[737Pilot]

I have a 327 and it has been running not so well. My dad and I got it much better this last week. However, it has an 8" harmonic balancer on it and it rubs on the two front motor mounts. In fact, they are notched out (the rubber) a bit so that it will fit. My dad thinks that 8" is way too big for a 327 and that it should be around 6". I don't know jack about these things. Is 8" bad? Obviously it is not good that the motor mounts have to be notched to fit, but would 8" effect how the motor runs? Should I put a smaller one on?

I should add, that the engine was running as if only on a 6 or 7 cylinders. Very rough. We fixed the timing and the choke. Did a compression test and all cylinders were around 160-170. The engine runs MUCH MUCH better, however, it still has a tad of roughness through 1200-1600 rpm or so. My dad was thinking maybe the balancer was contributing to that.

Thanks.

 

[Farm Boy]

An 8 inch balancer will work fine on a 327. Chevrolet used an 8 inch balancer on the high winding 302 in 67-69 Z28 Camaros. Just make sure that the timing tab on the timing chain cover is the correct one for your balancer. Pre 1969 balancers have the timing mark in line with the keyway. Starting in 1969 the mark on the balancer ring was moved 10º left of the keyway. Make sure you are using the correct timing tab for your balancer. In other words you should check your timing marks against TDC.

 

[oldfart]

Tri-fiver Raybob has a small Chrome balancer for sale in the classifieds.
I sold him a 6" non chrome lightweight balancer.He doesn't list the size but if its a 6",chrome would look great on your car.

 

[oldfart]

An 8 inch balancer will work fine on a 327. Chevrolet used an 8 inch balancer on the high winding 302 in 67-69 Z28 Camaros. Just make sure that the timing tab on the timing chain cover is the correct one for your balancer. Pre 1969 balancers have the timing mark in line with the keyway. Starting in 1969 the mark on the balancer ring was moved 10º left of the keyway. Make sure you are using the correct timing tab for your balancer. In other words you should check your timing marks against TDC.

Sure it'll work.But he says that it rubs on his motor mounts.

 

[MightyMouse57]

You might want to be sure it isn't from a sb 400, the 400 is externally balanced so the balancers are different.

 

[737Pilot]

You might want to be sure it isn't from a sb 400, the 400 is externally balanced so the balancers are different.

That's what my dad was saying is that he thought it might be from a 400. I think I'll go smaller anyway to get it from rubbing on the mounts. How do you find TDC with the engine all together?

 

[pistoncan]

Hello, Yes the 8 inch balancer can be made to work with the front motor mounts by notching the mounts, but a 6 inch balancer works much better.

If you have it running pretty well, I doubt the timing is off 10 degrees. You say it has a miss, so I doubt the problem is your balancer but I would change it out anyway.

You have done a compression test so you know its not a bad cylinder,

In the 1200-1600 range I would look at your carb. Thats about where they switch jets.

Early HB did not have a bolt holding them on, Later ones did so check and see if your crank has a threaded hole in the front end and get a balancer to match.

There are a couple ways to check TDC on #1 hold your thumb over the sparkplug hole and feel the compression build. Or take the valve cover off and visually confirm that both valves are closed on #1.

 

[737Pilot]

Hello, Yes the 8 inch balancer can be made to work with the front motor mounts by notching the mounts, but a 6 inch balancer works much better.

If you have it running pretty well, I doubt the timing is off 10 degrees. You say it has a miss, so I doubt the problem is your balancer but I would change it out anyway.

You have done a compression test so you know its not a bad cylinder,

In the 1200-1600 range I would look at your carb. Thats about where they switch jets.

Early HB did not have a bolt holding them on, Later ones did so check and see if your crank has a threaded hole in the front end and get a balancer to match.

There are a couple ways to check TDC on #1 hold your thumb over the sparkplug hole and feel the compression build. Or take the valve cover off and visually confirm that both valves are closed on #1.

When you say switch jets, are saying to go bigger? I have a holley 4160. Don't know what size jets.

 

[Farm Boy]

How do you find TDC with the engine all together?

You can thread a piston stop into the #1 spark plug hole and turn the engine over by hand until the piston hits the stop. Mark the balancer with a Sharpie at 0º then turn the engine over the opposite direction until it stops and make another mark at 0º. Your timing mark should be exactly between the two marks you made with the Sharpie.

Summit Racing SUM-900189 - Summit Racing® Piston Stop

 

[mickeywestsr]

going smaller (so it doesn't rub) is very good idea. I really like the record of your rebuild. Great job Hoss....plus I really like your garage.

 

[pistoncan]

When you say switch jets, are saying to go bigger? I have a holley 4160. Don't know what size jets.

No, I meant there may be a slight problem were the carb switches from the idle jets to the main jets. If things arn't right in the carb it may hesitate at that point. The carb should smoothly transistion from the idle jets to the main jets. (this is way before the secondarys kick in.