First timer Head Gasket replacement
Le Mans Master
Joined: Jun 2004
Posts: 6,231
Likes: 65
From: Seattle WA
St. Jude Donor '14
Interpreting what was said above, stock pistons are usually about .020 or so down in the bore. Adding an .040+ gasket makes for quench (the distance between the top of the piston and the cylinder head) about .060+. Best power (and lower detonation sensitivity) in a GEN I SBC comes from a quench of about .040 or so...so ideally you'd have a thinner gasket.
OTOH, those gaskets will work fine. There's about .5 point CR difference between the two gaskets, and while it's worth getting CR when we can - especially for engines like yours with relatively low CR - it's not a HUGE difference.
OTOH, those gaskets will work fine. There's about .5 point CR difference between the two gaskets, and while it's worth getting CR when we can - especially for engines like yours with relatively low CR - it's not a HUGE difference.
Last edited by billla; Aug 30, 2011 at 10:59 AM.
Le Mans Master
Joined: Apr 2006
Posts: 5,403
Likes: 95
I blew the head gasket when the water pump failed and I'm going to be a first timer pulling the heads on my '78 L48. I'm kind of excited to learn more, and understand that if I HAD to perform this HG replacement on any vehicle in the world, the Chevy 350 is probably the best to start on.
I'm ordering parts from zip-corvette.com today. Getting this kit and replacing all the gaskets while I'm at it (Part# EN-100) : http://www.zip-corvette.com/ProductD...L2-SR&CTitle=&
I've never done this deep in an engine before. The limit of my mechanical ability in the past has been things like replacing components like water pumps, fans, alternators, distributor caps, plugs, brakes, etc... basic to moderate auto maintenance. I think I have the aptitude for it (and a good shop manual), but I'm hesitant to try and pull this off all by myself.
I'll try and take pictures along the way and show the progress, but for right now I'm planning on beginning the tear down and rebuild within the next week.
I do not think I'll have the heads checked to see if they are true, as the engine was rebuilt before I got it a while back (by the paint on the block I would suspect about 5-10 years ago).
I have an oil leak at the pan, so I'm replacing the gasket there too, which comes in the kit.
Any pitfalls I should think about before undertaking this? Anything else I should consider doing while I'm in there with the engine all torn apart? My budget is around $200 for the whole job.
I'm ordering parts from zip-corvette.com today. Getting this kit and replacing all the gaskets while I'm at it (Part# EN-100) : http://www.zip-corvette.com/ProductD...L2-SR&CTitle=&
I've never done this deep in an engine before. The limit of my mechanical ability in the past has been things like replacing components like water pumps, fans, alternators, distributor caps, plugs, brakes, etc... basic to moderate auto maintenance. I think I have the aptitude for it (and a good shop manual), but I'm hesitant to try and pull this off all by myself.
I'll try and take pictures along the way and show the progress, but for right now I'm planning on beginning the tear down and rebuild within the next week.
I do not think I'll have the heads checked to see if they are true, as the engine was rebuilt before I got it a while back (by the paint on the block I would suspect about 5-10 years ago).
I have an oil leak at the pan, so I'm replacing the gasket there too, which comes in the kit.
Any pitfalls I should think about before undertaking this? Anything else I should consider doing while I'm in there with the engine all torn apart? My budget is around $200 for the whole job.
Melting Slicks
Joined: Jul 2009
Posts: 3,264
Likes: 3
From: Vero Beach FL
When you pull the heads if its been rebuilt maybe you will get lucky someone replaced the dished pistons. But if not and block not decked you will have roughly 7.5 compression using .041 gasket if your resusing your heads. With all the labor your putting into this chunk the .041 gasket.
Le Mans Master
Joined: Jun 2004
Posts: 6,231
Likes: 65
From: Seattle WA
St. Jude Donor '14
The goal is around .040 quench and < 10:1 CR to run on pump gas with full ignition advance.
It's important to measure how far the pistons are down in the hole, be able to estimate fairly closely what the CR will be, and be sure you'll have no issues with valve/piston clearance *before* you start messing around with thinner gaskets.
On a stock engine with a stock or mild cam, no issue and something around .020 is fine - but on anything that's been overhauled just to swap to a thin gasket can be an expen$ive mistake. This is where "blanket" advice can get someone in trouble without full context...
It's important to measure how far the pistons are down in the hole, be able to estimate fairly closely what the CR will be, and be sure you'll have no issues with valve/piston clearance *before* you start messing around with thinner gaskets.
On a stock engine with a stock or mild cam, no issue and something around .020 is fine - but on anything that's been overhauled just to swap to a thin gasket can be an expen$ive mistake. This is where "blanket" advice can get someone in trouble without full context...
Last edited by billla; Aug 30, 2011 at 08:14 PM.
Thread Starter
Instructor
Joined: Dec 2010
Posts: 106
Likes: 0
The goal is around .040 quench and < 10:1 CR to run on pump gas with full ignition advance.
It's important to measure how far the pistons are down in the hole, be able to estimate fairly closely what the CR will be, and be sure you'll have no issues with valve/piston clearance *before* you start messing around with thinner gaskets.
On a stock engine with a stock or mild cam, no issue and something around .020 is fine - but on anything that's been overhauled just to swap to a thin gasket can be an expen$ive mistake. This is where "blanket" advice can get someone in trouble without full context...
It's important to measure how far the pistons are down in the hole, be able to estimate fairly closely what the CR will be, and be sure you'll have no issues with valve/piston clearance *before* you start messing around with thinner gaskets.
On a stock engine with a stock or mild cam, no issue and something around .020 is fine - but on anything that's been overhauled just to swap to a thin gasket can be an expen$ive mistake. This is where "blanket" advice can get someone in trouble without full context...
Thread Starter
Instructor
Joined: Dec 2010
Posts: 106
Likes: 0
We pulled EVERYTHING but the heads tonight. A few things to note were that we are going to have to remove the headers to get down the head bolts. They are just simply too much in the way... but that is good because I am going to go get them blasted and having the coated in a chrome high-temp paint to get that "rusty" look off of them.
Here are some of the pictures:
Checking out the choke on the carb:
Getting ready to pull the Holley carb. We found out that it is practically brand new after wepulled it:
Pulled the carb successfully. We labeled everything and anything we could:
Pulled the distributor next to be pleasantly surprised that it had been rebuilt! Nice grease on it and threads looking great.
Next I pulled off the valve covers to expose the rockers:
Close up of the rockers:
Successfully pulled off the Holley Intake Manifold. It's in great condidtion!
I replaced the thermostat thinking it was originally the problem, so here it is a week after I just put it in
Looking down on the engine, you can see coolant/oil mix:
Pulled the rockers and push rods, securely labeled them all in nice little baggies
Here are some of the pictures:
Checking out the choke on the carb:
Getting ready to pull the Holley carb. We found out that it is practically brand new after wepulled it:
Pulled the carb successfully. We labeled everything and anything we could:
Pulled the distributor next to be pleasantly surprised that it had been rebuilt! Nice grease on it and threads looking great.
Next I pulled off the valve covers to expose the rockers:
Close up of the rockers:
Successfully pulled off the Holley Intake Manifold. It's in great condidtion!
I replaced the thermostat thinking it was originally the problem, so here it is a week after I just put it in
Looking down on the engine, you can see coolant/oil mix:
Pulled the rockers and push rods, securely labeled them all in nice little baggies
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)
Joe Kucinski
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
10 Revolutionary 'Corvette Firsts' Most People Don't Know
Joe Kucinski
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2
Michael S. Palmer
2027 Corvette vs The World: Every C8 vs Its Closest Competitor
Joe Kucinski
10 Most Common Corvette Problems of the Last 20 Years!
Joe Kucinski
Instructor
Joined: Sep 2010
Posts: 229
Likes: 1
From: Grants Pass Oregon
Once you get the heads off and see what you have,then make up your mind. My '78 l48, had been rebuilt at some point. Dished pistons had been replaced with flattops. I had a cracked head so when i got a pair of new heads { 76 cc } i used 1094 Gaskets. .15= 3.2 cc's.
Le Mans Master
Joined: Apr 2006
Posts: 5,403
Likes: 95
if you read what i said if the pistons are down block not decked pistons can be down .020 generally more then that have seen them .032 down.
Then you use what the factory did .018 thick gasket. .015 are easy to find.
Then you use what the factory did .018 thick gasket. .015 are easy to find.
Last edited by Little Mouse; Aug 31, 2011 at 10:57 AM.
Thread Starter
Instructor
Joined: Dec 2010
Posts: 106
Likes: 0
Le Mans Master
Joined: Jun 2004
Posts: 6,231
Likes: 65
From: Seattle WA
St. Jude Donor '14
Thread Starter
Instructor
Joined: Dec 2010
Posts: 106
Likes: 0
I'm started to get excited about all of this. We're not going to be able to work on it this weekend, so I've got some ideas on what I can do in the meantime.
#1 - I want to paint the headers. Anyone have good experience with this? They're pretty rusty right now and look like crap. Tips/tricks? I've read alot about it and it seems like I need to bake the suckers after prep/paint. Would it be better just to give them to someone and have them do it in a shop?
#2 - Considering painting the Holley Intake? It looks decent, and may look a lot better after I degrease and clean it up, but if I wanted to paint it with high-temp... any experience/suggestions? Or am I stupid?
#1 - I want to paint the headers. Anyone have good experience with this? They're pretty rusty right now and look like crap. Tips/tricks? I've read alot about it and it seems like I need to bake the suckers after prep/paint. Would it be better just to give them to someone and have them do it in a shop?
#2 - Considering painting the Holley Intake? It looks decent, and may look a lot better after I degrease and clean it up, but if I wanted to paint it with high-temp... any experience/suggestions? Or am I stupid?
Melting Slicks
Joined: Jul 2009
Posts: 3,264
Likes: 3
From: Vero Beach FL
I'm started to get excited about all of this. We're not going to be able to work on it this weekend, so I've got some ideas on what I can do in the meantime.
#1 - I want to paint the headers. Anyone have good experience with this? They're pretty rusty right now and look like crap. Tips/tricks? I've read alot about it and it seems like I need to bake the suckers after prep/paint. Would it be better just to give them to someone and have them do it in a shop?
#2 - Considering painting the Holley Intake? It looks decent, and may look a lot better after I degrease and clean it up, but if I wanted to paint it with high-temp... any experience/suggestions? Or am I stupid?
#1 - I want to paint the headers. Anyone have good experience with this? They're pretty rusty right now and look like crap. Tips/tricks? I've read alot about it and it seems like I need to bake the suckers after prep/paint. Would it be better just to give them to someone and have them do it in a shop?
#2 - Considering painting the Holley Intake? It looks decent, and may look a lot better after I degrease and clean it up, but if I wanted to paint it with high-temp... any experience/suggestions? Or am I stupid?
There is a aluminum paint just for intakes. I bought some at Advance last year. It will make the intake look like new.
Thread Starter
Instructor
Joined: Dec 2010
Posts: 106
Likes: 0
Pulled the heads last night! Here are some pictures:
My 5-year-old son helped jack up the car. We had to jack it up pretty far the get the headers off
Pulled the heads!
This is where the head gasket was blown:
My 5-year-old son helped jack up the car. We had to jack it up pretty far the get the headers off
Pulled the heads!
This is where the head gasket was blown:
Instructor
Joined: Sep 2010
Posts: 229
Likes: 1
From: Grants Pass Oregon
Good pictures and even better, your pistons have been changed. You might want to go with thinner headgaskit.
