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Old 10-19-2012, 07:49 AM
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BBC Cam journal

Hey I have a question; anyone know if the first two cam journal on a BBC 7.4 are supposed to be machine or as cast? 3-5 are machined. Thanks for any help on this.

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Old 10-19-2012, 08:40 AM
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Originally Posted by Dsr396gap View Post
Hey I have a question; anyone know if the first two cam journal on a BBC 7.4 are supposed to be machine or as cast? 3-5 are machined. Thanks for any help on this.
Uh... Im gonna need a picture of that. I would drive the block up to the machine shop and ask if they need to be line bored. hopefully they are honest. If i had to guess blind the answer is yes you need a machine shops help.

All journals are line bored at the factory and then the bearings installed. As cast they are not even the correct size for the cam to fit in. They are cast undersized then bored out to the cam bearing stock OD spec. Maybe I missunderstood you.

hope this helps.
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Old 10-19-2012, 09:30 AM
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I have attached a picture (hopefully attached). The Motor is a 496 stroker BBC that I bought from Blue Print. Had a noise that I did not like so I did a tear down and found the noise and figure I change out all the bearings while it was apart. I did not think I had a cam issue until took the bearings out. Waiting on the new cam bearings to find out what the OD of the bearing is supposed to be.
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Old 10-19-2012, 09:41 AM
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Quote:
Originally Posted by Dsr396gap View Post
I have attached a picture (hopefully attached). The Motor is a 496 stroker BBC that I bought from Blue Print. Had a noise that I did not like so I did a tear down and found the noise and figure I change out all the bearings while it was apart. I did not think I had a cam issue until took the bearings out. Waiting on the new cam bearings to find out what the OD of the bearing is supposed to be.
That texture looks to have been caused by bead blasting.

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Old 10-19-2012, 09:58 AM
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Quote:
Originally Posted by Dsr396gap View Post
I have attached a picture (hopefully attached). The Motor is a 496 stroker BBC that I bought from Blue Print. Had a noise that I did not like so I did a tear down and found the noise and figure I change out all the bearings while it was apart. I did not think I had a cam issue until took the bearings out. Waiting on the new cam bearings to find out what the OD of the bearing is supposed to be.
Thats a spun bearing that someone tried to fix by ruffing up the surface a little and using stock sized bearing. It should have been bored out by the engine builder. Hardly what i would call blueprint engine. It needs to be line bored dont order cam bearings. Its got to go to the machine shop. You will need to run over sized bearings from now on. Larger OD, ID stays the same.

Dont ever buy anything that says blueprint. Catch word that usally means junk.

Sorry to see it.
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Old 10-19-2012, 04:47 PM
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I have seen more issues with BBC cam tunnels more then SBC. It looks like line boring is a must.
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Old 10-19-2012, 05:59 PM
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I have seen more issues with BBC cam tunnels more then SBC. It looks like line boring is a must.
Yep bead blasting the cam bearing surface after a spun or worn bearing will allow the new bearing to stay in place for enough miles to get it out the door. Bad thing is you can for sure know that someone new it had a spun bearing and went to effort to conseal it. Its a common trick among slack machanic's, that and little locktight and it will stay in place until you drive out of the shop. You can even see where it had spun before and was sanded/beaded smooth again.

Sorry to see it wish i knew a trick as cheap to getting it fix. But line boring is the only way. Good news is it will be fix right.

Now the crappy part.... If the cam bearings were spun from wear before it was rebuilt. I bet the crank bearings need to be line bored also. Good time to add in stronger crank caps and bolts since it needs the line bore there as well. Make sure you have a trusted machine shop check all the specs bores and everyhting never know what was done before it came your way. Some engine builders are terrible. With zero pride for there work. US/Mexico whatever doesnt matter.
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Old 10-20-2012, 07:44 PM
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Wanted to thank everyone that replied, looks like trip to the machine shop. Have a great day. This is a pic of what motor is for.
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