Rebuilt Replacement Engine

[SAATR]

My biggest point was that the fuel economy will not suffer as greatly with a 383 as you would have the OP believe, as you cited 4 to 5 mpg. The OP posted up a crate engine, a 350 yes, but I said that a 383 would be a better choice for a truck given its better torque curve, and that an LT4 cam in said motor would be ideal. I also said that the extra displacement would tame the cam. I lumped my reply to many of the above comments in two paragraphs, but my main point to you was that the fuel economy would be fine with such a setup and not in the toilet. Also that a 383 with said cam would be great.

 

[97c1500]

My biggest point was that the fuel economy will not suffer as greatly with a 383 as you would have the OP believe, as you cited 4 to 5 mpg. The OP posted up a crate engine, a 350 yes, but I said that a 383 would be a better choice for a truck given its better torque curve, and that an LT4 cam in said motor would be ideal. I also said that the extra displacement would tame the cam. I lumped my reply to many of the above comments in two paragraphs, but my main point to you was that the fuel economy would be fine with such a setup and not in the toilet. Also that a 383 with said cam would be great.

It would be at best 10/12 and that driving grandma style while most if not all people that build this kind of power drive it like a bat out of hell and get 4/5

and yes the Lt4 hotcam 383 combo has a great torque curve

 

[jeff's88silverado]

Thanks everybody for their advice I appreciate it. But i'm not getting rid of the 2.73 gears since i can still burn off the tires on take off and only run 1,500 rpms at 60mph with 255/70/r15's. But i'm going to talk to my chip maker and my buddy thats builds engines on occasions. so I'll probably go with stock LT1,LT4, or ZZ4 cam Just so I dont have to do head work to run the LT4 hot. I'll let everyone know tomorrow.

 

[97c1500]

Thanks everybody for their advice I appreciate it. But i'm not getting rid of the 2.73 gears since i can still burn off the tires on take off and only run 1,500 rpms at 60mph with 255/70/r15's. But i'm going to talk to my chip maker and my buddy thats builds engines on occasions. so I'll probably go with stock LT1,LT4, or ZZ4 cam Just so I dont have to do head work to run the LT4 hot. I'll let everyone know tomorrow.

on the ZZ4 cam you have to run comp 26918 springs and 787 retainers to get the required lift out of the vortec heads and the lt1 cam is near identical to a stock L31 cam

 

[Badass69]

Did not know that comps tech line sucks

If you look at a dyno graph for a Lt4 Hot Cam you will see it starts out low and builds up as the Rpm increase not what you want in a truck that's why I recommended the ZZ4 It give more torque and horsepower at low rpms where you need it most in a truck i'm not hating on the Lt4 Hot cam i'm just saying it's not a very good truck cam


I'm Not trying to start a war so calm down

Neither am I. It's just that the ZZ4 cam is such a mild step that it's not really worth it. That and for torque I would go with a better cam than that. The Comp XR 264 would be a better choice than the ZZ4. Even the XR258. I was originally going to run the XR264 in my L31 but am going a different route with a Voodoo 60121. I know that everyone that goes to the ZZ4 wishes they would have gone a step larger further down the road. Realistically that's why they are so plentiful and so cheap. That said the OP seems very stuck on 2.73 gears.... which are awful gears so in that instance I would stay with the stock Vortec cam.

 

[Badass69]

Thanks everybody for their advice I appreciate it. But i'm not getting rid of the 2.73 gears since i can still burn off the tires on take off and only run 1,500 rpms at 60mph with 255/70/r15's. But i'm going to talk to my chip maker and my buddy thats builds engines on occasions. so I'll probably go with stock LT1,LT4, or ZZ4 cam Just so I dont have to do head work to run the LT4 hot. I'll let everyone know tomorrow.

You don't need anymore head work for the LT4 HC than any of the others. Use the same beehive springs as I mentioned earlier ( I would use LS6 springs as Comp's beehives are somewhat sketchy at best).

Really if you are stuck with using the 2.73's than stay with a small cam. Honestly the stock L31 cam is fine. The B body( Caprice, Fleetwood, Roadmaster) LT1 cam is the L31 cam btw, so there is absolutely no difference there. I know, my daily driver is a 96 9C1 Caprice. They builld decent low end power and can cruise at ridiculous low rpm with zero ill affects. That and if you buy a GM crate you can probably keep your warranty on it, if that matters. You could just add 1.6 rockers and run it like that. Either way the L31 will make more power than your stock LO5 can dream about without some work at least.

 

[jeff's88silverado]

You don't need anymore head work for the LT4 HC than any of the others. Use the same beehive springs as I mentioned earlier ( I would use LS6 springs as Comp's beehives are somewhat sketchy at best).

Really if you are stuck with using the 2.73's than stay with a small cam. Honestly the stock L31 cam is fine. The B body( Caprice, Fleetwood, Roadmaster) LT1 cam is the L31 cam btw, so there is absolutely no difference there. I know, my daily driver is a 96 9C1 Caprice. They builld decent low end power and can cruise at ridiculous low rpm with zero ill affects. That and if you buy a GM crate you can probably keep your warranty on it, if that matters. You could just add 1.6 rockers and run it like that. Either way the L31 will make more power than your stock LO5 can dream about without some work at least.

What year model car do i need to look up for the LS6 springs?


Also why do I need to change the gears. I'm not wanting to race the truck and I dont haul nothing in it and maybe pull an 8ft trailer every now and then with a riding lawnmower or something small on it. And I just want a little more get up and go than what its got now. The LT4 cam is for the sound I like to have that little lope in the idle.

 

[97c1500]

What year model car do i need to look up for the LS6 springs?


Also why do I need to change the gears. I'm not wanting to race the truck and I dont haul nothing in it and maybe pull an 8ft trailer every now and then with a riding lawnmower or something small on it. And I just want a little more get up and go than what its got now. The LT4 cam is for the sound I like to have that little lope in the idle.

you change the gears for two reason
1.) mechanical advantage
2.) bring you motor into the power range quicker
also like i said earlier in this post 2.73 and LT4 Hot Cam Do not mix if you like the sound and want to use that cam go ahead but you will be very disappointed in power output
just changing the gear with a stock cam will be like night and day

 

[Badass69]

you change the gears for two reason
1.) mechanical advantage
2.) bring you motor into the power range quicker
also like i said earlier in this post 2.73 and LT4 Hot Cam Do not mix if you like the sound and want to use that cam go ahead but you will be very disappointed in power output
just changing the gear with a stock cam will be like night and day

Bingo. Exactly what he said. Mechanical advantage gets you moving, and trucks are heavy. That and you are running a 29" tall tire, same as I am on either of my trucks. My Vortec 350 knocks down around 20 mpg US if I drive like a sane person. That and it has 3.73 gears. The engine is turning around 2 grand at 65 mph. My 94 TBI 350 did similar mpg with 3.42 gears as well. Why am I giving you these examples you ask? Because I am trying to convey that a gear ratio change will not kill your trucks mpg.... and in instances will probably increase it. Now what does the mechanical advantage give you? Better acceleration, no matter the engine. My 96 was Gm's trailer package of the day, hence the 2wd with 3.73's. That better acceleration will feel like more power, and it is in a sense I suppose. Jump that truck even to 3.42 gears and that TBI 350 under the hood as it sits would feel like a whole new engine.

My Caprice is another perfect example. Dumped the stock 3.08's and went to 3.42's because I was changing out my dead Auburn LSD anyhow. It's a whole new car and my cruising mpg has not changed. The 3.08's are fine if you want to cruise at 90 mph all day long but otherwise were completely useless. Made the car doggy at any speed. A simple gear change made the car feel like it has 30 extra horsepower.

I don't know whats wrong with your original 350 if anything, but I am being serious about the gears. Might make you think you don't need another engine, who knows.

These are the LS6 spring I am talking about.

12565117 Valve Spring --
LS6 valve spring. Used with P/N 12480033 “Gen 3” Hot Cam.
GM PART # 12565117
CATEGORY: Engine Valve Spring
PACK QTY: 1 CORE CHARGE: $0.00
GM LIST: $9.63
OUR PRICE: $5.49
DESCRIPTION: SPRING
These valve springs are intended for heavy duty applications in Gen III Vortec small-block engines. This spring is original equipment in LS6 engines

The engine that used them were the LS6 equipped Z06 Vettes. So 2001-2005 model years.

 

[jeff's88silverado]

Would the 3.42 gears be good enough with the hot cam and also could I get by with just changing ring gear and pinion since the rear end is still good in the truck? And I believe I just might try this before the motor swap. The reason for removing the original 350 is the valve guides are bad, done replaced valve guide seals but still smokes from time to time on take off. and when i sold it one time the guy had a dumbass **** put a starter on and they busted the outer side of the block so i got the one bolt holding it up and another long bolt going up the side of the block keeping the starter from twisting.