Is it OK to replace one of my Gen.5 454 with a Gen.6 motor?

Unchained · Post by **Unchained** » Mon Jan 02, 2012 1:20 pm

I didn't have computer access the last day or so. Bob, in answer to your question, I bought the boat early last year and had no information on the engines hours or past maintenance records. It was purchased from an estate sale a few years back and was only used a handful of times by the person I bought it from. All I know is that the engines were replaced at some point from Gen. 4 to Gen. 5 blocks with the large rectangular port heads, aluminum intake manifolds (Winters #6269318, 1972 Vintage?) and Holley 850CFM double-pumpers. I was aware of the lifter noise in the starboard engine when I purchased it. I changed the oil in the engines when I got the boat and ran Valvoline racing oil along with a zinc additive from Risoline. I only ran the boat three times and not very hard before I decided to take the manifold off and investigate. The lifter on the wiped cam lobe was damaged pretty bad, like someone had smashed it with a hammer. It was about 1/8" shorter than the rest of the lifters. There was also one bent pushrod on a different cylinder. Thanks, Mike

1995 390 express · Post by **1995 390 express** » Mon Jan 02, 2012 2:03 pm

hi unchained i just replaced 2 454 crusaders in 1995 boat with a gen 5 and a gen 6. the reason why is that the gen 6 was a brand new factory long block and just needed a few bolt ons from old engine. i could only get a remanufactured short block gen 5 right hand rotation for the starboard side. i was assured they produce the same H P @320 horse. one is roller rocker and the other is flat tappet. the only differance in the the 2 engines i have found is the bolt pattern on the gen 6 is different on the timing chain cover. also i would reccomend using the stock oil pans if you go with a long block. the pan that came already installed was good quality but had a standard car dip stick tube inlet that just pushed in. lousy set up for a boat. good luck

rossjo · Post by **rossjo** » Mon Jan 02, 2012 6:31 pm

prowlersfish wrote:I have replace many cam shafts and never had a issue with the lower end ( rods and mains )

Ditto here - on my Corvette. No problem, and you can upgrade components in the process. You'll end up with 2 very nice, reliable engines for far less than the new Gen 6 (and won't have one old Gen5 with an old cam in it).

And yes - Zinc is good for flat tappet iron cams and lifters. I run Mercury 25w40 oil in my 454 boat and Rotella-T 15W40 (high in ZDDP = zinc) in all 4 of my diesels. Modern oils do NOT have ZDDP/zinc as newer engines use rollers - and may be why you toasted a cam.

mitch · Post by **mitch** » Mon Jan 02, 2012 7:52 pm

Well Mike, when do you think, you will have your boat back in the water and running?

Unchained · Post by **Unchained** » Mon Jan 02, 2012 10:06 pm

Thanks for all of your responses. I knew there would be someone out there who has been through the same thing. I have a little time to decide being in Illinois where the season doesn't start until the end of April but it will be here before you know it. It's 18 degrees right now. Hey Mitch, I tried to contact the guy with the two 454's for sale to find out if they are marine engines and if one is an RH (reverse rotation), but have no response yet. That was a nice find I didn't notice those. Thanks, Mike.