Cam change question
#1
04-25-2013, 07:06 PM
Cam change question
First off I want to say this forum is awesome. It gave me the confidence and knowledge to perform a bar installation and now a cam swap. I purchased the cams, pushrods and lifters from Fuel Moto. I read all the threads and watched all the videos......which led me to buy a dial for measuring my cam runout, the Axtell oil bypass spring, zippers cam chain tensioners and even a Hayden primary chain tensioner...lol (this forum has cost me a lot of money too!).
I was reading the lifter install directions from Fuel Moto and it says to run a compression check with the throttle open after adjusting the pushrods. This is the first time running across this test when reading about a cam change. Is this necessary or is it for those doing the big builds or more complex engine work? Or should I plan on buying a new tool for my ever expanding collection to go along with my new torque wrenches, cam bearing install and removal tool, magnetic lifter holding tool, cam chain locking tool, machinist dial with magnetic base........etc
I was reading the lifter install directions from Fuel Moto and it says to run a compression check with the throttle open after adjusting the pushrods. This is the first time running across this test when reading about a cam change. Is this necessary or is it for those doing the big builds or more complex engine work? Or should I plan on buying a new tool for my ever expanding collection to go along with my new torque wrenches, cam bearing install and removal tool, magnetic lifter holding tool, cam chain locking tool, machinist dial with magnetic base........etc
#2
04-25-2013, 07:31 PM
IF you just replaced the cams and adjusted: they might be thinking that you may have Screw-Up on the adjustment and might have Not followed good Pre-Loading the lifters. IF too much, you might have a leaking valve.. (not closing)
ME, I'd want to know the compression of this New Cam in my old engine. Only a ccc test will show you the increase OR decrease of cold cranking compression.(very important number to write down ) compare front cylinder to the rear cylinder and Total compression.......Hopefully they are within 10% at most a pound or two different is what I like to see.
The cams intake valve Close has a lot to do with CCC...
If it is an early close like SE255's at 25* compared to the Stock cams intake were closing at 30*. CCC is a way to see the New higher compression.
I like a Base Line for compression. Taking it occasionally will tell you the shape of the upper build.
IF you added a cam that close the intake Late and did nothing but Cam that motor, IT will tell you IF You Screwed up by doing so.
Cams are a give and take. Later intake opening May Require a higher compression of parts to allow the cams to work properly.
(head work,pistons,bored)
Higher compression like over 195 at sea level, might be Too Much
(like 215#), will also need to be addressed as pre-ignition or timing problems may result.
Plus ADDED Fuel Needed.... Dobeck Performance (TFI, Gen3, Gen4) is a helper here.
Just My Take
signed....REDHEAD
ME, I'd want to know the compression of this New Cam in my old engine. Only a ccc test will show you the increase OR decrease of cold cranking compression.(very important number to write down ) compare front cylinder to the rear cylinder and Total compression.......Hopefully they are within 10% at most a pound or two different is what I like to see.
The cams intake valve Close has a lot to do with CCC...
If it is an early close like SE255's at 25* compared to the Stock cams intake were closing at 30*. CCC is a way to see the New higher compression.
I like a Base Line for compression. Taking it occasionally will tell you the shape of the upper build.
IF you added a cam that close the intake Late and did nothing but Cam that motor, IT will tell you IF You Screwed up by doing so.
Cams are a give and take. Later intake opening May Require a higher compression of parts to allow the cams to work properly.
(head work,pistons,bored)
Higher compression like over 195 at sea level, might be Too Much
(like 215#), will also need to be addressed as pre-ignition or timing problems may result.
Plus ADDED Fuel Needed.... Dobeck Performance (TFI, Gen3, Gen4) is a helper here.
Just My Take
signed....REDHEAD
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