• If you log in, the ads disappear in the forum and gallery. If you need help logging in or getting registered, send request to: webmaster@southernairboat.com

5.3 build advice on my first airboat!

C

CrossAK

Member
Hi everybody, Im new to airboats and need some direction setting up my new boat with a upgraded 2004 5.3
I’ve ran a lot of river boats,
But no airboats. I can’t wait!
I purchased a older 15x7’ 30” DEEP 1/8” hull 1/4” transom
aluminum boat with a mild 350 Direct Drive 72” whirlwind 2 blade prop. No poly yet.
I’m selling the 350 motor and prop.
I Heard pretty quick the 350 DD wasn’t going to do well for hunting in this giant beautiful rocky swamp called Alaska!
I just bought a used 2.37 Rotator gearbox.
I Will be purchasing 78” 3 blade stump puller prop.
And 3/8 poly.

I have a low mile complete 5.3 with 862 heads, Dbw gas pedal, harness ect. I want to run factory fuel injection.
And make the engine as solid as possible. Not looking for anything wild yet. I need to learn how to drive it!
Some day I will get a bigger more powerful boat.

Looking to build a fairly capable hunting fishing boat. Most of the time it will be 2 people 200lb each, with maybe 100lb of gear. In the fall 600-800lb extra with the camp and meat. Shallow, gravel, and swamp running mostly.
I want to use the 5.3 factory stuff as much as I can to keep the cost down and keep it close to truck reliable. I’m not going to be hammering on this engine very often. Not too worried about the pistons at this HP.

Any recommendations for the harness re work and tune?
Other parts to consider?


I will be building the engine. I have built engines before.
Not airboat specific engines though.
A Reliable little tank and as quiet as possible is the goal
I gathered these parts from reading here and all over,
What do you guys think?

PARTS I HAVE:
Trunion upgrade kit
Hardened push rods
Ls7 lifters and trays
New Flat top factory pistons and rod bearings
Cam bearings
High volume oil pump
Oil pickup tube brace
Billet oil diverter barbell

PARTS IM NOT SURE ABOUT:
Quiet Exhaust system?
Texas speed stage 2 low lift cam with Ls6 springs?

Thanks for the help!
 
For Quiet exhaust search for comments by cntry141iq he built one of the quietest boat I have ever been around. I think he ran a summit RV muffler.

I ran a stock carbed 5.3 on a 14x7-6 alumitec used several different gear ratio's but the 2.55 and 2.68 performed the best. Boat is used for fishing the gulf and loaded it ran about 3800 to stay on plane.

I would find a 8qt pan for it.

Running a high volume pump to me would depend on your bearing clearances. Interesting you bought pushrods before your cam? I have always measured for pushrod length after I installed a cam.

GM ASA cam it can be a little hard to tune at idle but has a very flat torque curve and it works with LS6 springs. The base circle is slightly smaller the most cams and requires different pushrod length

BTW the stock 5.3 now in my garage has over 600hrs on 2 different boats and had 113K when it was pulled from the truck.
 
Good to hear you’ve got a lot of hours on yours with no big issues! Do you Have any experience with the factory efi setup? Do you know who would be a good shop to re work the harness and tune it? I had the push rods already when I was planning on just beefing up the top. I will exchange them if I need to. Very few options in Alaska
 
I have stripped a factory harness down to the basics but never got to try it out. Got a deal on a Holley HP system and TBSS intake. Waiting til after fishing season here to make any changes.

There are a few people that have had great luck with the stock efi setups. TBSS Or newer truck intake with stock injectors will support around 450 I believe. That intake works great up to 5500 or so in the rpm range the average airboater runs.

BTW a bigger motor would be better for that size boat.
 
hyper pistons are not a great idea.... IMHO
you are geared wrong for that motor and a super wide prop. that will compound the problem with the hyper pistons. that motor stock is like 350hp not a lot by airboat standards. you will need to work that thing hard to make it go that is not ideal in a back country break down and suffer application.

if you keep the stock ecu you will be drive by wire on the throttle. need a aftermarket ecu like the HP or a mefi unit that can accept manual cable

you want aftermarket springs. the stock springs were not intended to spin 3000+rpm for hours.

use a 160deg thermostat.. yes they were made to run 200deg in cars but the load in a car is not like a airboat. if you run her hot she will die a quick and painful death.
 
You can get harness and ecm for 2000 truck with red and blue connectors and maintain cable throttle.For the cam call TX speed or cam motion and tell them what you will be running at and application.Valve springs and 4 corner steam port are needed also the hypertech pistons arent ideal so make sure tuner is good or it wont live 20hrs.
 
You must log in or register to reply here.
Back
Top