Repower Questions

[mlaymance]

Time for a repower, and I have several questions, hoping to get some answers from the pro's here.

Boat is an inboard.

Currently has a 226 HP? GM305 OMC.

Wanting to change it to a 5.7 carbureted mercruiser and I am wondering what problems I will encounter. Some of my concerns include:

1. The Borg Warner velvet drive should bolt to the engine with no modifications?

2. Currently the OMC engine has I believe 8" risers on the manifold, Most of the mercruiser Manifolds I have seen are offered with 3 or 4 inch risers. Will I need to locate taller risers or will the 3-4 inch models work?

3. Will my existing intake manifold work if I buy a block/heads combo?

4. I believe everything will connect electrically including the distributor/ignition assembly. It has a points distributor but will be converting it to electronic during this swap. Is there anything different electrically between the 2 manufacturers?

5. Will my existing oil pan and valve covers fit the furnished head and block.

6. It is my opinion from what I have read, that this should be a drop in swap. Is there anything that I am missing with regards to the swap?

7. I am considering a block/heads combo from Rapido Marine. Has anyone dealt with this company before?

Thanks in advance for all the assistance.

Regards,
Michael

 

[fishinpa]

Re: Repower Questions

well OMC did not build the engine Nor did Mercruiser..

they are most likely both GM engines .

what is different is on the outside .
exhaust ,manifolds ,brackets and such ,all the bolt ons can vary.

so a rebuilt long block will give you fresh power,so long as all your external parts are good it is a swap .


fish

 

[mlaymance]

Re: Repower Questions

All of the external parts are good, EXCEPT the Manifolds. It is currently running OMC manifolds, and I would like to change those over to Mercruiser, VP, etc. Something that I can get replacements for.

 

[Bondo]

Re: Repower Questions

Ayuh,...#1,... The flywheel cover you have now, will have to be reused...
#2,... There are riser blocks available in 3",+ 6" rise...
#3,... It depends on What you buy...
#4,... Of course they Different...OMC used whatever igntions,+ Merc uses it's T-Bolt igntions..
#5,... See #3...
#6,... Not that I see yet, other than you really don't understand how motors are built,+ sold...
#7,... Rapido has an Excellent rep. here at iboats, many members have done business with Raul...
#8,... The outlets of the Merc. manifolds, Vs. the OMC manifolds are of Different Diameters...