Good 'ol Rock Auto - they'll send you anything...

I ordered a 6 inch balancer. An eight inch arrived. Groan.

It has the same crankshaft size and it will clear the power steering pump - barely.

If I buy another timing mark plate thingy, can I use it?

 

Yes, you can.

 

It's been my experience that the 8" balancer goes on the high performance small blocks with a forged crank (LT-1 & L-82). Also the small block pickup trucks had a forged crank with an 8" balancer.

Will it work? Yes it will but I'm not sure if there would be any adverse effects.

Edit: The thicker balancer may also affect pulley alignment.

 

The thicker balancer has the same flush mount face for the pulley. They added to the back of the balancer so it's closer to the timing cover.
except for the small block 400 all of the small blocks are internally balanced so the part will interchange without adverse effects.

 

I wonder what the purpose is for the 8" balancer then? ❔

 

The heavier balancers do a better job of taking care of vibration.

 

What balancer came on a '74 350?

My motor is:===============

This universal 350ci engine uses a brand new block and can be used as a replacement for most GM vehicles from 1970-85. It produces 260 HP and 350 ft/lbs of torque with a 4-bbl carb and headers. It can be used as a replacement or as a retrofit into almost any vehicle. This brand new crate engine comes with a GM warranty and is covered for 3 years or 100,000 miles in applicable GM vehicles only. $2,218 (11 years ago - lol)

Specifications

·4-bolt main with 2-piece rear main seal

·Cast iron crankshaft

·LT1/LT4 powdered metal connecting rods

·Cast pistons (dished)

·Hydraulic flat tappet cam (.383''/.401'' and 112° lobe separation)

·Cast iron cylinder heads with 76cc chambers

·8.5:1 compression ratio

·Left and right hand dipstick

·4-quart oil pan

·Timing tabs for a 6-3/4'' or an 8'' balancer

·Recommended spark plug: Accel #111-574 or any spark plug with 14mm .460'' reach, 5/8'' hex, tapered seat, projected tip
==================

Apparently it can use both sizes? It did not come with a balancer (not shown in picture)

This is one, crazy motor. It shakes at speed. The timing mark is nowhere in sight when attempting to set timing. I assumed the balancer had revolved but now I see it is exactly the same when stacked on top of the old one. I will check out difference in thickness - something I had not considered. I ordered a new 'tab' for the 8" balancer from Jegs today.

I removed the front cover and the cam is in time. I guess the question is, do the two sizes balance differently?

Oh, for an old "sun machine.' I have only hand tools, of course I bought a new classic 650 holly. The motor does not like the PCV valve - at all. I'm running without it. Still seems to have low vacuum but if the timing is not set properly... I measured 22 inches of vacuum. Connecting the vacuum headlights all but killed it! They're only 48 years old .)

I bought a new HEI distributor w/tach drive. Had the devil's own time getting a rotor and cap that does not let the spark jump around inside it! Maybe that's still the problem? Can you recommend a cap/rotor that will not short out inside? Should I suspect the ignition amp?

I feel like a goddam fool! Here I am, with an ancient, pushrod motor, and I can't seem to fix it!

This vette is not a hotrod. It runs on regular gas (important to me) and gets `16 mpg. That would seem to say it runs well?
I never was a GM guy. Mopar was my game, back in the day.

I bought this vette for 11,400, thinking I would get it ruining right, then sell it. I'm 6'2" 250 lbs and you know how well that works - lol. The pedals - wow - my feet are not THAT big (10.5) but I can't hit the clutch without the brake lots of times...

Don't get me wrong - I'm pretty darn good with a wrench - have been, all my life (I'm 72) There seems to be a parts mis-match... or something!

I have the electric headlight motor kit. I want to get this vette running sharp. And I know when it's not...

The benefit of your experience would be greatly appreciated.

 

You can find where the timing mark is supposed to be by turning the crank 'til number one is at TDC on the firing stroke. Mark the balancer there at zero degrees on the tab.

Other than the four-bolt main caps, that engine sounds like it's about the same as the base 1974 small block that came in the Corvette that year. That being the case, it would have had a 6" balancer on it.

​​​​ I remember reading during the development of the HEI system that they had to dial back the voltage somewhat because it was breaking down the plug wires and other parts of the system like the cap. I don't remember the brand but personally I always use a distributor cap with brass terminals inside. That cap is blue.

 

Ok, I will try to help here. The 6"&8" balancers balance the same.
definitely get a cap with brass terminals, I usually get a "Standard motor parts" brand. Check your rotor very carefully, they can burn through the tab and plastic and ground out on the distributor shaft. (Really, don't ask how long it took to figure that out)
What intake manifold are you running? And what type of end seals are on it?
Cast iron sbc manifolds are known to crack. Once they warm up they start leaking.
As far as the timing goes what port do you have the vacuum advance hooked up to?

​​​​​ Pictures help. The vacuum reservoir is low in the front, it could be damaged or rusted out.
You may want to disconnect it and retest you vacuum readings. It could be a cure. Good luck!

 

============================

The HEI system is famous, for that! We used to fill the place under the metal piece in the middle of the rotor with silicone sealer... I guess I'll try that, next.

I have an aluminum manifold. It came with the motor. It came with a crater AFB (now called something else) - which was old and funky. The holy looks SO FINE! And, ever since they invented the 'backfire-proof' power valve, it really is the best carb you can buy. For $650, it should be! It has no vacuum pulloff and that makes it stumble, at startup.

I run the vacuum direct - not on the "ported" output (applies vacuum only when the throttle opens). I'm sorry, but I don't know what 'end caps' or a 'vacuum reservoir' are Yes, I do remove the hose from the distributor when I set basic timing - I remember that much from 'the old days

If the 'vacuum resivoir' is part of the pop up headlight system, it is disconnected. But that would explain why the motor all but dies when it is connected. That was DUMB. I didn't even try to fix it - I trashed it, instead. I will install the electric headlight motor kit and trash all the garbage chevy put on it.

As you can see, I'm no virgin - it has been my grand pleasure to put my wrenches on many a motor. A few of them were GM but my preference was always the 426 hemi. And the 440. "There aint no substitute, for cubic inches." (Stroker McGurk)

Those days are long gone - you can't buy gas that will run them, at least not at a regular gas station. I used to get 55 gallon drums of aviation regular and mix it, 50/50, with pump gas. Then they started demanding my pilots' license.

Working on this particular vette sure has been fun. Somebody used a fan shroud off a pickup truck and took a hacksaw to it. I had a BALL getting that !#$%^& off! I ended up busting it to pieces. One that fits is supposed to be on the way. Only $270... I have a new aluminum radiator, waiting to be installed.

All this with the vibration damper was a wild goose chase. Apparently, there's nothing wrong with the one I had

Thank you for taking your time to reply. I will fix this, eventually. 'Till then, the possibility that this motor is possessed by satan is a prime consideration! Do you know of a shop that does exorcisms?

Stick with me,OK? I NEED ALL THE HELP I CAN GET!