single carb vs dual

kinda wondering is there a big gain
i run a single qft 1250 now
if i were to run another
should i expect a big gain?

motor is a
4.150 stroke
4.500 bore
about 14-1 comp
tfs A-head

i run it in a pulling truck called super stock or st.mod
i was thinking about playing in the next class just to see how it might do
and that class dosent have much rules

the next class has a 630cid limit na
that is why i am strating to slowly build a 630
but till than i thought about doing what i can to my 530
or maybe just stay in my class till i get the big motor done?
alky i also allowed in the class

dfree383 wrote:I'd be tough for a well built 530" motor to compete against well build and running 630" motors. But Alot of places I've seen guys that know what they are doing woop on people with much bigger and better stuff if they know what the are doing and how to get-r-done.

It's even better when you do it with iron heads.

I'm not saying i can drive my truck, but I did spend 2 years working on the chassis and rest of the driveline before I even got the new 466 together. I am 100% positive it was all the testing with different setups to make my chassis work then drop the little motor in and it hooks and runs unbelievably hard and fast! Now I'm looking forward to seeing how it'll run when I get the new 500+ inch A headed motor in it!

500 in, that's for Quakers

crittersf1 wrote:500 in, that's for Quakers

I'm debating on a 514 like yours or just go with the long stoke to a 557. I like the quick rev's of a short stroke, but the torque of the longer stroke is nice too.

jesse wrote:kinda wondering is there a big gain
i run a single qft 1250 now
if i were to run another
should i expect a big gain?

The big gain would mostly be in consistency unless the engine is starving for more air.

how about 2 carbs on alky?
the only reason i would like to try 2 carbs is cause
if i cant keep up with the big cid motors all i gotta to do is
go back to a single gas carb and i can go back to my current class
i am very undecied on what to do
truck seems to hook very well it finshes in the top 3 most of the time
took some 1st's and 2nd's this season and it has been a test and tune for me since i built a new chassie
this past winter
the main reason i am considering jumping up a class is cause
alot of trucks in my class (530 cid single carb on gas dot tires)
are building motors that spin 9500+rpms
i dont like to abuse my stuff like that
it kinda seems big cid motors run in the 8000 range
and still get plenty of wheel speed
granted i get my tires movin very well at 7500-8000 rpm's now
is it possible thease bbf's have a better touq than the big duke gm motors?
and that is why thay spin them some much harder?
i had a gm guy tell me a few weeks ago once i told him what gear i ways running that day and
he said i was geared for a motor with 1,000 hp
well my motor is around the 800 range and i spun the tires and came off the rev chip
i took a 1st and got me thinking about touq vs rpm's i am more than happy with my current motor
but like all you guys know bigger isnt always better but is shure is nice to have

As most have offered, engine requirements should be the determining factor of two carburetors. If an 8V induction is required or though to be required, I think an intake manifold designed for the application and similar in IR design would offer a significant gain.

Just my $0.02.
Dave.

hows this for an awnser, ive never seen or had an engine with 2 carbs make less power then an engine with only 1 carb

"how about 2 carbs on alky?"
-------------------------------------------------------------
Not the way to go based on what I've observed...... 2 carbs on gas or injection on alky.

With Phillip making 1204 with only one carb, I don't know if I would fool with the extra carb, t-ram, linkage, fuel lines, etc.

good point

i have been thinkin about tunnel ram with 1 carb?
proubly wont be a big gain eather way iguess

David Willingham wrote:With Phillip making 1204 with only one carb, I don't know if I would fool with the extra carb, t-ram, linkage, fuel lines, etc.

Phillip and I were of the opinion that the mud/dirt dragrace may be about how quick the engine gets to 7,500 rpm...125'-200' pit... so that engine was carbed, camed and manifolded to get in a hurry from 5,500- 7,000 rpm. The dyno and on track performance seems to make that theory valid.
In the case of truck pulling it is my opinion that it is more about what happens above 7,000 rpm.

Lem, I've been watching and tweaking my combo for that exact theory. The big torque motors can claw their way through the deep mud pits, but the quick revving short stroke motors that have plenty of air and fuel to feed them can get the wheel speed faster to get on top of the mud. I think I proved it this past weekend when my little 466 with Freelander worked d0ve heads and your spec'd cam got me faster times than another ranger similar to mine that was running a 545 d0ve headed motor with much more compression.

your mostly right lem
but you also gotta have good tourq to get up there
we can take all day long getting the motor up to 4500-5000
befor we start to roll out that is why we like the slipper clutches
but once we at that 5k mark it needs to spin up to that 7500-8000+
in a hurry with alot of weight and force holding us back
it is good to have some lowend but need more higher
i come out around 4500-5500 depending on the track
so anything lower than 4500 dosent matter

jesse wrote:your mostly right lem
but you also gotta have good tourq to get up there
we can take all day long getting the motor up to 4500-5000
befor we start to roll out that is why we like the slipper clutches
but once we at that 5k mark it needs to spin up to that 7500-8000+
in a hurry with alot of weight and force holding us back
it is good to have some lowend but need more higher
i come out around 4500-5500 depending on the track
so anything lower than 4500 dosent matter

4,500 does not matter in most any racing engines. My advise is.....do not "take all day long" up to 4,500 rpm.