zero compression
Safety Car
Joined: Nov 2008
Posts: 3,707
Likes: 550
From: Seattle Washington
Before You remove the other Head why not blow compressed air in the spark plug holes and see where the air goes. Assuming the Rockers are way loose and or removed we know all the Valves are closed or supposed to be. In this situation there shouldn't be any reason why it should leak a lot of air, probably a little but not a lot. The Pictures make the engine look old a tired if it has no compression then the air should gush out as fast as your putting it in. It should be very obvious what's wrong. Since You have one head off why not take a look at some of the lifters, and then look down the hole at the Cam Lobe. If You see any trouble there go straight to the Oil Filter remove it and cut it open and look for metal.
Thread Starter
Pro
Joined: Jul 2020
Posts: 642
Likes: 104
From: Miami florida
some excellent advice thank you. the lifters I placed new. I looked in there after removing the old ones and didn't see anything particularly wrong. I will try the compressed air trick. thank you will report back.
2026 Loser of the Year
Joined: Sep 2013
Posts: 36,491
Likes: 6,968
From: New Or-leens Loo-z-anna
As for the crud...it seems normal for an 8 cylinder "smog pump".. Some Lucas/Seafoam/etc in the gas tank and down the carb would have removed all the crud *if the car could make it 5 miles down the highway and back .
Shouldn't O.P. be able to see the tops of intake and exhaust cam lobes at T.D.C.with a bright flashlight while the head is removedon the passenger side?
It's not easy to diagnose an engine problem on the internet. We keep going back to the camshaft, but a valve leak test will answer the other questions.
Le Mans Master
Joined: May 2007
Posts: 5,007
Likes: 1,114
From: North tonawanda NY
Yeah I dont understand how this could be anything other than the rockers not being adjusted correctly. there is no damage or marks on the valves or pistons from any type of mechanical strike as there would be if it hasnt ran since the problem began... And everything you described sounds like the valves arent opening and closing when they should properly. were the new lifters the same length as the old ones? did you use the same pushrods? did you soak the lifters in oil or pump them up with oil? (Not that it necessarily needs to be done).
Last edited by augiedoggy; Apr 6, 2021 at 06:51 AM.
Dr. Detroit
Joined: Mar 2012
Posts: 10,090
Likes: 4,015
From: New Braunfels Texas
You need to find someone to diagnose and repair this for you. You are 100% doing something wrong, and it is 100% the valve lash and/or cam timing. There is simply NOTHING else it can be. NOTHING. There is no damage to the valves or the pistons...to have zero compression you would have to have a hole in the piston or a stuck bent valve or the valve are hung open because of incorrect cam timing or improper lash.
BTW...never soak lifters in oil before installation.....it will hang the valves open for several revolutions until it settles and the engine will not start.
Verify cam timing and set lash via the TDC method starting at #1.......the answer is here.
Jebby
BTW...never soak lifters in oil before installation.....it will hang the valves open for several revolutions until it settles and the engine will not start.
Verify cam timing and set lash via the TDC method starting at #1.......the answer is here.
Jebby
Last edited by Jebbysan; Apr 6, 2021 at 07:27 AM.
Le Mans Master
Joined: Aug 2017
Posts: 8,336
Likes: 2,809
From: Cool Northern Michigan
Every time someone says they don't want to spend over a $1,000 on a pair of heads, those posters tend to show an option that in their eye is much cheaper.
For example:
Acme Anvil Iron head, BARE,
$320 EACH
So now you're at $640 pair.
How much is a set of valves?
How much is a set of springs?
Retainers?
Split-locks?
Stem seals?
And on and on and on $$$$$$$
Next thing you know, you have $1200 invested.
For example:
Acme Anvil Iron head, BARE,
$320 EACH
So now you're at $640 pair.
How much is a set of valves?
How much is a set of springs?
Retainers?
Split-locks?
Stem seals?
And on and on and on $$$$$$$
Next thing you know, you have $1200 invested.
Last edited by HeadsU.P.; Apr 6, 2021 at 09:08 AM.
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Thread Starter
Pro
Joined: Jul 2020
Posts: 642
Likes: 104
From: Miami florida
Before You remove the other Head why not blow compressed air in the spark plug holes and see where the air goes. Assuming the Rockers are way loose and or removed we know all the Valves are closed or supposed to be. In this situation there shouldn't be any reason why it should leak a lot of air, probably a little but not a lot. The Pictures make the engine look old a tired if it has no compression then the air should gush out as fast as your putting it in. It should be very obvious what's wrong. Since You have one head off why not take a look at some of the lifters, and then look down the hole at the Cam Lobe. If You see any trouble there go straight to the Oil Filter remove it and cut it open and look for metal.
Thread Starter
Pro
Joined: Jul 2020
Posts: 642
Likes: 104
From: Miami florida
Yeah I dont understand how this could be anything other than the rockers not being adjusted correctly. there is no damage or marks on the valves or pistons from any type of mechanical strike as there would be if it hasnt ran since the problem began... And everything you described sounds like the valves arent opening and closing when they should properly. were the new lifters the same length as the old ones? did you use the same pushrods? did you soak the lifters in oil or pump them up with oil? (Not that it necessarily needs to be done).
Thread Starter
Pro
Joined: Jul 2020
Posts: 642
Likes: 104
From: Miami florida
You need to find someone to diagnose and repair this for you. You are 100% doing something wrong, and it is 100% the valve lash and/or cam timing. There is simply NOTHING else it can be. NOTHING. There is no damage to the valves or the pistons...to have zero compression you would have to have a hole in the piston or a stuck bent valve or the valve are hung open because of incorrect cam timing or improper lash.
BTW...never soak lifters in oil before installation.....it will hang the valves open for several revolutions until it settles and the engine will not start.
Verify cam timing and set lash via the TDC method starting at #1.......the answer is here.
Jebby
BTW...never soak lifters in oil before installation.....it will hang the valves open for several revolutions until it settles and the engine will not start.
Verify cam timing and set lash via the TDC method starting at #1.......the answer is here.
Jebby
Thread Starter
Pro
Joined: Jul 2020
Posts: 642
Likes: 104
From: Miami florida
Every time someone says they don't want to spend over a $1,000 on a pair of heads, those posters tend to show an option that in their eye is much cheaper.
For example:
Acme Anvil Iron head, BARE,
$320 EACH
So now you're at $640 pair.
How much is a set of valves?
How much is a set of springs?
Retainers?
Split-locks?
Stem seals?
And on and on and on $$$$$$$
Next thing you know, you have $1200 invested.
For example:
Acme Anvil Iron head, BARE,
$320 EACH
So now you're at $640 pair.
How much is a set of valves?
How much is a set of springs?
Retainers?
Split-locks?
Stem seals?
And on and on and on $$$$$$$
Next thing you know, you have $1200 invested.
Le Mans Master
Joined: Aug 2017
Posts: 8,336
Likes: 2,809
From: Cool Northern Michigan
If you are asking for my two cents worth, yes I guess they would be alright for your app. Comes out to $ 707 a pair.
I see at Summit that for $ 727 a pair you can get a smaller chamber. A 67 cc instead of those 72s. That would bump the CR a little bit higher.
They got real good reviews at 4.75 stars out of 5.
What ever you decide, on after market heads, note that your old style sparkplugs will not reach anymore.
And before you install one of the heads the temp sensor port is smaller than stock diameter. A quick trip to the machine shop, drill & tap will fix that.
Is there a reason you don't want to go with aluminum?
I see at Summit that for $ 727 a pair you can get a smaller chamber. A 67 cc instead of those 72s. That would bump the CR a little bit higher.
They got real good reviews at 4.75 stars out of 5.
What ever you decide, on after market heads, note that your old style sparkplugs will not reach anymore.
And before you install one of the heads the temp sensor port is smaller than stock diameter. A quick trip to the machine shop, drill & tap will fix that.
Is there a reason you don't want to go with aluminum?
Last edited by HeadsU.P.; Apr 6, 2021 at 07:07 PM.
Thread Starter
Pro
Joined: Jul 2020
Posts: 642
Likes: 104
From: Miami florida
462624 is my stamp on original heads 68cc from what I researched (assuming 67 is basically same deal). Why have the machine shop mess with the port? why not find a temp sensor that'll fit? and aluminum I never thought about. link me. thanks heads up as always.
Le Mans Master
Joined: Aug 2017
Posts: 8,336
Likes: 2,809
From: Cool Northern Michigan
Well you can. Wilcox sells one. But I bet it cost more than a machine shop. I paid $30 to have a new head drilled & tapped for the sender. Took half hour.
That way I know 100% that my previous sender is calibrated to the gauge.
That way I know 100% that my previous sender is calibrated to the gauge.
Thread Starter
Pro
Joined: Jul 2020
Posts: 642
Likes: 104
From: Miami florida
wait a minute. those are vortec. direct fit? other than the temp sensor?
https://www.summitracing.com/parts/sum-152123
https://www.summitracing.com/parts/sum-152123