mpi to carb conversion
 

i would rather sell my whole efi setup and buy an intake carb distributor and coil and call it good. i have no issues with carbs that i can think of and it seems to work for everyone else so what do i specifically need to get to make this work


motor is a 98 502
rectangle port heads
roller cam
bored .034 over
everything new and rebuilt by shop

above is all the same as gen 6 502mag

what size mechanical carb do i need

what kind of distributor would be best( with box or with out)

what kinda of intake manifold


etc!!!



thanks for the help guys!

800cfm
Merlin or Dart single plane intake manifold
MSD distributor and box

just did the same thing....

I have heard nothing but good about these.

http://www.performancedistributors.com/marinedui.htm

My question is- why do you want to do this? The EFI in stock configuration will give you better drivability, somewhat better fuel economy, and better resale value in the long run. Unless you are going on a radical performance build where the EFI setup will not work, I would say you are going backwards. Just my 2 cents.

+2

Best thing I did getting rid of all the MPI. But of course mine was not a mag EFI.

EFI is ok for stock setups, from there very expensive to get right with tuning the ECM with mods...pieces for EFI are high $$$ and I can tune a lot on a carb...

x2 thats what I use

Really? You can get a custom tune done for under $500.

www.mefituning.com is a great source for tunes.

Got rid of my EFI. no more vapor locking for me.

It still amazes me you guys are spending thousands of dollars to go backwards.
EFI ain't that difficult if you know the right people.
To each his own.

I thought about also, but stayed with efi!! Can't beat turning key and crack!! No pumping lever ever...

Prop less, I bought the merc kit that added an aux pump and cured my vapor lock for $100... Easy plug n play!

jeffswav i know you are a big name on this site and you have helped me before so what can you tell me about the hei distributors.... the mechanic at my company runs one on his circle track car and said the same thing....

drop the need for a coil i get that but what about a ignition box....


i have been told edelbrock performer air gap single plane + 800cfm holley marine 0-9022 carb......


my question is do i need a box if i use that or just the hei distributor carb and intake?

also any thoughts on a particular intake manifold?


someone told me to go with a airgap which seems good power 1500-6500 but im pretty sure everyone on here says single plane.....

remember this is just a roller 502 with retangle port heads

looking for drivability, not a huge fuel loss, and reliability!

Air Gap manifold is also a good choice. It is a dual plane and I doubt you will loose any top end power with it and your combo.

I am sure more people are running dual than single plane intakes manifolds when running in the 5,000 RPM range.

I have RPM Airgap, RMBUIILDER cams, and Holley 800 D.P.
jetted up to 78 -91 with power valve, and thunderbolt ignition set at 34 degrees.

I turn it up to 5,200 and that manifold works great.

no with the HEI you do not need a box, just drop it in and run...ran one a bunch..and you guys can have your $500 tune...and sending back and forth trying to get it right...both setups have their advantages..just have to asked yourself whats it worth to you...

hey what kind of motor are you running? what kind of hp? boat? mph?

The DUI is a all in one, cap, coil, rotor and modual. No box needed, most I have spun it up to is 5600 RPM. I have run it 2 seasons and no corosion or rust like you get with MSD. I have the electronic advance version but the mechanical work well also. I kind of agree with Jason, I like MPI, starts better, quicker, better fuel economy, ect.... I however use the Holley Aftermarket system so I can program mine on the fly with the laptop. The merc comp needs to be programed by a pro.

When I boat my boat I wanted cards!!! Here so many problems with efi and big power. Boy I could not be happier!!!! Turn key all day and has not missed one beat!!! LOVE IT!!!! Boost and cards just works great. Like must better than tuning with a map sensor. Do it u will not look back.
Skydog

Ok so I'm buying a Holley 0-9022 Thursday, ordering the d.u.i marine 7000 series tonight online and searching for a good intake!

Anyone have some helpful hints?
Timing advance?
Jetting of carb?
Furl pump and or regulator?
Currently I have the mechanical to electric to rail set up with return line.... Can I use one or both and a regulator?


Tryin to be floating this weekend!
Thanks guys