81’s tri power or dual 97’s

[Daveyjonez]

Hi Guys:

I have a nicely built 276 Flathead and I am deciding on the fuel system. I have 2 very nice 81’s and I thought acquiring 1 more and running a 3x2 setup might be a consideration. Or, should I stick to 2 97’s on a dual carb manifold (I would have to purchase a couple of 97’s.??

Any input?

Thanks!!
Dave

[frnkeore]

Personally, I think three 81's would be a very good, all around setup. Especially with a mild cam.

Could give better gas mileage, too if you an keep your foot out of it But, I love the sound of a over carburated engine, winding up!!!

Frank

[JSeery]

Might read JWLs book, he list dyno runs on several setup.

[uncle max]

It's hard to beat the throttle response of three 81's on a rascally flathead!

[deuce_roadster]

I am running 2 81s on an old Eddie Meyer manifold and am quite happy with them. I'm sure you could get 3 to run very well.

[Daveyjonez]

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Thank you guys! I really wanted to use the 81’s- I really appreciate the input.

[Ol' Ron]

Yes, the 81's should give better "street" response. Might be alittle shy at the top end. Depends allot on the cam. 1007B would be nice/

[Daveyjonez]

I had Pete grind me 1007b, which is in the motor- I felt like it would lend itself well also, thank you Ron

[Init1]

I prefer 2 carbs . 3 carbs can be difficult to tune and will take some tinkering to make work right.
You probably would only use 2 anyway most of the time with a progressive linkage.
But...the 3 carbs look really cool.

[qmdv]

I have an original Navarro 3 carb manifold that I thinking of parting with. Been told that it was way good

[KiWinUS]

3 Stromberg 81s @ a KiWi-L100 & you can’t go wrong!!! So many know this but won’t admit ��
Enjoy
Cheers
Tony

[scicala]

[QUOTE=uncle max;1794012]It's hard to beat the throttle response of three 81's on a rascally flathead!

Uncle Max, can you educate me ? Is the 81 a smaller carb (airflow wise) than 48's and 97's ? Also what years and on what engine were the 81's used ?
Thanks for any info.


Sal

[cas3]

81's were the 60 hp carb

[aussie merc]

eye candy appeal you cant beat a tri power just dont over carb but its up to you and what ever makes your bell ring [but ring it long and loud]

[scicala]

Originally Posted by cas3

81's were the 60 hp carb

Thank you, Sal

[JWL]

For a "driver" the better combination is a center 81 with two ends of 97 or 48 with progressive linkage. However, the setup time and expertise should not be ignored.

[Daveyjonez]

Thanks JWL, that makes sense given the increased volume provided by the secondary carbs- good throttle response low, and volume up high.

Thanks Again

[drolston]

Take whatever time needed on the bench to get the progressive linkage set up perfectly, so that both end carbs are precisely and fully closed at idle, with the idle adjustment screws backed completely off. Do that with the carb tops off of the carb base so that you can easily see the throttle plates. If the throttle plates are not perfectly centered or stick a little, fix them. Completely close the idle jet adjustments on both end carbs so that idle adjustment is all on the center carb. Don't go cheap on the progressive linkage as the cheap stuff tends to flex and adjustments slip. One of the end carbs pulls or pushes the other end carb; you can take the accelerator pump spring off of (or simply unhook) that carb to lessen the strain on the linkage.

I put 2" risers on my tri-power, which enabled me to invert the progressive linkage. That way I could use banjo fittings for plumbing fuel lines to the carbs, and I could retain the manual throttle control on the center carb. Took just a little grinding on one end riser and the underside of the fuel pump to get clearance for the linkage.

[Daveyjonez]

Looks good, thanks for the reply

[Bored&Stroked]

Originally Posted by KiWinUS

3 Stromberg 81s @ a KiWi-L100 & you can’t go wrong!!! So many know this but won’t admit ��
Enjoy
Cheers
Tony

Now Tony - relax a bit . . . you don't have the only cam that can't go wrong! Also, I've done many bad things - and remember only a few! LOL

Cheers Dude!
B&S

[Pete]

Originally Posted by drolston

Take whatever time needed on the bench to get the progressive linkage set up perfectly, so that both end carbs are precisely and fully closed at idle, with the idle adjustment screws backed completely off. Do that with the carb tops off of the carb base so that you can easily see the throttle plates. If the throttle plates are not perfectly centered or stick a little, fix them. Completely close the idle jet adjustments on both end carbs so that idle adjustment is all on the center carb. Don't go cheap on the progressive linkage as the cheap stuff tends to flex and adjustments slip. One of the end carbs pulls or pushes the other end carb; you can take the accelerator pump spring off of (or simply unhook) that carb to lessen the strain on the linkage.

I put 2" risers on my tri-power, which enabled me to invert the progressive linkage. That way I could use banjo fittings for plumbing fuel lines to the carbs, and I could retain the manual throttle control on the center carb. Took just a little grinding on one end riser and the underside of the fuel pump to get clearance for the linkage.

Moderators take note, I am going to create controversy here.

In the first place the photo is out of focus. That is definitely not consistent with an aerospace engineer.
Next is plastic fuel line. NO WAY is safe.
The progressive linkage in the photo is mechanically perfect and should work forever.

While progressive linkage can be made to work ok, straight linkage will out perform it in ALL categories every time.
This has been proven many times on the dyno in actual driving simulations.
Believe it or not, where the straight linkage shows best is at low throttle settings where most people think it should be worst. It is due to more even fuel distribution from the mixture travel path being more equal to all cylinders.

[Daveyjonez]

Thanks Pete, I will reach out when setting up my fuel system.

[Ronnieroadster]

Pete as usual your telling what needs to be told good for you and a big Thank You. Now I bet the economy posts might start look out. LOL
Multi carbs and economy will never be a match.
Ronnieroadster

[drolston]

Originally Posted by Pete

Moderators take note, I am going to create controversy here.

In the first place the photo is out of focus. That is definitely not consistent with an aerospace engineer.
Next is plastic fuel line. NO WAY is safe.
The progressive linkage in the photo is mechanically perfect and should work forever.

While progressive linkage can be made to work ok, straight linkage will out perform it in ALL categories every time.
This has been proven many times on the dyno in actual driving simulations.
Believe it or not, where the straight linkage shows best is at low throttle settings where most people think it should be worst. It is due to more even fuel distribution from the mixture travel path being more equal to all cylinders.

Clear vinyl fuel lines from Summit Racing; not plastic. Perfectly safe. I love to watch the bubbles when it is vapor locking. Sorry about the blurry picture. Get almost 17 mpg on the highway.

[Tinker]

Originally Posted by Ronnieroadster

Pete as usual your telling what needs to be told good for you and a big Thank You. Now I bet the economy posts might start look out. LOL
Multi carbs and economy will never be a match.
Ronnieroadster

I still run one carburetor. Something is wrong.

[Bored&Stroked]

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In the end, I believe I have too few carbs, bad fuel economy and I'm going to do something about both! One will get better and one will probably get worse . . . LOL

[Tinker]

Originally Posted by Bored&Stroked

In the end, I believe I have too few carbs, bad fuel economy and I'm going to do something about both! One will get better and one will probably get worse . . . LOL

I'm just a driver guy. No dog in this hunt.


Best to however you want to do what you do.



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