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Gen V 454 Connecting Rod's

 
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journeyman
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PostPosted: Thu May 15, 2014 11:59 pm    Post subject: Gen V 454 Connecting Rod's Reply with quote

All,

I have a Gen V 454 and the connecting rod's don't seem to have a chamfere'd side to them. I had read that the chamfered side goes out towards the crank surface and the flat side mates with the other flatside of the sister connecting Rod....

But both sides of my Rod's are flat. Am I making sense? Does this make sense?

Thanks!!
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Big Dave
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PostPosted: Fri May 16, 2014 11:30 am    Post subject: Reply with quote

A picture would help.

Big Dave
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journeyman
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PostPosted: Sun May 18, 2014 11:23 pm    Post subject: Reply with quote

OK here are a couple pictures. Basically I don't see a difference between the two sides of the connecting rod. Is that normal?


https://drive.google.com/file/d/0B8kKPJNjpNkYd1VqQm5HbExLTzQ/edit?usp=sharing

https://drive.google.com/file/d/0B8kKPJNjpNkYYU1kWW5PVEVPdEk/edit?usp=sharing
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Big Dave
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PostPosted: Mon May 19, 2014 10:52 am    Post subject: Reply with quote

The second photo had the chamfer you needed but the big end has been resized at some point; and the machinists didn't cut a new angle on the rod like he should have to complete the process.

Big Dave
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af2
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PostPosted: Mon May 19, 2014 5:13 pm    Post subject: Reply with quote

The first picture. Rod to rod. The second picture goes to the outside.

If the crank has a big radius you will be in trouble.
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journeyman
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PostPosted: Wed May 21, 2014 10:54 pm    Post subject: Reply with quote

Thanks guys,

Big Dave, can you further explain your comments on the "big end" ?

Sorry- I just don't understand what you are talking about there... and I sure want to! Smile
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Big Dave
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PostPosted: Thu May 22, 2014 9:38 am    Post subject: Reply with quote

When you rebuild a motor you check the size of the crankshaft against what it should be (as specified by Chevrolet as being acceptable). If it has worn away, you grind it down further to the next size main bearing. Same for the crankshaft throws that the rods bolt to.

The "big end" of the rod is the part that unbolts to allow you to attach it to the crankshaft. It can get out of round from bolt stretch or wear. The caps and rods are unbolted and the flat separation line is ground down. This makes the hole smaller, which is then bored out to the proper size again with the caps attached and torqued to spec.

After this is don the machinist is supposed to cut a forty five degree angle on the crank face to clear whatever the chamfer is on your crank (when you grind the crank under size you attempt to increase the chamfer to relieve stress). You then have to trim the bearing down to clear the chamfer in the crank by sanding it down to the correct width to fit and clear the crank chamfer. You then use a pocket knife (I used to use a double bladed stainless steel six inch Case knife for this task until I was told it was worth $2,750, I then bought a new stainless steel Puma to replace it).

Your big end doesn't appear to have been relieved by a large counter sinking cutter like it should have been. That is the responsibility of the machinist.

Big Dave
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af2
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1933 Willys Coupe

PostPosted: Thu May 22, 2014 9:06 pm    Post subject: Reply with quote

Big Dave wrote:


Your big end doesn't appear to have been relieved by a large counter sinking cutter like it should have been. That is the responsibility of the machinist.

Big Dave


NO! That is up to the guy bringing the the rods to the shop. The machinist should tell them but the customer has the last word...
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journeyman
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PostPosted: Thu May 22, 2014 11:47 pm    Post subject: Reply with quote

Hey Big Dave, wow- that's quite a description... I get some of it but not all of it... I don't see in my picture yet the chamfer that is missing.

I need to process what you said a few more times I guess and hopefully will get it... so let me ask a silly question in this way --- having seen the pictures, and concluded that the 45 degree angle has not been cut, what is the "downside" -- what can go wrong because of this?

Thanks!!!
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clay
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PostPosted: Mon May 26, 2014 6:00 pm    Post subject: Reply with quote

The others have done an excellent job of describing the rod chamfer however maybe this sketch will help a little more. I thought I had a good picture but after finding it it's pretty blurry. If the chamfer is too small you'll wind up with a "ring" of contact and an oil film can't develop. This will cause the rod to attempt to become "one" with the crank by pressure welding and basically at this point it's game over. Clay


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PostPosted: Tue May 27, 2014 1:11 am    Post subject: Reply with quote

I will also point out that the bigger the crank chamfer the stronger the crank gets but the bearing contact area decreases, which is good for reducing internal friction, but reduces the load carrying capacity of the rod. It also creates a massive internal oil leak which helps to keep the back side of the piston cool as the crank squirts out oil, but it requires a larger volume oil pump to keep up. You need a high volume oil pump not a high pressure oil pump left over from the sixties. I use a billet Moroso oil pump

http://www.jegs.com/i/Moroso/710/22163/10002/-1?CAWELAID=1710864667&CAGPSPN=pla&catargetid=230006180000514807&cadevice=c&gclid=CL_-2Yaey74CFZBxOgodOTkAOg

in my builds if using a Moroso oil pan (which I usually do assuming the oil pan will clear the car's chassis); if not, it is a Milodon 18910 billet oil pump inside a Milodon pan.

Neither are cheap but they are the heart of the motor keeping it supplied with oil. A new Melling 10778 oil pump will do the job for a quarter of the price, just be sure to buy the correct oil pick up for your oil pan and bolt as well as weld it to the top of the oil pump and machine the surface flat again after wards. (stock pan requires a hand bent piece of quarter inch wide metal with bolt hole to fit the securing bolt that holds the top onto the pump to be welded to the pick up to brace against vibration).

Big Dave
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journeyman
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PostPosted: Tue May 27, 2014 10:52 pm    Post subject: Reply with quote

Thanks a million for the sketch!!! Very cool and clear.

I still don't quite get the part of my rod's that wasn't done correctly but I'll hassle my machinist about that.

With regards to the oil pump… Big Dave, are you saying you use the high volume pump on your 454 builds? What about this concern that I've heads about where a high volume pump will send all the oil up top leaving none down below.

I have a stock GM 6 quart pan and built this with a standard melling pump as per recommendation of both Melling and my machinist. Now is a good time to switch it out though since the bloody thing is torn all back apart searching for piston rattle.

And why machine down the welds?

So many questions!
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PostPosted: Wed May 28, 2014 10:18 am    Post subject: Reply with quote

journeyman wrote:
Thanks a million for the sketch!!! Very cool and clear.

I still don't quite get the part of my rod's that wasn't done correctly but I'll hassle my machinist about that.

With regards to the oil pump… Big Dave, are you saying you use the high volume pump on your 454 builds? What about this concern that I've heads about where a high volume pump will send all the oil up top leaving none down below.

I have a stock GM 6 quart pan and built this with a standard melling pump as per recommendation of both Melling and my machinist. Now is a good time to switch it out though since the bloody thing is torn all back apart searching for piston rattle.

And why machine down the welds?

So many questions!


If I use a forged crank that has large chamfers and chamfered bearings then I use the high volume pump to compensate for the bigger oil leak caused by a chamfered crank. If you have a stock build a stock Mellings will work as intended.

I don't use any Chevy parts at all in my builds because everything from sheet metal to bolts is bought in the aftermarket.

Big Dave
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clay
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PostPosted: Wed May 28, 2014 11:54 am    Post subject: Reply with quote

He's not talking about machining down any welds. He's talking about tacking the pickup to the pump as the press fit alone isn't totally reliable and vibration can cause the pickup to work it's way out of the pump. After the pickup gets tacked on the pump plate needs to be lapped flat to correct any warpage. Even if you don't tack the pickup the end plate still needs to be lapped in as all of them I've seen so far aren't flat as they can be. I use a thick piece of marble, something like 320 grit sandpaper and light oil (WD40 or penetrating oil are usually very readily available). Use a figure 8 motion until the entire surface has been cleaned up. Then I quickly hit the pump body. Next I put the gears back in the pump and check the gear / plate clearance with a straightedge and feeler gauges. Seems like I shoot for 0.002". Detailing the pump like this really does help with oil pressure. A standard volume pump will be fine for you. High volume pumps won't pump the pan dry. Oil flow through the engine won't change - flow is determined by bearing clearances and the restrictions built in the lifters. What happens is it bypasses more oil but the bypassed oil stays in the pan. About all that can happen is the oil will be heated and possibly aerated more. I've ran HV pumps in the past with no problems but I've converted a few years back to a detailed standard volume pump is more than enough. Clay
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