More Power!

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walshd
walshd
SA
601 posts
SA, 601 posts
18 Nov 2009 8:35am
Hi fellas.

I just got myself a boat. She is a 5m C-Craft fibreglass tunnel hull with a 253V8.

It has the standard carby and intake on it and goes bloody well but lacks a bit in top end IMO.

Flat out she does 42km/hr but the engine is only revving a bit over 3,000rpm. At this rpm, the motor would barely be seeing power band.

In the top end, there is very little difference between flat out and the throttle backed back. Flat out the motor bogs a bit like the mix aint quite right.

Question is, does anyone have much experience with the 253 motor? I could put a smaller prop on it to see if I find that hidden power with a few more revs, but it feels about right when cruising. It cruises nicely at 2500rpm.

One day I'd like to try a better intake and a 600 holley, but would like to keep reasonable fuel ecconomy.

Any thoughts?
choco
choco
SA
4186 posts
SA, 4186 posts
18 Nov 2009 10:18am
We used to call the old 253's Yabby motors all shell and no guts.
mineral1
mineral1
WA
4564 posts
WA, 4564 posts
18 Nov 2009 9:26am
choco said...

We used to call the old 253's Yabby motors all shell and no guts.


doggie
doggie
WA
15849 posts
WA, 15849 posts
19 Nov 2009 11:21am
253 = two flies & a bee
walshd
walshd
SA
601 posts
SA, 601 posts
19 Nov 2009 4:33pm
Does anyone know if a 308 intake manifold will fit on a 253 then?
thommo 000
thommo 000
1670 posts
1670 posts
19 Nov 2009 2:38pm
You`ll need a red 308 manifold from around the same era as your engine,provided of course it doesn`t have blue heads on it. A 308 manifold will bolt straight onto a 253
doggie
doggie
WA
15849 posts
WA, 15849 posts
19 Nov 2009 2:51pm
thommo 000 said...

You`ll need a red 308 manifold from around the same era as your engine,provided of course it doesn`t have blue heads on it. A 308 manifold will bolt straight onto a 253


Will still have a two barrel or four thommo? Wernt they standard two? 308s that is?
thommo 000
thommo 000
1670 posts
1670 posts
19 Nov 2009 3:55pm
four
doggie
doggie
WA
15849 posts
WA, 15849 posts
19 Nov 2009 4:12pm
thommo 000 said...

four


What carb on the four barrel then carter?
thommo 000
thommo 000
1670 posts
1670 posts
19 Nov 2009 4:41pm
Yes, Carters are an easy way to add some grunt without costing an arm or leg, same with the Holleys.....i`d just stick with the 253 IMHO

doggie
doggie
WA
15849 posts
WA, 15849 posts
19 Nov 2009 4:45pm
A Hollie with an adaptor plate to give a bit more stick 600cfm with vacum secondaries should do the trick. Ive seen on some ski boats that they have a carb adaptor thats on an slight angle so the carb is horizontal so the floats read correctly. That should wake the two flies and a bee up
thommo 000
thommo 000
1670 posts
1670 posts
19 Nov 2009 4:56pm
doggie said...

That should wake the two flies and a bee up


doggie
doggie
WA
15849 posts
WA, 15849 posts
19 Nov 2009 4:59pm
Mini blown chev

chronic
chronic
NSW
318 posts
NSW, 318 posts
19 Nov 2009 11:38pm
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YEAR: 2001

BINDING: Soft

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cisco
cisco
QLD
12365 posts
QLD, 12365 posts
20 Nov 2009 1:13am
walshd said...

Hi fellas.

I just got myself a boat. She is a 5m C-Craft fibreglass tunnel hull with a 253V8.

It has the standard carby and intake on it and goes bloody well but lacks a bit in top end IMO.

Flat out she does 42km/hr but the engine is only revving a bit over 3,000rpm. At this rpm, the motor would barely be seeing power band.

Any thoughts?



Yes.

Why would you buggerise around with all that stuff (5m C-Craft fibreglass tunnel hull with a 253V8) plus trailer for the sake of 42kmh, when a Zodiac 3.1 m inflateable with a Mariner 15hp on the back (legal that hp and 4 people) will do 3kmh more and you can fir it into the boot of your car.

This ( 5m C-Craft fibreglass tunnel hull with a 253V8 ) when turned turtle and filled with water has only one direction it will go without air bags and we know what that is don't we??

Whereas this (Zodiac 3.1 m inflateable with a Mariner 15hp on the back ) in the same circumstances will remain fairly stationary (subject to wind and tide conditions) while you get your act together from which situation it may be possible to continue the speed fun if the motor has not been completely drowned or get back to dry land using the sheilas (oars).

One has to ask what the purpose of the excercise is here. Is it towing water skiers or scurfers? The Mariner could probably handle one. Maybe it is just going fast on the water. I love it in a minimalist way. Every yacht needs a Zoomer.

Hopefully your motivation is not this male, macho, V8, phallic extension thing that posesses these jerk offs that roar around our neighbourhood in their (usually black) wankey utes.

You asked for "Any Thoughts". To understand mine, a sense of reality AND the ridiculous may be required.

Whatever you do, make sure you have fun and don't get serious because none of us are going to get out of this LIFE thing alive. It ain"t a rehearsal. Cheers Cisco.
walshd
walshd
SA
601 posts
SA, 601 posts
20 Nov 2009 8:36am
Na mate, you couldn't be more wrong. She is a fishin boat. Would av preferred something around the 6m mark but found this one on the cheap.
These rigs are usually fitted with a ford 250 or the old 200.

You wouldn't see me floating around in an inflatable condom on some of the decent snapper drops over this way. It would be a Jessica Watson moment no doubt if noah gave you a visit.

The C-craft hull is an excellent sea hull, similar to the Nereus but a bit wider and more free board.

Because it is a tunnel hull, they are'nt very efficient, but shound be capable of 60km/hr if the engine had the horses.

My mates got a 308 red motor manifold with the 600 holley fitted, so I might give that a go one arvo. Cheers guys.

Hopefully the weather is good on the weekend!

walshd
walshd
SA
601 posts
SA, 601 posts
20 Nov 2009 8:52am
We get lots of these things around here:








While fishing for these:



Sailhack
Sailhack
VIC
5000 posts
VIC, 5000 posts
20 Nov 2009 10:07am
Nice king & mako (around 200kg?)...although the 'pinkies' look a little undersize for your area?

I'm planning a fishing trip maybe over your way in the next year with a couple of mates, we're trying to decide whether we go to Whyalla, Freo or Darwin...although after my father (grey nomad) recently returned from NT, reckons the sharks are too much hassle. Here, we try to catch them!
cisco
cisco
QLD
12365 posts
QLD, 12365 posts
20 Nov 2009 10:56am
Inflateables certainly don't like spikey things and yes, I would be wanting 6m of solid boat between me and that big thing hanging by the rope around it's tail.

Best of luck with the donk issue.
Squid Lips
Squid Lips
WA
708 posts
WA, 708 posts
20 Nov 2009 10:19am
walshd said...

In the top end, there is very little difference between flat out and the throttle backed back. Flat out the motor bogs a bit like the mix aint quite right.


When motors feel boggy it is more often related to timing than fuel, in my experience. A service and a decent tune will probably make a fair bit of difference. I would have thought opening up the intake with bigger manifold and carb (without changing anything else like cam or compression ratio) would only increase the top end power, and possibly sacrifice a bit of low end due to the air velocity reducing and not keeping the fuel suspended as effectively at low rpm. Since you're only getting up to 3000rpm flat out you should be tuning it for low down torque rather than top end power. It could probably take a couple of extra degrees base timing, which may otherwise cause knocking at high revs - but since you wont be going into that range you'll gain more power down low. Just a thought anyway and consult a mechanic, don't take my word for it.

I don't know enough about boats to comment on props but I guess that could be just as likely to cause the issue if it's just thrashing the water instead of doing its job.
walshd
walshd
SA
601 posts
SA, 601 posts
20 Nov 2009 1:26pm
Sailhack said...

Nice king & mako (around 200kg?)...although the 'pinkies' look a little undersize for your area?

Na it is a white that one of the pros got in their longline.


I'm planning a fishing trip maybe over your way in the next year with a couple of mates, we're trying to decide whether we go to Whyalla, Freo or Darwin...although after my father (grey nomad) recently returned from NT, reckons the sharks are too much hassle. Here, we try to catch them!


Well since your victorian, I'd say go to Freo or Darwin. There are already too many mexicans coming over here and poaching our snapper.

If you do decide to visit Whyalla, get on a charter. They have their own drops that don't get raped by the tourists.
Sailhack
Sailhack
VIC
5000 posts
VIC, 5000 posts
20 Nov 2009 2:10pm
walshd said...

Well since your victorian, I'd say go to Freo or Darwin. There are already too many mexicans coming over here and poaching our snapper.


I always thought you guys were the foreigners! (with that pommy accent )

If you do decide to visit Whyalla, get on a charter. They have their own drops that don't get raped by the tourists.

Yep, definitely a fan of charters, although from what I've heard, some of the NT charters spend most of the time travelling between spots, and near-no fishing (possibly to get away from those Noahs). We're thinking of doing a 3-5 day full offshore charter...not sure yet, still in planning (& saving).

On topic...timing (as said above). You should be able to set the timing to fix that prob and lift the revs...from memory though it can adverse issues at lower revs?!?
walshd
walshd
SA
601 posts
SA, 601 posts
20 Nov 2009 2:00pm
I might grab my mates tuning kit and have a play on the weekend If I get bored.

Cheers guys, I'll read up on the manual and check the timing.

Hopefully it doesn't have any adverse affects because it starts and runs beautifully. Better mark what everything is set at before playing with it.
sandman
sandman
WA
432 posts
WA, 432 posts
20 Nov 2009 12:45pm
try here too;

www.aussiev8.com.au//v8-boats/

or

www.aussiev8.com.au/holden-v8s/

very helpful bunch of lads most topics about compatibility covered at some point.
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