Engine: 289 tune up

[61Hawk4sp]

I bought my first Stude, a nice 61 Hawk 289 4 barrel a few months ago. The engine was totally rebuilt to original 15,000 miles ago. It starts right up and runs fine, however, it has a little idle miss, seems a little doggy on full throttle and there is valve float at about 3500 rpm. It was suppose to be tuned about 1,000 miles ago, so I took it on a 250 trip to my class reunion, thinking I could check things after putting some fresh miles on the car. I am back now and this is what I found: The car used no oil, the plugs look new, are clean and gapped according to specs, the plug wires appear new, the cylinder compression test shows 150 in all 8 cylinders, the carburetor is adjusted fine, the dwell on the distributor is correct. What else could I do to improve the performance and smooth the idle on this sweet car?

[JohnM15]

Oooo, tough one! Sounds like the carbs idle circuit has a flow/mixture problem. You could try to clean out the idle circuit by removing the idle screws and blowing compressed air into the holes and replace the screws. Adjust the idle using a vacuum gauge.

[61Hawk4sp]

Also, do you think the coil could be the culprit?

[brian6373]

I'm with John, check your vacuum. If your carb is original, it could be letting air around the throttle shafts. You also might check for vacuum leaks in the vacuum advance pot on the dist. or the carb mounting gasket. If you have power brakes, a leaky diaphram in the brake booster can also upset the fuel/air mixture. that's the easy stuff. If all that checks out, it could be weak valve springs. Just throwing things out there, Good luck!

[Mike Van Veghten]

These engines have mechaincal cam shafts...
Have you checked the valve lash ? This will play havoc with the way an engine runs if not correct.

Question, "valve float"...? At 3500rpm ? In a fairly new (refreshed) engine ?
IF...this is a true happening, you'll need new springs. New springs is the "only" way of fixing this problem.
Valve float will sound like the engine is trying to come apart, it will fall on it's face power wise, and the springs will show a sudden loss of "more" of their tension. Which will cause earlier valve float.

Mike

[JoeHall]

You might look at the distributor. Even though tis a Delco, the shaft bushings may be worn to where the points are "bouncing" and causing the problems you describe. You may also want to doublecheck valve clearance. A light valve tick is preferable to a silent Stude V8. Also, STOP beating the crap out of it

[PackardV8]

Also, STOP beating the crap out of it

Joe and I agree on many things, but we'll differ on this one. When everything is as it should be, Studes can be run hard with no ill effects.

Also, check the accuracy of the tach. Some of the older tachs get lazy and maybe you're floating the valves at 4,500, which is completely normal.

If, after rebuilding the distributor, setting the valves, getting the carb right, it still doesn't like to run more than 3500 RPMs ,the springs and valve stem seals can be replaced without removing the heads. I've got a box full of NOS valve springs. I'll sell you a set for $40 delivered.

jack vines