AGVI

Would it be a wise choice to purchase this engine as a replacement for my original L-48? Should I just store the original?

How upgradeable is this engine?
Anyone have one, and what mods have you done to it?


Just getting ideas, Les

Fevre

That is the same eng I have, known as the GM Goodwrench Universal Engine or LM1. I put a little larger cam in when I got it (204/214 .424/.444 Summit brand) and was pretty happy for the $ spent. I then put alum heads with a roller cam (222/230 .560/.580) in it and it screamed pretty good, 13.4 in the qtr mile. I am putting it back in with the alum heads and another flat tappet cam (214/224 .444/.464). I think you could use this cam with the stock heads that come with it and see somehwhere around 300 hp. I am still hoping to get a stroker or 400 based eng going and wanted to have the roller cam avail for dyno testing so I did not put it in the eng.

BTW If you decide to put a diff cam in it before install you can reuse the lifters that come with it since they have not been used, saves you $20 or $30.

markdtn

Chevy High Performance did a multistage buildup on one of these a few years ago. THe stock bottom end is OK. Can't remember the final numbers but it was impressive.

AGVI

Thanks Fevre/Mark. Which cam would you recommend?
I'm assuming the Comp Cam 270H would be too much cam.

Les

jdmick

Myself and some others here are also looking at that engine.
http://forums.corvetteforum.com/showthread.php?t=965979
What have you found for pricing? Summit gets just over $1400 plus around $100 extra shipping. My local chevy dealership wants $1500 pls $100 core.

MIKER

It made around 415 HP

isosceles

I put a Com Magnum 270H in my L48. Would still idle at 650 rpm. I don't think it did all that much good as the heads and compression were stock.

SKYCOP1

Could you get 400hp with zz4 heads on that engine, w/a different cam??

Todd68

I got one from a local dealer for my 4X4 truck rebuild about for years ago. I left it 'stock' except for headers, intake, carb. Absolutely zero problems in four years and it served as my daily driver for about three years. I called four different Chevy dealers in my area when I bought it, and the prices varied by about $300, so call around. I paid $1245 & picked it up at the dealership myself.

Shark Racer

241 rwhp / 283 rwtq AFR heads Crane 272 cam (216/216 dur). If I bumped the compression up to ~10.5 I'd make >300 rwhp probably.

AGVI

So, basically, with a head, cam, and piston upgrade I'll be in the 300rwhp area...

Sounds like a good deal. It'll be better than rebuilding original and blowing it up.

bobs77vet

why not just buy a short block and start from there?

AGVI

good idea, but I'd like to have something in there this Spring. The heads, pistons and cam will be installed after a couple of years...I mean why void the warranty on a decent engine?

Fevre

PSSST, put a bigger cam in, GM will never know. I bet the head flow for the heads that come on it would warrant a dual pattern cam.

I am going to leave the bottom end alone and just use it for a spare eng when I decided on an eng to put in some time in the future, nice to have one to throw in just in case you blow one up.

bobs77vet

sounds like a plan ........

AGVI

With my intake/carb and headers, I should have about 265HP/350TQ...It's better than original and I can always build on it later.

Les

page62

ZZ4 heads are the same as L98 Corvette heads from the '80s. You'd be better off with Fastburn or Vortec heads.

AGVI

was thinking about some Sportsman II's....they would work, no?

page62

Sure, but so will these...for a lot less $$$



Go to Summit Racing and search for SUM-152123

cardo0

I have a LM1 in my '74 and upgraded it only because it was/is still in the car and i had to R&R radiator & core support - opportunity to change cam (and install headers). The pistons are the weak link and not what i would push over 350 hp - but thats me. Those heads are wheezers too and deffinatly not worth moding to make power.
Only mods i would make is to elongate the push-rod slots for 1.6 rockers and install. Install 0.015" steel shim head gaskets for better quench and a little more desparatly needed compression. Then advance the stock cam a few degrees. So for less than additional $100 u might reach 300 hp at the flywheel with the stock ram exh manifolds. But it would run hard and race on forever. Start quietly and idle glass smooth too.
If u want to build ur own try PAW block kits. Short blocks $1100 for 350" and $1700 for long block kits with World Product heads (much , much better head). Stroker 383" short blocks $1600 and long block 383" kits for $2100.
Good luck. cardo0