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it’s been a while since I’ve posted here but I’m finally back on track with my 73 L82 Vette’s engine replacement/upgrade project.
About two years ago I bought an LT-1 warranty replacement (CE) short block with all its forged components from the C3 parts section here. This was all before Covid hit and my all too busy engine builder having time for me. During this time, I had been purchasing parts for what I was originally planning on an LT-1 type engine build but without solid lifter cam. With the LT-1 being the precursor to the L82 model engine it seemed like a fitting tribute for its replacement of the existing non-original gutless engine (w/wrong casting #, 512 vs. 010 block).
My engine builder and the machine shop suggested dumping the domed pistons and going with the flattops which he did. He said it looked to him like the engine had never been fired before. The bores are 4.0” and no evidence of wear just some surface rust which he honed out. There was evidence that the engine had gone through a machine shop before though. He said the deck was off some 50 thou in the corners so the shop decked it and he said it turned out well and is now a zero-deck engine.
The parts list includes Summit Racing’s flattop pistons (Speed Pro’s?), Comp Cam 268HE hyd FT & lifters, Dart’s entry level aluminum heads, mostly all ARP bolts, new Performance Chevy Holley 770 carb (also bought here), old school aluminum Winter’s intake, aluminum valve covers, etc. etc.
He was supposed fire it off this week, but he just texted me to say he needs “stuff to connect the exhaust”. I bought what I thought were some cheap headers for this but ended up being just some extender pipes!?, so I gave him the old cast manifolds to use. Not sure what he needs to connect? He has a running stand that he
This has the 5 qt. oil pan with the trapdoor so I’m going to have to modify my steering to accommodate it. I currently have the 4 qt. pan with factory power steering but I’m going with the Borgeson conversion so I’ll scrap the factory stuff and may have to replace the center link but hopefully that’ll work. Optionally, I have a 4 qt. pan with shorter windage tray from a 72 LT-1 I can use if I must.
I also have a March front runner system designed for the C3’s so there will be some additional “while you’re at it” things to do. Like replacing the Rad with an aluminum unit, upgrading the ac components, replace the power cable to the alternator with a larger gauge wire, etc.
As I’ll be retiring in a month, I’ll should have more time to work on the Vette!
Here’s some pictures of the before and after (so far).
Best to all! LT-1 CE Short Block Zero Decked Assembly Progress Getting Closer!
afaik, seems 17351C piston is not forged (as OE LT1) but is hypereutectic ...
...and does not have 1.560" compression height (as OE LT1) but has much shorter 1.540" CH. That's a budget rebuilder piece.
Block appears to be decked but also appears head bolt holes may not have been chamfered with adequate lead-in.
Was Your LT1 returned to you with Your OE LT1 Forged crankshaft ? Did you Verify ?
Was this Assembly Balanced ? Have you seen or copied the balance sheet ?
EbbnFlow,
Thanks for the feedback,
Yep, knew they were hypereutectic, less noisy I've heard, it's ok.
Gotcha.
Good catch on the deck holes, didn't think of that, don't know if he did that before assy, I'll ask.
Forged crank still in there and looked good, so did the bearings, but he replaced them anyways.
Engine was previously balanced, but no didn't see the sheet, I'll ask.
"As I’ll be retiring in a month, I’ll should have more time to work on the Vette!"
Pssssst.....don't tell your wife you are retiring.
Just leave your house the same time every day.....
sneak back into your garage.....
work quietly on your Vette "until it's time to clock out"......
My engine builder got the engine fired yesterday. What do you think? He says that the Holley doesn't want to idle under 1k. Thinks it might need a smaller power valve? It's a 770 cfm model from Performance Chevrolet. I never used Holley carbs before but read up on this on Holley's website some last night. Also, he said the B&M flex plate runout was not good, so he was going to pull it and double-check alignment, etc. Could be out of spec from manufacturing? I'll just get another/different one in need be. He also commented that it had good throttle response. The old school Winters intake looks like it's got taller runners than the eddy performer that's on the engine in the car.
Yes, the new cam has a bit lower vacuum, builder said it was around 13 – 15 which is probably ok. He did change the pv to a 4.5 inches unit and which he thinks improved how it runs.
I remember when I was re-building my 427 and I wanted a "Forged Crankshaft" as my old one had some "tiny" stress cracks. We kept buying them and having them Magna-fluxed to check for any cracks. I was using high compression so I wanted a crank with Zero cracks. It was either the 9th or 10th crank we finally bought as it was perfect. Finding an aftermarket BB crank in the early 1990's was expensive so I stayed with stock Forged crank.
Forged Crank, Forged Connecting Rods and Forged Pistons help with the compression and hopefully longevity.
Good Luck with your new to you engine! Take a good picture of it and put it on your Christmas Cards! My builder used my engine as a "showpiece" at his shop for the annual Christmas Party he held. The engine was in the center of his shop while he and I built it. He could have sold my engine a dozen times before I hauled it out and put it into the Corvette. It was Gorgeous like your new engine IS!!
Stock 6.5 pv is just fine that ones too small.
Maybe a touch of fine tuning will take care of things, may or may not need a hair more initial timing
That cam/heads/intake combo should make good torque on the street. Hard to go wrong with the 268
ctmccloskey,
427, nice! My last Vette had the 454 engine, gotta love that low end torque! Yes, engine is looking good, thanks!
gkul,
The engine builder is a long time former colleague from work, millwright by trade, builds lots of engines for family, friends and former colleagues like myself, very trustworthy person. More of a Ford guy though. Yeah, not up to speed on pv's yet and their interaction, something for me to research more. I'll probably put the original one back in. Carb was cheap to me, at 770 it's close to what would have been on this period correct engine. I believe my stock Rochester Quad is rated at something like 800. I hope this to be more of a performance engine with this build. Thanks for the info on modern forged pistons, I can always change them down the road.
cv67,
Gotcha, I have lots of options. Once I get the engines swapped out I've got my original Rochester that runs perfectly that I can put on to do a comparison test, also got a little 650 eddy I can play with. But I'll try the various suggestions here on the Holley first. And, yes I hope that combo of parts, etc. gives me the performance I'm looking for!
I really appreciate the information, help, feedback, and even the occasional flaming as I continue to learn from you all on this forum!
You can read up on the circuits of a carb. Generally if someone told me that they can't get the idle speed down on a new install. I would look into vacuum leaks. Air increases idle rpm
Vette Engine Project Back on Track
