"Unbalanced" new 356 motor?

[sprintstar67]

Hello all,
help required to a) put my mind at rest and b) solve an annoying problem!

I picked up the 356C on saturday after waving goodbye to the Speedster and let me tell you it is a revelation in comparison, apart from the spongy brakes which clearly need bleeding, the car drives great, looks great and feels really tight.
However the more I drive it I can't help feeling the engine feels "unbalanced" as there is a little too much vibration under load. When its idling it does tick over lovely and there are no untoward noises internally.
The engine has just been rebuilt by Strasse of Leeds, so I'm sure its can't be something major and at the moment I'm putting it down to the worn carbs being incorrectly balanced so in effect one side is firing stronger than the other? Would the relevant "experts" on here agree?, Secondary to that I thought the clutch could be misaligned?
Any thoughts and/or theories gladly received, as its the only thing spoiling my new car experience!

Cheers, Andy

[912uk]

well I would have the carbs looked at or try and balance they your self..

have you checked the acclerator jets all work when you put your foot down?
Linkage check that it's adjusted correctly eg it pulls both carbs evenly..I use a straw with a cocktail stick though the top to stop it falling though and I mark the straw with a perninant marker and just slightly move the trottle and look to see they are moving the same each side..

then check the air flow with a meter..

It's taken a while to learn all this.. but my car is running as smooth as it has ever done

after that.. hmm would need to see it really but could be at the other end of the scale a unbalanced flywheel to the crank..

lets start with basics.....

[sprintstar67]

Yeah, I'm leaning toward the carbs being unbalanced. I know they really need reconditioning, as the guy who set them up for the previous owner is a good friend of mine (who looks after several classic grand prix cars) and said he had literally 'done his best' with them.

So I think I'll start with getting them done.....anyone got any recommendations for where to get them done?

Also anyone got any other theories I can check, as I'm pulling the motor out anyway?

Cheers, Andy.

[Helen]

i am presuming all the engine mounting bolts were done up tight when the engine was put back in and then checked again after a few 100 miles.

[cubist]

Check the front box mounts, shifter end... i had a soft one which eventually sheared and caused some horrendous vibration. Before it sheared the vibtration was really only felt at foot off from higher speeds - until it sheared completely becoming a wobbly, gear throwing, tempremental bastid to drive!

[sprintstar67]

hmmm interesting theories.....all of which I'll check! Only had the car two days, so I'm still finding all the niggly little issues
Still a great car though, although not perfect (which is a good thing!) Its just right.......apart from the vibration!
Interestingly I had also suspected the gearbox mounts as the cabin noise is also more than usual, but the engine sounds fine and quiet from the outside
hmmmm much to think on!

[Mike Smith]

Exhaust or any part attached to the engine - Touching the Body / Bumpers

Mike at PR

[sprintstar67]

I think the key here is to pull the motor, check (replace) the gearbox mounts, check and re-align the clutch for peace of mind, then put everything back correctly as I've got a feeling the exhaust is touching the rear bumper too.
Stick it back in and see if it makes any difference.
Carbs really need a rebuild, so they'll get done as matter of course over the winter anyway.

I know what I'll be doing tonight then!

[sprintstar67]

Theres now some suggestion (from a reputable source) that it could be the cam timing?

[rocket280]

How can the cam timing go out of adjustment. The cam is bolted to the cam gear which drives off of the crank. if the cam gear was worn to the limit and it had loads of back lash I still don't think this would alter the cam timing that much. do you think he means the tappets need adjusting. I don't understand. Are you sure he knows what he is talking about. Maybe someone else can shed some light on it.

[sprintstar67]

Because the engines just been rebuilt, it could have been misaligned during reassembly? Thats what he was suggesting.....but I have the simple things to go through first!

[Graham]

The cam gera can go on one of 3 ways, one is correct the other two it wont run at all!

[sprintstar67]

This is all specualtion anyway at this point, and hopefully it'll be nothing, but I think he meant it could be out by a tooth or two......which I find hard to believe from a reputable outfit.

[rocket280]

I doubt if it would run at all if it was out by a tooth or 2 the valves may even hit the tops of the pistons. one way to be sure is to remove the front part of the case then you will see if the alinghing marks line up or not. you could even do this with the engine in the car and sort it out if it needs it. but I very much doubt this is your problem

[Graham]

I doubt if it would run at all if it was out by a tooth or 2 the valves may even hit the tops of the pistons. one way to be sure is to remove the front part of the case then you will see if the alinghing marks line up or not. you could even do this with the engine in the car and sort it out if it needs it. but I very much doubt this is your problem

Agreed,especially as it ticks over well,maybe throttle rods opening carbs unevenly?