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Unshrouding the valves

Here is a set of heads that I am working on.
By unshrouding the valves the heads breath better giving more power and cooler temps.



This shot is in the middle of being unshrouded.
Old 03-22-2005, 01:14 PM
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Here is Stock.


You can see how much is removed from the exhaust valve wall.

Last edited by SteveStromberg; 03-22-2005 at 01:25 PM..
Old 03-22-2005, 01:15 PM
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How are you going to make up for the lower CR due to the increased combustion chamber volume? Not a lot of deck height to play with on these engines. (mine was .040" IIRC)
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Old 03-28-2005, 09:39 AM
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thanks for teh pics.
here is a little CC/CR/DECK calculator I would like to share. Its fun to play with. at 55cc chambers on a 96x71motor, .040 would only run on race gas. even 94s would be in teh 9.+CR range

I thought about flattening out that angled ridge oposite the spark plug but I had no known good combustion chamber shapes to base it upon. My experience w/SBC heads tells me that shape is critical to high end or low end performance and has not been as intuitive as simply removing material in teh way of flow. the shape guides teh air in a specific maner as it enters or leaves teh chamber (directional swirl...)

I wonder; why did Porsche put that big ridge oposite teh spark plug??

where is the best place to buy barrel shims?

can you stack them or is a single shim required?
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Old 03-28-2005, 10:40 AM
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It was 10 + to 1 it now is at 9.2 to 1. with .055 deck.
This ia a 103x71 engine with Flat top J E pistons.
Going into a Baja Bug
Old 03-28-2005, 06:39 PM
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I see.

Never did care for the sharp edges in the combustion chamber, seems like a good place for a "hot spot" (ping, ping, ping).

Plan on any high-tech coatings for the pistons and combustion chamber? Or just going to polish it up to help keep the heat where it's supposed to be.

Sounds like a Bad-ass Baja Bug! Sure miss mine
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Old 03-28-2005, 09:35 PM
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what say yous' about specific shapes?
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Old 03-28-2005, 10:35 PM
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I use the TECH LINE COATINGS products. I just bought a new oversize oven for curing the coatings.
If you need anything coated let me know.
Here is a list of there products.

http://www.techlinecoatings.com/articles/application_guide.htm
Old 03-29-2005, 06:40 AM
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That's what we used on my old 2.0 heads.

Old 03-29-2005, 11:52 AM
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wow. that is what I just did. the shape looks almost identical. I did eliminate the slight hump between the spark plug and teh intake. Our exhaust bowls look identical. how shallow did you make the ramp opposite teh spark plug? why is that there? is it quench corresponding to the valve pocket? (same as cheby). we used to put about a .010-.015 radius to help with detonation (SBC) and advance the crap out of our engines to drag race. we radiused the valve pocket to but not as much
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69 911 w/82 turbo look on 275 35 18s (for sale)
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Sean M!
Old 03-29-2005, 07:23 PM
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