otto Posted October 1, 2017 Report Share Posted October 1, 2017 Hi friends! How many mm can i shave off the head to get higher comp? Thanks Otto Quote Link to comment Share on other sites More sharing options...
55 Fargo Posted October 1, 2017 Report Share Posted October 1, 2017 I all depends Otto, has this head been verified to have not been machined before. Safe would be to .050 of an inch, radical to .080 or even .100 of an inch. Are you running multi carbs and dual split exhaust, are you having the cam ground for more lift and duration? I would contact Tim Kingsbury on this forum, for some advice on this topic.... Quote Link to comment Share on other sites More sharing options...
Matt Wilson Posted October 3, 2017 Report Share Posted October 3, 2017 (edited) Since you may have difficulty in determining if someone else has already milled the head at some point in the past, it may be best for you to cc all the combustion chambers in the head and then calculate your current compression ratio. The hard part after that is figuring out how much to remove to get a certain compression ratio, but you can remove some and cc it again, and repeat until you get where you want to be. A tedious way of doing it, but might be the safest. Alternatively, maybe someone here will chime in with the original head thickness if you post your head number, and you can see how much it's been machined already. To avoid valve clearance issues, it would also be a good idea to use modeling clay to determine how much clearance you have currently between your valves and your head. As mentioned above, if you are planning to use a higher-lift cam, you'll need to take that into account as well. Edited October 3, 2017 by Matt Wilson Quote Link to comment Share on other sites More sharing options...
Don Coatney Posted October 3, 2017 Report Share Posted October 3, 2017 This might or might not help. Quote Link to comment Share on other sites More sharing options...
59bisquik Posted October 5, 2017 Report Share Posted October 5, 2017 My 55 started out at 7.25 and shaving off .050 would give me around 7.7. After measuring the head, it appeared to be stock and I was going to shave off .060 to get a little closer to 8.0. However, while your at it, I would add dual exhaust and carbs to get the most out of it. Cam would help too, but requires teardown. Besides adding a Pertronix unit, those are all the easy bolt ons. Quote Link to comment Share on other sites More sharing options...
otto Posted October 6, 2017 Author Report Share Posted October 6, 2017 Thankyou all for your thoughts. Otto Quote Link to comment Share on other sites More sharing options...
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