pinellas50
New Guy
Where to start? OK my motor has always had a slight vibration to it at heavy to WOT throttle. The vibration always seemed to show up around 3200 to 3400 rpm. I have solid motor mounts and in the past it kind of felt like the motor at idle. I did a full tune up on the truck and replaced all vacuum lines. New fuel filter as well.
A few months ago, the motor ate a head gasket. It burnt through a fire ring and compromised the cooling system. This led to coolant getting into a cylinder and burning off. I pulled the motor down and visually checked the pistons. All seemed to come up the exact same height so I didn't think there was any problem with a bent rod or anything. I put the motor back together with fresh L35 heads. I put #1 at TDC and the harmonic balancer was dead on with the timing mark. I didn't see any wobble to it when I was setting base timing.
After that I never ran the truck out at WOT. In the back of my head was the fear that the new heads might cause fueling problems with the stock system. I had done several 1/2 to 3/4 throttle pulls up to that vibration point and found that it was still there. I pulled the prop shaft out and the vibration remained.
I recently got Datamaster and decided to take it out and log what it is doing on a WOT pull. Well, that vibration is 100 times worse now. Once it got up into the mid to upper 3000 rpm range, it shook the crap out of the truck and it felt like power started to drop off. I backed out of the throttle when it did this. Afterwards, it still ran the same as it has at part throttle.....really smooth.
Datamaster showed that when the vibrations started, KR spiked to 4.6 and then slowly started backing down.
So, I believe that this is a mechanical issue given all this. But what? The things that come to mind are the balancer, torque converter, or god forbid a bent rod.
Where do I start? And yes, I did search this as well and spent quite some time finding post after post that never came to someone's conclusion as to what was causing their issues.
I have the datamaster file saved and I'm working on getting a way to post it.
Any ideas on where I need to start?
A few months ago, the motor ate a head gasket. It burnt through a fire ring and compromised the cooling system. This led to coolant getting into a cylinder and burning off. I pulled the motor down and visually checked the pistons. All seemed to come up the exact same height so I didn't think there was any problem with a bent rod or anything. I put the motor back together with fresh L35 heads. I put #1 at TDC and the harmonic balancer was dead on with the timing mark. I didn't see any wobble to it when I was setting base timing.
After that I never ran the truck out at WOT. In the back of my head was the fear that the new heads might cause fueling problems with the stock system. I had done several 1/2 to 3/4 throttle pulls up to that vibration point and found that it was still there. I pulled the prop shaft out and the vibration remained.
I recently got Datamaster and decided to take it out and log what it is doing on a WOT pull. Well, that vibration is 100 times worse now. Once it got up into the mid to upper 3000 rpm range, it shook the crap out of the truck and it felt like power started to drop off. I backed out of the throttle when it did this. Afterwards, it still ran the same as it has at part throttle.....really smooth.
Datamaster showed that when the vibrations started, KR spiked to 4.6 and then slowly started backing down.
So, I believe that this is a mechanical issue given all this. But what? The things that come to mind are the balancer, torque converter, or god forbid a bent rod.
Where do I start? And yes, I did search this as well and spent quite some time finding post after post that never came to someone's conclusion as to what was causing their issues.
I have the datamaster file saved and I'm working on getting a way to post it.
Any ideas on where I need to start?
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