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Author
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Topic: What did you do with your intake valve guides?
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MattN
Journeyman Posts: 69
From: Mattoon, IL.
Registered: Feb 2002
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posted 03-02-2002 02:11 PM
   
I am cleaning up a set of 4V Cleveland heads and was wondering what I should do with the intake valve guides. Should I just taper them? Should I shorten them, if so how much? The heads will be 95% strip. I will run a decent solid cam, over .600" lift. If anyone has any pictures, I would like to see them. Thanks, Matt.
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JCQuinn@work
Gearhead Posts: 935
From: Lakewood, CO, USA
Registered: Jun 2001
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posted 03-02-2002 05:02 PM
Matt
I have spent hundreds of hours flowing all sorts of heads and have seen that the valve guides are a significant flow restriction. The best flow is obtained by removing them but this shortens the guide a lot and offers less support for the valve stem and will accellerate wear. Most of the flow restriction is caused by the width of the guide so you can narrow them and improve flow. This will allow a full length guide and (depending on how much you grind off) keep the support.As with all things you have to decide how much is enough guide support. For my own street cars I shorten the guide about 1/2 inch and thin the sides to the point that the sides are about .100" including the bronze insert. I also shape the guide as near to a teardrop profile as I can get it. Round end upstream and taper downstream. This shape is pretty efficient. Combine this guide work with cleaning out the bowl area under the valve head and remove any sharp ridge. In race heads I always remove the guides. I found that filling the lower part of the Cleveland intake port, between the manifold flange and the hump that the air turns over just before the valve, had a very small effect on flow and helped velocity. Fill the lower part of the manifold also. The guide in the exhaust port has got to go, these ports need all the help they can get. Do everything you can to raise the roof. John Quinn
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kid vishus
Gearhead Posts: 6590
From: middle of NC
Registered: Oct 2000
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posted 03-02-2002 06:07 PM
quote:
Originally posted by JCQuinn@work:
The guide in the exhaust port has got to go, these ports need all the help they can get. Do everything you can to raise the roof.John Quinn
I left the guides in mine on the exhuast, but narrowed them as much as possible. Plus I alos widened the port substantially. I completely ground the head bolt hump off flat with the opening of the port. It seems to have done some good, as my heads flowed 225 cfm @ .600 lift. On the intakes I narrowed them as much as possible still leaving material for strength (used to run solid rollers and was a little concerned about premature guide wear without enuff support), flattened the sides up towards the top. The overall shape of mine is more of an elongate oval. They seem to work well, but since I lost my cheap access to a flow bench I never got an opportunity to try different shapes (basically, that means JC's idea is probably most efficient). My current cam is just over .600 lift (.628 intake/.625 exhuast) and works very well. I havent had a lot of experiance porting so my knowledge is significantly more limited than JC's. ------------------
member #773
'69 mustang, 351C, 9.97 @ 133 mph 1/4, 6.27 @ 108 1/8, 1.344 60'
'70 mustang, flintstone power
'93 F150 Lightning http://www.geocities.com/slariviere/KidV.html
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V8 Thumper
Gearhead Posts: 4681
From: Phoenix, Arizona
Registered: Dec 2001
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posted 03-02-2002 07:28 PM
Wow! How's that for answers? I'd say you came to the right place, Matt. Welcome! 
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MattN
Journeyman Posts: 69
From: Mattoon, IL.
Registered: Feb 2002
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posted 03-02-2002 10:09 PM
Thanks all. I have some chebbies to outrun this year. My two friend with 68 Camaros with smallblocks don't scare me yet. The one with the 454 73 makes me a little nervous. Then there is my dad with a hopped up windsor and n2o. If I don't upgrade, I will most likely get left behind. Thanks again. Matt.
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84stang
Journeyman Posts: 9
From: Alpharetta, GA
Registered: Jan 2002
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posted 03-02-2002 10:39 PM
I've already started porting a set of Windsor E7's, and already completely took out the valve guides. What type of problems will I run into if I stick to a hydraulic cam (Comp 270H)?
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