Thread: Jegs crate motor choices vs. local rebuilder

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Where in NorCal are you?

hpcbmw, the issue with the flat tappet cam has been discussed a bunch here, and it's not the cam/lifters but the fact that oil was changed due to the heavy metals (zinc & phosphorus) that were added to provide lubrication of high pressure contact loads (lifter sliding on cam lobes) were found to be plugging CAT's. When this came about virtually all of the OEM's had already switched to roller lifters, to take advantage of reduced friction, faster acceleration ramps, etc, so dropping the zinc and phosphorous was not a big deal for them but it caused tons of failures of older engines, especially those built for better performance - modified cam profiles.

You may get away with breaking in a new flat tappet cam, and have trouble free operation if you run oil marketed for racing, like Brad Penn's or Joe Gibbs' products, but you'll need to be religious with it for the life of the engine, and you're still in a bit of a crap shoot, IMO. I'd opt for roller lifters, period.

Originally Posted by hpcbmw

Deuce4dad - Is the problem with the flat tappet that if it's not broken in correctly, the cam will shed metal particles into the engine? What is the correct way to break in a 350 sbc? I've never had a new motor!

This tutorial that I wrote for the Crankshaft Coalition wiki should explain all the pitfalls of running a flat tappet cam....
http://www.crankshaftcoalition.com/w...ips_and_tricks

If I were in your position, I'd look for an L31 engine complete from a wreck. Here's a wiki article that includes all the cars and SUV's that used that motor. It's a Gen I motor with Vortec iron heads and will make a good foundation for a truck motor for the street, factory roller cam and all. Use a high-rise, dual-plane intake manifold such as the Edelbrock 7116 and carburetor of your choice.
http://www.crankshaftcoalition.com/w..._cylinder_head

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You might check out these guys. They've built up quite a name in the off-road arena, providing takeouts for buggies and extreme jeeps - Engines - Engine & Transmission - Products They're in Gilroy, CA - no idea if that's close to you or not....

Looks like Roger has it found for you-if I remember Gilroy is near bay area----------
these are on a pallet and have wiring harness ecm and alt, power steering, serpentine belt etc etc etc

Roger - I think you found the perfect solution for me! I called Pacific Fabrication and they were very helpful. The 4.8l LS motor with all accessories for $1,750 looks like a great package for me. They've got adapter mounting brackets to mount this in the SBC mounts for another $75.00 and they tell me the stock bellhousing for my sm420 trans will bolt right up. Plus, they are only about 2 hours drive from me (I'm just east of Sacramento).

It's a bit of a risk, not knowing how many miles are on the motor, or what shape it's in, but they've got a 12 month warranty. I'm pretty sure this will be my motor. I assume I could buy a motor cheaper from a junkyard, but then I'd have to figure out how to flash the ecu, sort out a wiring harness and I'd have no warranty.

Thanks to Roger and Techinspector for the info on the flat tappet cams. I'll have to read through the wiki when I get a chance.

I'm assuming the 4.8l LS engine has roller cams, since it looks like they were produced starting 2007.

Thanks for all the help guys! I'll be back with a bunch of questions soon. I've got some rust repair and paint work to do on the engine compartment before I get the motor in, but hopefully I'll be picking up a motor from Pacific Fab in about a month. Here's what my truck looks like right now, so I got some work to do before dropping a motor in.

You might want to re-read Roger's post at #4 above. Does this engine come stock with an ECU and the related installation complications?

Glad it's looking like a good solution for you. I think that when you get ready to pull the trigger they can tell you the origin of your engine (vehicle, VIN & miles), but I could well be wrong. I've just seen them popping up in the off-road world as a good solution to their needs. Hope it works out well!

Jack,
That's one of the neat features of this place. Their "Ready To Run"packages come with a pre-flashed ECU/PCM, new wiring harness, and all OEM accessories. Each one is custom matched to the specific needs, with lead times in the two to three week range, depending on volume.

The 4.8 would be ok, but I would price a 5.3 (327) before buying. These guys are probably hand picking their engines from local salvage yards in the Gilroy, Morgan Hill area according to mileage. The 4.8 and 5.3 should go at a much cheaper price than the larger displacement LS engines. The LS engine would be a plus for the value of the truck later on too. Sounds like a good way to go if they will give you some installation and start up support.

I bought a rebuilt long block from these guys, https://www.sandjengines.com/ , it was cheaper than having it built here in California, because labor here is astranomical. With shipping and core charge it was still about a 1000.00 less than having mine rebuilt here, and they will put whatever parts you want in it, and give you a good warranty.

Ouch! The guys in Gilroy are proud of the 5.3! $750 above the 4.8 @ $1750.

I agree with Duece -another $750 - OUCH! I've been reading and asking around about the 4.8 vs the 5.3. It's about 20 more hp and 20 more ft lbs torque. Also, it seems the 5.3 is more amenable to bolt on hp mods. With either motor I'll have plenty of power (I say that now, but I'm sure I'll want more once I drive it awhile). What do you guys think of the 4.8 vs. 5.3? I doubt I'll have the budget for an extra $750 for the 5.3 but anything is possible.

I realize I'll need a new radiator, new exhaust (LS motor comes with stock exhaust manifolds, but I need new exhaust pipes), gas pedal cable routing, clutch and flywheel. They say my existing bell housing will work.

Pacific Fab quoted me $650 for a clutch and flyweel -does this sound right?

Originally Posted by hpcbmw

Pacific Fab quoted me $650 for a clutch and flyweel -does this sound right?

It's in the ballpark, assuming it's new in the box. What brand are they supplying?

The 5.3 engine is most definitely adequate. Think fuel injected 327 sbc. The 4.8 may be underpowered, based on cubic inches. Think fuel injected 283 sbc. Lol!