496 mag to 496 mag HO conversion
03-05-2010, 06:27 AM
#31
example would be, if the bleed/vacoum hole was to big the ecu would command the IAC pintle all the way out to bring the idle down which that could trigger a false code,making the ECU thinking the engine has a vacoum leak or running lean.
if the bleed/vacoum hole was to small then the ecu would command the IAC pintle out so it could keep a idle at a certain rpm.
Last edited by boatnt; 03-05-2010 at 06:39 AM.
03-05-2010, 06:35 AM
#32
I know its going to take some time but if I gain the speed others have with the same boat and engines as mine and make it a 80mph it will be worth it.
when someone asks how fast is your boat 80 sound so much faster then 75,also not that I want to sell the boat but resale value is much higher with 496 mag HOs then 496 mags,
only time will tell,thanks again for all the input
Last edited by boatnt; 03-07-2010 at 09:19 AM.
03-05-2010, 07:52 AM
#33
so for the guys that have done this before,what kind of harmanic puller did you guys use?I beleive merc uses a different harmanic balancer then GM so I dont know if the puller I have at the shop is the same.
how about a harmanic installer?pleese dont say use a hammer.
how about a harmanic installer?pleese dont say use a hammer.
03-05-2010, 08:23 AM
#34
Registered
Join Date: Jan 2007
Posts: 1,667
Likes: 0
Received 0 Likes
on
0 Posts
Don't for get to pull those heads and replace!!
Last edited by SDFever; 03-05-2010 at 08:26 AM.
03-05-2010, 09:24 AM
#35
Gold Member
Gold Member
All older stock MerCruiser EFI engines 496/8.1 and below idle at 590- 610ish RPM's
As of somewhere around 2007ish the idle speed has been dropped down to 540-550 RPM's on small blocks V6 & V8,
Here is the list for non emissions engines.
Vazer engine is at 600 rpm
4.3 mpi is at 550 rpm
5.0 mpi is at 550 rpm
350 mag is at 550 rpm
377 mag is at 550 rpm
496 mag and HO is at 600 rpm if it has the mechanical shift
496 mag with DTS is 575 rpm (including Axius)
496 mag HO with DTS is at 625 rpm (including Axius)
And here is a list of engines with emissions.
Vazer engine is at 650 rpm
3.0 MPI with emissions is at 700 rpm
5.0 mpi is at 550 rpm
350 mag is at 550 rpm
350 mag is at 550 rpm
377 mag is at 550 rpm
496 mag and HO is at 650 rpm (ALL MODELS)
All the V6 & V8 carburetor engines should be set at 640- 650 RPM's, And the 3.0 TKS should be set at 700 RPM's.
As of somewhere around 2007ish the idle speed has been dropped down to 540-550 RPM's on small blocks V6 & V8,
Here is the list for non emissions engines.
Vazer engine is at 600 rpm
4.3 mpi is at 550 rpm
5.0 mpi is at 550 rpm
350 mag is at 550 rpm
377 mag is at 550 rpm
496 mag and HO is at 600 rpm if it has the mechanical shift
496 mag with DTS is 575 rpm (including Axius)
496 mag HO with DTS is at 625 rpm (including Axius)
And here is a list of engines with emissions.
Vazer engine is at 650 rpm
3.0 MPI with emissions is at 700 rpm
5.0 mpi is at 550 rpm
350 mag is at 550 rpm
350 mag is at 550 rpm
377 mag is at 550 rpm
496 mag and HO is at 650 rpm (ALL MODELS)
All the V6 & V8 carburetor engines should be set at 640- 650 RPM's, And the 3.0 TKS should be set at 700 RPM's.
But I ahve a Raylar cam and big heads.... Still 650?
03-07-2010, 08:57 AM
#36
Well Port side is a 496 mag Ho and the Starboard side is a 496 mag.
Got a later start yesterday then I had hoped for,
started around 11:00am and finished around 5:30 pm
the Port engine is complete and put back together,filled with antifreese.
today, as soon as my back is up to it I will go and do the Starboard engine.
Got a later start yesterday then I had hoped for,
started around 11:00am and finished around 5:30 pm
the Port engine is complete and put back together,filled with antifreese.
today, as soon as my back is up to it I will go and do the Starboard engine.
