1969 Engine/Trans rebuild
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Burning Brakes
Joined: Sep 2006
Posts: 1,079
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From: Columbus NJ
1969 Engine/Trans rebuild
Hello all, I have a 1969 numbers matching 350/300 motor and a 4 speed, not sure which model, I haven't looked at any of the stampings yet. It has 51,xxx original miles and hasn't been together since the later 70's. I'm restoring the whole car body off and it only makes sense to get all my mechanics rebuilt. I was thinking about giving my motor to corvette paramedics to rebuild because they're literally 3 miles away from my house and my transmission to one of my fathers friends who is about 12 miles from me, certified reputable shop etc. Does any one have any suggestions where to go for the greatest deal, I don't need anything fancy, maybe a higher lift cam and forged internals. I appreciated the upcoming advice! 
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Le Mans Master
Joined: Oct 2006
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From: Gladstone MO
C3 of Year Finalist (appearance mods) 2019
After setting since the late '70's, maybe some new seals.
If you're wanting to go back to brand new and the numbers all match on the parts you have, maybe think about getting a crate engine and running that. Just the cost of rebuilding your original will nearly cover a crate engine. If you decide to go with rebuilding your original, be SURE and tell rebuilder, and get it in writing with the shop owners signature, that if the deck the block and remove all the numbers from the stamp pad, they owe you.
Thread Starter
Burning Brakes
Joined: Sep 2006
Posts: 1,079
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From: Columbus NJ
I don't want to do a crate motor because it's ALL original, all numbers matching, all dated parts etc. I want to rebuild because it's over 40 years old and has been sitting since the late 70's. I'm doing a frame/body off restoration. I have to take everything apart and I'd rather spend a few grand prior to completion than to have it all back together and have something go wrong and take the chance of damage to the finished car. As far as the decking of the block, I've heard that it's possible to deck it at a slight angle to avoid the numbers and matching the reverse angle on the head, not sure how valid that is.
Le Mans Master
Joined: Oct 2006
Posts: 7,123
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From: Gladstone MO
C3 of Year Finalist (appearance mods) 2019
I understand your point- and appreciate it.
I've not heard about decking the block like you describe. Myself, I'd be careful about doing anything "odd" like that. Down the road somewhere it could cause problems if you forgot which head went where. As they left the factory, heads would fit either side and everything would swap side to side.
And no more miles that you have, unless you're trying to squeeze every bit of performance you can get out of it, you may not even have to deck, provided it's all flat. I can't recall all of the SBC's I've built that went to the machine shop for a hot tanking and cam bearings only. Never even checked the deck height or anything. And everyone of them ran just fine in some pretty "abusive" situations.
I've not heard about decking the block like you describe. Myself, I'd be careful about doing anything "odd" like that. Down the road somewhere it could cause problems if you forgot which head went where. As they left the factory, heads would fit either side and everything would swap side to side.
And no more miles that you have, unless you're trying to squeeze every bit of performance you can get out of it, you may not even have to deck, provided it's all flat. I can't recall all of the SBC's I've built that went to the machine shop for a hot tanking and cam bearings only. Never even checked the deck height or anything. And everyone of them ran just fine in some pretty "abusive" situations.
Race Director
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I don't want to do a crate motor because it's ALL original, all numbers matching, all dated parts etc. I want to rebuild because it's over 40 years old and has been sitting since the late 70's. I'm doing a frame/body off restoration. I have to take everything apart and I'd rather spend a few grand prior to completion than to have it all back together and have something go wrong and take the chance of damage to the finished car. As far as the decking of the block, I've heard that it's possible to deck it at a slight angle to avoid the numbers and matching the reverse angle on the head, not sure how valid that is.
Do NOT disassemble the engine just for fun, do it for proven cause only.
Thread Starter
Burning Brakes
Joined: Sep 2006
Posts: 1,079
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From: Columbus NJ
I may just have a builder inspect the internals and replace what's worn and keep what's good for the most beneficial and economic solution. I just don't want to put it all back together and have something go wrong that could've been prevented, you know. It's really low miles so I can assume that it doesn't need to be completely rebuilt, but seals definitely as well as carb rebuild.
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Melting Slicks
Joined: Aug 2005
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From: Working on the car NY
(for the most part). You could pull the heads and check the condition of the lifters. Mine were scored at 90K miles. An insignificant minor cost might be a new timing chain and gear but at 50K, it's probably not needed either - but what the heck.
Melting Slicks
Joined: Feb 2006
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From: Japan
Honestly, if you just want to make sure everything's in decent working order just do a leakdown test on the engine as it sits. If no problems are indicated and you're happy with the way it runs already there is not one good reason for tearing into that motor. Handing it to a machinist is an invitation to months of frustration and potential disaster. Don't ask me how I know this...
Melting Slicks
Joined: May 2009
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2024 C3 of the Year Finalist - Unmodified
Doing a complete frame off restoration on an original car and ignoring an engine that hasn't run in over 30 years doesn't make much sense. Spend the effort and if necessary the money now, while the car is apart, or be prepared to do it all over again later. You either trust who you give your parts and money to or you don't. If you can't find anybody trustworthy, then you probably shouldn't be restoring an old vette.
My engine had been sitting for 20 years with 56k miles when I bought it in 2004. First the water pump started leaking, front seal leaking, rear seal leaking, timing chain ready to let loose, valve stem seals gone, internals heavily varnished. Fast forward to 2009. Annoying blue smoke out the exhaust, constant engine and tranny oil on the floor and then the ticking started. After the clutch broke, decided to pull the engine, tranny and begin restoring the car. My trusted machinist found two stuck lifters, wiped cam and one broken piston ring. The tranny needed a new 2nd gear, synchros, thrust bearing and seals. With upgraded parts and a total rebuild/blueprint, my engine sounds and performs great...undoubtedly better than when it was new.
My engine had been sitting for 20 years with 56k miles when I bought it in 2004. First the water pump started leaking, front seal leaking, rear seal leaking, timing chain ready to let loose, valve stem seals gone, internals heavily varnished. Fast forward to 2009. Annoying blue smoke out the exhaust, constant engine and tranny oil on the floor and then the ticking started. After the clutch broke, decided to pull the engine, tranny and begin restoring the car. My trusted machinist found two stuck lifters, wiped cam and one broken piston ring. The tranny needed a new 2nd gear, synchros, thrust bearing and seals. With upgraded parts and a total rebuild/blueprint, my engine sounds and performs great...undoubtedly better than when it was new.
Le Mans Master
Joined: Jun 2004
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From: Seattle WA
St. Jude Donor '14
I think you're borrowing trouble on this one. As noted, the engine is really just broken in 
My recommendation would be to pre-oil the heck out of it and just run it. You certainly don't want to start mucking about with changing deck angles and all that madness.
If you really want a bit more power then stepping up just a bit from the factory cam would be a reasonable scope - something like the L-46 cam would be an ideal choice; a more modern cam would make more power, but the L-46 is still a very good cam. As part of that process, a good mechanic can pull the heads for a look and possible spring upgrade and valve seal replacement.
I certainly wouldn't go any further than that. I understand not wanting to pull the engine later if there are issues, but honestly it's not that big of a deal.
My recommendation would be to pre-oil the heck out of it and just run it. You certainly don't want to start mucking about with changing deck angles and all that madness.If you really want a bit more power then stepping up just a bit from the factory cam would be a reasonable scope - something like the L-46 cam would be an ideal choice; a more modern cam would make more power, but the L-46 is still a very good cam. As part of that process, a good mechanic can pull the heads for a look and possible spring upgrade and valve seal replacement.
I certainly wouldn't go any further than that. I understand not wanting to pull the engine later if there are issues, but honestly it's not that big of a deal.
Le Mans Master
Joined: Jun 2004
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From: Seattle WA
St. Jude Donor '14
My engine had been sitting for 20 years with 56k miles
First the water pump started leaking, front seal leaking, rear seal leaking, timing chain ready to let loose, valve stem seals gone, internals heavily varnished.
After the clutch broke
two stuck lifters, wiped cam and one broken piston ring. The tranny needed a new 2nd gear, synchros, thrust bearing and seals.
First the water pump started leaking, front seal leaking, rear seal leaking, timing chain ready to let loose, valve stem seals gone, internals heavily varnished.
After the clutch broke
two stuck lifters, wiped cam and one broken piston ring. The tranny needed a new 2nd gear, synchros, thrust bearing and seals.
But it is, after all, a Corvette - and so not meant to be driven with a light right foot
Melting Slicks
Joined: May 2009
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2024 C3 of the Year Finalist - Unmodified
Back in '69 my brother's '66 tri-power 442 started going thru a quart of oil every tank of gas and fouling plugs. Car had 60k HARD miles, some at the drag strip. When we pulled the heads, #1 piston was wobbling in the hole. Muscle cars were never meant to be babied and still be running around 42 years later.
Le Mans Master
Joined: Jun 2004
Posts: 6,231
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From: Seattle WA
St. Jude Donor '14
What might be interesting here is how you went about starting it. Did you pre-oil the engine? Squirt oil into the bores? Wet the seals? What oil was used? Might be too OT, but I'd be interested in the answer via PM
Melting Slicks
Joined: May 2009
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2024 C3 of the Year Finalist - Unmodified
I didn't. The PO's son fired it up. I changed oil when I got the car in 2004, but several pieces of valve stem seals were already in the crankcase as well as the nylon off the timing gear teeth. Using low zinc/phosphorous Castrol and Shell products until the lifters started ticking in 2009 probably sealed the deal. The heavy varnish (seen on the internals when I dropped the pan) probably played a part with one lifter being stuck in the hole and having to be knocked out. The piston ring was probably broken when it was fired. Sure caused the .030 overbore.
