11 Guests, 0 Users

Author Topic: Update on sidedraft SU HIF carburetors on 73 2.0  (Read 810 times)

0 Members and 1 Guest are viewing this topic.

Offline LongTimeFordMan

  • PCCA VIP
  • Pinto Sr. Member
  • ***
  • Posts: 361
  • FeedBack: +181/-0
  • Gender: Male
  • 1973 Red Pinto Wagon

  • Total Badges: 5
    Badges: (View All)
    Topic Starter Signature Windows User Linux User Mobile User
Update on sidedraft SU HIF carburetors on 73 2.0
« on: May 07, 2018, 10:36:10 PM »
Well i finally got the manifold finished and installed on my car.. factory stock engine 70k miles, stock cam, advanced cam 4 degrees, eliminated vacuum advance on distributor and limited centrifugal advance to about 14 degrees, initial timing 13 degress BTDC.

Carburetors are HIF 4 from 72 mgb. Custom manifold.

After adjusting jets and installing holley fuel pressure regulator set at 3 psi. Car runs VERY strong past 5000 rpm in 1st and 4000 in 2nd at less than half throttle.

Much more torque fron 2500 to past 5000, with stock cam. And much more responsive than stock holley webber 24/36

could probably rev to 6000 but dont want to stress engine
Red 1973 pinto wagon DD, SoCal desert car, Factory 4 speed, 3.40 gears, Stock engine, 14" rims and tires, 60 K original miles

Offline Wittsend

  • Pinto Master
  • *****
  • Posts: 2210
  • FeedBack: +241/-0

  • Total Badges: 8
    Badges: (View All)
    Tenth year Anniversary Mobile User Topic Starter Poll Voter 1000 Posts Linux User Windows User Fifth year Anniversary
Re: Update on sidedraft SU HIF carburetors on 73 2.0
« Reply #1 on: May 08, 2018, 11:37:10 AM »
Looks great on the engine. I noticed there are welds on the center area. Did you put a divider in?  In essence it looks like a side draft 2X1 bbl. version of 2X4bbl. tunnel ram manifold. I'd think the manifold design would be more suited for high RPM with the large pluenum but I also understand you can't form sheet metal and tubing to ideal forms as casting would allow.  It seems you are getting desirable results and you can't argue with that.  I look forward to seeing how this all plays out on the new engine.  All the best.

Offline LongTimeFordMan

  • PCCA VIP
  • Pinto Sr. Member
  • ***
  • Posts: 361
  • FeedBack: +181/-0
  • Gender: Male
  • 1973 Red Pinto Wagon

  • Total Badges: 5
    Badges: (View All)
    Topic Starter Signature Windows User Linux User Mobile User
Re: Update on sidedraft SU HIF carburetors on 73 2.0
« Reply #2 on: May 08, 2018, 11:57:19 AM »
I fabricated the manifold from tubing salvaged from a direct tv antenna mount and some 1 3/8 diameter thinwall emt.

Main log or plenum is open to equalize flow from both carbs to all ports since optimal flow would be 1&4 from one carb and   2&3 from the other.

Preliminary testing seems to indicate drastically improved performance from 2000 all the way to 5500 with stock cam and throttle response is great all thru range.

Am working on finding the proper throttle cable since the position of the accellerator cable in pinto requires a lot of bends and results in some sticking which maked precise c9ntrol difficult.

Will be experimenting with some bicycle type cables.

Red 1973 pinto wagon DD, SoCal desert car, Factory 4 speed, 3.40 gears, Stock engine, 14" rims and tires, 60 K original miles

Offline Pintosopher

  • 33yrs SCCA, 19yrs Egroups/PCCA ,40yrs enlightenment
  • PCCA Charter Member
  • Pinto Master
  • *
  • Posts: 1993
  • FeedBack: +383/-1
  • Gender: Male
  • Essses my Nirvana , Liberty to play, my mission

  • Total Badges: 8
    Badges: (View All)
    Topic Starter Signature Poll Voter 1000 Posts Windows User Tenth year Anniversary Fifth year Anniversary Photographer
Re: Update on sidedraft SU HIF carburetors on 73 2.0
« Reply #3 on: May 08, 2018, 01:27:02 PM »
 Your efforts and execution are admirable!  The Results do show that with the Engine mods you have , the Power curve does demonstrate just how limiting the stock Carburetor can be. With My original stock 2.0L in my 72. and just headers, I could not get the power up with any modded version of the 32/36 carb. Just adding mildly touched up stock manifold with a 38/38 DGAS weber made the car pull very hard up to the cam limitations at 5500 rpm.  No need to mash the pedal and waste gas to get moving quickly.  My race motor 2.0L with 10:1 flat top pistons 288/ 450 /108 Norris cam and dual 40 DCOE actually did get decent mileage and was easily capable of 7000 rpms
 Too Much fun it is!
 Keep the experiment going!

 Pintosopher,  Horses waiting to be delivered..  ;)
Yes, it is possible to study and become a master of Pintosophy.. Not a religion , nothing less than a life quest for non conformity and rational thought. What Horse did you ride in on?

Check my Pinto Poems out...

Offline LongTimeFordMan

  • PCCA VIP
  • Pinto Sr. Member
  • ***
  • Posts: 361
  • FeedBack: +181/-0
  • Gender: Male
  • 1973 Red Pinto Wagon

  • Total Badges: 5
    Badges: (View All)
    Topic Starter Signature Windows User Linux User Mobile User
Re: Update on sidedraft SU HIF carburetors on 73 2.0
« Reply #4 on: May 08, 2018, 02:30:44 PM »
Well the irony is that among mgb guys the "hot" setup is supposed to be replacing the  SU s with a 24/36 "webber".

I had a 72 wagon bought new in 72 with the 24/36 ans it performed badly as well.

The thing I like about the SU is that mixture can be changed by just adjusting  the needle height with an external adjustment screw.

Supposedly the HIF 4 can flow about 160-180 cfm each so 2 should flow 350 cfm.

Will continue to post experiments.
Red 1973 pinto wagon DD, SoCal desert car, Factory 4 speed, 3.40 gears, Stock engine, 14" rims and tires, 60 K original miles

Offline Wittsend

  • Pinto Master
  • *****
  • Posts: 2210
  • FeedBack: +241/-0

  • Total Badges: 8
    Badges: (View All)
    Tenth year Anniversary Mobile User Topic Starter Poll Voter 1000 Posts Linux User Windows User Fifth year Anniversary
Re: Update on sidedraft SU HIF carburetors on 73 2.0
« Reply #5 on: May 09, 2018, 05:25:18 PM »

"Well the irony is that among mgb guys the "hot" setup is supposed to be replacing the  SU s with a 24/36 "webber"."

From what I read that seems to be the case with the Volvo 544/122 guys too.  I had SU's in my '72 240Z, Volvo 544 and currently my Datsun 510. Kind of had a love/hate relationship with them. At my age I prefer a Uni-Sync to a tube in my ear. LOL

Offline LongTimeFordMan

  • PCCA VIP
  • Pinto Sr. Member
  • ***
  • Posts: 361
  • FeedBack: +181/-0
  • Gender: Male
  • 1973 Red Pinto Wagon

  • Total Badges: 5
    Badges: (View All)
    Topic Starter Signature Windows User Linux User Mobile User
Re: Update on sidedraft SU HIF carburetors on 73 2.0
« Reply #6 on: May 25, 2018, 07:02:36 PM »
Another update on the SU carbs on custom manifold.

Ive been tweaking on the carbs and working out the mixture. The great thing about SUs is that tbey use tapered needles that meter the fuel larger diameter lean, smaller rich so if you start with the lean needles, you can chuck the needles into a drill and modify the taper by spinning them and reducing the diameter with 400 grit wet or dry to get the mixture profile you want.

Well after doing tbis, the car with stock cam, compression runs like a scalded cat.

Before with stock holly weber 24/36 eit would barely rev to 4500 and at 4000 rwn rough and felt like ti was comming apart and i thught I had ign or timing problems when aqctually it was just running out of carburation.

Now the engine pulls hard from 2000 to 5500 and would probably go to past 6000 if i pushed it.

It idles smoothly at 1000 to 1100 has good low speed performance and on a 100 mile drive i got 26 mpg, up from the 17-20 with the webber.
Red 1973 pinto wagon DD, SoCal desert car, Factory 4 speed, 3.40 gears, Stock engine, 14" rims and tires, 60 K original miles

Offline Wittsend

  • Pinto Master
  • *****
  • Posts: 2210
  • FeedBack: +241/-0

  • Total Badges: 8
    Badges: (View All)
    Tenth year Anniversary Mobile User Topic Starter Poll Voter 1000 Posts Linux User Windows User Fifth year Anniversary
Re: Update on sidedraft SU HIF carburetors on 73 2.0
« Reply #7 on: May 25, 2018, 09:15:44 PM »
Sounds like it was a worthwhile venture. I love these kinds of project. Congratulation s.