I finally got around to starting the stroker and I noticed that the Harmonic balancer and pulleys wobble a bit. I pulled them off and tried to reseat them but no luck in straightening it out. The balacer goes on pretty tight so I don't think its on crooked but the recessed end of the pulleys is really tight. Again, I tried to re fit them and tighten up the pulleys but it still wobbles. The engine is a 383 from a 327 build using a GM 400 crank and 30 over on the bore. Could he have given me the wrong balancer? I'd like to get a new one that has timing marks on it cause the timing gauge just about completely covers the balancer making it VERY difficult to set the timing. The gauge is a new looking chrome peice that bolts onto the timing cover. As far as engine specs, the comp is up there around 10.5:1 - 11:1 and around 450 HP at the crank according to the guy I got it from. I'm guessing at the cam specs, but I remember him saying .525 lift and 244 dur. with 1.6 and 1.5 rocker arms. It has a Team G intake (3500-8500) and 1964 fulie heads w/ pocket porting and he said the block was zero decked. I wanted to ask him again but he hasn't returned my call yet. Right now it idles good around 1100 with a lumpy idle and is very crisp. The wobbles kinda smooth out a little when I rev it, but the belts don't look good. I can even see them flex from the drivers seat.
I'm probably going to get a new one anyway, so how do I choose one thats right for my engine given the specs and characteristics. This is not my DD and will be used at the strip. Here are a couple of videos.... http://s85.photobucket.com/albums/k4...e628/Corvette/

 

I'm sorry to say that you have some seriously mismatched parts. 40+ year old tiny port iron heads and a big single plane manifold. The whole idea of using 400 externally balanced cranks is something people did back in the 70's before they had such a nice selection of good aftermarket internally balanced cranks. Who ever did this was not your friend!

If in fact that your crank is externally balanced you can't go down and buy just any old damper because the whole rotating kit has to be balanced as a package.

I use the adjustable pointers from Summit racing. For about $25 and you buy them for what ever diameter damper you have.

 

When I was buying a new damper for my 400 build, I found an auction for a new Speed Pro Fluid Damper. Said it was for 400s too, so I assumed they knew it needed to be externally balanced. Is this correct? Could I have bought a balancer that won't work properly for my 400? Sorry to hijack but you raised a concern.

 

DB, all you have to do is look at the back side of the damper. For Externally balanced motors you will see holes drilled to various depths that were done to balance the whole rotating assembly. Damper/crank/rod=pistons with bob weights/ and the flex plate or fly wheel.

"IF" every part in the rotating assembly was exactly the same and balanced you could feasably take the damper off one motor and place it on the other. It would be reasonably close. That is all the factory did. Any alteration of parts and then the balance would be way off. That is just another reason to build internally balanced motors.

 

The reason mine is still external is because I re-used the stock crank. I was budgeting myself, and a $400-$500 crank was a lot more than the $80 to turn my old one.

I will look for the drillings when I get home today.

 

My balancer has the holes drilled into it and also the flywheel. They are a matched set. Can't I just take my balancer to a machine shop and have them build me another one just like it or will that be too difficult to duplicate with having the whole engine. What if I brought them the whole car, is there a device that they can connect to the engine while it's running to find out where to balance it like the way they do tires?


And what do you mean by mismatched parts? All the parts were carefully selected after getting the engine, like the carb, gears, converter and exhaust. The intake was already on this engine PLUS I saw his 79 malibu with a clone engine just like mine that ran 11.80s. Mine even sounds like his. He put alot of time into these heads to get them the way they are but I know they aren't going to flow as well as the newer aftermarket stuff. I just like the old nostalgic engines and that's why I chose this engine.

 

244 dur. with 1.6 and 1.5 rocker arms. It has a Team G intake (3500-8500) and 1964 fulie heads w/ pocket porting

I just don't feel like those are a good match. I use a Team - G and it port matches my AFR 210 and Dart 227 CC heads. I also rev my 383 to 7500 quite often. I'm not really a fan of big cams that have the race car sound, but they are not really street friendly.

If your damper is tight on the crank snout. I'm unclear on how it could wobble. Yes, you could take you existing damper to a shop and have it drilled the same and it would be close on balancing. the machinist would know best

 

Yeah it does sound a bit racey but here it is in a video I made the other day there are actually 2 and the one showing the engine bay you can't really tell if the balancer is wobbling because I was leaning on the fender while it was running.

http://s85.photobucket.com/albums/k4...e628/Corvette/

 

For what it's worth.... I bought a 383 stroker (externally balanced) from ARracing about 2 years ago. I damaged the balancer they sent with the motor so I purchased a 8 in from Summit (SUM-161400). Initially I had the same problems with the wobble. Once I put the counter weights on the problem disappeared.

 

How do you know where to put the weights on the balancer. By the way thanks for that part #.

 

There are 2 pre-drilled holes for mounting the weight. I was thinking just like you when I installed mine. Seems like there should be a specific location it needs to be mounted on the balancer. I could not get a answer at the time I installed mine as to why it get's mounted where it does but it fixed my problem.

 

I was looking at this one, it's for an ext balanced crank. http://store.summitracing.com/partde...5&autoview=sku

Or this one, it's more money but other than this one showing the weight of 11.56 lbs what would be the diff? http://store.summitracing.com/partde...5&autoview=sku

I was just going to have the speed shop that is going to be doing the alignment check it out after the new year. They have a good machine shop and have been specializing in Corvettes for 30+ years.

 

Star Performance has an EXTERNAL balance damper for sbc that's 6 1/4" ... probably weighs 8-10 lbs ... NOT SFI ... price $39 ... P/N 6517 ... Star 1-800-625-9454.

-edit- same thing in 8" probably about 12-14 lbs ... price $45 ... P/N 6513.

BOTH are EXTERNAL & EITHER are correct for an OE sbc 400 crank.

 

Kalway and MdjIce both got screwed by shops with 30+ years of hotrod experience, both seeming to have lots of Corvette experience. I don't trust when a guy says that unless he can pass a test. I literally test guys before they work on my Vettes.

Anyway, I'm curious how all this works because I now find myself doubting the balancer I installed on my 400.

 

Yeah I know, but I've heard great things about these guys and I've been going there for advice and odds and ends for 12 years now. I always see C2 and C3s in there getting engines rebuilt and rears setup. That's where I got my rear setup. They never steered me wrong yet. I just ordered my bumper covers so over the holidays I'll fit them up and get the vette registered and insured then I'll let them have it. I know they will be able to do something. I just like to know whats going on before I give my car to someone so when the say "You need a new muffler bearing", I can call BS. Or even the fact that I will be able to decide for myself on what kind of part I want instead of them telling me that this is a must have part. They keep telling me that if I ever need anything done to the car I can bring it in. I'll keep you updated Durangoboy, hey what did you guys think of the video?

 

Thanks. As for the vid, it was cool, and I still can't think what the reasoning would be behind a wobbly balancer. The way it installs it should never be able to do that.

 

Mabey it's just the pulleys that aren't on right and the balancer looks like its wobbling because the engine has a lumpy idle. I guess I'll pull them off again and scrutinize every clearance.

 

I know that the pulley should have a small lip on it's back, that seats in the balancer's face. If that isn't seated properly it'll wobble. I would just take off the pulley and make sure it's seating right.

 

I know for a fact that its a tight fit back there and I guess I'll have to clearance the lip and make sure there are no burrs. I actually tried to clean it up before and it still wobbled, but I'll do it better this time.

 

I think your problem is the pulley and not the balancer. I would highly suggest, just for peace of mind...to get another crank pulley and use it, or at least check it against the other one for truancy differences.