[donald d locklear]

1 Gen 5 HO 454 435 hp crate eng bought from summit racing, warranty expired, bought 2015, has had vibration since installed, went Thru wheels and tires first, Trk driven very little as time expired before mileage exceeded warranty.
2 3k or less miles
3 has vibration 1500 rpm up in body, @55 mph real rough and not drivable , at speeds below 50 u can drive it.
4. Flex plate replaced, no change, removed transmission and ran mtr Thru rpm and vibration still there
5. Took all belts all , vibration still there
6 no noise ever in mtr, reving eng there is no noise, eng revs easy and vibration is mim.
7. Do I have a harmonic balancer issue?
9. Does have poly mtr mounts.
ANY Help or Suggestions ????

 

[billdini]

Do you have the correct harmonic balancer for that engine. Did it come with it. If it has vibrated since you bought it why would you have not returned it? Poly mounts MIGHT add a little vibration over rubber mounts but not as you describe. Is it RPM related or speed related. Comment 1 and 6 conflict with each other.

 

[donald d locklear]

First thought it was wheels/ tires and time just slipped by, here we r today, Sitting still, as you rev eng above 1500 rpm you can feel vibration in SHEETMETAL and steering wheel, but I cannot feel any vibration in engine , and at 55mph, as stated above it does get rough

 

[billdini]

This is just a stupid question and I apologize if this question is insulting but is it possible you have a header hitting against the steering column or something else. They are very few ways a car exterior can vibrate standing still but the engine doesn't. If not I would swap out the poly for rubber although my car does not vibrate my car at all and I use poly on the engine and tranny. Are you sure some previous owner didn't use solid steel, poly or rubber in a combination. If the header or something else isn't hitting then change all mounts to rubber. Also do you have a crossmember mounted Muncie shifter like I have or a Hurst tranny mount shifter. Look for something to be hitting metal to metal.

 

[DZAUTO]

With what little information we have, I'm REALLY inclined to look at the harmonic balancer, or flywheel, or both.
The down side is that a proper balance CANNOT be achieved with the engine in the car (at least, not to my knowledge).

 

[donald d locklear]

First thought it was wheels/ tires and time just slipped by, here we r today, Sitting still, as you rev eng above 1500 rpm you can feel vibration in SHEETMETAL and steering wheel, but I cannot feel any vibration in engine , and at 55mph, as stated above it does get rough

yes it has factory damper on it

 

[donald d locklear]

Poly mts throuh out, stock manifolds, no headers, unable to find body parts touching drive line, with flex plate replaced and belts off, as sted, still had vibration in body, veh was bought after restoration engineless and this engine we installed new from summit, frame on restoration .

 

[Jasons 69 Chevelle]

Could the cab be setting on the frame rails or solid mounts? Maybe rock hard rubber body mounts? How’s the firewall clearance?

 

[CorvZ061]

So you have a neutral weighted flywheel or an offset balanced flywheel?

 

[BillK]

If it is in the engine it will be RPM related.
The Gen 5 engines did use a slightly different balance flywheel but I wouldnt think it would be as bad as you are describing if that was the issue. Does the crankshaft have a dowel pin in the back to located the flexplate ?

Do you have the part number of the flywheel you have on it now ?

Also, was this an actual GM crate engine or somebody elses ?

Where are you located ?

 

[LeoP]

Mathews, NC, Bill, it's in his profile.

 

[billdini]

Are your exhaust hangers rubber isolated or did someone weld a solid rod from the pipes to the frame or body.

 

[DUTCH MAX HEADWORK]

Can you post a video? Might have to upload to youtube then post link here.

Remove all of your belts and run it up to speed. I chased a similar issue, it was the water pump, fan, and fan clutch combination. Don't run it for too long, just long enough to check for the vibration....sorry, you did this already.

The harmonic balancer is of the externally balanced type. It will have an offset weight in the hub.

The flex plate is also externally balanced and will have a prominent offset weight attached. It is aligned to the crank flange by a locating dowel.

 

[1975TypeS-3]

The Gen V used a counter weight in the flexplate/flywheel. However, the cast crank uses a different flexplate/flywheel than the steel crank. Could it be possible you have the wrong flexplate/flywheel?

 

[billdini]

First thought it was wheels/ tires and time just slipped by, here we r today, Sitting still, as you rev eng above 1500 rpm you can feel vibration in SHEETMETAL and steering wheel, but I cannot feel any vibration in engine , and at 55mph, as stated above it does get rough

This post makes it sound like you have two issues. Your words "it gets rough after 55mph " is a wheel balancing issue and "vibrates after 1500RPM". Does 1500rpm corollate with 55 MPH? In one of your post you stated that you removed all belts and changed the flex plate. Do you have a receipt and part number for the flex plate and the old one removed that you can share with the team? Assuming it is not the engine you didn't answer how the exhaust hangers are attached to the pipe and frame/body. Rubber isolated or welded rod. With everything that you did why not replace the harmonic balancer, easier then a flex plate. What has changed in your opinion that may have made it worse, anything small or large. To the team: Possible converter balance issue?

 

[donald d locklear]

Vibration has stayed constant, will ck muffler and tail pipe hangers,flex plate was ordered specific for eng. hen V 454 ho 435hp, I am aware that flexpate and harmonic bal is different from eairly BBC. Tires and wheels have been caked and rechecked. Did not replace harmonic balancer first because we were trying to eliminate trans (400 turbo) / rear end issues.
So far, vibration is constant, harmonic bal is probably next on list, was looking for suggestions and open to any help from the professionals on site. What gets me, is that reving engine at carb, I can not detect vibration above idle(mim amt due to poly mtns) but you can feel it in the SHEETMETAL and bucket seats the higher the rpm and driving it just gets worst 50 mph up

 

[DUTCH MAX HEADWORK]

Vibration has stayed constant, will ck muffler and tail pipe hangers,flex plate was ordered specific for eng. hen V 454 ho 435hp, I am aware that flexpate and harmonic bal is different from eairly BBC. Tires and wheels have been caked and rechecked. Did not replace harmonic balancer first because we were trying to eliminate trans (400 turbo) / rear end issues.
So far, vibration is constant, harmonic bal is probably next on list, was looking for suggestions and open to any help from the professionals on site. What gets me, is that reving engine at carb, I can not detect vibration above idle(mim amt due to poly mtns) but you can feel it in the SHEETMETAL and bucket seats the higher the rpm and driving it just gets worst 50 mph up

Did you check the balancer and flexplate for the added offset weight?

 

[donald d locklear]

Flexplate was cked, will be inspecting undercarriage body mtns , muffler mtns and anything else that would cause vibration balancer

 

[hydro462]

I had this weird rattle, every time I would hit a bump with both wheels, not one wheel, it had to be both front wheels. The new gas tank seems were very lightly touching the frame. I cut and massaged both sides then greased it. Never in a million years would I think it would be the gas tank..

-Did you check to see if the parking brake cables are too tight...

-Did you try to drive in second at 50..

 

[DUTCH MAX HEADWORK]

I'll throw a Hail Mary out. Check your plug wire routing and firing order. Specifically 5 and 7.

You might pull and replace the plugs, cap and rotor. Let's see if the plugs tell us a story. Read the plugs.