fix for water reversion

[redsnapper386]

guys,does any one have a known fix for water reversion.i recently rebuilt my 1987 350 alpha-1.before rebuild i never had a problem.at 46 hours i had hydrolock.i insalled all new parts on the motor.the motor is now 30 over with stock cam .400 lift.carb-4bbl,machinest says 300 h.p. which was the goal.i have read other posts about cams& valve over lap,riser extensions,thru hull exaust with flappers,hytek marine headers,comp x-treme marine cam,and the list goes on.i have also measured the water line compared to riser ht.note,upon dissasembly of risers i noted a rust ring and a rust pudle laying in the starboard riser from the 90 degree elbow back toward the uphill part of riser.the motor is ok,as i removed all plugs & fogged the motor good.should i have changed the cam on rebuild.lots of possibilitys here.also i do have water shutters installed in y-pipes.sorry for long post.need advice ,and what to do next.thanks in advance.

 

[Docksidemarineservices]

Are the manifolds and risers new? Did you pressure test them?

 

[redsnapper386]

yes,headers are new,but not tested yet.thanks.

 

[kghost]

From my experience I do not recall any issues with that year vintage and any reversion issues.........Especially with a mild cam as you are running!!

Reversoin issues have typically occurred with very large/high lift cams with a large degree of overlap. Big blocks of that year vintage suffered most, models like the 454 HO/Mag or more powerful with a much more aggresive cam shaft profile. If I remember merc had to use aftermarket exhaust manifolds to over come the big block water reversion issues.....

Never heard of it on the SBC. (stock or mild biuld)

Do you have thru transom exhaust? Any exhaust modifications? Are the manifolds merc or after market?

 

[RicardoMarine]

He's using the term "headers". Are these by chance not a typical I/O cast iron marine exhaust manifold system?

 

[Docksidemarineservices]

yes,headers are new,but not tested yet.thanks.

Assuming you are running a cast iron or Aluminum exhaust manifold with a header pipe bolted to the top.
Over the years I have had no less than 10 new out of the box defective manifolds that leaked water after the engine was shut down.

 

[redsnapper386]

i have exaust thru the out drive,and thru the prop,new glm manifolds,risers.thanks.

 

[Docksidemarineservices]

Ok, so you do not have headers. You have stock Style exhaust. We call GLM "Good Luck Marine" They do not make a good product. Chances are you have bad mating surfaces between the manifolds and the risers. Have them pressure tested.

 

[redsnapper386]

thanks chris,like the old saying(pay me now or pay me later).i think its time to get a good stainless system.5 years warranty on most of them.what about hy-tek systems out of austrailia.also,cmi has a good product.(custom marine inc). thanks again.

 

[Docksidemarineservices]

I would test your GLM parts for leaks first. If they are leaking then a set of Osco or Barr Iron manifolds and risers will do the trick with out breaking the bank.

 

[redsnapper386]

thanks chris.