Backfire

[shelbydoug]

The 427 and 428PI  weigh in at about 18 lbs. Both have an incorporated single groove pulley. The PI has the beveled edges  and timing marks where the 427 damper simply has small v groove on the front edge of the pulley. They are about 7 X 2.2" and is  massive. To my recollection they weigh more a Boss 351 damper.
The are the heaviest harmonic damper I have seen. Interestingly enough I was surprised that it wasn't chosen for use on the CJ nor the SCJ. Both wound up with the thinner FE damper and the SCJ wound up with the small counterweight in place of the spacer.
                                                                                            -Keith

I have both here. The PI and the Boss 351. I did weigh the Boss dampener, but don't remember what it was.

It is definitely thicker then the PI. Since the PI incorporates the pulley, I have to think that it is part of the mass calculation?

The PI is still on the shelf in the shop. The Boss is on the car. So I can't do a side by side for you.



In the case of the Cleveland, the stock 4v balancer is only good to about 5,000-5,500 rpm's. The engine will turn more then that but that block in particular reacts adversely to harmonics and during it's racing days typically would crack through the #2 main bulkhead, then up into the cylinder wall.

The thick balancer is really a necessity for the Cleveland. In the day, it was successful at adding much durability for "high-performance" use.



Interestingly enough, my 67 427 side oiler block failed in exactly the same way as a "raced" Cleveland would. The #2 main cracked (sawtoothed bad). The engine builder said I twisted the block due to a high rpm inbalance. He's the one that balanced it so what do I know right?

Simply put, 427 Ford blocks are junk. The best ones are the hydraulic blocks with the square cylinders. That doesn't mean they are good. Just better.

They really are just the evolution of the 352.

Ford tried to fix the block weakness with the cross bolts and when they were just a couple of hundred bucks new as a service part, that was sufficient. NASCAR engines only lasted one race. If you were lucky. Then you threw it away and put a new one in it.

The problem is block flex. Sideoilers were just lip service and originally made for the Cam'ers. Oiling is not really the issue here. The problem is you can't make a donkey into a race horse champion.



One difference is that in the case of the Cleveland, the iron crank is the way to go rather then steel. It flexes more and as such absorbs more of the harmonics.

All a steel crank does is pass through more harmonics to the block and give you one or two more rebuilds on the crank because the harder crank doesn't let the bearings embed themselves as much in the races.


All things aren't equal between the engines though. They just have some similarities. For one thing they are balanced differently.

The 351C NASCAR or Austalian blocks have noticeably thicker bulkheads but the cylinders are still thin cast and many have "core shift" and if they have are useless for racing use. Those they actually put into trucks in Australia.


But I think that, yes, the Boss balancer is up there in weight also. 18 pounds sounds about right.

[shelbydoug]

I just measured and weighed my PI balancer.

The ring is 1-1/2" thick. It weighs 18 pounds with the bolt on pulley. It weighs 8 pounds without it.

The Boss balancer ring is 2" thick.

It's very difficult to find a production balancer thicker then the Boss balancer. I don't know of any.

Many people confuse the 4v Cleveland balancer with the Boss. The 4v is 1" thick. That's the one that the ring spins on. It's not bonded to the hub like the Boss balancer is.

I may have one of those here? If I do I'll take a pic and show you the difference. I may have junked that one though? Not sure?


I can say that I can see where the PI's have the timing marks worn off. My front anti-sway bar has a definite mark in it where it rubbed on the balancer.

I've seen starter rings on flywheels "machined down" where they rubbed against the inside of the bell house also. I don't have a picture of that but do remember the sparks after I put a new ring on the flywheel.

Who exactly was in charge of engineering these things? Was it some sort of work release program? Florida's gonna' let them vote now? 

[Bob Gaines]

The 427 and 428PI  weigh in at about 18 lbs. Both have an incorporated single groove pulley. The PI has the beveled edges  and timing marks where the 427 damper simply has small v groove on the front edge of the pulley. They are about 7 X 2.2" and is  massive. To my recollection they weigh more a Boss 351 damper.
The are the heaviest harmonic damper I have seen. Interestingly enough I was surprised that it wasn't chosen for use on the CJ nor the SCJ. Both wound up with the thinner FE damper and the SCJ wound up with the small counterweight in place of the spacer.
                                                                                            -Keith

The 64/65 427 balancer is a C4AE and the 66/67 427 balancer is the C6AE unit. They are identified with the characteristics that you mentioned. A slight revision is in order because the 428  Super Cobra Jet balancer was also a larger diameter one. It is different then the standard 428CJ/390 balancer . It is similar to the 427 balancer but without the made in pulley.