Originally Posted by fastestbowtie (Post 3168395)

Thanks... I am hoping it is just bad gas, but it does worry me that it could be a bad injector, loosing fuel pressure, or something like that causing a lean condition which could destroy my motor. The previous owner had actually had the motor pulled out in 1995 and sent off to a place that specialized in marine engines (drawing a blank on the name) and they completely went through the motor, forged pistons, rod bolts, decked, balanced, and they added a set of Dart iron heads and a Crane cam and then dyno'd it (with headers). It made right at 400 HP and then they replaced the ECU (not sure if they added any custom tuning or not but they did have the specifics on the spark advance) and then it made 424 HP (all with the 320 EFI injection setup). I really hate the idea of back stepping back to a carb, but the lack of parts and the difficulty diagnosing problems with this EFI does have me considering it. I would really like to switch to that new Edelbrock EFI, but that cost 1/3 the cost of the boat.

Originally Posted by hallj (Post 3168488)

Replace your merc ECUs with GM speed density units.

These guys can help you with the swap, http://tpis.com/

You will love the way it runs!

Jeff

Originally Posted by hallj (Post 3170786)

I did something similar, I changed from a carb and used a 320 lower manifold(didn't have the upper). Made a custom upper with an LS1 throttle body. I had to make an adapter plate for the exhaust to fit O2 sensor. I dynoed the engine on their dyno, they did the tuning at that time.
If you give them the engine specs they should be able to burn you a PROM and get it right on. I can send pics to your e mail if you would like.

Jeff

Originally Posted by andyt25 (Post 3166939)

does anyone know what heads came on the 88 320 efi engines I seized one of the engines 2 weeks ago and I'm pulling both engines and plan on bulding 383s and going to carbs just wondering if I need to price in new heads in the build. The engines are being pulled out in the next week or so.

Originally Posted by hallj (Post 3170786)

I did something similar, I changed from a carb and used a 320 lower manifold(didn't have the upper). Made a custom upper with an LS1 throttle body. I had to make an adapter plate for the exhaust to fit O2 sensor. I dynoed the engine on their dyno, they did the tuning at that time.
If you give them the engine specs they should be able to burn you a PROM and get it right on. I can send pics to your e mail if you would like.

Jeff