1971 Tri-Sonic Riviera (any other ones out there)?

Cody.atx

Recruit
Joined
Jul 8, 2025
Messages
2
I got a 1971 Tri-Sonic Riviera, Straight 6, Mercruiser 120hp, it needs some engine work like distributor cap and gas tank, and possibly new floor from sitting over the years. I got it from a buddy and with title in my name, I’ve seen like 2-3 of this exact kind out there, not many left..

It was registered in 2009 and after that parked for awhile, came from Austin TX, it now lives in north Texas.

If anyone has any information on more about them, I would love to know, going to get this back on the water after 16 years of sitting and make this 54 year old boat run again like new :)
 

Attachments

  • IMG_9131.jpeg
    IMG_9131.jpeg
    732.1 KB · Views: 2
  • IMG_9132.jpeg
    IMG_9132.jpeg
    636.1 KB · Views: 2
  • IMG_9161.jpeg
    IMG_9161.jpeg
    595.1 KB · Views: 2
  • IMG_9160.jpeg
    IMG_9160.jpeg
    515.6 KB · Views: 1
  • IMG_9134.jpeg
    IMG_9134.jpeg
    390.8 KB · Views: 1
  • IMG_9133.jpeg
    IMG_9133.jpeg
    393.5 KB · Views: 1
  • IMG_9149.jpeg
    IMG_9149.jpeg
    498.9 KB · Views: 2
  • IMG_9135.jpeg
    IMG_9135.jpeg
    481.4 KB · Views: 2
  • IMG_9136.jpeg
    IMG_9136.jpeg
    423.4 KB · Views: 2
  • IMG_9137.jpeg
    IMG_9137.jpeg
    440.9 KB · Views: 2
  • IMG_9138.jpeg
    IMG_9138.jpeg
    479.9 KB · Views: 2
  • IMG_9148.jpeg
    IMG_9148.jpeg
    455.2 KB · Views: 2
  • IMG_9151.jpeg
    IMG_9151.jpeg
    648.2 KB · Views: 6
  • IMG_9152.jpeg
    IMG_9152.jpeg
    436.1 KB · Views: 6
  • IMG_9153.jpeg
    IMG_9153.jpeg
    399.5 KB · Views: 6
  • IMG_9155.jpeg
    IMG_9155.jpeg
    488.6 KB · Views: 3
  • IMG_9154.jpeg
    IMG_9154.jpeg
    391.4 KB · Views: 3
  • IMG_9158.jpeg
    IMG_9158.jpeg
    575.9 KB · Views: 3
  • IMG_9157.jpeg
    IMG_9157.jpeg
    613.3 KB · Views: 3
  • IMG_9159.jpeg
    IMG_9159.jpeg
    234.9 KB · Views: 3
Last edited by a moderator:

mr 88

Commander
Joined
Nov 3, 2010
Messages
2,235
My guess is it's a 4 cylinder (120hp , as the valve cover states ). The in-line 6s usually were rated at 165hp and up . How many spark plugs are there ?
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
Staff member
Joined
Jul 23, 2011
Messages
50,936
texas has had some cold temperatures over the last 16 years. I would pressure test the water jacket to make sure the block and heads are not cracked. I would remove the manifold and do an acetone test.

a lot of work to get that boat back up to snuff.
 

nola mike

Vice Admiral
Joined
Apr 22, 2009
Messages
5,614
"possibly new floor" = rotten floor, stringers, transom = complete gut job
 

jbcurt00

Moderator
Staff member
Joined
Oct 25, 2011
Messages
25,176
@Cody.atx stop posting parts are available, solicitation is prohibited.

Selling off bits & pieces doesn't jive w the statements there arent many left and getting it back on the water rehab.

It's a full gut, big project

Good luck with your planned rehab.
 

Texasmark

Supreme Mariner
Joined
Dec 20, 2005
Messages
14,804
I "lusted in my heart" (Jimmy Carter) for one of those "Trihedral Hull" babies back in the early 1970's but raising 4 kids came first. We had our water fun but didn't have the rough water capabilities that hull had.
 
Top