7 blade fan question

[fgpope2000]

I own a 1968 Dart GTS with a 440 engine and have the following concern. First question is it acceptable to run a seven blade mechanical fan without a fan clutch? I have no cooling problems but the drivetrain has a vibration under acceleration. Second question what is the recommended fan clutch I should be running on this non numbers matching 1968 big block? The car was originally equipped with a 383 H code engine. Thanks for any help!

 

[marksmopar1]

Hi, Using a clutch fan saves some power and puts it to the wheels. A vibration? Are you thinking is being caused by the fan? I guess anything is possible a fan could cause this, but maybe a u joint? I had this once under acceleration only and that is what it was. Worn u joint made the driveshaft slightly out of balance. Just a thought. IM thinking the clutch fan for the car would be the fluid type (without the thermo spring on the front). I am sure others will have ideas as well... these are mine

 

[famous bob]

Hi, Using a clutch fan saves some power and puts it to the wheels. A vibration? Are you thinking is being caused by the fan? I guess anything is possible a fan could cause this, but maybe a u joint? I had this once under acceleration only and that is what it was. Worn u joint made the driveshaft slightly out of balance. Just a thought. IM thinking the clutch fan for the car would be the fluid type (without the thermo spring on the front). I am sure others will have ideas as well... these are mine

I`m running a mech. seven blade -17" fan on my 505" barracuda, due to clearance problems. works fine- no problems----bob

 

[BillGrissom]

Don't know the PN, but a mechanical fan doesn't fit a thermal clutch. Clutch fans are much different, w/ a big center hole. Someone might have installed a special "clutch eliminator" stand-off.

If the fan was the cause, then vibrations would be noticed just revving the engine in neutral. I once had a bad U-joint in my 69 Dart. I got a slight vibration at 55 mph, then went away. The U-joint was totally rusted and loose, w/ no more needle bearings. I guess that is why I got a clunk when shifting into R, for ~4 years before I found it.

 

[fgpope2000]

Thanks for every ones help! I didn't know that Chrysler made a seven blade fan that did not use a fan clutch. I will check the driveshaft and pinion angle next.

 

[nm9stheham]

Rev the engine in neutral and see if the vibration is still there.

Is this a manual or auto trans?