Dose anyone know for sure if the crankshaft on a 454 and 502 gen 6 are the same diameter on the shaft? I need to replace my front main crankshaft / oil seal and I can only find listing for 454's and nothing for a 502. I guess what I am asking, are the timing chain covers and the front / rear main seals the same part number for a 454 and a 502?

Dose it matter if the crankshaft is out of a Mag engine (forged vs non-forged)? Are the seals for a forged crank different from a non-forged crank?

I'm 99.9% sure they are all the same for BBC's. You should be able to get one at Napa.

Hay Griff, ya I am 99.999% sure but once I put the motor back in and I am squirting oil out that is a bad time to find out were wrong! lol. I am pretty sure they are the same but I even went to the Napa on 60th an Grover Street (the main warehouse) and they don’t have a listing for a 502 since it was only sold as a crate motor. There stupid book didn’t even have anything. I just pulled the balancer and I am going pop the seal out and see it I can chase any numbers off of it. I did see a National number on it so I at least I know Federal Mogal made the one that is in there. I tried to cross the number that is on the outside on the seal and came up with nothing. Google dint even know what the number was, haha. I ll let you know what I fing out. Again, I think they are the same I am just looking for some insurance if anything. I ate to admit it, but I have been wrong before! lol

HEY THE BLOCKS AND THE SEALS ARE THE EXACT SAME EXCEPT FOR THE PISTONS IN A 502 ARE BIGGER AND THE CAM IS ONE SIZE BIGGER THATS IT. IF YOU WANT TO BE POSITIVE FOR YOUR SELF BUY YOUR SELF A CHEVY HIGH PERFORMANCE GUIDE BOOK FROM YOUR LOCAL DEALER AND THE BOOK HAS ALL THE SPECS. ON BOTH BLOCKS.

The part numbers for the seal for a 454mag and 502mag are the same at www.mercruiserparts.com

Yep it sure is, thanks buddy. I think the jack-off at the parts counter was a retard. I went back this morning and got one. I ended up helping regalman pull and engine out of a Blazer this morning and now I am going to try o get my boat motor back togeather and the transom wraped in biax tonight. I am thinking I might be able to gel coat the bilge this week and drop the block back in this weekend. Isnt the marina a bunch of crap? Regalman and I drove down there yesterday and I dreging guy said they would be done my the end of the week, (meaning Memorial Day Friday) grrrr. THanks again.

I talked to the guy dredging last Tues night. He said if the city was supposed to move the last 2 piers on Weds am. He said if they moved them north, that he might be able to get done dredging by Friday(2 days ago). If they had to move the piers, south, he said they would have to unhoook the dredge and that would take another day or so. He said the big problem is they keep sucking up trash like carpet and junk and plugging up the machine.

As it ends up, the city didn't do their job and move the piers and the guy dredging can't do anymore work.

I'm probably gonna splash tomorrow at the public ramp or maybe even drive up and launch at Dodge Park.

Just an FYI, they are making good progress at the marina. I see no reason it shouldn't open by the weekend. BTW, putting in/pulling out at the public ramp SUCKS!!!! We went out this afternoon.

Ya the public ramp is no good if you have a mid size or bigger boat. There is a dock board meeting tonight at the Bellevue City Hall at 5:30 pm. I plan on attending. This marina issue is out of hand.