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Date:         Tue, 9 Jan 2001 23:35:12 EST
Reply-To:     Wolfvan88@AOL.COM
Sender:       Vanagon Mailing List <>
From:         Robert Lilley <Wolfvan88@AOL.COM>
Subject:      Bare AMC heads: Why...
Content-Type: multipart/alternative;

I would have rather gotten my heads bare because I would rather have stronger parts designed to handle the increased power than the weaker stock VW parts, to avoid a future problem:

1) Valves: The stock Italian valves pulled through the keepers. I wanted to use the better German. **I would have used stainless steel valves it I had the time to obtain a source because they flow more than steel due to a smaller radius and are lighter in weight.

2) Spring retainers: I wanted stronger than the stock steel retainers. I wanted to avoid a retainer failure. The valves would be able to close faster due to reduced valve train weight (light weight push rods and aluminum roller ratio rockers) and the spring will be traveling a longer distance due to increased lift. There is a chance that the force, over time is more than a stock retainer is designed. Cromoly retainers are lighter than stock retainers. I settled for Cromoly retainers that are about twice the strength of stock.

3) Valve keepers: I chose a racing keeper because it was harder and stronger than the stock. I did not want a keeper to fail due to the increase stress on the valve. Plus they were designed to not damage the groves of the valves over time.

4) Valve springs: Actually This is the only stock part used. I did not want to increase the spring tension because that would increase wear on the cam and lifters. The stock valves redline at 5800 RPMS faster than I would push the engine. Plus any power gain is lost due to increase friction on the cam and lifters. The problem is that with the increased lift stronger valves are needed. I decided to reduce the weight that the spring pushes through using lighter than stock parts. The effect is that the spring has to push less weight, so it in effect was like putting in heavier springs BUT without the penalty of power loss or increased wear. Life using stock springs, pushing less weight, but a bit further should equal out in wear as more weight with less travel.

5) Labor for cutting the valve seats and valves: Stock the seats and valves are not maximized for flow but cost effectiveness. They are cut the fastest for production. It is faster to cut 2 angle rather than 3 angles on the seats and NO angles on the valves.

A racing valve job or three-angle cut causes the flow to increase through the port Add a two angle cut to the valve and the flow is increased. (The 3 angle seat/2 angle valve flow is better than simply mild porting alone and just a two angle seat and no angle cut on the valve). I know that you can open the port up to flow better, but I am talking about a street engine not a racing engine. Also the cost for porting (the racing valve job is standard) can get expensive Vs the results and the power band is moved up the rpm range where low end power is lost.

6) Cleaning up the ports in the head. This is not done at the factory and robs the engine of power. Doing this will increase power, efficiency and mileage. All it takes is some time and sanding equipment: Dremil and sand paper.

I would have liked to have put the money, I paid for stock parts that I was not going to use, go toward the better parts I would be using and not be wasted.



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