Created a unusal problem with a homemade high compression head - F22b2
#1
Created a unusal problem with a homemade high compression head - F22b2
I doubt anyone has asked this question before. I replaced the head on my 380,000 mile accord (burned valve) with a low mileage head from a wreck. I followed a DIY head resurfacing video on YouTube to clean up my "new" head. I worked it until every low spot on the was removed.
When I compared the two heads I realized I took off considerably more aluminum than I expected. There was at least a drivers license thickness difference in the valve area. On top of that my old head was milled previously when I replaced the head gasket years ago. So all in all I would say at least .0045 was taken off, about a 1.5:1 increase in compression. Always down for an experiment I opted to put the head on the car (after checking piston to valve clearance. So all back together, valves adjusted ect. Now the fun starts.
I know milling heads throws off cam timing. Everything set perfectly as it would be stock the car can barely move. I moved the distributor full advance and I can get around but it stumbling like crazy below 3k and still missing 1 cylinder in the upper RPMs. So I move the timing belt 1 tooth Advanced, car starts fast. I drive around, from a stop it doesn't break up unless you get past 1/2 throttle. Floor it and it feels like I'm missing 1 cylinder until 3k when it wakes up and moves, it has much more power than it had in the past, I was very impressed. The stumble gets more sensitive to throttle input after fully warmed up (open loop?). I tried 2 teeth advanced and the stumble almost is completely gone when warm, except on a hard stab from a dead stop it will do it for a couple seconds and then go, but the power band is shifted too low and it can't turn fast enough for the automatic to shift to the next gear when I am wide open throttle. And it pinged terribly, still pinged even with 93 octane.
I switched it back to 1 tooth advanced and I am trying to think of tricks to eliminate this stumble below 3,000 rpms. I feel like additional timing will solve the problem but the distributor is giving me all it has, unless I can modify the bolt openings to get a little extra advance. Perhaps adjusting my valves a bit out of spec might correct this? My goal is to work this out without buying an adjustable cam gear.
When I compared the two heads I realized I took off considerably more aluminum than I expected. There was at least a drivers license thickness difference in the valve area. On top of that my old head was milled previously when I replaced the head gasket years ago. So all in all I would say at least .0045 was taken off, about a 1.5:1 increase in compression. Always down for an experiment I opted to put the head on the car (after checking piston to valve clearance. So all back together, valves adjusted ect. Now the fun starts.
I know milling heads throws off cam timing. Everything set perfectly as it would be stock the car can barely move. I moved the distributor full advance and I can get around but it stumbling like crazy below 3k and still missing 1 cylinder in the upper RPMs. So I move the timing belt 1 tooth Advanced, car starts fast. I drive around, from a stop it doesn't break up unless you get past 1/2 throttle. Floor it and it feels like I'm missing 1 cylinder until 3k when it wakes up and moves, it has much more power than it had in the past, I was very impressed. The stumble gets more sensitive to throttle input after fully warmed up (open loop?). I tried 2 teeth advanced and the stumble almost is completely gone when warm, except on a hard stab from a dead stop it will do it for a couple seconds and then go, but the power band is shifted too low and it can't turn fast enough for the automatic to shift to the next gear when I am wide open throttle. And it pinged terribly, still pinged even with 93 octane.
I switched it back to 1 tooth advanced and I am trying to think of tricks to eliminate this stumble below 3,000 rpms. I feel like additional timing will solve the problem but the distributor is giving me all it has, unless I can modify the bolt openings to get a little extra advance. Perhaps adjusting my valves a bit out of spec might correct this? My goal is to work this out without buying an adjustable cam gear.
Last edited by SVTMike; 05-06-2014 at 07:52 PM.
#3
I watched too much MacGyver when I was a kid and the sprocket probably costs more than the car is worth.
Jim, thanks for responding, whenever I've asked a weird question you have replied.
Jim, thanks for responding, whenever I've asked a weird question you have replied.
#4
Fixed it. I had lost a insulator boot off a spark plug wire end while taking the valve cover on and off several times adjust the timing belt. It had burned through the plastic and was arcing to the head causing my stumble. It runs exceptionally well.
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