merc 350 heads

[thundercat 9]

What is the difference, if any, between heads on a merc and heads from a normal 350? Not withstanding the differences in CC's. Do any automotive heads cross over? Where can I find a good head,new or used? My motor is an 87' 350 merc, 260hp.

thanks
jeff

 

[thundercat 9]

Re: merc 350 heads

Hey guys,

Since no one bit on the first thread, I'll revise it. I removed the factory head(the bad one,no gasket mating surface left between the water jacket and cylinder, salt just ate it away) has a casting # 14096217, I checked into it and it's supposed to be a crate engine, 55-86, 350cid, 285/300hp, 64cc chambers with either 72 or 90 degree center intake manifold angles. The other head, which is a replacement, has the casting # 14102191 and all I could find out about that one was it was a 350 manufactured from 1987 on. Before I took the bad head off, I did a compression test and the compression is running around 160 PSI on all the good cylinders. Can anyone tell me were they get 260hp from for this motor?

thanks
jeff

 

[Bondo]

Re: merc 350 heads

At this point,......
You have Very different heads that Shouldn't be run together on the same motor........
There was a slight change in the angle of the intake center bolts in 87.......

Do any automotive heads cross over?

Ayuh,........
They All do,..... But, you need a Matched Set,.......

Go to Mortec.com to find the different casting #s,+ details of Which are What......
While you're there,....
Check the Casting # of your Block,+ see if it's actually an 87, or an earlier motor......
You need to match the Intake bolting to the heads you need.... You might find the casting #s for it at mortec.....

 

[thundercat 9]

Re: merc 350 heads

thanks for the info

 

[Mkos1980]

Re: merc 350 heads

You can also run a set of 083 Tuned Port Injection heads. Those were also used in place of the 217's and yield the same specs. If the center intake bolts are 72* then the 083 heads would work. 193's would prob work too. Accually doing a quick search alot of people sell these heads to replace eather of the 3. I'm doing dyno tests with a stock 260HP 5.7 motor now with 217 heads.

http://www.speedwake.com/upload/showthread.php?s=&threadid=52583

 

[John_S]

Re: merc 350 heads

With stock 14096217 heads, you should have dished pistons. I wouldn't bother trying to stay with them. It is a good time to upgrade to vortec heads. You will need a new intake, but overall you will gain 30+ hp.

 

[John_S]

Re: merc 350 heads

Mkos1980,

Thanks for the info posted on Speedwake.

 

[thundercat 9]

Re: merc 350 heads

hey guys,

thanks for the responses. My pistons are not flat tops but have a little "dish"
shape with the indents for the valves. My heads also have the 72 degree center bolts with 1.94 intakes and 1.5 exhaust. I just want to keep it stock for now, this is my first time boating so I might not like it.....don't want to sink to many greenbacks into it....

 

[thundercat 9]

Re: merc 350 heads

After alot of research, here is what I found. You can replace cylinder head casting # 14096217 with #14101083/ #14102191/ #14102193/ and possible # 14011083.

I hope this can help someone when they find themselves looking for replacement heads.

cheers
jeff

 

[John_S]

Re: merc 350 heads

Nothing wrong with keeping it stock. I mention the vortec heads because they are stock on latter mercruisers and would be a bolt-on with your dished pistons. Also, it is very hard to beat the price of new vortec heads, but you do have the "penality" of buying a new intake. That small penality is easily overcome by the performance increase. It was just something to consider.

 

[thundercat 9]

Re: merc 350 heads

I appreciate your input John, and maybe in the future I might think about swapping, but for now I'm just going to put a replacement(used) head on that I picked up. With my luck, if I upgraded to the vortec heads, I would end up shredding my Alpha1 outdrive...


jeff

 

[Mkos1980]

Re: merc 350 heads

When I get done with the Crane Cam install with stock 217 heads I'll post them up. The 217's are not "that bad" but as mentioned above the vortec are alot better. I was going to do it but its alot cheaper for a cam swap.

 

[John_S]

Re: merc 350 heads

Mkos1980,
I'd be interested in that pull results, especially if you do it with stock exhaust.

 

[Mkos1980]

Re: merc 350 heads

IJ, I will post the results with the headers, stock OEM Manifolds and my New Revolution Manifolds. Cam Specs are 214/220 452/465 112LSA

 

[John_S]

Re: merc 350 heads

Great! So you will be changing the rockers back to 1.5:1? DM indicates that cam is good for 20-25HP in a stock 350.

 

[Mkos1980]

Re: merc 350 heads

Correct as I dont want to run into guide or seal to retainer clearance issues. Now assuming my stuff is good, I may run the extra lift to see what happens, but then I get into the whole pressed in stud issue and them ripping out at higher lift cams and more spring pressure.

 

[thundercat 9]

Re: merc 350 heads

Hey mkos, one thing I did notice about the replacement head I used was that the holes in the head were the pushrods go through are round and the ones from my original head are rectangular. The round holes cause my rocker arms to shift from side to side on top of the valve stem. Is there some sort of pushrod guide plate available to solve this problem?

thanks
jeff

 

[John_S]

Re: merc 350 heads

You need self-aligner rocker arms. My 217 heads came with them. Same is used on the vortec heads. Guide plates should work, as well (but will require removing heads for machining, drilling, etc).

 

[thundercat 9]

Re: merc 350 heads

Just another update....heads that were manufactured after 1988 use self aligning rocker arms.

jeff

 

[Mkos1980]

Re: merc 350 heads

Just another update....heads that were manufactured after 1988 use self aligning rocker arms.

jeff

1987