165 merc performance modifications

[freelunch]

As brought up in one of my few earlier posts I have a 1972 sea ray with a 250 cid inline 6 cylinder. My cylinder head is off at the machine shop for some hardened exhaust valve seats and a general cleanup with a valve job. I've been looking into the possibility of installing a new cam since I already have the engine 90% torn down with the lifters out anyway. I've also been curious if anyone has had any luck swapping a carb like an edelbrock 500 cfm onto this engine using a square to quad jet base plate adapter. One of the camshafts I have been looking into is from Clifford with around .513 lift on the intake. The other is from Napa and has around .488 lift on the intake. I would just like to hear from anyone who has had success in cam-carb swapping on these engines and could offer some advice, thanks alot.

 

[Bondo]

Re: 165 merc performance modifications

165 merc performance modifications

Ayuh,........

The Best Bang for the Buck is dropping a 292 into the hole that 250 lives in...................

If there's a local Stockcar Track around your area,..... Try to find an old Racer who ran the old Super Stock class,...... They ran the 'ell out of those 250s....

 

[freelunch]

Re: 165 merc performance modifications

Interesting, is the 292 a stroked 250 or a totally different engine entirely? If so do all the bolt patterns match up?

 

[Bondo]

Re: 165 merc performance modifications

Stroker..................

 

[freelunch]

Re: 165 merc performance modifications

Do you have any links with information that would give me the details on the 292 before i start pummeling you with questions, lol?

 

[HT32BSX115]

Re: 165 merc performance modifications

The following link has a lot of info on inline engines and performance.

http://www.inliners.org/



Regards,

Rick

 

[freelunch]

Re: 165 merc performance modifications

Hey thanks but i actually found that link in a previous thread, it doesnt have what I was looking for. I did a google search and didnt come up with much on a 292 stroker either :'(

 

[Bondo]

Re: 165 merc performance modifications

It isn't known as a Stroked 250, or a 292 Stroker......

Google up Chevy 292 6 cylinder........
They were in Millions of Bread Trucks thru the 60s, 70s,+ 80s.......

 

[freelunch]

Re: 165 merc performance modifications

Ok well I found only very limited information about it on wikipedia and it said that it was a different block with a higher deck height than the 250 which would make it a different block entirely and not a stroker, is this what you were talking about or something else?

 

[jfcar]

Re: 165 merc performance modifications

292 on Crigslist milwaukee.craigslist.org/pts/299554991.html

 

[freelunch]

Re: 165 merc performance modifications

thanks but id like to get more information about the engine before i go to buy

 

[HT32BSX115]

Re: 165 merc performance modifications

When I had my Mark Twain with the 230 cu-in 6 I found out that the best replacement is to use another 230 or 250.

The front eng mount appeared to interfere with the 292 vib damper.

You can do a lot to a 250 to make it run good.

The limiting factor is exhaust. You can only cram so much gas flow out thru the current exhaust system. Any thing you do to make the engine breathe better on the intake side will require better flowing exhaust unless you install a thru hull exhaust.
If you REALLY want a lot of power come get this King Cobra I have sitting on the floor!!

Just kidding....you DON'T want it!

 

[freelunch]

Re: 165 merc performance modifications

ha, i dont think i would ever see over the bow of my boat again with that thing hooked up to my stern drive

 

[ziggy]

Re: 165 merc performance modifications

i,ve got a 250 too. i've also done a little research on mods for it. i also have not found much to do to it. so......i've given up and have decided i'm happy with what i have. a good low end torque engine that has a good track record of running a good long time that is fairly fuel effeciant for a boat engine.......keepin it stock surely can't hurt for longevity of the engine i don't think either.....i do think doing the hard valve seats is a good mod though and have cosidered doing that because of the fact that ya can't get leaded fuel anymore. as for now, i run lead additive + the premium fuel it says it wants.....i'll leave the mods to the wanna go fast guys w/ v8s in them and will concentrate my efforts on just keeping my stock L6 in good, proper tune........

 

[freelunch]

Re: 165 merc performance modifications

Well hey if you have any good links for tuning the Rochester 2 bbl we have on our engine along with timing adjustments pass them on, I'd greatly appreciate it. Thanks alot !!

 

[ziggy]

Re: 165 merc performance modifications

well, sorry, i don't have any links for ya. everything i have is out of the mercruiser service manual. (a book)
wot: 3900-4300
dwell: 31*-34*
idle: 500-600
-timeing: @idle, 6*BTDC
plug gap: .035"

not sure what ya want for the carb tuneing. here's the procedure for adj. the mix screws of the 2GC carb, if that helps....

-connect a tachometer and vacum gauge to the engine.
-with a thoughly warmed up engine, ck that choke is fully off (open)
-start engine and allow to idle. adj. idle speed screw to 475 rpm
-adj ea. idle mix screw separately to give peak vac. and rpm indications on the tach and vac gage (note) make approximate idle misxture adjustment by setting idle mixture screws lean to modeate rough idle, which will give a slight vacuum and speed loss, then back screws out (enrich) 1/4 turn. IMPORTANT do not turn idle mixture screws tightly agaisnt stop, or needle seat will be damaged.
-shut off engin and remove tach and vac. gauge
-test boat to check performance
there is also info on float lever and drop adj., pump rod adj. and unloader adjustment. if ya need more. i post them up for ya too. good note is the auto choke adj. in it's normal setting is such that scribed mark on the cover is in line with the long case mark on the choke housing casting. and there is no choke rod adj. as there is no adj. of the fast idle speed. is that the kinda info ya were lookin for? hope it helps........

 

[freelunch]

Re: 165 merc performance modifications

Actually yea thats the procedure i was looking for, thanks