340 Sedan Bridge 454
03-21-2022, 06:08 PM
#1
Registered
Thread Starter
340 Sedan Bridge 454
Hiya... I have a 340 Sedan Bridge with twin 454s. Last year, I let the smoke out of my port side standard rotation, and it is getting replaced. I picked up a Gen 4 454 from an 87 pickup truck, and am starting with that block. Dead engine was an 86 vintage 340 horse.
Boat is straight inboard, water lift mufflers, and not a race boat by any means. Just figured while I have it out, why not bumps things up a bit while staying in the boring rpm range ha ha. I'll be matching this build with the other side later this year, then looking at props. This one is out, so starting here.
Here are the main points....
030 overbore on Gen 4 block, hypereutectic flat top pistons, cast internals
Comp Cams XM270-HR-12, Hydraulic Roller, Advertised Duration 270/276, Lift .510/.510, LSA 112, with correct lifters and valvesprings
Vortech L29 Heads from a ‘96 Suburban
Edelbrock Performer Intake 2161, Dual Plane, Spread Bore, Chevy, 396-454, Oval Port
Stock Q-Jet, set up appropriately
Stock Merc manifolds and risers
Any thoughts on this vague combination? It will live most of it's life probably around 3,500. Boat comes on plane effortlessly as is-well, it did- see above regarding smokeless engine ha ha. Looking for eventual faster cruise when everything is done, and well, you know... This is OSO... Can't ever put things back the way we found them... Thanks! Den
Boat is straight inboard, water lift mufflers, and not a race boat by any means. Just figured while I have it out, why not bumps things up a bit while staying in the boring rpm range ha ha. I'll be matching this build with the other side later this year, then looking at props. This one is out, so starting here.
Here are the main points....
030 overbore on Gen 4 block, hypereutectic flat top pistons, cast internals
Comp Cams XM270-HR-12, Hydraulic Roller, Advertised Duration 270/276, Lift .510/.510, LSA 112, with correct lifters and valvesprings
Vortech L29 Heads from a ‘96 Suburban
Edelbrock Performer Intake 2161, Dual Plane, Spread Bore, Chevy, 396-454, Oval Port
Stock Q-Jet, set up appropriately
Stock Merc manifolds and risers
Any thoughts on this vague combination? It will live most of it's life probably around 3,500. Boat comes on plane effortlessly as is-well, it did- see above regarding smokeless engine ha ha. Looking for eventual faster cruise when everything is done, and well, you know... This is OSO... Can't ever put things back the way we found them... Thanks! Den
03-22-2022, 06:09 PM
#2
Registered
iTrader: (4)
My opinion only. But I don't believe you will gain much on that hull. I believe it is a very high cost/low reward investment. You might gain maybe 1 mph for the extra $2500 in cam upgrade. I'd put it back together stock and maybe put that extra money into different props. My friend changed props on his 370 sedan and it made it a completely different boat. Cruise, top speed and fuel consumption. But, I believe he invested nearly $3000 in new 4 blade props.
Play around with the numbers here.
https://www.go-fast.com/Knowledge-ba...eed-calculator
Play around with the numbers here.
https://www.go-fast.com/Knowledge-ba...eed-calculator
Last edited by Rookie; 03-22-2022 at 06:12 PM.
The following users liked this post:
muc (03-29-2022)
03-22-2022, 06:31 PM
#3
Platinum Member
Platinum Member
Join Date: Jun 2004
Location: St-Hyacinthe, quebec, canada
Posts: 7,731
Received 372 Likes
on
250 Posts
same thought... it will take MASSIVE upgrade to even see a mph difference imo. bad investment i think,,,
but while it is out, right?
why not!
As long as you are having fun that's all that counts!
but while it is out, right?
why not!As long as you are having fun that's all that counts!
