Modding a GM Engine 10067353
Thread Starter
Race Director
Joined: May 2003
Posts: 11,814
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From: Science Bitch! Mississauga, Ontario
Canadian Events Coordinator
Modding a GM Engine 10067353
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
How upgradeable is this engine?
Anyone have one, and what mods have you done to it?
Just getting ideas, Les
Race Director
Joined: Mar 2001
Posts: 11,322
Likes: 1
From: Living in the Hartland
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.
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.
Safety Car
Joined: Oct 2004
Posts: 3,725
Likes: 5
From: Minnesota
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.
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.
Melting Slicks
Joined: Oct 1999
Posts: 2,581
Likes: 14
From: Tolar Texas
Originally Posted by 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.
Melting Slicks
Joined: Jul 2002
Posts: 3,128
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From: Deltona (son of Deland and DAYTONA) FL
Originally Posted by AGVI
Thanks Fevre/Mark. Which cam would you recommend?
I'm assuming the Comp Cam 270H would be too much cam.
Les
I'm assuming the Comp Cam 270H would be too much cam.
Les
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Racer
Joined: May 2004
Posts: 259
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From: Eagle WI
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.
Thread Starter
Race Director
Joined: May 2003
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From: Science Bitch! Mississauga, Ontario
Canadian Events Coordinator
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.
Sounds like a good deal. It'll be better than rebuilding original and blowing it up.
Race Director
Joined: Sep 2004
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From: Arlington Va Current ride 04 vert, previous vettes: 69 vert, 77 resto mod
Originally Posted by 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.
Sounds like a good deal. It'll be better than rebuilding original and blowing it up.
why not just buy a short block and start from there?
Thread Starter
Race Director
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From: Science Bitch! Mississauga, Ontario
Canadian Events Coordinator
Originally Posted by bobs77vet
why not just buy a short block and start from there?
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?
Race Director
Joined: Mar 2001
Posts: 11,322
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From: Living in the Hartland
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.
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.
Race Director
Joined: Sep 2004
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From: Arlington Va Current ride 04 vert, previous vettes: 69 vert, 77 resto mod
Originally Posted by 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?sounds like a plan ........
Thread Starter
Race Director
Joined: May 2003
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From: Science Bitch! Mississauga, Ontario
Canadian Events Coordinator
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
Les
Le Mans Master
Joined: Mar 2002
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From: Coming home from Luckenbach Texas
Originally Posted by SKYCOP1
Could you get 400hp with zz4 heads on that engine, w/a different cam??
Le Mans Master
Joined: Oct 2002
Posts: 7,098
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From: Las Vegas - Just stop perpetuating myths please.
Not worth upgrading.
Originally Posted by 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
How upgradeable is this engine?
Anyone have one, and what mods have you done to it?
Just getting ideas, Les
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
