3 Chrysler heads compared. 70hp, 75hp, 85hp

[Frank Acampora]

Re: 3 Chrysler heads compared. 70hp, 75hp, 85hp

All the WB carbs for the larger engines have the same basic casting and same inlet bore. Some 70 and 75 HP engines have a 1 3/16 venturi and almost all 85 and up have a 1 5/16 venturi. Additionally, Some of the carbs for higher horsepower engines have a slightly larger butterfly yeilding slightly less restriction to airflow at full throttle.

As horsepower increases, jet size also increases and although the larger jets will deliver more fuel at full throttle this is basically to compensate for different venturi size and air venting of the carbs.

HOWEVER, putting 85 90, 100, 0r 105 carbs on a 70-75 HP engine will not yeild any significantly increased horsepower.

 

[Fuzzz]

Re: 3 Chrysler heads compared. 70hp, 75hp, 85hp

Hi,
I'm french and i just bought a seventies boat 16' with a 75hp chrysler 1975.
In the driver manual it is indicate that the max RPM of the 85hp is higher around 1000tr over the 75hp that have max RPM around 4500tr/min. I dont have the document under my eyes so it is not the right figures
So i think the difference could be in the timing, perhaps in the cdi box and perhaps in the carb with oversized jets.
The displacement is the same for the two motors in this guide.

 

[jerryjerry05]

Re: 3 Chrysler heads compared. 70hp, 75hp, 85hp

Fuzzz you should start your own threads.
The suggested RPM's is what the motor runs at for the designated horsepower.
The difference could be the prop?
The jets?
The stroke will make a difference too.
What are you trying to do?