Logo
FULL SITE MENU

350 vortec fuel injection to 4bbl rochester conversion

S

salt life

New member
i recently swapped out a old 260 alpha one with a newer 98 vortec 350. the vortec was a marine engine with fuel injection we are using a cast iron mercury 4 barrel intake with a rochester quad. the boat will rev fine in nuetral but under load it bogs down and starts to flood out when trying to get on plane. at idle it runs fine. i put in anew carter elec fuel pump and a new rebuiltquad. we used the thunderboltiginition but cant seem to get the motor to suck the fuel down into the intake. will a spacer bar make more vacumm.

salt life.
 
NO

You need to find out what cam is in there.

Also you might have used a dual plane aluminum such as a air gap style manifold.

What thunderbolt ignition?

IV or V

What did the carb come from? a boat or car/truck?

Who rebuilt it?

If it is flodding the carb needs to be adjusted correctly or recalibrated IF it is the carb.

Whats your base timing? How did you set it? depends on which iginition you are using.

One type of thunderbolt needs input from a knock sensor........


way too many questions and WAY NOT ENOUGH INFO AGAIN!!!!
 
I did that conversion, from a 1994 5.7 to a 2006 vortec that was FI. I reused all my accessories including the carb. I found a used aluminum hi-rise marine intake and added a marine electric fuel pump. My ignition is thunderbolt IV. You may have a timing issue. Mine runs like a scalded dog.
 
the carb was a rebuild unit from ebay and supposed to set up for marine use. as for the 4 or 5 thunderbolt i will check at first light on that. we have walked the timing all over the range and set it as best we could without a light. the cam is the original equip for mercruiser 300 horse 5.7 ltr vortec. sorry about the lack of info just trying to get ideas.

thanks for any and all help
 
No Ideas without info.

YOu want ideas for a general question? there is no such thing as a general question about motor performance or problems.

THE DEVIL IS IN THE DETAILS..........


Ebay carb and you do not know if it is a marine carb or a automotive????

They are not the same.......................................

No timing light???? No way to see if your ignition module is advancing the timing as it should. GET A TIMING LIGHT!!!~

MY OPINION!!

If you do not have some basic tools or understanding of what you are doing, I will be hard to answer your questions.
 
A spacer won't make any vacuum. The engine doesn't suck the air/fuel mixture into it; the atmosphere pushes it into the cylinders.

Do like Kghost suggests and get a timing light and set the distributor correctly.
 
Back
Top