Go Back   The Ford Barn > General Discussion > Early V8 (1932-53)

Sponsored Links (Register now to hide all advertisements)

Reply
 
Thread Tools Display Modes
Old 01-03-2017, 09:40 PM   #1
Bursonaw
Senior Member
 
Bursonaw's Avatar
 
Join Date: Apr 2013
Location: Tolland, CT
Posts: 273
Default Progressive linkage vs straight linkage on a 2x2 manifold

I am planning to upgrade my flathead and run dual Holly 94's on a slingshot manifold. My motor is pretty much stock with some high compression heads and a set of headers. Eventually I plan to upgrade the cam but for now am starting with the intake manifold. My question is when setting up the manifold, are there any thoughts on running progressive or straight linkage?






Sent from my iPad using Tapatalk
Bursonaw is offline   Reply With Quote
Old 01-03-2017, 10:09 PM   #2
Ken/Alabama
Senior Member
 
Ken/Alabama's Avatar
 
Join Date: May 2010
Location: Alabama
Posts: 2,356
Default Re: Progressive linkage vs straight linkage on a 2x2 manifold

With two carbs you need straight linkage and make sure carbs are synchronized.
Ken/Alabama is offline   Reply With Quote
Sponsored Links (Register now to hide all advertisements)
Old 01-03-2017, 10:29 PM   #3
uncle max
Senior Member
 
uncle max's Avatar
 
Join Date: May 2010
Location: SLC Utah
Posts: 772
Default Re: Progressive linkage vs straight linkage on a 2x2 manifold

That slingshot manifold is one of the very few dual carb rigs where all the mixture goes down the same hole. You will be just fine with progressive or direct linkage. If it were me, I think I'd try progressive and see how it feels.
__________________
RIP Tyler... My Son, Helper & Best Friend.
Feb '78 to Father's Day '10.
www.97-express.com ~ info@97-express.com
uncle max is online now   Reply With Quote
Old 01-04-2017, 12:46 AM   #4
scicala
Senior Member
 
scicala's Avatar
 
Join Date: Jun 2010
Location: Detroit suburb, MI
Posts: 2,942
Default Re: Progressive linkage vs straight linkage on a 2x2 manifold

I agree. Progressive linkage may give you better throttle response and possibly better fuel economy, depending on you're driving style.

Sal
scicala is offline   Reply With Quote
Old 01-04-2017, 10:54 AM   #5
flatjack9
Senior Member
 
flatjack9's Avatar
 
Join Date: May 2010
Location: Oshkosh, Wi
Posts: 3,782
Default Re: Progressive linkage vs straight linkage on a 2x2 manifold

It would be just like a 4 barrel with mechanically operated secondaries.
flatjack9 is offline   Reply With Quote
Old 01-04-2017, 11:25 AM   #6
Kahuna
Senior Member
 
Kahuna's Avatar
 
Join Date: May 2010
Location: NorCal
Posts: 2,617
Default Re: Progressive linkage vs straight linkage on a 2x2 manifold

Sponsored Links (Register now to hide all advertisements)
Yep
Progressive
Kahuna is offline   Reply With Quote
Old 01-04-2017, 12:36 PM   #7
funrunr
Senior Member
 
funrunr's Avatar
 
Join Date: May 2010
Location: Belleville,MI
Posts: 1,372
Default Re: Progressive linkage vs straight linkage on a 2x2 manifold

I have a slingshot as well and used straight linkage. It works good, however, I like the response you received and curious to try progressive as well.
On a side not, you will notice one of the manifold mounting bolts on the left side does not allow a hex head bolt. I used an allen head on mine. Just a heads up. Please let us know which way you decide and how you like it.
__________________
Thank God
this is only a hobby!
funrunr is offline   Reply With Quote
Old 01-04-2017, 08:10 PM   #8
Bursonaw
Senior Member
 
Bursonaw's Avatar
 
Join Date: Apr 2013
Location: Tolland, CT
Posts: 273
Default Re: Progressive linkage vs straight linkage on a 2x2 manifold

Quote:
Originally Posted by funrunr View Post
I have a slingshot as well and used straight linkage. It works good, however, I like the response you received and curious to try progressive as well.
On a side not, you will notice one of the manifold mounting bolts on the left side does not allow a hex head bolt. I used an allen head on mine. Just a heads up. Please let us know which way you decide and how you like it.


Thanks for all the replies. I will keep you posted. I'm leaning towards trying both as for a nominal investment I can convert to a progressive linkage.


Sent from my iPad using Tapatalk
Bursonaw is offline   Reply With Quote
Old 01-04-2017, 08:29 PM   #9
Bursonaw
Senior Member
 
Bursonaw's Avatar
 
Join Date: Apr 2013
Location: Tolland, CT
Posts: 273
Default Re: Progressive linkage vs straight linkage on a 2x2 manifold

With progressive linkage brings up another question. Does the secondary carb need any modification in this application? In my tri-power setup the outer carbs are modified with no mixture control and heavier butterflies to avoid leaking fuel caused by engine vacuum.


Sent from my iPad using Tapatalk
Bursonaw is offline   Reply With Quote
Old 01-04-2017, 08:51 PM   #10
Bursonaw
Senior Member
 
Bursonaw's Avatar
 
Join Date: Apr 2013
Location: Tolland, CT
Posts: 273
Default Re: Progressive linkage vs straight linkage on a 2x2 manifold

Quote:
Originally Posted by Bursonaw View Post
With progressive linkage brings up another question. Does the secondary carb need any modification in this application? In my tri-power setup the outer carbs are modified with no mixture control and heavier butterflies to avoid leaking fuel caused by engine vacuum.


Sent from my iPad using Tapatalk

I think I answered my own question. Here is a write up I found about The Holley 94 Secondary carb.

CARB BASE-HOLLEY 94 Secondary Base Assembly-w/Spring This is what you need to make your outside carbs work right. This base our new alum base reamed and fitted with a new throttle shaft-- and fitted with our new 12 degree throttle plates that give you a great seal with no sticking in the bores.Throttle plates are lapped to bore. This base is an exact reproduction of the original early holley 94-2100 base. These bases are used on the outside carbs on a 3x2 setup and on the outside carbs on a six deuce setup when running progressive linkage. They can also be used in any other location where you dont need or want an idle circuit such as the secondary carb on a dual setup running progressive linkage. These bases dont have any idle circuits And come with our new torsion return springs and carb arms. These eliminate the need for any throttle return springs and work much better. Due to the 12 degree plates --you dont need any throttle stop screws or hardware on your carb.










Sent from my iPad using Tapatalk
Bursonaw is offline   Reply With Quote
Old 01-04-2017, 09:10 PM   #11
Bored&Stroked
Senior Member
 
Bored&Stroked's Avatar
 
Join Date: Jan 2011
Location: Central Ohio
Posts: 2,724
Default Re: Progressive linkage vs straight linkage on a 2x2 manifold

Would be fun to try both setups . . . why the heck not! You'll probably need to buy a 3x2 progressive linkage and only use one "side" of it. Can't say that I've ever done it -but worth a try.

Can't see much of an issue with having idle mixture screws in both - you can still tune the idle . . . with one, with both, doesn't really matter. Once you get "off idle", then the main jets will come into play.

In my mind, the engine will only need a certain amount of air/fuel to go a certain speed - so can't really imagine that a progressive linkage setup has much to gain. As these carbs have really small throttle plates - don't think there is any real performance issue with having BOTH of them coming in at the same rate. BUT - will be interesting to see what happens in your "real world" testing.

Last edited by Bored&Stroked; 01-05-2017 at 08:24 AM.
Bored&Stroked is offline   Reply With Quote
Old 01-04-2017, 10:55 PM   #12
alanwoodieman
Senior Member
 
Join Date: May 2010
Location: upstate SC
Posts: 2,361
Default Re: Progressive linkage vs straight linkage on a 2x2 manifold

the two 94's will have to jetted down from the stock jets, no matter how you configure them. on the new strombergs we went from the stock 45 to 35 and syncronized them, worked out great
alanwoodieman is offline   Reply With Quote
Old 01-05-2017, 12:23 AM   #13
Alaska Jim
Senior Member
 
Alaska Jim's Avatar
 
Join Date: May 2010
Location: Palmer, Alaska
Posts: 1,345
Default Re: Progressive linkage vs straight linkage on a 2x2 manifold

Bursonaw, who makes that carb base? just curious.
Alaska Jim is offline   Reply With Quote
Old 01-05-2017, 12:48 AM   #14
Bursonaw
Senior Member
 
Bursonaw's Avatar
 
Join Date: Apr 2013
Location: Tolland, CT
Posts: 273
Default Re: Progressive linkage vs straight linkage on a 2x2 manifold

Quote:
Originally Posted by Alaska Jim View Post
Bursonaw, who makes that carb base? just curious.


The cab base I found at Vintage Speed. http://vintagespeed.com/

I think that speedway might have them as well.


Sent from my iPad using Tapatalk
Bursonaw is offline   Reply With Quote
Old 01-05-2017, 06:57 AM   #15
LOWRIDER
Senior Member
 
LOWRIDER's Avatar
 
Join Date: May 2010
Location: Kingman Az. 86409
Posts: 379
Default Re: Progressive linkage vs straight linkage on a 2x2 manifold

I used a couple of those carb bases on my yblock w/tripower. I worked forever trying to make 70yr carb bases seal at idle without success. Installing those fixed my vacuum leak at idle. Well worth the $$$.
__________________
Dan Kingman Az. 86409
LOWRIDER is offline   Reply With Quote
Old 01-05-2017, 08:50 AM   #16
scooder
Senior Member
 
Join Date: Jul 2010
Posts: 2,573
Default Re: Progressive linkage vs straight linkage on a 2x2 manifold

Quote:
Originally Posted by alanwoodieman View Post
the two 94's will have to jetted down from the stock jets, no matter how you configure them. on the new strombergs we went from the stock 45 to 35 and syncronized them, worked out great
Two 94's on his setup, I'd start with stock jets and play from there. Probably need the power valves playing with, 5.5 or such. May find all's well with stock jets and power valves.

45 down to 35!!!! Damn! That's a massive difference! you certainly wouldn't need that massive drop in numbers for 94's
Martin.
scooder is offline   Reply With Quote
Old 01-05-2017, 08:58 AM   #17
Bored&Stroked
Senior Member
 
Bored&Stroked's Avatar
 
Join Date: Jan 2011
Location: Central Ohio
Posts: 2,724
Default Re: Progressive linkage vs straight linkage on a 2x2 manifold

Me - would throw a straight linkage on it, sync the carbs with a UniSyn, jet them to match the engine and it's fuel needs and drive it . . . you'll probably not improve on that in my mind.

D
Bored&Stroked is offline   Reply With Quote
Old 01-05-2017, 11:42 AM   #18
Tony, NY
Senior Member
 
Join Date: May 2010
Location: Capital of Corruption , NY
Posts: 711
Default Re: Progressive linkage vs straight linkage on a 2x2 manifold

You may find those air cleaners to be restricting.
Tony, NY is offline   Reply With Quote
Old 01-05-2017, 12:04 PM   #19
chap52
Senior Member
 
chap52's Avatar
 
Join Date: Jun 2013
Location: Marana Arizona
Posts: 1,607
Default Re: Progressive linkage vs straight linkage on a 2x2 manifold

I run dual 94's with straight linkage. My engine is stock with mild Howard cam. As mentioned"Unisync" them. I was advised by "CharlieNY" to block off the PV"S and am very satisfied with the set-up.
chap52 is online now   Reply With Quote
Old 01-05-2017, 05:06 PM   #20
scooder
Senior Member
 
Join Date: Jul 2010
Posts: 2,573
Default Re: Progressive linkage vs straight linkage on a 2x2 manifold

Quote:
Originally Posted by chap52 View Post
I run dual 94's with straight linkage. My engine is stock with mild Howard cam. As mentioned"Unisync" them. I was advised by "CharlieNY" to block off the PV"S and am very satisfied with the set-up.
What size main jets you got in there?
Martin.
scooder is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Sponsored Links (Register now to hide all advertisements)


All times are GMT -5. The time now is 07:27 AM.