LS7

[avdoc]

I purchased a '64 chevelle drag car with a 427 crate motor from GM Performance parts. The code suffix is XCH with means it is a LS7. It has a Edelbrock C427X intake. The car supposedly ran 11's in 1/4. Does anyone know about these motors, and are they worth keeping?

[427TJ]

Wouldn't a C427X fit any Mark IV BBC with rectangular ports? If it's an LS7 then it's a 454. Sounds like a crate LS7 with a C427X intake. (However, I didn't check the pad code "XCH.") Sounds like a nice piece to have, especially if it's still standard bore and not damaged internally. 12.5 LS7 pistons and that 320 duration cam are a bit too much for 92 octane pump gas though. As far as keeping it, it's getting so that any old big-block (Mark IV short deck) is worth keeping. Another 10 years and guys will be throwing money down for 2-bolt oval-port engines. Look at what happened to small-blocks. Suddenly a 283 or 327 is something everyone wants, especially rat rodders. As this stuff gets old it becomes gold. (Rhyme not intended.)

[KENNY_PASCOE]

HAD A CRATE LS7 IN MY 70 CHEVELLE STREET CAR YEARS BACK. WITH A EDELBROCK INTAKE AND A 850 CFM HOLLEY IT WENT 11.0 AT 120 THRU FLOWMASTER MUFFLERS IN A 3600LB CAR. CANT BEAT A LS7... KP

[RichSchmidt]

Dependint on the date,it could be worth a lot.If it is a 512 block dated in 69,it could be made into a C.E. motor or even restamped for some unscrupulous collector.as far as regular bigblocks being worth something.I pay about $600 for a late 70's or 80's 454 truck motor from the junkyard with just a promise hat the block is at least rebuildable.I tried to get my hands on a 1974 impala 454 with a thinwall 2 bolt block,nodular heads,and large oval ports,and the engine was stuck and hadnt run in years,and there was no promise of rebuildabilty,I offered $500 for it and they guy laughed at me.It turns out he got over a grand for it.I know a guy who payed $350 for a set of junkyard worn out 049 casting heads.The going rate around me for any 454 bare block in washed out shape is $500 and up.Not a vintage 512 block,or a tough 289 block,but rather a used up old 445 or 959 block.This stuff is being gobbled up by street car guys and racers.

[avdoc]

Let me clarify this motor. It has 12.25:1 compression open dome pistons, XCH block, factory balanced forged crank, factory balanced pistons, factory titanium intake valves, and was supposedly cast in 1970. Word is these were going to be installed in the '70 Yenko chevelle's, but were not for some reason. How I ended up with it, I don't know. But supposedly has 465 Hp. I know everything is true but the Yenko bit, and the Hp rating. I really do not know much about these motors, but wandered if anyone else knew more. I have all the codes off of it, but most do onot decode off the regular build codes. And the car was built in CA in 1970, and who ever converted it knew what they were doing. I just am trying to figure out what I have. any help would be greatly appreciated.

[Keith Tedford]

I think GM had plans for the LS7 engine but cancelled. They also cancelled plans for the LS6 in the Camaros. The Camaro parts catalogues showed the parts but the cars weren't built. The LS7 was the 454 version of the L88. I don't think that the original valves would be Titanium. Don't think anyone was making them back them.
I have an Edelbrock C427X intake and it is/was Edelbrocks rectangular port intake. They flowed about the same as the Chevy intake. The C396X was the oval port version.

[cheveller]

just bought one for 4000 canadian,with the original bill of sale ,minus cam,lifters,oil pan and intake.All still original and standard bore,but it came with stainless valves.