chevy 6 cyl

75boater

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my boatr has the straight six chevy engine... its a 1972 reinell 165hp. 18ft. how do i find out info about the block itself? i want to change the head over to a reg unleaded head. right now i have to put lead additive in the fuel. that and it would just be nice to know c.i.d. and things of that sort
 

Bondo

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Re: chevy 6 cyl

It's a Chevy 250cid, I-L 6 cylinder.......

It'll Probably be Easier,+ Cheaper to have Your Head Rebuilt with hardened Seats.......
 

ziggy

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Re: chevy 6 cyl

18ft. how do i find out info about the block itself

a service manual works pretty good for that. if ya got a 72 165 ya need service manual c-90-68648 vol.s 1 and 2. if ya got a 75, like yer screename, ya need c-90-71707.

i, like you am just adding lead additve.....suppose the thing to do proper would be to do them hardend seats. it is kinda a drag to do the additive thing for sure........
 

75boater

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Re: chevy 6 cyl

thanks for the info guys... any clue what the cfm on the carb would be? i would like to upgrade to a new edelbrock or just somehting a little newer... also would it matter putting a new edel. or a holley on it even though it requires me to run the lead additive?
 

ziggy

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Re: chevy 6 cyl

i would like to upgrade to a new edelbrock or just somehting a little newer
why? do you have a goal in mind? does yer oem carb. work poorly?

also would it matter putting a new edel. or a holley on it even though it requires me to run the lead additive?
sorry, don't know the answer to that. but i would think that yer 2gc carter carb. was made to run on leaded fuel. (assumin that ya have a 2gc like my 72 L6 had) i've had 2 L6's with these carbs. and they seem to do ok. had many problems with my boats. but never any problems from the 2gc......aint never even had to rebuild one. though, if i did. 66 parts looks about as easy as it gonna get for carb rebuild to me...
 

75boater

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Re: chevy 6 cyl

its not so much that it works poorly its just that its preobly 30 years old and needs to be rebuilt. i have never had much luck when rebuilding carbs. i know how and do everything correctly, they just never run the same ya know?that and it would be nice to go to an electric choke. i have been tossing the idea of fuel inj. around too. no luck on finding a fuel injection system for that motor though.
 

freelunch

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Re: chevy 6 cyl

Hello there, I have a 165 L6 as well. I also had the same issue you are having. The lead addditive was too much for me to have to worry about all the time so I just pulled the head off and had my local machine shop install new exhaust seats.
While the machinists have your head it may also clear up alot of other issues that may be contributing to your problems. I had my valve springs shimmed to get back to proper seat pressure and confirmed my head was straight and in good condition.
All said and done my total expense for the job was 320 dollars. Sounds like a bit much just to get away from lead additive but probably far less than a new complete marine cylinder head.
I have also wondered about slapping on a new carb to try and pick up some more top end power, lemme know whatcha find.
 

bruceb58

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Re: chevy 6 cyl

If it was my engine, I wouldn't bother changing the heads or adding the additive until performance was suffering. Have you ever tested the compression on this engine? How many hours on it?
 

75boater

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Re: chevy 6 cyl

no clue how many hours are on it... the boat runs ok but when kicking wake to wake and getting into rough water it starts to sputter a bit... when it gets hot after running for a bit it also has trouble wanting to fire up... im thinking the sputter is just not enuf fuel pressure...
 

ziggy

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Re: chevy 6 cyl

bruceb58 If it was my engine, I wouldn't bother changing the heads or adding the additive until performance was suffering. Have you ever tested the compression on this engine? How many hours on it?
i'm with bruce. though i do add lead sub. myself. but i aint changeing anything till something goes bad. and not adding lead from what i read is really non consiquential. something else will go wrong. then when yer heads off ya can do the hard seat thing.

75boater, have ya done any tune up stuff to yer engine? or done a compression test like bruce is talking about.

had me a coil on my L6 that wouldn't work when it got hot.

if ya think it's fuel pressure, do a pressue test of the fuel pump. i believe it's supposed to be 3.5-4.5 psi.......have ya replaced any fuel filters? in my 32 year old boat i've got some crap in my fuel tank. i've been R&Rin fuel filters pretty regular. slowly it's cleaning up too.......

instead of modifieing yer engine w/ a new carb and hard seats. try to get it right the way oem wanted it. after that, and ya got it runnin right, then ya can play with yer engine. if ya can find anything parts wise to play with, which i don't think ya can.....

what book ya useing too? ya really need a mercruiser book so ya know the facts if ya want to play........
 

freelunch

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Re: chevy 6 cyl

yeah you could run it until your on the lake one day and smoke is pouring out of your engine because your valves stopped seating and possibly cause more serious damage, but why?
Either use additive or change the seats, your engine is 30+ years old, and if common practice suggests anything taking care of the issue beforehand will allow ya to plan when your finances will make the job easier to handle.
And not with a load of people and you stuck broke down on the lake.
 

freelunch

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Re: chevy 6 cyl

Oh and also hardened seats is exactly the way mercruiser would have done it today if leaded fuel wasnt a staple to the internal combustion engine at the time. Hence why they are made that way today, its a very good mod.
 

Silvertip

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Re: chevy 6 cyl

The Rochester 2GC carb is probably the easiest carb on the planet to rebuild. Any service manual for any GM car in the 70 would have detailed instructions. Obviously there are a few "marine" specific differences but nothing that would cause you to screw up a rebuild. All they ever needed was cleaning and an accelerator pump.
 

bruceb58

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Re: chevy 6 cyl

yeah you could run it until your on the lake one day and smoke is pouring out of your engine because your valves stopped seating and possibly cause more serious damage, but why?

Please explain how you think smoke will pour out of an engine or cause further damage because the valve seats are worn. You are just going to lose compression.
 

freelunch

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Re: chevy 6 cyl

im gonna go way out on a limb here and suppose his valve seats, and seals are almost certainly not in good condition. Oil can leak down through worn seals and get into cylinders with worn seats. Either way as long as he is aware of his problem he should take steps to prevent a problem, like loss of compression, and correct the problem before it further manifests itself
 

HT32BSX115

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Re: chevy 6 cyl

I have always thought that the unleaded valve problem thing was bogus. My dad bought a 66 Marktwain new with a GM 230 cu-in L6 (150hp)

He ran unleaded gas in it from new until I got it in 1997 and it never had a problem. I ran it from 1997 until I sold it last summer. The head had never been off the engine. It had over 2000 hrs on it and I would say it got very little leaded gas over it's life..... None after leaded gas was banned in the 70's

I suggest you just run the engine on the cheapest regular you can find. Don't waste your money on fuel additives.

You could buy AVGAS.... of course the price will probably be the same as mogas nowadays.....100LL is $4.25/gal up here in the NW.


If it bothers you then pull the head, get a valve job and ask them to put hard seats in it.

Otherwise, just go boating!


Cheers,

Rick
 

ParallaxBill

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Re: chevy 6 cyl

You aren't going all of a sudden start smoking on the lake from worn valve seats. Plus, worn seals will leak oil into the combustion chambers no matter the condition of the seats.

I also have a 72 GMC 250 L6 Mercruiser and add additive (when I remember to). It runs fine as designed with the Rochester 2GC. I have had 33 years experience with the same basic 250 L6 motor in my pickups and the same type carb in motor vehicles. You'll not likely to find a better or more reliable combination of either motor or carb for your vintage boat.

Just my .02.
 

SuperNova

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Re: chevy 6 cyl

I'm with ht32 here. I was told that lead was used in the old days because it was the only lubricant that would stay suspended in gasoline and even then it was intended strictly to lube the intake valve stem where the incoming fuel would was the oil off, not to lube the valve seats. Lead went away for two reasons.
1- It became known that lead was a poison and harmed children. (Anybody remember the old McDonalds glasses with the characters painted on all the way up to the rim with lead paint- they ended up getting recalled).
2- Modern science discovered new chemical compounds that will stay suspended in gasoline and not be harmful to peoples health and the environment. I, too have run old engines with no additives for years with no valve recession.
I currently have a set of '67 vintage fuelie heads from a small block chevy that I personally ran for at least 15 years on unleaded and they are perfectly fine. Valve height(also known as spring height) has not changed from when I set them up originally. Hardened seats were used for the same reason piston rings went from straight cast-iron to moly faced and ceramic faced on the newer engines and that reason has to do with longevity and cleanliness from an EPA standards point of view. Engines have to run at a certain efficiency for a certain length of time to get certified. The only way to meet those standard was to build better engines using better materials that lasted longer. It had nothing to do with leaded fuel.
--
Stan
 
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