I'm looking to buy a set of stainless risers to modify to fit my 360 Chrysler motors in my 27 Magnum, i came across these but am puzzled by the second hose nipple. They are 3" and expand to 4" at the end, supposedly came of a Formula 311 with 454s stock, any insight?







And how would I plumb them with the second nipple?

I'm going to make adapter/spacers to fit them to these manifolds

Sweet a mopar powered boat. What kind of drive setup does it have?

I believe those are some pipes that I had made for a 1988 311 back when I bought the boat new. The boat had 330 hp/454s. I had them made to work with the stock ex manifolds that Merc was using back then. The front nipple was for the hose from the thermostat housing and the one on the bottom went to the ex manifold. The gaskets that you would need would be the stock ones that merc used. If there is anything else I can help you with PM me and I will help you out anyway I can.

Just thought of something else. When you get the gaskets make sure you get the small metal cone that goes between the manifold and the tail pipe that keeps the water from going back down into the motor when you turn it off. When you buy the gaskets they will know what you need.

The boat came with Chrysler outdrives which were rebadged Volvo 260 drives. I rebuilt the transom and installed the 290/SP-A transoms and outdrives to give me power trim and tilt.

Kevlar 382 thanks for the info. I was just puzzled by the extra nipples. The guy that is selling them said he bought them to put on his 271 but they don't fit. When you had them they didn't leak or anything did they?

I owned them a long time ago but the guy that had them last, the one the guy with the 272 bought them from, is a friend of mine and they didn't leak. The reason he took them off was because he put a set of 500 hps in the 311 and used those manifolds and pipes. The reason they wouldn't fit on the 272 is because Formula used a 3in spacer between the manifold and riser that they didn't use on the 272 to make them come out where they wanted on the transom of the 311s because of the swim platform. If you would like you can call me. Rick 616 566 2679

the cone thing is a turbolator. i don't know if OP is expecting any performance gain from these. those 318 dodge manifolds look pretty restrictive...

THey are worlds better than the log manifolds that came stock They are a 15-20 HP gain over the logs, and while not as good as a set of headers they are a step in the right direction for 1/10th the cost. The ports are actually decent sized, they are bigger than any production car manifold by comparison. Eventually I'd like a set of headers, these would be a nice first step. I'm looking to get 450 HP per motor with 408 Cu In.

what about the stock risers that fit those manifolds without getting all custom?