7.4's
02-05-2008, 05:04 PM
#2
Registered
02-05-2008, 07:56 PM
#3
Registered
Join Date: Jan 2004
Location: Tylertown, MS
Posts: 406
Likes: 0
Received 0 Likes
on
0 Posts
266- I had 2 330 hp 7.4 rebuilt a year ago. they are 89 mark 4 engines. 2 different engine builders (a long and not so good story,search for cam problems in forums). They were built for a power increase and reliabilty. I do not have to be the fastest on the block and I usually cruise at 48-50 mph.
I am looking at my dyno sheet on the best engine it reads
best HP was made at 5200 RPM and 460.4 HP. Best torque was 487.1 @ 3500 RPM.
From 3200 RPM to 5200 RPM, torque never below 454.9 (this was at 5200 RPM)
Wanted engine to be strong in the rpm range that I drive the most and it is.
28 degree timing
93 octane
502 square port heads
stock alum high rise dual plane (Merc.)
Eldebrock 750 marine carb. Straight out of box.
Gill exhaust (thru hull)
water x over
163 thermastat
stock ignition thunderbolt
8 degree initial timing
Fluid dampner
Harland sharp roller rockers
bigger push rods
0.30 over
KB hyperutectic pistons
9 to 1 corrected compression
Billet custom roller cam and lifters from RM Builder
Stock rods ,crank, etc.
Stock heads.
Engine #2 has same parts except this one has 454 LS7 square port heads and different engine builder. (again,long story) Pulls only 439 hp.
Can get specific component lists and cam specs next week.Will not be home till the 16th. At work.
Boat is a 30 baja (91) big heavy turd. Runs well. Good low end and tops at 64-65 mph spinning 23 pitch 4 blades. Engines idle very well at 600-700 rpm. Have about 4,000 bucks each in them. I know nothing great but I wanted to keep it on mild side to hopefully not wrench on them much. Have 110 hrs on them so far with no issues.
I am looking at my dyno sheet on the best engine it reads
best HP was made at 5200 RPM and 460.4 HP. Best torque was 487.1 @ 3500 RPM.
From 3200 RPM to 5200 RPM, torque never below 454.9 (this was at 5200 RPM)
Wanted engine to be strong in the rpm range that I drive the most and it is.
28 degree timing
93 octane
502 square port heads
stock alum high rise dual plane (Merc.)
Eldebrock 750 marine carb. Straight out of box.
Gill exhaust (thru hull)
water x over
163 thermastat
stock ignition thunderbolt
8 degree initial timing
Fluid dampner
Harland sharp roller rockers
bigger push rods
0.30 over
KB hyperutectic pistons
9 to 1 corrected compression
Billet custom roller cam and lifters from RM Builder
Stock rods ,crank, etc.
Stock heads.
Engine #2 has same parts except this one has 454 LS7 square port heads and different engine builder. (again,long story) Pulls only 439 hp.
Can get specific component lists and cam specs next week.Will not be home till the 16th. At work.
Boat is a 30 baja (91) big heavy turd. Runs well. Good low end and tops at 64-65 mph spinning 23 pitch 4 blades. Engines idle very well at 600-700 rpm. Have about 4,000 bucks each in them. I know nothing great but I wanted to keep it on mild side to hopefully not wrench on them much. Have 110 hrs on them so far with no issues.
