1981 head gasket replacement
Thread Starter
Instructor
Joined: Apr 2019
Posts: 197
Likes: 26
From: Clifton, virginia
1981 head gasket replacement
Hey fellas,
I suspect blown head gasket and need to replace em. Hopefully it’s not the block. Did a test and blue liquid turned yellow so definitely exhaust fumes is getting into the coolant. However I drained the oil and it was fine, no milk shake. See no oil dripping from the engine. Popped valve cover, no signed of milk shake. No white smoke from tailpipe either.
my question is, after taking the rockers and pushrod out and replace the head gasket, when putting the rocker and pushrods, do I need to do a valve adjustment or just put them back on checking for slack and play? Do I need to use new head bolts or use the old ones?
thank you.
I suspect blown head gasket and need to replace em. Hopefully it’s not the block. Did a test and blue liquid turned yellow so definitely exhaust fumes is getting into the coolant. However I drained the oil and it was fine, no milk shake. See no oil dripping from the engine. Popped valve cover, no signed of milk shake. No white smoke from tailpipe either.
my question is, after taking the rockers and pushrod out and replace the head gasket, when putting the rocker and pushrods, do I need to do a valve adjustment or just put them back on checking for slack and play? Do I need to use new head bolts or use the old ones?
thank you.
Burning Brakes
Joined: Dec 2017
Posts: 1,043
Likes: 414
2023 C3 of the Year Finalist - Modified
Hey fellas,
I suspect blown head gasket and need to replace em. Hopefully it’s not the block. Did a test and blue liquid turned yellow so definitely exhaust fumes is getting into the coolant. However I drained the oil and it was fine, no milk shake. See no oil dripping from the engine. Popped valve cover, no signed of milk shake. No white smoke from tailpipe either.
my question is, after taking the rockers and pushrod out and replace the head gasket, when putting the rocker and pushrods, do I need to do a valve adjustment or just put them back on checking for slack and play? Do I need to use new head bolts or use the old ones?
thank you.
I suspect blown head gasket and need to replace em. Hopefully it’s not the block. Did a test and blue liquid turned yellow so definitely exhaust fumes is getting into the coolant. However I drained the oil and it was fine, no milk shake. See no oil dripping from the engine. Popped valve cover, no signed of milk shake. No white smoke from tailpipe either.
my question is, after taking the rockers and pushrod out and replace the head gasket, when putting the rocker and pushrods, do I need to do a valve adjustment or just put them back on checking for slack and play? Do I need to use new head bolts or use the old ones?
thank you.
if you can afford them, new head bolts are better. I have reused old but I prefer new.
Race Director
Joined: Jul 2015
Posts: 13,082
Likes: 3,399
From: SW Florida.
first, do the backyard a$$hole valve leak test. lay the heads on one side with intake or exh ports up. fill ports with water. flip over and do the other side. a couple of drips past the valve? lapping them will probably clean that up. peeing out? that valve at the very least is done. that seat could be bad. in that case they are going to a shop or scrap bin. now get a valve spring compressor. pop the valve springs. check the valve guides for looseness. a tiny bit of wiggle is acceptable. eyeball the valve seats for pitting. buy new valve springs and seals. maybe even 16 new valves. manley or ferrea. no ebay chinese crap. there is a positive seal that fits OE valve guides. umbrella for exhausts is fine. throw away the valve springs. they are 41 years old. now get some valve grinding compound and go to town on the valves and seats. redo the leak test.
Thread Starter
Instructor
Joined: Apr 2019
Posts: 197
Likes: 26
From: Clifton, virginia
I’m assuming this is a hydraulic lifter motor. You will need to set valve lash, there are several threads on it with different approaches. Essentially it’s just being each cylinder to TDC, remove the play between pushrod and rocker, and then an additional 1/2 or 3/4 or 1 whole turn. People have different preferences. I do 3/4.
if you can afford them, new head bolts are better. I have reused old but I prefer new.
if you can afford them, new head bolts are better. I have reused old but I prefer new.
Race Director
Joined: Jul 2015
Posts: 13,082
Likes: 3,399
From: SW Florida.
i have used head bolts over 5 times in the past on small blocks. they are torqued to a torque. and only about 55 to 70 lbs. subarus are torqued then cranked another half turn to stretch the bolt. that type is a one-use bolt. ARP head bolts are for 7000 rpm through the traps.
Burning Brakes
Joined: Dec 2017
Posts: 1,043
Likes: 414
2023 C3 of the Year Finalist - Modified
I use ARP bolts if it’s a higher HP motor, going to see high rpm’s a lot. Stock rebuilds I use stock components. For a SBC 350, I have never used thread sealer. Opinions may vary on this as well.
Last edited by randallsteel; Jun 25, 2022 at 07:45 PM.
Le Mans Master
Joined: May 2007
Posts: 5,009
Likes: 1,116
From: North tonawanda NY
I just pulled my intake after installing it a few weeks ago and found even though my oil looked fine the coolant ports were leaking into the oil galley. I just think its unlikely the head gaskets are your issue here (if you have a real issue) . What problem led you to do this test?
Last edited by augiedoggy; Jun 25, 2022 at 10:16 PM.
Thread Starter
Instructor
Joined: Apr 2019
Posts: 197
Likes: 26
From: Clifton, virginia
Good question. I have edelbrock high rise intake with fel pro. I didn’t know intake manifold leak can lead to exhaust gas in the coolant passage.
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Le Mans Master
Joined: May 2007
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From: North tonawanda NY
my understanding is crankcase fumes/ pressures are partially made up of exhaust fumes. (think breathers and pvc valves to help vent/remove this stuff especially if you have more blowby... That means that pressurized mess is in that galley where the intake gaskets are supposed to keep every passage isolated. rings are not 100% effective in sealing things.. reread my edited comments above.
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Before you go to far with this, And I can't believe no one has brought this up yet. Those stock heads are notorious for cracking. especially if the engine got hot.
If you don't find an obvious blown gasket and you know it's been hot. I would get those heads checked for cracks.
If you don't find an obvious blown gasket and you know it's been hot. I would get those heads checked for cracks.
Le Mans Master
Joined: May 2007
Posts: 5,009
Likes: 1,116
From: North tonawanda NY
Before you go to far with this, And I can't believe no one has brought this up yet. Those stock heads are notorious for cracking. especially if the engine got hot.
If you don't find an obvious blown gasket and you know it's been hot. I would get those heads checked for cracks.
If you don't find an obvious blown gasket and you know it's been hot. I would get those heads checked for cracks.
Race Director
Joined: Nov 2006
Posts: 13,150
Likes: 7,764
From: Sunshine Coast, Queensland, Australia
2025 C3 of the Year Finalist - Modified
2024 C3 of the Year Finalist- Modified
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Cruise-In VIII Veteran
I've owned 2 Corvettes with these heads. BOTH of them cracked both heads. I have Edlebrock heads for a reason.