TheSamba.com :: View topic - VW Tri-Power

Sun Jan 27, 2008 5:01 pm

Not sure how many are out there but here is a little preview of what my engine is looking like...

Still in the mock-up stage, just finished running the fuel lines and completed the linkage. Now it's time to take it all apart , start sandblasting, and paint everything.

Sun Jan 27, 2008 5:28 pm

I am not sure if it will work or not, But it looks cool as hell!!!

Sun Jan 27, 2008 5:39 pm

Hi,

I agree, it looks really "cool" but I am not understanding the principle behind the arrangement.

Could you enlighten us about the theory of fuel atomization and distribution it is based upon?

1 carb goes to all 4 cyl
1 carb goes to 2 cyl
1 carb goes to the other 2 cyl

Dave

Sun Jan 27, 2008 6:05 pm

djkeev wrote: Hi,

I agree, it looks really "cool" but I am not understanding the principle behind the arrangement.

Could you enlighten us about the theory of fuel atomization and distribution it is based upon?

1 carb goes to all 4 cyl
1 carb goes to 2 cyl
1 carb goes to the other 2 cyl

Dave

The center carb is for startup, low to mid range, it has a high air correction jet, .225, so it leans out at high rpm's. The side carbs, Tillotsons, work like vacuum secondaries, they are shut down during low to mid rpm's but open via a spring loaded center linkage, at higher rpm's. Tillotsons have a 25mm venturis and an adjustable jet which makes them perfect for this use.

Sun Jan 27, 2008 6:53 pm

Triple carburaton is tough to tune. Had a Tri-Power GTO and although nothing can match the cool factor, a single 4 barrel performed better. You may find that a larger single carb or a pair of carbs would work better. It does look cool though.

Sun Jan 27, 2008 8:07 pm

Pontiac Tri-powers had Rochester 2 bbl's I think, but they had thier jetting preset. What's good about these Tillotson's is the adjustable jet, I can blend how much fuel is added at the higher rpm. Should help with the tuning. :)

Mon Jan 28, 2008 3:39 pm

I get that it's unique but wouldn't you be able to get more power out of dual carbs? Or are you just seeing if you can make it work?

I just can't imagine you'll be able to get any benefit out of this. Plus I also can't imagine you can get a smooth transition during acceleration, changing from the single carb to the dual carbs...

:?

Mon Jan 28, 2008 8:21 pm

Corwin wrote: I get that it's unique but wouldn't you be able to get more power out of dual carbs? Or are you just seeing if you can make it work?

I just can't imagine you'll be able to get any benefit out of this. Plus I also can't imagine you can get a smooth transition during acceleration, changing from the single carb to the dual carbs...

:?

Corwin, you're right I can probrably make more power out of a straight dual carb set-up, but, I look at it as a unique challenge. It's viable only because of the Tillotsons. Before taking my engine out I tested different air correction jets and found out a .225 ac jet on the center carb starves the engine at about 1800 rpm. I then have to adjust the center linkage spring to open up the Tillotsons at around 1600 rpm. To maintain a smooth transition I then have to adjust the Tillotson jets to make up for the high rpm starvation of the center carb.
Don't get me wrong, I know it will take time to get it running right with alot of trial and error, but I think it will be worth it, after all, how many Tri-Powers do you see running around? Besides if it fails, then all I have to do is change to a stock intake and drive away. :wink:

Mon Jan 28, 2008 8:23 pm

That's cool, I give you tone of credit for trying it - it definitely is unique. Just wasn't sure on the why part. Lol.
:D

Mon Jan 28, 2008 8:29 pm

Corwin wrote: That's cool, I give you tone of credit for trying it - it definitely is unique. Just wasn't sure on the why part. Lol.
:D

I appreciate it Corwin, it's all about having a little fun. Hey!!! maybe I should turn a Heb into a drag car.... :? never mind :lol:

Mon Jan 28, 2008 11:28 pm

i saw a set up exactly like that at pomona swapmeet about 13 years ago. of course it wasnt for sale but it was in the swap booth anyways

Tue Jan 29, 2008 6:31 am

john7 wrote: i saw a set up exactly like that at pomona swapmeet about 13 years ago. of course it wasnt for sale but it was in the swap booth anyways

wow that's cool! that's makes 3 that I know of :o

Tue Jan 29, 2008 8:35 am

The long runner of the single carb intake, provides the low end torque that 2 barrels that no short intake dual carbs can provide. Nice set-up.

Tue Jan 29, 2008 12:30 pm

25horseboxer wrote: The long runner of the single carb intake, provides the low end torque that 2 barrels that no short intake dual carbs can provide. Nice set-up.

I did'nt know that. It's almost the best of both worlds, we'll see.

Tue Feb 12, 2008 4:47 pm

Just finished rebuilding my engine so here it is. I'm installing it tonight or tommorrow! :lol:

I like...

definatley oldspeed... I love those stacks!!

gonna have fun synchronizing :wink:

Tue Feb 12, 2008 5:05 pm

PREDICTION:

75% chance that it is too rich and will flood out
20% it will be too hard to tune
5% it will work and I will owe an appology for lack of faith

either way, that engine looks very nice.

Not a flame, just a mythbusters type prediction. All in good fun :D

Tue Feb 12, 2008 5:11 pm

sconord wrote: PREDICTION:

75% chance that it is too rich and will flood out
20% it will be too hard to tune
5% it will work and I will owe an appology for lack of faith

either way, that engine looks very nice.

Not a flame, just a mythbusters type prediction. All in good fun :D

75% chance that it is too rich and will flood out... Air correction jet leans center carb out at 1500 rpm, not a chance.
20% it will be too hard to tune... maybe but the adjustable jets on the Tillotsons will help out
5% it will work and I will owe an appology for lack of faith... One out of three ain't bad.. :lol:

thx sconord, I think it looks nice to!

Tue Feb 12, 2008 10:18 pm

What determines when the dual carbs kick in?

Wed Feb 13, 2008 5:31 am

Splitdog wrote: What determines when the dual carbs kick in?

The spring on the center linkage arm. The tighter you adjust the sooner it kicks in or looser the later it kicks in, then the amount of fuel is metered through the adjustable jets in the Tillotsons.

Wed Feb 13, 2008 2:30 pm

john7 wrote: i saw a set up exactly like that at pomona swapmeet about 13 years ago. of course it wasnt for sale but it was in the swap booth anyways

I have original versions of both the 36 and 40 hp models.