Vortec Head Modification/Upgrade

FreeBeeTony

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As some readers may be aware, I had trouble this season w/ broken rocker arm studs. I broke a total of (4) studs over the course of this season.
I rebuilt this engine myself over last winter and incorporated some upgrades LCQ Pistons, bored 0.040, decked the block to achieve a ~0.040 quench, installed roller rockers and last but not least a CompCams XM270HJR cam. The machinist installed springs he said should have been OK. Well after a season of replacing broken studs I finally found the reason.....coil bind on the intake valves, all stud failures were on the intake valves, See pics below.

I'm going to try and document the changes I am going to make.
I Plan on changing the springs to CompCams 986-16 which will require some machining I am going to attempt to do myself and also replace the push-in studs w/ ARP 134-7104 studs.
I have a set of not so great heads I am going to experiment on and share some pics.
 

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aimlow

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There's a poster on here who understands the coil bind issue. Scott Danforth. This ain't rocket surgery. Read his posts.
 

FreeBeeTony

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Did some experimenting last night.........removed 2 valves and rocker studs.
Machined down the rocker stud bosses and drilled and tapped to 7/16-14.
Bought some cheap studs from ACE H/W just for kicks.

Going to try the tool for the valve seat/guides today!
 

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Lou C

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Following this with interest Tony!
It will for sure help out those who want to hot rod their own boat engines, and not just do a standard re-power.
 

Bt Doctur

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Install everything and recheck for coil bind, You usually cut the base of the spring pocket
 

FreeBeeTony

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Thanks for the links.
I have done research on the installed ht vs lift vs coil bind already.
Going to cut the seat and guide on the sample heads and measure installed ht.
 

aimlow

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Thanks for the links.
I have done research on the installed ht vs lift vs coil bind already.
Going to cut the seat and guide on the sample heads and measure installed ht.

Don't cut too deep and get into a water jacket.
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
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surprised you didn't leave this in your other thread to effectively bring that to a close

if you are running roller rockers, you wont need guide plates. if your running ball/socket rockers, you will need guide plates

the tech line at comp can give you exactly how much to cut the heads for the 986 spring.
 

FreeBeeTony

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Going to run roller rockers......so no guide plate needed.
Will contact Comp Cams when ready, thanks.
Haven't had the chance to try that tool yet!
 

FreeBeeTony

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Tried the guide/seat cutter tonight.........
Bought a expander tool a caliper to measure installed height when ready.
Cut the seat/guide on 1 intake valve as a test of the cutter,,,,,,seemed to work very well.
I installed a spring from ACE H/W w. the stock Vortec retainer just as a test......didn't check installed height at this point, need actual retainer and locks for that.
Also, bought a cheap drill press from Harbor Freight.......seems to be adequate for this project, a bit tough to get the right angle though.
 

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FreeBeeTony

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UPDATE:

Continuing to experiment w/ my "sample" head.
Turned down the seat and guide on 1 cylinder and machined down the rocker stud bosses and tapped..
Pics below are of springs and studs installed........not too shabby.........a little time consuming though! I'm actually enjoying it so far,,,

S question: can I simulate a 0.503" lift w/o the head installed and the cam creating the lift?
 

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Lou C

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Interesting you can see how the tool allows the valve springs the proper travel they need....
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
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I personally would use your drill press.

however if your installed height for the correct springs is good, thats all that matters. the cam guys are smart enough to know which cam goes with which spring and what the installed height would need to be for clearance.
 

FreeBeeTony

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I did verify the installed height.
I also checked for coil bind using a cut-off push rod and a C-Clamp.
See pics below, adjusted for "zero-lash" and zero'd out my caliper, then adjusted the C-Clamp for ~0.35 lobe lift which would equate to 0.525 valve lift and took a pic of the spring.........looks like it still has more room so I'm pretty comfortable now.
Next step will be to get under the cover and pull the heads off the engine,,,,,,hopefully before XMAS!
 

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