Stoker "Performance Package"...

[mikiedreb]

Can anybody enlighten me as to what "offset chamber" heads on a 97 225 Evinrude Vindicator are about? Viewed externally, they
appear to have a red anodized circular insert, with the spark plug installed ....offset toward the outside. Do they bump the compression up? Any idea how much? Would a change in jetting have been required? The recommended plug for this setup is Champion QL78YC. Any info would be helpful.

Thanks,

Mike

[mikiedreb]

Must be "top secret" stuff.......huh?

Mike

[ShipBear]

The'll be people that know read this soon..

You may need to run a compression test, to see what you have..
I would say you need to run the best gas you can get.. To be on the safe side.. I'm not sure about jets.. So want guess..
I think your timing and fuel, needs to be right on....

Later Larry

[CRMERC]

You might want to get in touch with ron baker. He was making a set of heads with removable offset domes a couple of years ago.

[mikiedreb]

Would anybody happen to have Ron Baker's phone number handy?

Mike

[mikiedreb]

Would anybody happen to have Ron Baker's phone number handy?

Mike

[CRMERC]

he is at (www.scaryfast.com)

[mikiedreb]

Mucho thanks :D

[Rusrog]

YOu need to be careful with those... Offset chamber heads are a good piece and can really make a difference in the way a motor runs but....... When you nmove the spark plug towards the intake port you are essentially advancing the timing by several degrees. You will need to retard teh timing significantly before running off-set chamber heads or you will fry the motor. Now how far to retard the timing depends on how far the plug has been moved. I am not familiar with those particular heads so I have no idea but it is not umncommon to have to retard the timing by 4-6 degrees. Just be careful and watch your plugs and piston domes.

Hope I helped,

Russ Rogers

[mikiedreb]

Russ....more good information....thank-you.

I just got a response to an e-mail from Al Stoker. He says the heads are 46cc, a bit tighter that stock, and must run on 91 octane fuel. He also said the jetting was changed to accomodate the compression bump. No idea how much change....I'll know that when I disassemble I guess. How many cc on stock heads?

Mike

[racer]

Leave the timing alone, to little timing makes excessive heat. The engine in question should be set at a minimum of 16 to a max of 18 at 5000 rpm.

[BenKeith]

If you're scared of them, I'll be more than happy to send you a set of stock heads and pay all shipping cost. Heck, I will even send a new set of gasket too. Now ain't I being a very nice guy.

Those heads will usually give you a few more hp. The main reason for the offset is to move the plug's more in line with where the actual firing point needs to be inside the chamber.

They should have the chamber size on them also. I don't think you would want anything smaller than 50cc for a lake boat. Even at that, make sure you run 92/93 octane I would also think if someone went through the expense of putting those heads on, there are other mods done to the motor also.

[mikiedreb]

Thanks for the timing specs racer.....I'll be sure to check um..

Uh......Keith......uh........

I'll get back to you on the head swap......that's very generous of you to "even send a new set of gaskets too" :rolleyes:...... :D

Mike