Thoughts on new GM Crate Motor

[BrianG]

A while back I posted a thread asking for some opinions on which way to go with my needed engine correction/upgrade. Long story short, The motor in my truck is fairly fresh. However, when the previous owner had someone rebuild it. They "in my opinion" put way too big of a cam in it. Sounds like a built Harley, but has very little idle vacuum and just really doesn't impress with power until you really start to wind it up. It is a one piece rear seal block with World Products Stock replacement heads.

I 'WAS' considering a new top end kit for it, or going with a new 383 long block.

The 383 long block that I really want is pricey at $6,000. And I have not found the right top end kit plus honestly don't want to deal with Cam break in and lifter adjusting issues.

Soooo.. Fast forward to the present.

I see that GM is going to be offering this beauty very soon.

http://www.chevrolet.com/performance...-357-base.html

I'm thinking that this might be more in line with my budget. I've seen some online pricing suggesting that this new 350 is going to be in the $3,500 range retail.

I could build something similar using my block and crank. I do have a one piece rear main seal block, so the potential is there for a Hydraulic Roller, but I do not think that they put a roller cam in there when it was rebuilt. I would prefer a roller cam due to the power curve they can produce. Adding up the components separately (vortec heads, cam, lifters, cam spider, push rods, etc.) I would probably be well over $2,000. Still quite a bit less than $3,500 but I don't really get excited about the thought of rebuilding engines these days. Call me lazy, chicken, or what ever. I honestly like the thought of simply torqueing down an intake and using my existing carb.

My truck is a short box 4x4 with five inch lift and 33's with 3.73 gears. None of that is going to change.

So, to all those with way more knowledge than I have on these sort of things. What is your opinion on this new GM crate 350? Did they use the right cam, right heads? any changes you would make?

[truckster]

It's interesting that the spec sheet only shows torque above 3,000 RPM.

That's a lot of torque, as long as it kicks in low enough for your application.

[TwoFiftyShifter]

I posted about this motor a few months ago. Most of the users here blasted it due to their ability to build one cheaper in their garage.

[Coley]

Is your motor is in good shape overall?... and simply down on power...or more importantly torque?
Ok, this wouldn't be the first time the wrong decision was made in choosing/putting a 'thumpity thumpity' nice sound cam in a heavy vehicle.
Cams that sound like that...in a small block motor....make very little torque under 3500 rpm....and this problem is legendary for many.
This is not the cam to have in a heavy 4000lb vehicle....(and definitely if you run oversize tires and combine that with a single plan intake manifold...not that that is necessarily the case here)
Call a quality cam manufacturer and give them your truck specs (engine, vehicle weight, tire size, etc, etc) and they will get you the correct cam and lifter set for that truck.
I think what will get you moving (quickly) will be a cam that has more lift than duration (...which is the thumpity thumpity cams).
Call a cam manufacturer and simply talk with them...they can be of immense assistance.
Then you won't have to spend big bucks for nothing....and you will get your power back...and probably a lot faster.

My two bits.
Coley

[weq92f]

I'll have to read the other thread, but... that is a bunch of $$.

My vote is go with option #2 ( build what you have ). Take your existing components to the right machine shop, tell them what you want and they'll quote you up, probably well below 3500.

-klb

[BrianG]

Originally Posted by weq92f

I'll have to read the other thread, but... that is a bunch of $$.

My vote is go with option #2 ( build what you have ). Take your existing components to the right machine shop, tell them what you want and they'll quote you up, probably well below 3500.

-klb

I guess taking it to a shop is another option. Finding one I trust is another thing I guess. The guy I bought it from and they built him what is essentially a race car motor. I guess $3,500 is a lot of money. However just the heads, cam and lifters would be around $1,800. Figure in maybe new valve springs other necessary parts to go back to a roller cam and your well into $2,000. That's before labor. So maybe I'd be into it for $2,500 or so for the same long block if I use my short block.

[garyd1961]

I would just replace the cam with something more drivable.
Are you sure the World heads aren't vortec style heads. I am vaguely familiar with World Products and I haven't seen anything that I would call stock from them.
Anyway it sounds like you have a good motor that just needs the right cam. Get a cam for low end torque and you wont think it's the same motor. How much stall does the torque converter have? You don't need much stall with a high torque low rpm cam.

[BossHogg69]

They didn't build a race car motor if it's got World Products SR heads on it. If I were you, and the motor is healthy, just put a cam in it that suits your needs. If you're not worried about the money, put a nice hydraulic roller in it - being a 1pc rear main block it may have a hydraulic roller in it now(?) and you can reuse the lifters and possibly pushrods.

Do you have any idea what cam is in it now - did the guy you bought it from put a flat tappet cam in it?

edit: I checked out the link you posted, that SP350/357 seems like a nice streetable motor.

[BrianG]

World Products make a stock replacement head that can be used in place of true stock gm cast heads in some racing classes. That's is what I have. Supposedly similar to the camel hump heads for performance. I'm sure the right cam would wake the thing up. I just have no idea where I'd end up torque and hp wise. Don't want to spend the money for a cam only to be dissapointed. I think I'd like to be around 400 ft lb of torque. My stall is probably around 2,500.

[BrianG]

Originally Posted by BossHogg69

They didn't build a race car motor if it's got World Products SR heads on it...

Ha! Very true! Unless your talking a stock class. But the cam would disqualify that.

[davepl]

Unless the heads have huge unwieldy runners, I'd just swap in a reasonable cam. Done in about 4 hours for a couple of hundred dollars.

Then if you don't like that, buy a crate motor, but I bet you can get away with just a cam swap. Heck, pick the cam that comes in the crate motor, so it has the same "brains", and will act and drive largely the same way.

[BrianG]

Originally Posted by davepl

Unless the heads have huge unwieldy runners, I'd just swap in a reasonable cam. Done in about 4 hours for a couple of hundred dollars.

Then if you don't like that, buy a crate motor, but I bet you can get away with just a cam swap. Heck, pick the cam that comes in the crate motor, so it has the same "brains", and will act and drive largely the same way.

Would probably have to pull the motor. I don't believe it has a roller cam now but that is what I want. I don't want to deal with cam break in and setup. I have to take off a valve cover and see if I can inspect down an oil return or valve stem hole. If it turns out to be a roller then I'd be much more inclined to just do a cam swap. Probably would not achieve the numbers that the crate motor in the link has but would be a much less expensive alternative.

[BossHogg69]

I actually think the 400# tq number and 350 hp (or very close) are achievable, with the right cam if your motor is healthy and doesn't have any issues that wouldn't let the proper cam do it's job. I think something in the 214-220* @ .050 range would be okay (talking hyd roller). The GM HOT cam is a good, proven performer and it's 218* @ .050" The SP350 motor you posted uses a 215* @ .050 cam. Not trying to turn this into a 'recommend a cam' thread, but just wanted to throw that out there.

In a little bit different situation, my '05 GMC crewcab 1/2 ton (see sig) weighs 5200# with me in it, 32" tall tires, 3.73's and a little 5.3 engine - I have a comp cams 215* cam in it (265 advertised duration) with a 2600 stall yank converter and it runs very well - and it also pulls my 20' enclosed car hauler just fine. Yes it's a different style motor, but the same principles apply.

[garyd1961]

Originally Posted by BrianG

World Products make a stock replacement head that can be used in place of true stock gm cast heads in some racing classes. That's is what I have. Supposedly similar to the camel hump heads for performance. I'm sure the right cam would wake the thing up. I just have no idea where I'd end up torque and hp wise. Don't want to spend the money for a cam only to be dissapointed. I think I'd like to be around 400 ft lb of torque. My stall is probably around 2,500.

The reason I asked about the stall is you don't want a high stall with a low end torque cam. You would just blow right past your power range. I would stick to 2500 or less.
Find out what type cam it has. If it is a roller hydraulic it would be easy to swap a smaller cam. I'm in no way a cam expert but something in the .440 to .460 lift range should get you good low end torque.

[BrianG]

Does anyone have any experience with Comp cams Xtreme 4x4 cams.
If I decide to use my short block and add a cam and heads, I am considering this one.
http://www.compperformancegroupstore...ode=RLERCAM4X4
It looks to have similar characteristics as the one in the GM 350/357 crate that I first mentioned. I'd either top it with some Vortec heads or maybe something with just a little more performance capability.

[diggerbob]

I had not heard of this new offering but it certainly makes sense. I could never pull the trigger on the 330 HP Vortec 350 because of the flat tappet cam. I will be looking with great interest at reviews of this new engine once it hits the market.

Originally Posted by BrianG

A while back I posted a thread asking for some opinions on which way to go with my needed engine correction/upgrade. Long story short, The motor in my truck is fairly fresh. However, when the previous owner had someone rebuild it. They "in my opinion" put way too big of a cam in it. Sounds like a built Harley, but has very little idle vacuum and just really doesn't impress with power until you really start to wind it up. It is a one piece rear seal block with World Products Stock replacement heads.

I 'WAS' considering a new top end kit for it, or going with a new 383 long block.

The 383 long block that I really want is pricey at $6,000. And I have not found the right top end kit plus honestly don't want to deal with Cam break in and lifter adjusting issues.

Soooo.. Fast forward to the present.

I see that GM is going to be offering this beauty very soon.

http://www.chevrolet.com/performance...-357-base.html

I'm thinking that this might be more in line with my budget. I've seen some online pricing suggesting that this new 350 is going to be in the $3,500 range retail.

I could build something similar using my block and crank. I do have a one piece rear main seal block, so the potential is there for a Hydraulic Roller, but I do not think that they put a roller cam in there when it was rebuilt. I would prefer a roller cam due to the power curve they can produce. Adding up the components separately (vortec heads, cam, lifters, cam spider, push rods, etc.) I would probably be well over $2,000. Still quite a bit less than $3,500 but I don't really get excited about the thought of rebuilding engines these days. Call me lazy, chicken, or what ever. I honestly like the thought of simply torqueing down an intake and using my existing carb.

My truck is a short box 4x4 with five inch lift and 33's with 3.73 gears. None of that is going to change.

So, to all those with way more knowledge than I have on these sort of things. What is your opinion on this new GM crate 350? Did they use the right cam, right heads? any changes you would make?