If yall have paid attention to my new slant build, you know it has some pretty good compession. I'm encountering some light detonation. I knew going in it was a possibility, but, I forged ahead out of necessity.
As those of you who've followed the build know, the head ended up being damaged at the first machine shop,when it slipped off the broach on one end and Richard didn't catch it until some damage was done. No big deal. Mistakes happen. Richard was up front with everything and refused to charge me for it and even knocked a chunk off what I owed him for other work AND recommended someone who I've known a very long time, but I did not know he had the equipment that could fix the head.
Fast forward to Big Richie Griffin, in Gordon, Georgia. He runs a small, but very high end machine shop catering to really, really high end dirt tack boys. The the team he works for has two probably half million dollar a piece dirt tack cars. Yup. Serious bidness. Anyway, Richie took the head on this and fixed it. That's how it got a total of .155" off.
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So, since I had aleady done the valve job that head, it had to be utilized. Static compression on the engine ended up dead on top of 10:1 with the piston in the hole .175" at TDC. A perfect habitat for detonation. So, I had to choose a camshaft with a late intake valve closing (IVC) to help combat excessive cylinder pressure.
After talking with Ken Heard at Oregon Cam Grinders, we decided on onewith .465 lift, [email protected]" duration ground on a 108LSA. It has a 70 degree IVC.With the camshaft,that brought dynamic compression to 7.9. Hot dog, I got it licked, right? Naw. As luck would have it, that wasn't enough. The engine is experiencing a light detonation issue when crowded in 2nd or high gear. Follow along as I work to tune this out hopefully to run a high compression slant six on pump 87 swill. I've aleady made some which I will outline here as I continue to tune.
I have give all the credit to my beautiful wife, Kitty, because it was her who fist heard it and continues to be my "tuning ear" since the spark knock is out of the range of my terrible hearing. Accroding to her, we are about 2/3 the way there already.
Stay tuned. Pun intended.
