M&r motors 427 w

[shelby trans am]

Hello
I have build a 351 w stroked to 427. the main thing on this motor is a short block made by a firm called M&r motors california. The only info i have on this is that it should be balaced,and have a forged crankshaft and pistons.
i have put it together with 28 oz harmonic balancer and flywheel, but there are bad vibrations from the motor.
i have take down the gearbox and the vibrations are still the same ,so it have to come from the motor.
Could it be possibe that they balance this internial neutral ? Any other thing that are wrong ??
Is there any one that have one of this 427 w motors or short blocks so couldt tell me how they are balance ?? I think they called this moptor street fighter ? May be i have to bay a new flywheel, will it be bether to bay one in aluminium to reduce the mass weigth ?
i could have asked M&R motors but they are histoty as far i know.
i have new ignition and right firing order.
i hope someone could help me.
Thanks

 

[65coupe408w]

I think there is also a 51oz balance setup that some people run also. I am not to sure on the application. I would really try and get ahold of someone involved in putting your motor together. It is really hard to guess, and you could end up wasting money on things you dont need. Good luck

 

[10secgoal]

Stick a vacuum gauge to it, make sure it the imbalance of the engine, not a huge miss. Knowing m&r though, it's going to have an engine problem.

 

[shelby trans am]

i have never heard about a 51 oz version for the windsor motor.i think i stay with the zero -28 oz option. it is not so easy to ask the people who put it together since i live in Norway ,and M&R motors are history.
the best thing is if i could get in contact with someone who have the same kind of motor.
Maybe the have mark the crank with some number so i could find the balance on it ?
i have tryed a vaccum gauge ,and the vaccum is a litle low. But as far i i could ses there is not any ignition miss.
is ther anyone who have a opinion about the aluminium flywheel?

 

[68EFIvert]

If you are not using the original balancer and flywheel that was used when the engine was balance then you no longer have an engine that is balanced. If it were my engine I would take it out and bring it to a machine shop to see exactly what you have. Then have them balance it with the appropriate parts. I am not sure if they had harmonic balancers for 351 based engines but they did use them on 302 engines.

Adding an aluminum flywheel to your current engine will not fix the problem you are having. Are you sure both your flywheel and balancer are the same 28 oz? Do you have the old balancer or flywheel you could look at?

 

[shelby trans am]

the part that i start to build on was a short block that should be balanced when the make it.i thougt that all the 28/0 oz flywheels /dampers was the same so they just have to use the right weigth when they balaced it ?
i know that alu flywheel wont be a solution, but i wonder if it was wise to bay one if i allready have to change for zero balance.

 

[68EFIvert]

To balance an engine you need the flywheel, clutch and harmonic balancer. If there is not any modifications done to the balancer or flywheel during the balancing process you may be able to use an aftermarket one and it will be good enough. If the balancer or flywheel were adjusted then a off the shelf part will throw off the combo. My new engine for instance had weight adjustments to the flywheel and blancer so that less material was taken from the crank. If I have a problem with my flywheel I will likely have to have the engine rebalanced. I am not an expert by any means but I am speaking from my experiences with my engines.

My last 5.0 was all balanced on the crank so an aftermarket balancer or flywheel would have likely worked. The engine would not be perfectly balanced at that point but you likely would not notice any kind of vibration.

Another option you can look into is balancers and flywheels that have removable weights so that you can adjsut form 28 to 50 ov with relative ease. It seems like I have seen those around before but could not find one doing a quick search.

 

[shelby trans am]

is there anyone that have a 427 w " street thunder " it will help me with a starting point for the balancing.i would also be nice to be sure that it is a balancing problem .
If it should be balanced in zero, i have to order a ned flywheel.

 

[4MuscleMachines]

My friends engine had the same issue and it turned out to be a bad crank.