Engine Help with install Comp Cams GT40 valve spring kit.

93gtmustang

5 Year Member
Oct 21, 2006
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Comp Cams offers a GT40 valve spring upgrade kit. They don't have installation instructions. I was told that the installation is straight forward.
I have now knowledge or the specs on how to do it.
Thanks!
 
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So you install them at a 1.80” installed height and you are done. They install like any other single spring does. If you are not sure how to install springs then get on YouTube.
 
This is probably faster than a YouTube video, but I'm sure you can probably find a video if it makes you feel more comfortable watching someone do it beforehand.

Assuming the heads are sitting on a bench and not on an engine;

Compress old spring and retainer with valve spring compressor
Remove keepers
Remove old spring and retainer and any shims should there be any
Install new retainer with keeper on valve and check the distance from the seat to the retainer with the valve closed. It should be 1.8 (+/-.015") [according to Trick Flow's instruction sheet]
Remove spring compressor from old spring and compress new spring with retainer
Install shims onto spring seat if required, then install the new spring and retainer over the valve stem
Install keepers
Remove valve spring compressor
Repeat for the other 15 valves.

If the heads are still on the engine, you'll need to ensure the valves stay in place. The standard/preferred/easiest method is to use compressed air in the cylinder you're working on.
 
Research this a bit more. One of my iron GT 40 heads required a specific Comp kit that had two different retainers, to make up for removing the exhaust rotators.

That said, I have two sets of Comp springs on iron GT 40 and love them. First set went 12S.
 
while you have the springs off, I would install new viton valve seals. You can make a cheap spring height checker out of a piece of welding rod or a something stiff. Cut it to the needed length and you can check the spring height easy without using a caliper or measuring tool.
 
I purchased these from Alexs parts when I did my ' P ' heads......
Valve spring mic, viton seals.....
The height instructions came with the Beehive springs.....
Mic required a spacer that Alexs supplied for P heads.. Not sure if GT40 heads require it for the Mic to work....
DSCF1358.JPG
DSCF0824.JPG
 
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I purchased these from Alexs parts when I did my ' P ' heads......
Valve spring mic, viton seals.....
The height instructions came with the Beehive springs.....
Mic required a spacer that Alexs supplied for P heads.. Not sure if GT40 heads require it for the Mic to work....
DSCF1358.JPG
DSCF0824.JPG
That looks like a good kit. We'll check it out when we take in the Mustang this weekend after mounting the new tires from 4Wheelonline.
 
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While a spring swap isn't something hard, i find no reason to do it when you can typically spend $250 and have a machine shop valve job, bowl clean up and check seat pressure.
Let's call it $300. I can say for sure it's worth roughly 10 to 15rwhp.
In a naturally aspirated setup $300 for 15rwhp is a bargain. Not to mention you know the heads will be 100%.
 
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