Mainfolds on 454 Mercruisers

rnanaples · Post by **rnanaples** » Sun Aug 03, 2008 12:32 pm

Does anyone know if center risers work as far as the hieght goes. I have the original logs on mine while I do not think there are any issues I am thinking about replacing them anyway.

lobsta1 · Post by **lobsta1** » Sun Aug 03, 2008 3:40 pm

Well, considering none of us is a mindreader & knows what boat you have, they probably do fit. Al

rnanaples · Post by **rnanaples** » Sun Aug 03, 2008 5:15 pm

not to answer a smart comment with a smart comment but since I posted in the 33Flybridge spot it would be safe to assume it is a 33 Flybridge 1978 to be exact quote:Originally posted by lobsta1 Well, considering none of us is a mindreader & knows what boat you have, they probably do fit. Al 1978 33 FBC NITES OFF [img]http://www.bertram33.com/images/uploads/at sea2.jpg[/img]

rnanaples · Post by **rnanaples** » Sun Aug 03, 2008 5:16 pm

ps before any one beats me to it they are mercruiser 454's

lobsta1 · Post by **lobsta1** » Sun Aug 03, 2008 5:51 pm

Well, I have the same boat and engines & the center risers fit with a few inches of clearance. Al P.S. Sorry if I came across as a smart ass, but I go to a lot of forums where it's like pulling hens teeth to get the details. Also I am not sure if the later years with the tournament bridge have the same floor height.

JohnD · Post by **JohnD** » Sun Aug 03, 2008 6:02 pm

rnanaples, I cannot comment on the merc as when I had gas in my boat they were crusaders. I can comment on the change, plan for bolts to break and have to be drilled out. Also, it's better done on the hard where you don't have to worry about boat movement. I had it happen when chaning the mixing elbows on the crusaders and it was a tight fix. Unless you've had water ingestion, there's not much reason to change except for cost or availability of the parts. br,

khybskid · Post by **khybskid** » Mon Aug 04, 2008 9:16 am

Be very patient taking out all the bolts. It's so much more work clearing out a snapped bolt than leaving them soak in rust blaster or some other penetrant for a few days. I did my manifolds and risers on my 35 and it became a nightmare. Done now but also make sure there is NO belly in the exhaust hose. I learned the very hard way. Pete (khybskid)

ginmax · Post by **ginmax** » Mon Aug 04, 2008 1:33 pm

As stated by JohnD and Pete, plan on broken off bolts, "nightmare" of job. I am on the last side, did all around on Merc's. Four broken off bolts, two outside, two inside even after repeated soaks of PB Blaster over two week period. The only way to drill outside is salon floor up, starboard side meant galley cabinets out. Been high and dry for all this fun. Good luck!

rnanaples · Post by **rnanaples** » Mon Aug 04, 2008 1:54 pm

the only reason for doing it is my prt motro always hass some heating issuew had the exchanger ecored and no problems for months now it is leaking again. Really tired of that engines heating problems runs like a top and 300 on a rebuild. Maybe I will get the thing re re cored. Thanks for all the advice

captgene · Post by **captgene** » Mon Aug 04, 2008 2:51 pm

I have since replaced my Mercs with the new Crusader 8.1s, but I changed out center risers twice, and all the manifolds once on my old 454s. The inboard side was the easiest. If possible you should pull up the floor. It makes things so much easier tp get at and lift. I bought all my parts as aftermarket from eBasicPower.com. The P/N was OSC4354 for the 4.0 in. risers and OSC8503-GB for the riser blanks. I should have history of all the stuff I bought over the years. Heat Exchangers, Manifolds, Oil coolers, just about every single bolt on part you can think of. Couple things on the bolts. Buy a set of bolt extractor sockets from Sears just in case. You will need them one day anyway. Heat up the engines and then try to break the bolts loose. The expansion from a hot block helps. I did break one off once. So I replaced the whole manifold. The manifolds will need to be done sooner than later anyway. Have fun! Gene Dugan Boca Raton, Fl. "Nauti Marie" 1989 33 FBC

khybskid · Post by **khybskid** » Tue Aug 05, 2008 3:35 pm

Hi gene, You say that you replaced the 454's with the new 496' by crusader. I have plans to repower in the future and the capt.s choice from crusader caught me. Are you happy with your choice or should i be looking at another gas repower? They were also pushing the tranny that dipped down for the shaft angle. Pete Missick

alynnellis · Post by **alynnellis** » Wed Aug 06, 2008 6:04 am

Gene; We have not done much work on our new to me 87FBC. My experience with manifolds and risers was with my Grady White. I had to shanghi my son-in-law ( Mr.Florida in 1992 body building) to get the manifold installed and it was with an opened engine cover. So lots of luck and a heaping of patience to you. Capt LuLu

captgene · Post by **captgene** » Thu Aug 07, 2008 6:02 am

Pete, first answer. I love these 8.1s. they will snap your head back if you punch them a little. Cruise is 22 kts and burning 30 gph. Unless you are cruising, they sip fuel. You have to use the down angle xmissions, the engines sit in there flat. I rode in Tim's boat, and that further convinced me to go with the Crusaders. Merc has the same block, but after I compared fuel delivery and some other maint issues, I went with Crusader. LuLu, If you are close by, I'll be happy to supervise your manifold and riser replacements. All for a 12 pak of Corona. Gene Dugan Boca Raton, Fl. "Nauti Marie" 1989 33 FBC

alynnellis · Post by **alynnellis** » Fri Aug 08, 2008 12:51 pm

Gene; How about if I throw in a 1.75 of Mount Gay also. Capt LuLu

captgene · Post by **captgene** » Mon Aug 11, 2008 3:47 pm

Perfect. Rum, Beer or Vodka Gene Dugan Boca Raton, Fl. "Nauti Marie" 1989 33 FBC