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Author Topic: Cylinder Heads  (Read 1239 times)
MarkB
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« on: January 30, 2011, 03:48:16 PM »

Hi.
We have a set of 1969, 186 heads that are 1.94 valves, these heads have never been machined.  We would like to open them up to 2.02.  Is this a good idea, or for some reason a bad one?  Also, would you have a suggestion for a very good machine shop.
Mark & Shelley
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william
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« Reply #1 on: January 30, 2011, 04:05:08 PM »

Just putting in larger valves will not accomplish much without porting. When the factory did this there was another machining step to un-shroud the intake valve. That would also have to be done. While you're at it, you should convert to screw-in studs. One or more of the factory press-in studs are virtually guaranteed to pull out with stronger valve springs and some RPM.

When all is said and done you will have invested a bit of money in stone-age technology. Iron Vortec heads are available used or new and will bury the old 186 castings. They do require a specific intake but from I have read it is well worth the power. Paint it all orange, no one will know.
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Jon Mello
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« Reply #2 on: January 30, 2011, 05:45:20 PM »

The Vortec heads use the center-bolt valve cover design and are not visually identical from the outside just by painting them orange. Vortec heads also use a different design intake. It's all good stuff but does not have the original look, if that's something you care about. The 186s are a good set of heads. A competent local machine shop can pocket port down in the bowl and set you up with 2.02s. Definitely put in screw-in studs if you use the heads.

-Jon
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Jon Mello
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Jerry@CHP
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« Reply #3 on: January 30, 2011, 06:03:33 PM »

I'll chime in here too since we do so many engines at CHP.  That's the very rewarding part of the hobby IMO........building engines.  I always start out with 194 heads if we have to do a 302 or 350 engine.  If you find an original set of 202's they've ususally had so many valve jobs that the heads are junk with very deep sunkin valves.  The flow won't be very good when you're done either on a set of heads that had 15 valve jobs.  Building a new set of 194's allows you to cut the seats to the proper tolenances, machine the intake valve un-shrouded area and do a fresh competition valve job.  On the engine in my Stocker, that's what we did the heads on the engine that I set the NHRA national record with.............they are dated 291's that match the car.

For the factory look, I have several 302s in the machine shop now.  Pioneer makes a nice screw in stud that is round and looks just like the original push in stud.  Only difference is it's threaded on the end.  You remove the press-in studs, tap the head holes for the threads and install the new threaded studs with Locktite.  Torque and you're done!  That's all there is to it and you don't deviate from the stock appearing heads if the valve cover is removed.  And they are just as strong.  I would never cut an original set of heads for screw in studs and guide plates if I don't have to.  There are other options as I've mentioned here.   

Another note, guide plates are not needed if the push rod holes in the heads are not worn.  I do not have guide plates on any of my Stock Eliminator engines.  We were not allowed to use them for years.  And mine work fine the way they are now.

Jerry     
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Jerry@CHP
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« Reply #4 on: January 30, 2011, 06:06:03 PM »

Send the heads to us. 

I'll be glad to do them if you wish.  Burtonsville Machine who I use has one of the best reps in the country and have more NHRA National Record holder engines in the field than anyone else.

Jerry
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