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john Mitchell

Effects of R1 cam

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Quote Originally Posted by PackardV8 View Post
Quote Originally Posted by 5brown1 View Post
I'm trying to sort out some engine/automatic transmission issues and cannot find answers in my web/forum searches. The engine is a recently overhauled 289 which had a R1 camshaft and new valve springs installed. The engine was also bored .060 . The prior owner had the work done. So I have some questions. Life and engine performance require tradeoffs:

1. Will the camshaft require a higher idle speed over the stock 550 RPM? Idle seems rough at that RPM. Yes, the R1 increased duration doesn't idle as low and slow as the stock cam. The R-2 idles at 650 RPMs. Did he also have R1 flattop pistons installed?
2. Will it lower the engine vacuum? Currently vacuum is about 15-16. My other 289s both run at about 20. I can not find any vacuum leaks. Yes, increased duration lowers manifold vacuum.
3. Will the valve lash need to be changed from the stock settings? I saw reference to altered settings on a post during my searches. Yes, setting the valve clearances to the loose end of the allowable range will reduce duration and improve idle and vacuum. Conversely, setting tight will increase duration, rougher idle, lower vacuum and more top end power.
4. Any other pertinent information? Yes, an R1 ignition advance curve in the distributor is required to get maximum performance. A custom curve is still better. Adding a few degrees initial advance and restricting the total to no more than 36 degrees will usually improve idle and vacuum. If the builder did not install flattop pistons, experimentation with the advance curve is required, as he screwed the low end and isn't getting that much more on the top end.

I believe I have transmission issues but want to eliminate the engine as a cause.
Thank you.
jack vines
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