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454 LS-7 XCH


riverdogs00

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Mid 70s 454 LS-7 bought in the original crate a few years back. There are very few videos or information regarding these 50 year old engines. Those that have them, traditionally seem to add roller cams, aluminum after market heads and other internal speed parts. This engine was the successor to the LS-6 found in Chevelle's and Corvettes, and was slated to go into the Corvette. GM killed it due to emissions regulations. Subsequently, these were sold over the parts counter as a Off highway use only engine. GM rated the LS-6 at 450 HP, and the LS-7 at 465. The engine was only offered as a long block, no manifolds, carbs, distributor. This particular engine was located in 2020 still in the factory crate. It was purchased and shipped directly to my engine builder in las Vegas where it was disassembled, cleaned, and checked. We only replaced the following parts as a precaution, and maintained stock level parts for a true representation. Gaskets, rod and main bearings, Valve springs and seals, and rings. The engine received a light hone, but maintains its standard bore, and a light valve job as the valves were exposed for 50 plus years. This engine uses the same solid flat tappet cam as the 427 ZL-1, and was a step above what the 427 L88 had in terms of lift and duration. Parts added to this specific build to complete it were twin Holley 660 center squinters, Offenhauser tunnel ram, MSD E curve distributor, poly locks for the stock rocker arms, and the Edelbrock valve covers. Rated at 465 HP, this engine made 582 hp at 6000 rpm with no air cleaners, and 2 1/4" dyno headers. Installing my 1 7/8 American racing chassis headers (1970 Monte Carlo), and twin velocity stack air cleaners brought the power down to 570 at 6000 rpm. While I realize that this engine was never offered in a passenger car, its unique enough for those that are interested in the Big Block Chevy.  

Link to the video can be found here:   

 

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Looks good, thanks for sharing the info!

 

I bought 2 of the crate LS-6, part# 366250 engines back in the day. One is in my current '72 Custom, the other highly modified one now lives in my 69 Z/28.

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Did the same thing back in the day! Not in a Custom however. Currently runs a 67 Vette Rect. port 3x2, Edelbrock 110 CC oval port heads and a 5 Speed Stick among other mods. Got some pics of the engine and the car? Love to see any pics you have.

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36 minutes ago, LS65Speed said:

Got some pics of the engine and the car? Love to see any pics you have.

Both cars are in this thread. Lot of pics, and a lot of side tracking, but that tends to happen here a lot. I have a bunch of actual photographs of the engines as they came from the crate (back in the late 80's, complete with the black paint, 'Special Parts Notice' sticker on the valve cover, the XAA engine code, and the installations. I haven't converted those pics to digital yet, on the long list of things to do before I die.

https://www.firstgenmc.com/forums/index.php?/topic/19368-new-guy-here/#comments

 

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2 hours ago, Montemedic said:

Very nice build. What are your plans for it? Can you post the dyno sheet with the hp and torque numbers? 

Yup, I will.  He printed a couple of the pulls, then just gave me a thumb drive with all of them, but my pc didn't like 1 of the files and deleted it. Now I cant view any of them.  I will take a picture of 1 and load it

 

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6 minutes ago, riverdogs00 said:

Yup, I will.  He printed a couple of the pulls, then just gave me a thumb drive with all of them, but my pc didn't like 1 of the files and deleted it. Now I cant view any of them.  I will take a picture of 1 and load it

 

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20 hours ago, Montemedic said:

Very nice build. What are your plans for it? Can you post the dyno sheet with the hp and torque numbers? 

Good morning - I missed this question, and still am learning the nuances of posting and replying - I've primarily just lurked in the past.  The engine was the primary focus on this build. I've been looking for one since I fist read about it in a parts magazine in 81' (same year as I saw a picture of the SS 454 monte carlo and knew I would have one some day). I just love old factory muscle (all brands), all of the advertising and claims that went with them, and the whole vibe of that scene. The cammers,  super dutys and ram airs, the ardun conversions for the flat heads, etc...

 Once the engine was acquired, then the search for the right vehicle to put it into went into motion. What I really wanted was kind of a day 2 look.  I wanted original paint and interior, and for the car to look like someone had bought a car new, and swapped engines the same year.  Tasteful, period correct mods, manual trans, etc.   After looking daily for 18 months nation wide, I just was beginning to realize I could not afford what I wanted, and low and behold this 1970 car came up for sale 2 miles from the house. Its been repainted, but is severely faded, and pretty straight and original. It was a 350/250hp / turbo 350 / 10 bot car. Engine and trans out of it, and the guy was doing an LS swap. He wanted 8k.  I bought it for 6k, and let him keep the LS, but I took the original drivetrain. Sold the entire drive train to a buddy that's looking for the right body.

I decided to go with a 9" rear vs the 12 bolt simply out of cost, and ease of gear changes down the road. Its the only main deviation from the original plan. Its a Quick performance unit with 4.11's, trutrac, 35 spline axles, 1350 yoke and upgraded center section. Disc brakes were added when it became apparent that the drums they provided would have necessitated cutting off brackets and rewelding...then it would have to be re powder coated (well it should anyway). I've replaced the passenger floor pan, replaced all of the body bushings, converted to manual brakes (did not want to run a vacuum pump or reservoir), new wheels and tires, built all new brake lines, removed the AC, converted the pedal assemblies to manual, and am presently going through the column replacing the ignition switch/turn signal switch, etc... I'm maintaining the original interior (cloth bench). Yhe front will have a blanket on it due to wear and deterioration, the rear looks great, just faded. Carpet is waiting to go in, once I get the tunnel cut and hump installed.

The transmission is a M23. its an upgraded version of the original M22 purchased through https://midwestmuncie.com/ .   presently I am still waiting on this unit, having ordered it in November. They are waiting on the main case from  https://www.autogear.net/motorsports/  .   The engine is dyno'd and tuned. and ready to drop in, now that I finally have the headers as well. Hopefully the engine will go in, in the next week or 3. the car is just going to be a fun weekend burnout toy, and romp around machine. It runs off of $10/gallon 100 octane I can get at the pump here, so its no highway cruiser. My blue SS454 car is my other weekend cruiser, so will be fun to change it up.  Thats where Im at.

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12 hours ago, Tmac said:

Thanks for sharing this! 

Happy to. I've actually had this very post/idea in my head for the past 10 years, simply because there is nothing out there on some of these old Factory engines. everyone modifies them, and then, well, its not original anymore.  

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  • 2 weeks later...

Group,

The motor trend article came out for this engine.  I wish they would have contacted me first, as I found 2 errors, but the meat of it is there.   There was not 6 qts of oil put in it, and GM never rated it at 522 HP. It was factory rated at 465.

https://www.motortrend.com/how-to/original-454-ls7-big-block-chevy-crate-engine-dyno-westech/

 

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  • 5 months later...

Engine is installed, 4 speed in, and now starts, runs , shifts (on jack stands ).  The car has the original fabric bench which i want to keep. the front of course is trashed, hence the blanket. will just use that as I sort out the mechanicals as they come up. 

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3 minutes ago, MC1of80 said:

Moving along nicely!

Ty !  Now If I can get the coolant to stay in the radiator, then I will be almost home free.  I did not buy a new, nor check the old SBC rad that came with the car (3 row/AT).  It had a small leak which i fixed with JB weld, and was hoping to use it to get all sorted out before i drop $$$ on a nicer, more correct unit.  I'm running straight water for now just to get dialed in. The water that purges out of the rad is dark. Blackish. I presume its just residual oil in it, so am trying to flush.  what I dont get though, is that I fill it, run the car and can see the water circulating through the radiator. I left 3-4" of room in it, and as the temp comes up, the level simply overfills and out the neck. (I know it will expand, it just seems excessive). It will literally purge half the volume of the radiator. Was hoping to burp it, but need to keep the cap on to eliminate the resulting mess that comes after. I used a gallon jug as a temp catch can, and it will simply over fill that.  continuing to try and work through it

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  • 4 weeks later...

Coolant issue resolved, test drove vehicle for about a mile and all went well except brake lights which are now corrected. Decided to convert from rubber fuel likes to steel once I realized I would have a lot narrower hole in the hood.  Cut the hood - it went well. Waiting on the little vinyl pinch weld to finish trimming it. Once I had the piece cut out, I experimented with it as I could not tell if the grey color was a repaint, or simply oxidized original green. Turns out the only respray was on the front after a fender bender. The rest of the car has original paint which I love. Just scuffing with scotch brite and water for now. Once the car is all scuffed, then will re group and decide next steps - if any.

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Wow, this blog topic is so legendary and tons of great info. I have to share our build with you guys. 
 

We have an LS-7 my pops bought from 1991 over the counter. He’s had it ever since with no problems at all.(idk why but he immediately put a flat tappet cam in it 😕)

Recently, we decided to have the entire engine re-built, switched it up, and went with a big Howard’s hydraulic roller cam, .680 lift, 247/252 duration @ .50 lift. Kept the original 990’ heads which now are ported/polished, new valves, 4 angle valve job. Edelbrock Jr. Mid rise single plane intake, Intake is match-flowed to the heads 😎, Hooker 1 7/8 inch super comp. headers down to 3 inch collectors, 950 Holley double pumper carb. 
 

I’m not sure how much power we are pushing but I’m going to say it’s probably the same range as the dyno graph shared by Riverdogs00. If I can figure out how to share pictures and videos to this chat, I’ll share everything we have on our engine. It’s in a 70’ Nova with a TH400, 12 bolt rear end, 4.10 gears.

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  • 2 weeks later...
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Licensed / insured / and turn key now. That was the goal for this year - happy its accomplished.  Next year a radiator upgrade and maybe coil overs / drag radials.  we will see. for now, fun to fire it up and continue to break in the trans and rear diff.

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  • 3 months later...

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