c69vete

Hey all. I am looking at a GM 350/290 HP GM crate engine for a project. Specs are copied below. Question is would anyone suggest a cam change to bump up the hp a bit before installing? If so, what cam specs would you recommend? I want to keep the pump gas 87 octane ability as this would be in a daily driver. What say you? Thanks all.
2 year/50k GM Warranty

350/290 HP Deluxe

The 350/290 HP is the most popular GM Performance Parts crate engine because no one can deliver such performance for this kind of value. GM Performance Parts believes that everyone should be able to afford a high quality GM V-8 without going broke. The 350/290 is an answer to those car crafters who demand maximum return on their money. But, just because it's affordable, don't think that it's a stone. The 350/290 delivers 290 hp @ 5100 rpm and a solid 326 lb. -ft. of torque at 3750 rpm. With those kinds of numbers, it's the perfect replacement engine for the millions of GM vehicles that shipped with a small-block.


350 Cubic inches 4.00" Bore, 3.47" stroke 8.0:1 compression ratio. 290 HP @5100 rpm 326 ft. lbs of torque @ 3750 rpm

*Does not include Carburetor, Intake Gaskets, or Intake Bolts*

Features:
• Cast iron 4 Bolt main block with 2 piece rear main seal
• Nodular iron internally balanced crankshaft
• 5.7" Powdered Metal connecting rods
• Cast aluminum flat top pistons.
• Hydraulic flat tappet camshaft.
Intake Lift- .450" Intake Duration @ .050" 222
Exhaust lift- .460" Exhaust Duration @ .050" 222
Lobe Centerline-114
• Cast iron 76cc 1.94”I/1.50”E heads

Kacyc3

8:1 compression...better be a heavy truck where performance is low on priority list.

this may be a better option depending on your project

https://blueprintengines.com/product...lock-bp3503ct1

cardo0

If your ready to do a cam swap then the L31 Long Block Crate Engines 12681432 would be a better choice for a $1000 less. But you will need to install an electric fuel pump to use it. The L31 has a roller cam, hyper pistons and vortec heads. Good enough compression that a bigger cam should wake it up. Just much better motor to start with.

28buick

The 8 to 1 compression is the killer for this motor. Any increase in cam duration will continue to drain your dynamic compression. Swapping heads is the most effective way to get compression up and allow for cam upgrades but if your taking off the heads just get a short block and then put the heads you want on it.

jackson

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OP
that motor has poor heads & flat tappet cam: its 290hp measured free of any power-robbing accessories but with Open Unrestrictive headers & open exhaust

If you want a brand new genuine Chev/GM crate sbc ... this GM pn 12681431 is best deal out there. Has good Vortec heads & steel Roller cam. Under $1900 delivered ...
... Its 255hp/330tq measured with all accessories and full restrictive Single exhaust & muffler system ...
... bet dollars to donuts if both measured via same standards, the L31 Vortec makes more hp & tq than any post-1970 L48
https://www.ebay.com/itm/GM-OEM-NEW-...kAAOSw1UdcvxpQ

Popular cam swap for L31 Vortec is GM cam pn 12677151 .... makes about 357hp/407tq ... reference GM crate pn 19367080 ...
... put that 12677151 cam in the L31 pn 12681431 crate and you'll have a 350/357 crate pn 19367080 GM ...
... GM pn 24502586 "Hot Cam" plus beehive/LS6 springs plus 1.6:1 rockers is popular swap and make easy 375 - 400hp.

GM L31 Vortec specs (as installed) here:
https://www.gmheritagecenter.com/doc...xpress-Van.pdf

Radley Chevrolet Richmond VA (Performance Parts Manager Chris Rogers: 540-898-4000)
https://www.radleychevrolet.com/

jackson

above x432 has 2-bolt main ... x431 has 4-bolt main ... otherwise same ... see my post just above

Little Mouse

Both the 222 .0050 int. Dur. And 114 lobe seperation all wrong for an 8.0 comp. Engine. A shorter duration and tight 108 lobe center, combined with as much lift and quick opening rate for those. 194/150 valves would make better power everywhere. Cam there using 50 years old tech cam. All just a moot point, changing the cam would void the warranty.

CheezMoe

The GM 350-HO is the best bang for the buck here. I know 3 people who have bought them and they love em. Reliable, smooth starts and idle speed and all in all a good motor for the price. ....and you keep the warranty.

https://www.jegs.com/i/Chevrolet-Per...10007/10002/-1

c69vete

Thanks guys for the input. Lots of good suggestions and information. Now I have a decision to make. Thanks again.

leigh1322

If you are trying to make it run well, 8.0-8.5 CR is leaving a lot of power and response on the table. If you get a combo with 9.5 CR you have more response, can still run pump gas, and it responds better to a mild performance cam. My favorite SB cam is the L-46 350HP cam, or it's modern cousins. That amount of duration is about the max a SB will take while still having excellent bottom end and street manners, stock like torque and driveability, runs like a 300HP cam til you floor it, but will run up to a 6000+ redline very strongly. A little under that and you lose top end but don't gain much on bottom. A little more and the bottom end starts going away quickly.

200-220 duration is very mild. An L46 has about 226 duration so cams in the 226-230 range would work great and give you a very broad powerband, but like a little compression. At 242 you're into the LT-1 type cams and start to lose bottom end.