time so it'll feel like a different truck regardless.

Should I go gears or converter to get my off the line punch? Maybe go mild on both? MPG is only mildy important to me as I do drive the truck to work or out of town sometimes but I'm not gonna cry over 1 or 2 MPG's.

Thanks for the help, guys. I always come to this site first.

FFDP

iTrader: (2)

What gears do you have now?

I'd think 3.73's or 3.90's would be perfect for still having some fun and being decent on fuel mileage. (tire size depending, I'm figuring you have the standard 30in tires still)

The cam and a stock converter would work or maybe going up slightly in the stall wouldn't hurt, maybe a 2200ish.

the33z33

The truck currently has the 3.23 gears... which are shitty and probably need to come out anyway. 3.90 is exactly what I was thinking anyway. I just know that the 4l80 had that tall AF gearing from the jump and gears are practically mandatory but the converter... not sure on that one yet.

I thought the factory converter stalled 2200ish though... maybe? Speaking of converters, what size is recommended for this application? 278mm? I'm not well versed on this subject but I see that being a common choice.

Joejamesatou

I would go 3.90 or higher. I drive a 2500 suburban and it has 3.73's and I wish it had 4.10s or 4.56. That first gear is steeper than you imagine, especially with a cam.

the33z33

Are you on the stock converter?

Joejamesatou

Yup... It's my daily driver and does some towing.

Bluecollar Hotrods

iTrader: (18)

What size tires? A friend of mine has that cam, 4.10s, and 275/55-20s. Has a 3000 stall and the 65E still. If it had an 80E, it would be a slug without a stall converter.

If you have the standard 30" tall tires and do a lot of highway driving, 3.73s and a 3000-3200 converter. Less highway driving, 4.10s and a 3000-3200 stall. Taller tires, step up in gear.

MrHorsepowerLSx

iTrader: (13)

Put in some 4:56’s and let her eat

Joejamesatou

245/75/16. Would rather do 4.56 before I do a stall since I don't do drag racing. Probably just a 4.10 limited slip swap.

the33z33

I'm glad you mention that combo because I was thinking of running that same wheel set up. 275/55/20. I did some reading last night on converters and apparently one rule of thumb is to choose a stall lower than hwy cruising RPM? Otherwise it'll never achieve lock up?


Also, apparently you want to try and get around 500ish higher than the beginning of the powerband for your cam. My cam range I think makes power from 1400 - 6200.


Of course gears, wheel size, and other mods can tweak all this. So I'm on the fence. 4.10s or 3.90 are looking attractive. 4.56 as mentioned would be fun but I do take the hwy in to work and I plan to take it out of town on occasion. So I'll need something kind of in the middle for gears.


Still on the fence about the converter though. Was actually thinking the smallest I could get at 2800 stall.