more 4.3 questions
 

I have done some research and heard you can put higher compression flat-top
pistons in the 4.3 and gain a few HP. Who makes these pistons? I have done a
bunch of searches and come up empty handed.

A related question, I have also read that the 4.3 is a 350 minus two
cylinders and that the pistons and rods are the same. Is this true or false?




--
John

WWW.Firewalk-NC.com

"Be the change you wish to see in others"

----Gandhi

Unless you are rebuilding the engine anyway, I would not waist my money. It
takes a lot of hp to gain any real benefit on the water. Most quote 15 hp
to 1 mph. Spend your money on a 350 assuming your boat is 18' or bigger. A
17' will probably run sideways from the torque.

Biggest bang for the buck is usually found by going to a good performance SS
prop. You can see 5 mph gain with the right prop over a cheap aluminum one.

--
Tony
my boats and cars at http://t.thomas.home.mchsi.com

-
"Gorf" wrote in message
...
I have done some research and heard you can put higher compression
flat-top
pistons in the 4.3 and gain a few HP. Who makes these pistons? I have done
a
bunch of searches and come up empty handed.

A related question, I have also read that the 4.3 is a 350 minus two
cylinders and that the pistons and rods are the same. Is this true or
false?




--
John

WWW.Firewalk-NC.com

"Be the change you wish to see in others"

----Gandhi

In article ,
says...

I have done some research and heard you can put higher compression flat-top
pistons in the 4.3 and gain a few HP. Who makes these pistons? I have done a
bunch of searches and come up empty handed.

A related question, I have also read that the 4.3 is a 350 minus two
cylinders and that the pistons and rods are the same. Is this true or false?

Almost everything swaps with most 350's. Of course there are 'large jounal'
and 'small journal' 350's, and one can't really make more than a generalized
statement about the 4.3 262 being a 350 minus two jugs. As for flat top
pistons, Geez, everyone makes them for a 4.3, wiseco, TRW, Sealed Power
(who is TRW in disguise anyway) Keith Black Silv-O-Lite. It isn't worth
your time or trouble unless your motor is already apart. If so, go with
forged aluminum. They can take the most abuse, it's all the blower crowd
would ever consider.

"Gudmundur" wrote in message
...
In article ,

says...

I have done some research and heard you can put higher compression
flat-top
pistons in the 4.3 and gain a few HP. Who makes these pistons? I have
done a
bunch of searches and come up empty handed.

A related question, I have also read that the 4.3 is a 350 minus two
cylinders and that the pistons and rods are the same. Is this true or
false?

Almost everything swaps with most 350's. Of course there are 'large
jounal'
and 'small journal' 350's, and one can't really make more than a
generalized
statement about the 4.3 262 being a 350 minus two jugs. As for flat top
pistons, Geez, everyone makes them for a 4.3, wiseco, TRW, Sealed Power
(who is TRW in disguise anyway) Keith Black Silv-O-Lite. It isn't worth
your time or trouble unless your motor is already apart. If so, go with
forged aluminum. They can take the most abuse, it's all the blower crowd
would ever consider.



engine is already apart.
This spring when I tuned it up and hooked the hose to it to time it, got
LOTS of water in the oil. I bought a long block for it before I took it
apart. When I took it apart it was the intake manifold that was screwed. I
decided to use the new long block anyway. Putting it together I found a
valve cover bolt broken off in the head which I had to drill and ez-out.
Got it running and it kept backfiring - found the wrong size pushrod in #6
exhaust. But the straw that broke the camels back was, after 1.5 hrs
running the intake rocker arm on number was loose, must have been a stuck
lifter. So I have returned the motor and am going to rebuild my old block
(or at least plastigage the bearing etc). That is where I am at, I am
considering the pistons and need at least a gasket kit. I replaced the 2
bbl intake with a 4 bbl intake and adapter plate for my 2 bbl, hopefully I
will get 10- 15 hp from this. With the pistons maybe 10-15 more HP????

Any recommendations where I can purchase the pistons and the gasket kit?

Give a call to 'The Bowtie Connection', they are super nice folks
with all kinds of Hi-Perf Chevy parts. The blond gal knows her stuff! I
see them every year at Fall Carlisle. Also Jegs, or Summit Racing has
nice stuff. If you replace the pistons, you are going to get some machine
shop time involved, boring/honing, cleaning. You may get some bucks tied
up in your motor, but if it will run W.O.T. all day and not blow apart
it was worth it! Drop in new Cleavite bearings, that is a good move even
if you are just 'freshening up' a factory size set. Boats are so hard
on bottom end parts!!!





In article ,
says...


"Gudmundur" wrote in message
...
In article ,

says...

I have done some research and heard you can put higher compression
flat-top
pistons in the 4.3 and gain a few HP. Who makes these pistons? I have
done a
bunch of searches and come up empty handed.

A related question, I have also read that the 4.3 is a 350 minus two
cylinders and that the pistons and rods are the same. Is this true or
false?

Almost everything swaps with most 350's. Of course there are 'large
jounal'
and 'small journal' 350's, and one can't really make more than a
generalized
statement about the 4.3 262 being a 350 minus two jugs. As for flat top
pistons, Geez, everyone makes them for a 4.3, wiseco, TRW, Sealed Power
(who is TRW in disguise anyway) Keith Black Silv-O-Lite. It isn't worth
your time or trouble unless your motor is already apart. If so, go with
forged aluminum. They can take the most abuse, it's all the blower crowd
would ever consider.



engine is already apart.
This spring when I tuned it up and hooked the hose to it to time it, got
LOTS of water in the oil. I bought a long block for it before I took it
apart. When I took it apart it was the intake manifold that was screwed. I
decided to use the new long block anyway. Putting it together I found a
valve cover bolt broken off in the head which I had to drill and ez-out.
Got it running and it kept backfiring - found the wrong size pushrod in #6
exhaust. But the straw that broke the camels back was, after 1.5 hrs
running the intake rocker arm on number was loose, must have been a stuck
lifter. So I have returned the motor and am going to rebuild my old block
(or at least plastigage the bearing etc). That is where I am at, I am
considering the pistons and need at least a gasket kit. I replaced the 2
bbl intake with a 4 bbl intake and adapter plate for my 2 bbl, hopefully I
will get 10- 15 hp from this. With the pistons maybe 10-15 more HP????

Any recommendations where I can purchase the pistons and the gasket kit?

concerning summit and Jeggs, I'm always concerned about their nice
glossy catalogueing with phrases like "your low price...."
and "The part you want at the price you want to pay....."

I've found the best bang for the buck is http://www.pawengineparts.com/
The guys are massivly huge! and cary performance stuff for about
anything you can imagine (almost!)

Wanna build a stroker out of a 500CID caddilac engine..they got it. you
can build your own 426 hemi. etc. etc.
very comprehensive inventory
and compare prices with Summit and Jegs, and I think you'll find they
are verrrrry competetive.

Tim

I ran flat top pistons in my 350 for a while but could not get away from the
detonation problems. Todays premium gas is about like the old days regular.
I went back to the partially dished with a flat top where the squish area is
from keith black. KB has the high silicon cast pistons that take a bit more
abuse similar to the ones gm puts in it's high end engines.. Forged pistons
are the strongest but they have a higher expansion rate and require a looser
fit. Makes them a bit trickier to fit correctly in marine applications
because marine engines are far less consistent about operating temp.

The v6 is basically a v8 minus two cylinders. Not sure exactly what parst
are completely interchangable but it doesn't really matter, the aftermarket
v6 parts are just about as cheap as the v8 ones. It is handy because a lot
of the external bolt pads are the same so the v6 and v8 are easily
interchanged.

You'd be far better off with a 350 that trying to build up a 6 cyclinder.
It takes a whole lot of hp to go faster on the water and the v8 has more
heavy duty options like 4 bolt mains. On the water you can't build hp with
rpm's like you can on land so on water displacement is everything. All the
serious go fast boats have 502's. If you have space in the engine
compartment it's probably almost completely a bolt in substitution.

"Gorf" wrote in message
...
I have done some research and heard you can put higher compression
flat-top
pistons in the 4.3 and gain a few HP. Who makes these pistons? I have done
a
bunch of searches and come up empty handed.

A related question, I have also read that the 4.3 is a 350 minus two
cylinders and that the pistons and rods are the same. Is this true or
false?




--
John

WWW.Firewalk-NC.com

"Be the change you wish to see in others"

----Gandhi

IMHO I would not go for the 2bbl to 4bbl conversion. It sounds like you
want more power. I would upgrade to multiport fuel injection. I helped
my cousin who has a donzi with a 4.3L convert from a carburator to fuel
injection. He got the manifold and stuff from a smashed S10 blazer in a
junk yard. The computer, distributor and wireing harness came from some
place I forget, its been 3 years. We got all the mechanical and
electrical done. Got every thing running in the driveway. Took it to
the river called the computer people hooked my laptop upto the engine
computer they walked me through the programing once we were done he had
more HP, better throttle response and better fuel economy to boot. The
who process took a weekend to install. and about two hours on and off
the phone with tech support to get the computer right.
It still runs great today. The only problem was last year the plastic
hose from the fuel pressure regulator (under the manifold) cracked. A
common problem with the Chevy 4.3L.

Paul

Problem with that is that the marine mpi is different from the automotive
one and if your cousin's boat catches fire and his insurance figures out
what he did they won't pay.

"Paul" wrote in message
oups.com...
IMHO I would not go for the 2bbl to 4bbl conversion. It sounds like you
want more power. I would upgrade to multiport fuel injection. I helped
my cousin who has a donzi with a 4.3L convert from a carburator to fuel
injection. He got the manifold and stuff from a smashed S10 blazer in a
junk yard. The computer, distributor and wireing harness came from some
place I forget, its been 3 years. We got all the mechanical and
electrical done. Got every thing running in the driveway. Took it to
the river called the computer people hooked my laptop upto the engine
computer they walked me through the programing once we were done he had
more HP, better throttle response and better fuel economy to boot. The
who process took a weekend to install. and about two hours on and off
the phone with tech support to get the computer right.
It still runs great today. The only problem was last year the plastic
hose from the fuel pressure regulator (under the manifold) cracked. A
common problem with the Chevy 4.3L.

Paul

Tony, don't sound like anyone believes you with the 15hp = 1mph faster! I
do!


"tony thomas" wrote in message
news:PiKpe.27752$x96.17450@attbi_s72...
Unless you are rebuilding the engine anyway, I would not waist my money.
It takes a lot of hp to gain any real benefit on the water. Most quote 15
hp to 1 mph. Spend your money on a 350 assuming your boat is 18' or
bigger. A 17' will probably run sideways from the torque.

Biggest bang for the buck is usually found by going to a good performance
SS prop. You can see 5 mph gain with the right prop over a cheap aluminum
one.

--
Tony
my boats and cars at http://t.thomas.home.mchsi.com

-
"Gorf" wrote in message
...
I have done some research and heard you can put higher compression
flat-top
pistons in the 4.3 and gain a few HP. Who makes these pistons? I have
done a
bunch of searches and come up empty handed.

A related question, I have also read that the 4.3 is a 350 minus two
cylinders and that the pistons and rods are the same. Is this true or
false?




--
John

WWW.Firewalk-NC.com

"Be the change you wish to see in others"

----Gandhi

I didn't see anyone disputing that.

"Woodchuck" wrote in message
.. .
Tony, don't sound like anyone believes you with the 15hp = 1mph faster! I
do!


"tony thomas" wrote in message
news:PiKpe.27752$x96.17450@attbi_s72...
Unless you are rebuilding the engine anyway, I would not waist my money.
It takes a lot of hp to gain any real benefit on the water. Most quote
15 hp to 1 mph. Spend your money on a 350 assuming your boat is 18' or
bigger. A 17' will probably run sideways from the torque.

Biggest bang for the buck is usually found by going to a good performance
SS prop. You can see 5 mph gain with the right prop over a cheap
aluminum one.

--
Tony
my boats and cars at http://t.thomas.home.mchsi.com

-
"Gorf" wrote in message
...
I have done some research and heard you can put higher compression
flat-top
pistons in the 4.3 and gain a few HP. Who makes these pistons? I have
done a
bunch of searches and come up empty handed.

A related question, I have also read that the 4.3 is a 350 minus two
cylinders and that the pistons and rods are the same. Is this true or
false?




--
John

WWW.Firewalk-NC.com

"Be the change you wish to see in others"

----Gandhi

I will. I added 15 hp to one of my boats and more than doubled my
speed. 9.8 HP outboard = 7~8 mph I switched to a 25 HP = 20~25MPH
depending on load. 15HP increase = 13~17MPH speed increase. on an 16'6"
aluminum boat.

Paul

JamesgangNC wrote:
I didn't see anyone disputing that.

"Woodchuck" wrote in message
.. .
Tony, don't sound like anyone believes you with the 15hp = 1mph faster! I
do!


"tony thomas" wrote in message
news:PiKpe.27752$x96.17450@attbi_s72...
Unless you are rebuilding the engine anyway, I would not waist my money.
It takes a lot of hp to gain any real benefit on the water. Most quote
15 hp to 1 mph. Spend your money on a 350 assuming your boat is 18' or
bigger. A 17' will probably run sideways from the torque.

Biggest bang for the buck is usually found by going to a good performance
SS prop. You can see 5 mph gain with the right prop over a cheap
aluminum one.

--
Tony
my boats and cars at http://t.thomas.home.mchsi.com

-
"Gorf" wrote in message
...
I have done some research and heard you can put higher compression
flat-top
pistons in the 4.3 and gain a few HP. Who makes these pistons? I have
done a
bunch of searches and come up empty handed.

A related question, I have also read that the 4.3 is a 350 minus two
cylinders and that the pistons and rods are the same. Is this true or
false?




--
John

WWW.Firewalk-NC.com

"Be the change you wish to see in others"

----Gandhi

Probably enough power to get the boat to plane. Displacement speed before.
Bill

"Paul" wrote in message
oups.com...
I will. I added 15 hp to one of my boats and more than doubled my
speed. 9.8 HP outboard = 7~8 mph I switched to a 25 HP = 20~25MPH
depending on load. 15HP increase = 13~17MPH speed increase. on an 16'6"
aluminum boat.

Paul

JamesgangNC wrote:
I didn't see anyone disputing that.

"Woodchuck" wrote in message
.. .
Tony, don't sound like anyone believes you with the 15hp = 1mph faster!
I
do!


"tony thomas" wrote in message
news:PiKpe.27752$x96.17450@attbi_s72...
Unless you are rebuilding the engine anyway, I would not waist my
money.
It takes a lot of hp to gain any real benefit on the water. Most
quote
15 hp to 1 mph. Spend your money on a 350 assuming your boat is 18'
or
bigger. A 17' will probably run sideways from the torque.

Biggest bang for the buck is usually found by going to a good
performance
SS prop. You can see 5 mph gain with the right prop over a cheap
aluminum one.

--
Tony
my boats and cars at http://t.thomas.home.mchsi.com

-
"Gorf" wrote in message
...
I have done some research and heard you can put higher compression
flat-top
pistons in the 4.3 and gain a few HP. Who makes these pistons? I have
done a
bunch of searches and come up empty handed.

A related question, I have also read that the 4.3 is a 350 minus two
cylinders and that the pistons and rods are the same. Is this true or
false?




--
John

WWW.Firewalk-NC.com

"Be the change you wish to see in others"

----Gandhi

Your talking about a 1.5 times increase in hp. We are talking about adding
15 hp to an engine that has 190 hp to begin with. Going from 190 to 205
will not increase the speed by 13~17 MPH. It may increase it by 2 mph if
your lucky.

--
Tony
my boats and cars at http://t.thomas.home.mchsi.com

-
"Paul" wrote in message
oups.com...
I will. I added 15 hp to one of my boats and more than doubled my
speed. 9.8 HP outboard = 7~8 mph I switched to a 25 HP = 20~25MPH
depending on load. 15HP increase = 13~17MPH speed increase. on an 16'6"
aluminum boat.

Paul

JamesgangNC wrote:
I didn't see anyone disputing that.

"Woodchuck" wrote in message
.. .
Tony, don't sound like anyone believes you with the 15hp = 1mph faster!
I
do!


"tony thomas" wrote in message
news:PiKpe.27752$x96.17450@attbi_s72...
Unless you are rebuilding the engine anyway, I would not waist my
money.
It takes a lot of hp to gain any real benefit on the water. Most
quote
15 hp to 1 mph. Spend your money on a 350 assuming your boat is 18'
or
bigger. A 17' will probably run sideways from the torque.

Biggest bang for the buck is usually found by going to a good
performance
SS prop. You can see 5 mph gain with the right prop over a cheap
aluminum one.

--
Tony
my boats and cars at http://t.thomas.home.mchsi.com

-
"Gorf" wrote in message
...
I have done some research and heard you can put higher compression
flat-top
pistons in the 4.3 and gain a few HP. Who makes these pistons? I have
done a
bunch of searches and come up empty handed.

A related question, I have also read that the 4.3 is a 350 minus two
cylinders and that the pistons and rods are the same. Is this true or
false?




--
John

WWW.Firewalk-NC.com

"Be the change you wish to see in others"

----Gandhi

But with that increase in HP you should be able to run a higher pitch
prop. A 2" pitch increase at a prop speed of 2500 rpms should give you
4.7 MPH speed increase. My 9.8 would never be able to get to WOT with a
13" prop on my boat. But the 25 HP has no problem. If you do get more
ponies from an engine upgrade. You should look at changing the prop. A
prop turning at a certain speed is only going to go so fast not matter
how much horse power is behind it.

Paul

You forgot to divide by the gear ratio. With a 1.87 gear and taking into
account an efficiency of 90% for a SS prop you get 2.2 MPH. But increasing
from 190 to 205 hp is probably not enough to increase by 2" of pitch on top
end. You could go 1" of pitch and get 1.1 MPH or the extra rpms w/ the same
pitch will give you the same.

Again - your comparing a 1500% increase to an increase of 8%. Don't come
close to being the same.

--
Tony
my boats and cars at http://t.thomas.home.mchsi.com

-
"Paul" wrote in message
ups.com...
But with that increase in HP you should be able to run a higher pitch
prop. A 2" pitch increase at a prop speed of 2500 rpms should give you
4.7 MPH speed increase. My 9.8 would never be able to get to WOT with a
13" prop on my boat. But the 25 HP has no problem. If you do get more
ponies from an engine upgrade. You should look at changing the prop. A
prop turning at a certain speed is only going to go so fast not matter
how much horse power is behind it.

Paul

The 2500 RPM was the prop speed. That would be 5000 RPM on the engine.
I accounted for the gear reduction. So a 2" pitch increase would give
you a 4.7 MPH increase. I know it is not a 100% efficient. And whether
or not the extra 15 HP can turn a 2" bigger prop 2500 RPM I do not
know. But if do several modifications that give you 15HP here, 5HP here
and 10HP there it all adds up. You can do headers, Fuel injection,
upgrade the ignition, camshaft, computer etc... The 4.3L motor is very
a versatile motor. I personally have seen (out of vehicle on a dyno) a
10 hp increase just by adding a spacer (a $100 item
http://www.jetchip.com/TBI/chevFSTBI.cfm) under a TBI unit on 4.3L
motor. I would put one on my Blazer but I would not be able to close
the hood. I have done a lot of work on the 4.3 in land vehicle
applications. Limited, but expanding, in boating applications.

Paul

You have to remember how many of these add-ons are advertised. They use the
word "up to" a lot. They may claim a 15hp increase but the results may only
be 2hp in real world. Granted the 4.3 can make some good power, but building
one for marine use is different than a car/truck. You need to build and
engine to make torque.

"Paul" wrote in message
ups.com...
The 2500 RPM was the prop speed. That would be 5000 RPM on the engine.
I accounted for the gear reduction. So a 2" pitch increase would give
you a 4.7 MPH increase. I know it is not a 100% efficient. And whether
or not the extra 15 HP can turn a 2" bigger prop 2500 RPM I do not
know. But if do several modifications that give you 15HP here, 5HP here
and 10HP there it all adds up. You can do headers, Fuel injection,
upgrade the ignition, camshaft, computer etc... The 4.3L motor is very
a versatile motor. I personally have seen (out of vehicle on a dyno) a
10 hp increase just by adding a spacer (a $100 item
http://www.jetchip.com/TBI/chevFSTBI.cfm) under a TBI unit on 4.3L
motor. I would put one on my Blazer but I would not be able to close
the hood. I have done a lot of work on the 4.3 in land vehicle
applications. Limited, but expanding, in boating applications.

Paul

I agree torque is a big factor in boat engines. That is where your
choice of cam shafts comes in. Just like the car world manufactures put
"stock" components in a car for cost reasons. But with some
tweaking and adding an after market computer, cam shaft, ignition or
what ever else is out there. You can really boost your power and
torque. I have learned a lot by putting a user programmable computer in
a boat. You can change all kinds of settings. Dwell and timing for
spark and fuel. With an MPI system that is really cool. There are many
variables and there fore, very easy to mess up. You can even have
presets, like a skiing and a just plain cruising. The preset for skiing
changes to give you more torque to pull someone up. For cruising it can
be to give the best economy at a comfortable speed.
Grant it, not everyone likes, want or has time to tweak. With the
people I know and the line of work I am in I get the chance to see and
play with new technology. A lot of stuff is meant for the car world but
can very easily be adapted to the boat world because boats do not have
emissions standards, yet. Trying to find a place to put a threaded hole
for an o2 sensor in a marine exhaust manifold was fun. Not.

Paul