Regular Gas on 500HP Carb
 

I know on the 500EFI you can run regular gas, but can you on the 500HP carb?

Re: Regular Gas on 500HP Carb
 

yes 87 min I run 89 to avoid getting less than 87 but if you trust the station and supplier your all set. Waste of money to burn anything higher.

Re: Regular Gas on 500HP Carb
 

Here's the specs for both the engines in question:

The "Bulldog" and Hp 525 show 87 Octane as well and Merc jumps it to 92 Octane recommendations in the 575 and above.

HP500 Specifications :
Propshaft Horsepower: 470/350
Displacement (Liter/CID): 8.2/502
Cylinders: V-8
Bore (in/mm): 4.47/113
Stroke (in/mm): 4.00/102
Compression Ratio: 8.75:1
Fuel Requirements: 87 Posted Octane (R+M)/2
Full Throttle RPM Range: 4800-5200
Ignition Type: Thunderbolt V
Alternator (amps/watts): 55/776
Length (in/mm): 38.3125 /973
Width (in/mm): 32.75/832
Height (in/mm): 23.5/597
Weight (lbs/kg): 1305/592
Warranty: 1-year limited, 3-year limited corrosion


HP500EFI Specifications

Propshaft Horsepower: 470/350
Displacement (Liter/CID): 8.2/502
Cylinders: V-8
Bore (in/mm): 4.47/113
Stroke (in/mm): 4.00/102
Compression Ratio: 8.75:1
Fuel Requirements: 87 Posted Octane (R+M)/2
Full Throttle RPM Range: 4800-5200
Ignition Type: Digital
Alternator (amps/watts): 60/847
Length (in/mm): 34.3125/872
Width (in/mm): 33.75/857
Height (in/mm): 22.0625/560
Weight (lbs/kg): 1305/592
Warranty: 1-year limited, 3-year limited corrosion

FYI

HP525 EFI - 525 HP
Specifications
HP: 525
kW: 410
Full Throttle RPM Range: 4800-5200
Displacement Liter/CID: 8.2/502
Bore & Stroke (in): 4.47/4.00
Bore & Stroke (mm): 114/102
Compression Ratio: 8.75:1
Cylinders: V-8
Alternator Amp: 65
Alternator Watt: 917
Fuel System: MPI
Ignition System: PCM 038 distributorless
Fuel Requirements: 87 Posted Octane (R+M)/2, (92 RON) International
Transmission: (Six) w/Huber 600 Series
Drive Options: Bravo One XR, Bravo One XR w/ITS, Bravo One XR Sport Master (Standard or Short), and Bravo One XR Sport Master (Standard or Short) w/ITS. Dry-Sump Six w/Huber 600
Length (in/mm): 39.5/1003
Width (in/mm): 34/864
Height (in/mm): 24/610
Weight (lbs / kg): 1201/545
Warranty: 1-Year Ltd. for Recreational Boating/3-Year Ltd. Corrosion
SmartCraft: Yes


Definately true about variance in brands and stations. I had a knock and switched brands in the same octane rating and the problem went away.