Rear Riser to center riser manifolds

[nitedmn]

I have a '78 Mercruiser 898 (305) with the older style manifolds (with the riser in the back). I managed to crack both of them and they need to be replaced.<br /><br />What would it take to replace the manifolds with the newer, center riser, manifolds? I know I've seen conversion kits from Siearra but the prices seem a little high (around $1000) considering that I've seen the manifolds on ebay for around $150 each, new.

 

[Scaaty]

Re: Rear Riser to center riser manifolds

Bite the bullet.....like ya said, old one piece not made anymore, but you can get the centerrise for closer to $600 with 2 man's, risers, 2 rubbers exhaust connectors and a elbow, gaskets and bolt kits. Just make SURE you get the right parts

 

[ron7000]

Re: Rear Riser to center riser manifolds

i replaced the merc logs and rear risers on my '76 233 to osco manifolds with center risers.<br />All the conversion is, is a 6" piece of rubber exhaust hose from the center riser to an elbow which fits the exhaust y-pipe.<br />oscomotors.com or basicpower.com has some decent pics of what's available.<br />Mine ran around $600, but that was back in 1992.<br />Mine are FL-CR818 manifolds and CRR1 risers, they are for ford but just to give you an idea.<br />page 26 of osco catalog, page 27 has GM 305/350 manifolds.<br /><br />The hardest part will be understanding your cooling system. My original setup had a billion freakin hoses, but there was a new thermostat housing available which simplified everything, so now I just have two hoses coming out the thermo housing, which is one to each manifold.

 

[nitedmn]

Re: Rear Riser to center riser manifolds

I just saw a pair of center riser manifolds sell for $75 on ebay. Apparently the guy wanted to get rid of them right away. <br /><br />Is it just two pices of r rubber exhaust hose that connect an elbow similar to this? <br /> http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=4571968908&sspagename=ADME:B:SS:US:1

 

[nitedmn]

Re: Rear Riser to center riser manifolds

A couple other questions I just thought of. <br /><br />1Do these manifolds have the bolt holes for my alternator bracket? <br /><br />Also. On my current setup the starter selenoid was bolted to the end cap of one of the manifolds. Will I have to find another place to mount this or will I still have bolt holes on the end of the manifold?<br /><br />Thanks for the info so far.

 

[ron7000]

Re: Rear Riser to center riser manifolds

i'd be careful with manifolds or risers off of ebay unless it's a legitimate store selling new. Too much risk on used manifolds especially if you can't see them before you buy and don't know their history.<br /><br />yes, just like your link for the elbows. Wet exhaust hose, 3" or 4" inside diameter can be bought at west marine or any boat store.<br />for your application, call basicpower.com and tell them what you have and they'll tell you what you need and what's available or is typically done.<br />On mine, nothing bolts to the manifolds so it was real simple- alternator bracket is off the block and water pump, and starter solenoid is remote mounted. You can always get a universal starter solenoid and remote mount it.

 

[nitedmn]

Re: Rear Riser to center riser manifolds

Selenoid is minor. There is enough play in the wires that I'm sure I could find something else to bolt it to. I just need to make sure I can still mount the alternator.<br /><br />I always hesitate buying off of ebay but it's usualy a good place to go to get a rough idea what something is going to cost.<br /><br />Thanks for the info.

 

[Scaaty]

Re: Rear Riser to center riser manifolds

I am in the process of upgrading my 350 with the old style manifolds to new center rise. New off a mailorder dealer, and will do for around $600+ shipped. It will be a few weeks waiting on parts, and when I get my parts , I can give you the source (not Marineparts). Email address at bottom, email me on the side in a week or so. Yep, I want to make sure I get mine first! You need a few things, and I have done all the work for you. This setup should work on a 305 no problem..click the links. First is the manifolds and riser you need. The top two. Second link is the elbow (need 18-1992.1 probably). Then all you need is hose and clamps. Your alternator should bolt up. but if not, a minor problem. Now, click .. manifolds-risers and ,, elbow