Folks,

My freshly rebuilt A15 has a vibration. I have adjusted and changed the mounts and confirmed that this is not a condition of the engine/trans/exhaust touching the chassis/body. I wonder if the engine was not correctly balanced at the machine shop. Please see the data provided by the machine shop pictured below and tell me if anything looks out of place.

Well, in the meantime I will share the wife's recipe for country fried steak AKA chicken fried steak.

COUNTRY FRIED STEAKS

STEAKS:

5 tablespoons flour
¼ cup cornmeal
½ teaspoon salt
¼ teaspoon pepper
4 beef cube steaks (about 1 lb)
1 egg white
1 tablespoon water
cooking oil for pan

GRAVY:

1 tablespoon butter
2 tablespoons flour
1 ½ cup milk
1 teaspoon beef bouillon granules
½ teaspoon dried marjoram
¼ teaspoon dried thyme
1/8 teaspoon pepper

TO MAKE STEAKS:

Combine flour, cornmeal, salt and pepper; set aside. Coat steaks with additional flour. Beat egg white and water. Dip steaks in egg white mixture and then dredge in flour mixture. In a skillet over medium-high heat, cook two steaks at a time for 5-7 minutes or till steak is cooked all the way through. Remove steaks and keep warm. Cook other two steaks the same way.

TO MAKE GRAVY:

Melt butter in the same skillet that you used for making steaks (drain the remaining oil first). When butter is melted add flour and mix together till well blended. Gradually add milk; bring to a boil over medium heat. Boil for 2 minutes, stirring constantly. Add bouillon, marjoram, thyme and pepper; simmer uncovered for 5 minutes, stirring occasionally. Serve over steaks and mashed potatoes.

all cylinder have same compression?

The specs look OK.

What kind of vibration does it have, and when does it occur?

If you have ever been in a race car with solid mounts then you know the sort of vibration I am having. If the balance specs look OK, then I will investigate further when I pull the engine/trans out to rebuild the trans. I will also consult with the machinist at that time. It's a good shop and I am a repeat customer.

Engine has lots of power. No problem there.

Ah, so it is the normal race-car vibration. Nothing to worry about.

...only I don't have solid mounts.

I only found a balancing problem in your wifes chicken FS recipe :)

whats your flywheel and clutch setup?

Stock flywheel (unlightened) and stock type LUK clutch set. The flywheel and the pressure plate were balanced with the rest of the reciprocating assembly. No change in vibration when clutch is depressed.

Problem here is I have no frame of reference and no friends with A series engines. This is a simple 4 without a balance shaft. Maybe this is what happens when you stuff in a 262 duration, .425 lift cam. Just doing some research.

The A-series engine is one of the smoothest 4-cylinder engines and Datsun did a precision balance at the factory. That being said, occasionally one will have a vibration issue. For example, if the flywheel bolts are loose, if a modified engine is not balanced correctly, or if one part is out of specification (e.g. a heavier than stock piston is replaced).

A cam won't cause a vibration when run in the RPM range it was designed for. A large-duration cam may shake at idle, but when revved up will be smooth.