454 Chevy problems

I have a 1969 Corvette in the UK and the original trip power engine did a big end last year. I decided to use a crate engine from the USA and bought a 454 Chevy from All Chevy of Texas. The engine looks and sounds fantastic but I get a bad vibration at higher revs. All Chevy seem to have gone out oif business and I only have a basic spec for the engine. It says 292 Crane cam, it's got pro topline heads, it starts well and does not overheat but it's shaking the gearbox to pieces. Maybe the flywheel is damaged or the crank was never balanced properly ? Any suggestions from the land of the big block V-8.

Bill

Doncaster England

I think the real question to start with is a 454 externelly balanced or are there variations of balancing? Did you use the same flywheel and balancer?  

hello  ...

vette in the uk... cool..

anyway the 69 vette should've had a 396 or 427 big block in it...  was it??

if it was and you used the clutch flywheel and balancer..  thats your problem...

all big block  except the 454 are internally balanced  the 454 is extrenally balanced meaning there is a counter weight on both and if you used the 396-427 parts the engine is out of balance...

g.m. still makes the parts...try  scoggin-####.com

it's a g.m.performance drealer...

I suspect you used the parts off of the original engine(i.e.396c.i. or 427c.i.)which are both internally balanced engines.The 454c.i. engine is externally balanced.I'm sure you will be able to find the right parts in a number of places,jegs,summit(they both ship to the U.K.)and probably e-bay among a lot of places.Keep us updated over here.I'm sure you interested a few with a vette in the U.K.  

The engine came with an external GM harmonic balancer and a flywheel. It looked like it had been bench tested so I think the crank balancing will be OK.

Bill

Doncaster

Thats very interesting, thankyou I will look into that. The original engine was a 427 400 bhp Tri power, I assumed as the blocks are the same all the other bits would be.

Bill

Doncaster

Thanks again. We had quite a few problems making the 454 fit as the Ali heads are much bigger that the old cast iron ones and then it came with a huge Edlebrook inlet manifold and 850cfm carb. We ended up having to fit an L-88 scoop otherwise the bonnet { sorry hood !} would not shut !

I bought the car in 1992 and have done 11 of the 12 RAC Euroclassic runs to Europe in it { this year was Chantilly in France to Florence Italy}. In it we get to drive on motor racing circuits and I have taken the 'vette around places like Spa, Nurnbergring, Monza , Le Mans etc. It's normally the only Corvette on the run { circa 200 cars most being Jaguars, MG, Triumph etc with a sprinkling of Porsche and Ferrari} and is one of the fastest cars around the track. I was though blown off by an RSR Carerra and thought the extra power of the 454 { it's supposed to be about 530 bhp} would sort that out !

Thanks for everybodies comments.

Bill

Doncaster

Just checked with George who fitted the engine and it did come with a new flywheel so we have not used the old stuff except for the clutch which is a Centreforce upgrade.

Bill

Doncaster

but was a balance in the engine or did your helper use the one from the 427  ..(it's behind the crank pully(belts) ???  

It came with a harmonic balancer at the front and a new flywheel. We are going to have a bash at adjusting the valves again, I'll let you know how we get on.

Bill

Doncaster

hello

o k  it came with a balancer... that good, but people can and do screw up...

get the car up in the air(on a lift if possable) then  with a flash light look at the balancer from the back of it (with you under the oilpan and shine the light at the backside of the balancer...  you will see a balane weight on the back (inside circle ) or reach behind the balancer and feel for the balance pad on the inside circle on the backside of balancer....

2) take clutch inspec  cover off( if there is one and look at flywheel on the backside there should be a weight pad near the starter ring gear..

if both are there then that is not your problem...

3) you say  vibrates at high rev's...

whats high to you?

with car in gear or not?

with clutch ingauged or not?

car moving or not?

in all gears or some> and what ones?

and what is the compression of the engine?  if it's to high for the fuel used the uncontrolled light off of cyl. (out of time) can make it viberate..

if it viberates with the clutch petal on the floor..  you then know it's in the engine or clutch...

do a compression test and see if all cyl. are equal...

take valve covers off and see if you killed a lobe on the cam..(if one cyl) not doing the same work as the others it viberate as you rev it up..

if the cam is not a roller and you didn't "break it in right" you may have lost a cam lobe and that would make one or more cyl.. not fire( or fire with almost nothing in it) and viberate..

and one more thing.... I don't know about over there but here the parts guy's look up parts by use...meaning by "car"  so if you bought a clutch for a 69 vette bigblock and  well a 454 wasn't factory so the parts guy won't ask you if it's there, he'll just hand you a clutch for a 69 vette with a 396/427... and if(I don't know) the clutch is also different for a 454 then you might have the wrong one..  and it spins with engine all the time..

food for thought... hope this helps..and hope it's not the camlobe..

Take your clutch, pressure plate, flywheel to the balance shop and have them check the balance assembled and rotating, a weight of the pressure plate might have come loose and fallen out, or it can be 180 degrees off from the previous balance job, also check you u joints on your driveshaft for wear, the additional hp could be putting an extra load on them.

Thanks we are working through the various lists. It vibrates badly above about 2000 rpm whether in gear or not. It gets worse the faster you go. The clutch I bought was a Centreforce one from Ecklers of Florida which is an upgrade and not engine specific. I am next going to put it on a rolling road nearby to confirm that all cylinders are firing and that timing etc is OK. It's 10 to 1 compression and it vibrates whether I use super or normal unleaded. The engine though ticks over lumpily but happily, starts well, and does not overheat.

Thanks again

Bill

Doncaster

There are no weights at the back of the harmonic balancer ! Maybe we have found the problem. I don't know anybody who can externally balance a V-8 in the UK so I think we may have to take the crank out to get it done. Thanks for your help.

Bill

Doncaster

just buy a 454 balancer and  flywheel....  that fix your problem if there is no weights on the inner back of the balancer....