Hot Rods HARPER intake manifold 265 Mopar

IMG_0752 by Pat posted Aug 12, 2024 at 6:40 PM

I commend you on recreating the original linkage! I’ve successfully ran a Harper for many years on my Chevy 6 roadster. I run 81’s with straight linkage. Excellent throttle response. On cold morning drives I could see condensation forming on the intake runners! Felt like extra horsepower!

551921 105134706302860 921594004 n by Pat posted Sep 25, 2013 at 2:10 AM

 

Clive at Stromberg is the BEST !!!
I Emailed to ask if I could buy 3 carbs with unfinished throttle shafts, so I didn’t have to remove the ends from brand new shafts in order to install my custom ones once made. Explained what the finished setup would be - split carbs, custom linkage etc.
He said “I gotta see this”
So I sent him the link to this thread
He pretty much said “ you’re insane … I want to help” (I’m paraphrasing)
So he sent me three unfinished standard throttle shafts at a smokin’ “bro” price to help me out !

I can’t thank him enough for helping move this project forward !

pic shows all the random pieces I’ve been gathering, including the 3 new shafts from Stromberg in the center.

the only thing of note right now is that I’ve disassembled an original throttle shaft and end linkage so I can transfer dimensions to my first piece

 

Thanks for sharing your progress. Sounds like your contact with Clive is a good thing.

 

This is a very interesting thread bu a little complicated for my tiny mind! I have a dual Ellis I’ll be using on my Fargo...

 

Roughed in the first linkage arm

 

Basically the primaries (first set of linkage) would be just straight but only opening 1/2 of each carb. The secondaries would also be all 3 the same with just the ratio to come on later and then fully open quicker. It is progressive linkage running different sides of 3 carbs instead of running 3 different carbs. It just looks so cool!

 

you make it sound so simple !
what I'm hoping for is to create one linkage arm casting that I can cut down for all the positions... the primary side all 3 need the accelerator pump link balls, while the secondary side don't. both sides center carb will need center engaging, while the other four don't
really though, it's the center progressive that I'm most concerned about trying to figure out

 

Not belittling your task. just saying the concept is pretty simple. The complexity and craftsmanship of the original Harper linkage is a thing of beauty.

 

Damn man, 97's with secondaries. Without the second pump shot when the other side starts to open I wonder if there will be a bit of a hesitation until the other venturi catches up.

 

it's interesting how different the Chevy is from the Mopar

 

I don't now why the linkage would be different. Isn't it doing the same thing? Maybe the initial connection and being on the other side of the engine.

 

I don’t know what the linkage on the Chevy car looks like, but it seems like maybe it comes from down low and pushes up ?
The Mopar crosses the head and pushes sideways

 

You are right the Chevy comes from below the intake from a stud off the side of the block. The linkage there turns the fore & aft movement to up and down.

 

We’re gonna find out !

 

Nice pictures of the most complicated part. The linkage on the center carb is the brains of the outfit.

 

For anyone who cares, the carbs have #43 jets on the primary side, and #45s on the secondary side.

 

best pic I've seen yet of the center linkage - thank you !

 

Page 2 in this thread.
https://www.jalopyjournal.com/forum/threads/my-235-harper-intake-showed-up-today.619486/page-2

 

in the third pic - it looks like the "upper" "U" shaped piece runs the secondary side, and the "lower" "U" runs the primary side ? --- the pins through the axle, that the torsion springs are hooked around -- is that what engages the two to act as the "progressive" engagement ? I understand the "slider" arrangement on regular progressive dual quads and triple twos -- having a hard time deciphering it on the Harpers

 

I'll have to take another look at it.

 

would you be willing to measure the lengths of some of the arms ? from the pivot "axles" to the linkage or actuation points ? I'm betting i know what the measurements will be, but want to verify

 

Sure, but I won't be able to before the weekend.