It's finally time - a new engine

[mySAVIOReigns]

Gotcha, thanks guys

[bigblock73]

I have enjoyed reading this thread, but I think some ppl are missing one key point, one Ken briefly mentioned. The type of vehicle, and it's purpose, will play a big role in the decision on which engine to go with, a built one or a crate version. If we all agree crate engines are good, for say, a car...then they should also be good for a truck, that is mainly just for transportation and fun. Not ALL trucks pull trailers, haul loads, or carry a camper in the back. On top of that, a 2wd swb truck doesn't weigh all that much more than a Chevelle, Camaro, etc..

Just something to think about.

[Billla]

Originally Posted by bigblock73

I have enjoyed reading this thread, but I think some ppl are missing one key point, one Ken briefly mentioned. The type of vehicle, and it's purpose, will play a big role in the decision on which engine to go with, a built one or a crate version. If we all agree crate engines are good, for say, a car...then they should also be good for a truck, that is mainly just for transportation and fun. Not ALL trucks pull trailers, haul loads, or carry a camper in the back. On top of that, a 2wd swb truck doesn't weigh all that much more than a Chevelle, Camaro, etc..

Just something to think about.

That's a great point, and I agree there isn't a significant weight difference for an older 2WD truck vs. a car of the same vintage. If it's a hotrod or around-town truck, no pushback. Diff ratio plays a part here as well; hotrod cars/trucks will typically have a lower ratio as well which means they get up into the sweet spot of the crate engines and get there quicker.

[mySAVIOReigns]

So you're saying it won't be all that great if I have a low gear ratio? Mine has a 2.73 ratio, so while I don't think I'll be able to peel off down the road, I'd like to get down it Thanks

[N2TRUX]

Originally Posted by mySAVIOReigns

So you're saying it won't be all that great if I have a low gear ratio? Mine has a 2.73 ratio, so while I don't think I'll be able to peel off down the road, I'd like to get down it Thanks

What transmission do you have. If you have a T350 then the 2.73 is pretty high no matter what motor you use. If you have a 700r4 it has a decent first gear that will help quit a bit.

As a point of reference, my 77 has 3.08's with a 700r4. I thought I might have to go with 3.42's or 3.73. I was pleasantly surprised that the 3.08's are not a bad combo. I suggest you focus on getting the right motor and worry about gears later. You can always buy a complete used rear end rather than changing yours.

[mySAVIOReigns]

T350, yea, it shouldn't be a big deal. Thanks,

[Billla]

Originally Posted by mySAVIOReigns

So you're saying it won't be all that great if I have a low gear ratio? Mine has a 2.73 ratio, so while I don't think I'll be able to peel off down the road, I'd like to get down it Thanks

I'm saying that a crate engine that's made to put out power at higher R's won't do all that well that at that ratio. The options are a) buy/build an engine that puts out more power down low or b) change ratios. I push back a little bit on the buy an engine now and worry about gears later, since the relationship between gear ratio and the engine is significant, but as noted you can buy another rear-end or a new gearset/posi if you want to go that direction.

All things are relative

[piecesparts]

Look at your gear ratios closely. My son's truck had a 3.08 rear end gear and with the install of the 700 R4 we LOST gas mileage. Imagine that, we were cruising around 1900 to 2000 RPM on the highway at 70 MPH and loosing gas mileage. The problem was that the motor had to work harder to make up the lose of speed on hils and inclines that it actually used more gas. I changed the rear end to a 3.73 gear ing and we picked up 2 MPG. The motor runs at 2500 RPM on the highway and kicks butt on acceleration. The V-8 does have a sweet spot and the RPMs are around 2200 to 2500 RPM on my trucks. If you drive in the city a lot, then you will work that motor to death accelerating from stoplights and leaving parking places. The 3.42 combo is slightly better, because my truck had that combo and I also changed it t o a 3.73 for acceleration improvement.
The 2.73 gears that you have are really high for an overdrive tranny and may cause you to dislike what you install. The carb size that you install will make the acceleration feel bad or great, depending. Since you are installing a 350 and you are wanting to drive it daily for a general use vehicle, then consider staying around 600 CFM to 650 CFM size. If you go bigger than that then you will loose inlet air velocity in your carb and cost you performance and gas mileage.

As for motors, look for a moderate performance upgrade, unless you wnat an all out fire breathing weekend cruiser. A 350 with about 300 HP due to an improved cam install will give you a good running daily user. The install of a dual plane intake with a moderate high rise in it, also will give you good improvements on the street. Some will give positives and negatives on what to use, but the Performer RPM has worked well for my Son's and my trucks. The Performer has a little bit lower power curve, but topped out to soon for me.

[72C203503ONTHETREE]

An engine gets the best gas mileage when its in its max power produced at that RPM. So if an engine makes max power at 3,000 RPM driving at a speed that has the engine turning near 3K will give you best mileage since the engine is at peak efficeincy. If the engine makes peak power at 5 grand you will lose mileage at 3K cruicing. You will generally get more mileage with a highway gear(2.73) with any engine but only if the road is completely flat and you dont have to give it gas. Of course torque convertot stall speed makes a big difference to, a stall of 3 grand will not be good for mileage(or heat production) at less than 3K cruising since its slipping, but would be great fro drag racing. Theres so many different things that you need to decide on when picking/building an engine, gear ratios, stall speed if an auto trans, intended use such as cruising at a single speed or a lot of stop and go traffic, cost of course, if you power brakes and an automatic trans unless you get a vacuum canister for big cammed engines, etc.

[84slopwaggin]

Well as for crate engines I like these two that Jegs offer. The only thing they lack is one less year of warranty than the ones that GM offers. I feel the decision varies depending on the person. There are so many people that are not mechanically inclined, and a crate engine might be the better decision. I think if a person has the ability and tools to do a engine swap they can save time by choosing a crate engine() .

https://www.jegs.com/webapp/wcs/stor...5480_-1_395120

https://www.jegs.com/webapp/wcs/stor...5486_-1_395137