new head
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From: grass valley
new head
after installing a rebuilt head on my 86 f150 with 300 i was not getting any compression on the # 1 cyl a friend came over and placed a washer under the rocker in effect shorting the pushrods our theory was that with the head having been surfaced and the valves ground deeper into the seats that the pushrods were actually holding the valves from closing it worked but im not sure if this is proper any thoughts thanks Frank
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From: Muskegon, MI (home)
Did you have any compression before installing the new cylinder head? How many miles did you have on this engine when you replaced the head? I replaced mine at 135k, it ran beautiful for a month or two, then I spun a rod bearing. I do not recommend replacing or doing a valve job on an engine with over 100k. I have been told what happened to my 300 after replacing the head is not uncommon.
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From: grass valley
when i replaced the head i also installed new rings ,rod bearings mains, oil pump , water pump , the truck had 121000 miles i plastigauged everything and have now put 6000 miles . I got he truck not running and with the head already removed . I am trying to find a good carb other than the stock feedback something like a 32 36 weber I am just looking for smooth running not performance better than stock I also need to know which dist to install in order to get advance without a feedback carb thanks for any help frank
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Joined: Feb 2003
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From: Muskegon, MI (home)
As for the loss of compression, it almost sounds like maybe a comp. ring is not seated properly or maybe a piston was put in backwards (yes it can happen). Did you cut the ridge down at the top of the cylinders and run a hone on the cylinder walls before driving the pistons home? As for the carburetor I am running the factory feedback Carter YFA 1bbl, it runs very smooth. It's a remanufactured piece from Holley. For your application I would run the Duraspark II ignition, it's definately one of the most reliable systems out there. I am currently running the EEC IV system in my 84 which has been working great, when it decides to crap out the DS II system is going in.
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From: Remsen, NY
From http://www.remanufactured.com/Engine...nosis_101.htm:
Old Wives Tale number 53.
The engine has a problem so the head is replaced to correct the problem.
Immediately afterward the engine starts knocking or ticking.
The misdiagnosis is that the valve job gave the engine too much power making the weak bottom end fail.
What probably really happened is that mechanics all around the world burp the heads and timing covers off without draining the coolant from the engine first. The coolant spills into the bottom end of the engine. Even one oil change may not get all of the spilled glycol antifreeze out.
When you mix the smallest amount of antifreeze and water with motor oil you end up with a low grade acid that attacks the bearings. When you autopsy the engine you will find that the bearings are darkened and with time the bearing surface becomes rough.
That's why it developed a bearing knock immediately after the heads were done.
The right way is to open the drains or knock the back freeze plugs out.
Vee engines have two separate water jackets on each side so don't forget that you have two drains, one each for the right and left.
Old Wives Tale number 53.
The engine has a problem so the head is replaced to correct the problem.
Immediately afterward the engine starts knocking or ticking.
The misdiagnosis is that the valve job gave the engine too much power making the weak bottom end fail.
What probably really happened is that mechanics all around the world burp the heads and timing covers off without draining the coolant from the engine first. The coolant spills into the bottom end of the engine. Even one oil change may not get all of the spilled glycol antifreeze out.
When you mix the smallest amount of antifreeze and water with motor oil you end up with a low grade acid that attacks the bearings. When you autopsy the engine you will find that the bearings are darkened and with time the bearing surface becomes rough.
That's why it developed a bearing knock immediately after the heads were done.
The right way is to open the drains or knock the back freeze plugs out.
Vee engines have two separate water jackets on each side so don't forget that you have two drains, one each for the right and left.
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