Will a harmonic balancer from either my 86 305 or 76 350 fit my 69 327? I dont want to buy a new one if i dont have too. Also, is there a seal that i will have to replace when replacing my harmonic balancer?

There are various thicknesses and bolt patterns for pulleys. If your pulleys will bolt on and line up, yes, the 305 or 350 units will be fine (internally balanced).

The front seal is in the timing cover. If there's a leak, or you "hurt" it taking the old balancer out, it will need to be replaced. If it's still soft and not deformed, it should be fine.

Jim

Ok took off my 305 balancer today, cleaned it, and put it on. I looked at the old 327 one and the rubber was worn. 305 balancer was smaller in diameter, but that doesnt matter. Anyway started it by jumping: had dead batter, even though I charged it. Cranked over real slow but got going: 40 degrees temp outside. Anyway it was running perfectly. I went to shut if off, and then tried to start it, wouldnt start. Starter bogged down and went real slow. Took battery out, put new one in from my S10 and started right up, but there was a wierd noise. Cant really tell where its coming from, maybe starter. It went away after I ran it, but i could still hear it a little. Now the engine seems to run poorly, not like it did right after harmonic balancer install. Idles rougher and still makes a faint noise. I was thinking the timing gear on the crank may have been messed up from crankin it over and it may have skipped a gear? Also, there is no transmission fluid in it, only 2 quarts not enough to reach the dipstick. This is weird, but I also had a dead spot right at 1700 rpms, the engine would rev and when it hit 1700 rpms it would die real quick like someone cut the gas off suddenly, but after 1700 it was fine. That dead spot is now at 2300 rpm and it was never that high. What is that? Carb or timing? Im scared i may have meesed up timing on gear. Also maybe rigs, i have loose for revin faster and blue smoke comes out when i rev it past 3k.

Sounds like you have problems unrelated to the balancer installation... "loose" rings? Sounds like time for a new "engine guy"...

Jim

I bought the engine like that. Still has good compression and goes real good in a 86 k10 4x4. I think the problem is a bad plug or wire. Started it today, ran perfectly except a skip in one of the passenger side cyclinders. I got dual exhuast with out a cross over, just straight off header. Passengerside seems to be skipping. Increased idle to 1000 and still does it. I played with timing and still does it, so im thinkin bad plug. It has a history of skipping. When i bought it, it skipped alot. Found out the allready short plugs that were in it were hitting the dome tops with thier ground electrodes. I tried indexin plugs, because the gound electode would hit if it was facing the pistons. I found some real real short plugs that just enter the combustion chamber with the electrodes. Lately its been sitting because I didnt want to start it with bad harmonic balancer. Other then the skip, runs good, revs faster now. I love the engine, I cant wait to rebuild, do more head work, put bigger valves in like 2.05s or 2.08s, splayed 4 bolt mains, and a tunnel ram. I want my 331 to rev to 8k simular to dz 302s.

bolt pattern is the same one

there was only one pattern

if its before 86 then you can run whatever balancer you want

technically it is not a balancer

is actually a dampner

400 and 454 engines were balancer

you can use any before 86 and it will work fine

but the timing covers were different

the timing tabs were in different locations from 6 1/4" to 8" balancers


as you have found out there were two different 6.25" thicknesses

super wide, and narrow and actually i think there was a second narrower width 6.25" one as well

i have forgotten now

'55-'85 ones work fine




good luck

i put the one from my 86 305 on to it. It seems to be fine. Its also smaller then the 327 i took off. The 327 one rubber was definitly warn in middle. Seems to rev faster.