Big Block in a 23' Tsunami ?

abl1111 · #1 09-09-2003, 03:29 PM

As many of you know, I am re-doing a '75, 23' Tsunami. Transom is done.

The conversion from (2) i/o's to (1); new motor beds and bulkhead are in. Old i/o holes structurally sealed ( not cosmetically yet ).

I am starting to think about which motor to put in - not to mention the drive. A book can be written about the different opinions of which drive to use !!!

I was leaning to the Mercruiser Horizon 5.7 - 300 HP. Would anyone recommend going larger, like a 454 ? Remember - the boat had (2) 4 cyl's in there originally... Any opinions here; pros and cons ?

Thx

gss036 · #2 09-10-2003, 12:50 AM

I would stay away from the GM motors. They have a real problem with piston slap. I have one in my new truck and they rebuilt the engine at 11000 miles, didn't stop it and at 15000 dropped in an out of the box factory engine. I now have 31000 on the truck and I am startting to get the slap back again. I have hear this story over and over and personally know of 3 friends who have had the same problem. Check the GM forums and read all the misery stories, a lot like the 1st stories on Mercury OPTIMAX's. GM now say's it is normal and will not do anything with the engines even though they slap. Sounds like a stuck hydrolic lifter on a cold start-up.

TUGBOAT · #3 09-10-2003, 06:03 PM

Gary,Take Your GM Truck back to the Dealership or another ,let them verify this condition (Must have proof) Then call 1-800-222-1020,at that point they(gm) will extend Your engines warranty to 1000,000 miles.They were doing engine replacements/changing to teflon topped pistons etc.Which neither fixed.There have been No real failures because of this problem.Just a Pain in the EARS !The warranty will only be applied to direct results of the clatter condition.Not bad /low oil etc.
A Siren told Ya this whilst fishing in the Fog !!
Scream'n reels'

gss036 · #4 09-10-2003, 08:48 PM

I managed to get the WARRANTY extended out to 5 years/60,000 wirh a letter from GM. If it gets where it is consistant I will definately get it back in before the 5 years are up. I don't drive enough to hit the 50k.

TUGBOAT · #5 09-10-2003, 11:31 PM

Gary Maybe Your area(NorthWest) is diff. from southEast(Warrantys).There is a 100,000 mile No Years attatchment.Maybe Your 31000 miles is added to the 60,000 which comes to 91000 .close enough?
It'll last that long ! [img]images/icons/cool.gif[/img]

John R · #6 09-11-2003, 08:53 AM

You guys are scaring the crap out of me, my 4.8 has had a "lifter" tap from time to time - I got 10K on it [img]images/icons/mad.gif[/img] - I knew some of the Fords had some piston slap, especially the Hi-Po motos )Lightening, Harley) but I'd just started to hear about the GMs

[ September 11, 2003, 07:55 AM: Message edited by: John R ]