se7ensport
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| posted on 8/2/07 at 10:01 PM |
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Pinto stage 3 head
Decent 2.0 pinto head wanted, preferably unleaded & with cam, cash waiting.
Cheers
Alex
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roadrunner
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| posted on 8/2/07 at 10:02 PM |
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Me too.
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macnab
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| posted on 9/2/07 at 05:16 AM |
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What’s the difference between a stage 2 & 3 except the big jump in price. I notice that there are stage 3's available for my v6 but
I'm not sure if their worth the extra.
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flak monkey
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| posted on 9/2/07 at 08:12 AM |
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Depends who you talk to, my understanding of the stages is this:
Stage 1: Ports cleaned up and smoothed off, std size valves
Stage 2: Ports enlarged, somtimes bigger inlet valves
Stage 3: Ports fully enlarged, bigger valves fitted
But like i say it varies. Best talking to whoever makes the heads.
David
Sera
http://www.motosera.com
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macnab
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| posted on 9/2/07 at 11:47 AM |
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thanks David, that helps
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snapper
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| posted on 9/2/07 at 12:17 PM |
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Beware the "Bigger the valves the better" train of thought, unless you are using max revs most of the time with a very lumpy cam i.e.
racing, then on the pinto the exhaust valve can be left at the standard size, 3 angle valve seats and some good blending in of valve seat to port will
suffice. Inlet valve is good at group 1 spec with some seriouse work on the seat to throat area.
There is room on both inlet and exhaust to widen the valve seat and throat with the standard valves, although you may as well go for a bigger inlet
valve while you are in there.
Quote Burton Performance "any valve lift at the seat over 1/4 Y when Y = valve diameter , will give no extra flow.
Multiply valve lift for your cam by 4 to find the ideal valve diameter, remember inlet valve lift is usualy more than exhaust valve lift
[Edited on 9/2/07 by snapper]
I eat to survive
I drink to forget
I breath to pi55 my ex wife off (and now my ex partner)
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Memphis Twin
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| posted on 9/2/07 at 01:26 PM |
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.
Quote Burton Performance "any valve lift at the seat over 1/4 Y when Y = valve diameter , will give no extra flow.
This assumes that the valve flows equally around it's circumference. Pinto inlets, because of the poor port shape, flow far more on the long
radius side than the short radius side (which hardly flows anything). Therefore the valve can be lifted much further than the theoretical 1/4 valve
diameter ideal and still increase flow.
I've heard of some pinto race heads with 14mm of lift!
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DaveFJ
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| posted on 9/2/07 at 01:54 PM |
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Everything that I have read about the Pinto says that the inlet (especially on the later inj head) is fine for most applications andf valve is already
oversize. Problem lie with the exhaust valve which is too small and the port is easily opened up by several mm... (according to my book the exhaust
valve is the same on all pintos independant of capacity!)
Dave
"In Support of Help the Heroes" - Always
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Memphis Twin
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| posted on 10/2/07 at 10:36 PM |
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quote:
Originally posted by DaveFJ
Everything that I have read about the Pinto says that the inlet (especially on the later inj head) is fine for most applications andf valve is already
oversize. Problem lie with the exhaust valve which is too small and the port is easily opened up by several mm... (according to my book the exhaust
valve is the same on all pintos
independant of capacity!)
The Pinto exhaust valve at 38mm is actually very large, but the port does need a lot of work.
The inlet port also needs a lot of work around the guide boss/valve throat area. If you're going to all that trouble, you may as well fit a
larger inlet valve.
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