496 HO Throttle Body Question
 

Last week I had the spark arrestor off of my 496 HO. Out of curiosity I checked the throttle plate opening at full throttle. I noticed that the linkage hits the the throttle stop that is cast into the throttle body before the throttle plate is completely horizontal. Had no way to measure but it appears to only allow it to open about 85-90%. Common sense tells me it should open to completely horizontal but perhaps that is not the case. Anybody have any thoughts on this?

Thanks,

Mike

That is a normal problem. I recently had my throttle body bored and put a new butterfly in each one. We slightly bent the metal stop on the linkage till the butterfly was horizontal. You need to also make sure the throttle cable does not have a bunch of slack in it or the stop isnt really a "stop".

Only problem is if you dont have a modified 496 or arent at or close to the rev limiter by being over propped it wont really do anything.

How did you bend the stop on the linkage? I tried bending that tab whith the throttle body still installed on the intake but could not get it to budge. Not much room to get tools to it.

I do not have slack in the throttle cable. At full throttle the linkage is in contact with the stop.

I had the linkage apart and the throttle body off the intake. The throttle body comes off easy.... 5 minute job.

You might be able to leave the throttle body on and grind the stop down with a Dremel, its only aluminum.

Again, unless you are at or near WOT and think it will make a change, is it worth the trouble?

I was thinking along those lines. Should be easy enough to take a little off the stop with a dremel. May net absolutely zero gain, however should be a simple job and every little bit helps. Also, the peace of mind knowing it is getting true full throttle will be worth the effort. It is bothering me now that I know it is not openning all the way.

I Am Bored, What Can I Do To My Merc 496????
 

I think you should have my answer to your email you sent directly to us a Raylar , but in any event for the other 496MAG and HO owners here on OSO, I will elaborate.

The only real and measurable gains that can be made for a Merc 496 MAG or HO are:
1. Upgrade the cam and ECM program in a stock 496Mag to HO spec or Raylar 103 camshaft. 50-65 HP gain.
2. Add a good header exhaust like Dana Flo-torque, or CMI Sporttube , Lightning, Hardin, or Stellings headers. Plus 30-40HP on both MAG and HO's
3. Upgrade the engine with a Raylar BCK103 kit which adds 150HP on a 496MAG (with HO -reprogramming), and 100HP on 496HO (no reporgramming needed) and both of these with stock Mercury 496 exhaust.

Playing with throttle bodies that are showing 98% to 100% on a scan tool, playing with ECM reprogramming on stock Merc 496's, K&N air filters, etc.etc.,etc. will not any real net power or torque. How does Raylar know for sure, beacuse over the last 8 years we have tried every concievable type simple lower cost change and we never saw any real measurable horsepower or torque increase on our stingy dynos nor in any boat we in the water tested.

Answer is: Leave your 496 alone if its running and operating fine and its reaching close to maximum rpms under load in your boat. If its not achieving top rpms under load, check your boats setup( ie: prop type, pitch, fuel system filters and screens, water sperating fuel filter, etc, and make sure with scan tool you are running at 100% power and not in a 90% power semi-guardian mode.

In the mean time, Save your money, wait for inheritance or lottery money or rob a bank (NO) and when you've got enough green to make meaningful upgrades to your 496, "GETT'ER DONE"!

Old Chinese proverb- "IF IT AIN'T BROKE, DON'T FIX IT!!

Until then, polish and clean that puppy and get ready to enjoy your boating season! Be Safe! Have Fun!

Best Regards,
Ray @ Raylar

The Gm LS1 and 6 have the same problem, which use the same throttle body. On a car it can make a few HP but on a boat you wouldn't see any gain in speed etc.. because....... well, it's a boat :)

I'm looking for a trottle body for a spare engine i'm building,who has the best one for the money?

If you are using the standard Merc 496 or marine 8.1L then we have a polished 80MM throttle body we build that has linkage arm to connect properly directly to your thottle cable in the stock location. They are $595 each plus UPS S&H. we also stock take off stock throttle bodies with or without Merc linkage. they are $250 plus UPS S&H.

Best Regards,
Ray @ Raylar

now this is a true gentleman.....
someone who makes his living satisfying our need for speed telling us to not boink with it unless absolutely necessary
tips hat to ray and company