I have a 1973 Mav with a 1979 302, few mild upgrades , It has a c5 with a shift kit . The engine starts and runs fine only problem is that it shakes like a jack hammer when its reved, I was told it was the harmonic balancer so I went to summit and grabed a 28oz balancer for the front, counted the teeth on the flexplate and it has 164 teeth witch should be a 28oz flex, Do you guys have any idea what could be my issue the engine was rebuilt by my Dad he had the crank machined and the heads shaved everything is brand new, I was told it could not be fireing hot enough?
checked mounts, and firing order both are spot on. When the car is reved the only thing i could compare it to is a jackhammer super vibrations.
Check fireing order...be certain all valves are adjusted properly and you have no vacuum leaks.Make sure all spark plugs are gapped correctly.Its possible to have spark plugs that dont like certain ignition systems such as running platinum plugs with an MSD box.Good luck.
It could be a 50oz like stated and it might also have a 351w cam in it. I have seen that happen several times. Try a 351w firing order and wee if that helps. I have seen an engine run when the timing was 180 out of time also. When people find TDC by the finger in the spark plug hole it is easy to feel air getting pushed out the hole while it is on the exhaust stroke instead of compression stroke. Best way it to pull the valve cover and watch the valves. My bet is on plug wiring. clint
check the plugs and clean them // what does it sound like at idel and while reving // to find TDC pull the number 1 plug and kick it over untill you feel the air blow out and try to stop it as close as u can then put a screwdriver in the whole and turn the motor over by hand backwards or forward till the piston is at the top //
one of my old friends he did the firing order mistake too, car would run with the non ho firing order but would misfire like crazy
I checked the firing order , the cam uses the factory firing order, its in time , no broken mounts anywhere . Tomorrow the trans is coming out and new converter and flex plate is going it. Will keep you guys posted thanks for all the help
I have had a c4 torque converter be out of balance before. I had just put the tranny back together and back in the truck and thought I had messed something up. It was not that bad of a shake but more than I was going to live with. How are you sure the cam is the right firing order? Was the cam replaced right before the problem started? Reason I ask is there have been cam shafts boxed wrong before. A 302 and 351w cam look alike or mostly so. Did you try a 351w firing order just for the heck of it? Did you check your harmonic balancer? clint
thanks Thanks for all the info guys , I got the trans back in today with new converter and flex plate and she is running fine with no vibration at all thanks again for all the info
Great! Thanks for letting us know what the trouble was. Adds to the knowledge base. Glad you got it all together and running right clint
