Requesting input on ordering a reman engine...
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Joined: Oct 2012
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Requesting input on ordering a reman engine...
Hi all,
I have an '81 F150 with the 4.9L I6. I am considering ordering a new engine to be shipped in from engineguy.com. I was discussing this with my dad since he owns a few of these I6 trucks, one in LPG), and he recommended that I choose the year engine that has the highest compression. When I was looking through the engineguy list, they have a LOT of them.
Does anyone have any input on which year engine has the highest compression but not need too many junkyard trips for parts (oil pan, mounts, etc...) to get it into my '81?
I know there are a few styles:
Oil pan dipstick (mine)
engine block dipstick
head with smog ports
head with no smog ports (mine)
Other things I have already done:
Offy DP intake, Holley 390CFM carb, modified AIR system to connect and operate with the new intake/carb setup (and passed colorado emissions!).
Other things I have ready and waiting:
I have EFI exhaust manifolds all cleaned up and ready to install wen I do make the swap.
I also plan to upgrade the cam for gas mileage improvement before installing the engine when it gets here, and possibly switch to GM 250 (1.7 ratio) rocker arms.
I am hoping someone has had this thought before and gone down the path and can share their insight.
Thanks!
John
I have an '81 F150 with the 4.9L I6. I am considering ordering a new engine to be shipped in from engineguy.com. I was discussing this with my dad since he owns a few of these I6 trucks, one in LPG), and he recommended that I choose the year engine that has the highest compression. When I was looking through the engineguy list, they have a LOT of them.
Does anyone have any input on which year engine has the highest compression but not need too many junkyard trips for parts (oil pan, mounts, etc...) to get it into my '81?
I know there are a few styles:
Oil pan dipstick (mine)
engine block dipstick
head with smog ports
head with no smog ports (mine)
Other things I have already done:
Offy DP intake, Holley 390CFM carb, modified AIR system to connect and operate with the new intake/carb setup (and passed colorado emissions!).
Other things I have ready and waiting:
I have EFI exhaust manifolds all cleaned up and ready to install wen I do make the swap.
I also plan to upgrade the cam for gas mileage improvement before installing the engine when it gets here, and possibly switch to GM 250 (1.7 ratio) rocker arms.
I am hoping someone has had this thought before and gone down the path and can share their insight.
Thanks!
John
Lead Driver
Joined: Jul 2009
Posts: 6,477
Likes: 19
From: Sheffield, AL
Welcome to the forum, John!
Compression seemed to run between 8.0 and 8.9:1. Later fuel injection engines [1987-1996] had higher compression [~8.9:1] due to smaller combustion chambers, but also incorporated fast burn design. Without computer control or EGR, this combination is detonation prone.
My recommendation for simplicity sake is to stay with what you have [1981 specification rebuilt engine], but instead of replacing the camshaft ["upgrade the cam for gas mileage improvement before installing the engine when it gets here"], I would ask the selling company [engineguy.com] if they could provide the camshaft you are desiring already installed. Sometimes, rebuilders can get the same part(s) for less and the installation labor is the same. They will likely upgrade the valve springs, too.
Ask them what they would charge to clean the valve pockets and exhaust runners. Have them backcut the intake valves. This will enhance performance as well as fuel economy, if you keep your foot out of the throttle.
If you upgrade the camshaft, you will not need to go with the GM higher lift rockers.
When you install the EFI exhausts, be sure to read up on how to provide heat to the underside of the Offy DP intake manifold [very necessary].
Sounds like a good project. Please keep us informed.
Compression seemed to run between 8.0 and 8.9:1. Later fuel injection engines [1987-1996] had higher compression [~8.9:1] due to smaller combustion chambers, but also incorporated fast burn design. Without computer control or EGR, this combination is detonation prone.
My recommendation for simplicity sake is to stay with what you have [1981 specification rebuilt engine], but instead of replacing the camshaft ["upgrade the cam for gas mileage improvement before installing the engine when it gets here"], I would ask the selling company [engineguy.com] if they could provide the camshaft you are desiring already installed. Sometimes, rebuilders can get the same part(s) for less and the installation labor is the same. They will likely upgrade the valve springs, too.
Ask them what they would charge to clean the valve pockets and exhaust runners. Have them backcut the intake valves. This will enhance performance as well as fuel economy, if you keep your foot out of the throttle.
If you upgrade the camshaft, you will not need to go with the GM higher lift rockers.
When you install the EFI exhausts, be sure to read up on how to provide heat to the underside of the Offy DP intake manifold [very necessary].
Sounds like a good project. Please keep us informed.
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