32/36DGAV versus 38DGAS

**Dyno** · 22-05-2022, 07:27

Wanted to share this info, just to show again you don't need 38DGAS so fast. I was selecting the carburetor for my MX5 1800 Turbo engine. The carburetor for a turbo engine does not need to be any bigger as the one that give you max power in NA form. So I fitted the original MX5 exhaust manifold and tested both 32/36DGAV against a 38DGAS with 2mm enlarged chokes (the standard 38DGAS chokes are almost the same size as the one fitted to 32/36DGAV). This "enlarged" 38DGAS is some kind of a stock version I use for larger V6 engines or small V8's. On a Stag V8 the enlarged version makes 10-15 Bhp more power.

As can been seen in the graph, both carbs made the same max power.

Both carburetors made a dip round 2500-3000 RPM. Caused by a slightly rich mixture but because I was only interested in the max power potential I did not made any mods to the carbs to correct it.

This time I was surprised how well the 38DGAS was reacting at the throttle compared to other test work I did with this carb on other engines, despite the rich spot at full load round 2500-3000 RPM (which I could easy fix if I wanted) the mixture was very good overal. Only at the point I added the turbo the tuning advances of the progressive 32/36DGAV became more and more clear.

**Ken B** · 22-05-2022, 20:56

I've just changed from a 38DGMS to a 32/36DGAV on my Zetec'd Corsair. One of the issues for me was at low speeds, the 38 wasn't particularly nice and smooth/progressive, because of both chokes opening together I guess. It was a bit on or off. The 32/36 drives much nice at lower speeds, and tbh I've not noticed any drop in acceleration or power, which backs up your findings. The other bonus is my MPG has improved slightly as well.

**Dyno** · 23-05-2022, 06:06

Originally Posted by Ken B

I've just changed from a 38DGMS to a 32/36DGAV on my Zetec'd Corsair. One of the issues for me was at low speeds, the 38 wasn't particularly nice and smooth/progressive, because of both chokes opening together I guess. It was a bit on or off. The 32/36 drives much nice at lower speeds, and tbh I've not noticed any drop in acceleration or power, which backs up your findings. The other bonus is my MPG has improved slightly as well.

100% correct and proven once more the 32/36 is large enough to supply all the air what is needed. On later cars it was replaced with DMTL version and had smaller throttle plates and chokes for the same kind of engines, so the carb has some spare build in for extra air supply.

And yes, the best part of the 32/36 is being "progressive". You can "program" the first step lean for good economy and when the second comes in you can change this in a power mixture. In practice it means you can alter the fueling over a large range. Lucky, in 99% you just have to play a bit with the jets to get it al done.

**Graham** · 23-05-2022, 07:03

good stuff, ive just kinda tested this the other way, 38dgas ( unmodified ) against a 40 dfav, dfav on a 148bhp pinto only 2 bhp difference

**Sidways93** · 23-05-2022, 07:09

Interesting, was this separate to the 40DFI test? The DFAV has a power valve I think so I thought it might work with the pinto manifold a bit better than the DFI. If 2 bhp up over a Dgas then I guess it could well be up 5-6 bhp on a 32/36? With some downsides maybe.

Cheers

Originally Posted by Graham

good stuff, ive just kinda tested this the other way, 38dgas ( unmodified ) against a 40 dfav, dfav on a 148bhp pinto only 2 bhp difference

**katana** · 23-05-2022, 08:02

Originally Posted by Ken B

One of the issues for me was at low speeds, the 38 wasn't particularly nice and smooth/progressive, because of both chokes opening together I guess. It was a bit on or off.

I wonder if an eccentric quadrant would help on the throttle shaft ie. slower opening at, say, first 1/3rd with faster opening up to WOT? to give better / finer control in the low end range.

**Dyno** · 23-05-2022, 08:43

Originally Posted by katana

I wonder if an eccentric quadrant would help on the throttle shaft ie. slower opening at, say, first 1/3rd with faster opening up to WOT? to give better / finer control in the low end range.

the original 32/36 is working like this

**Dyno** · 23-05-2022, 08:50

Originally Posted by Sidways93

Interesting, was this separate to the 40DFI test? The DFAV has a power valve I think so I thought it might work with the pinto manifold a bit better than the DFI. If 2 bhp up over a Dgas then I guess it could well be up 5-6 bhp on a 32/36? With some downsides maybe.

Cheers

Not on a simple 4 cylinder. The extra 2 Bhp almost for sure came because of different pulse tuning, not because the other carb was too small. It could have been 2 Bhp less for the same money. 32/36 DGAV and 38 DGAS never make a real different in power on a Pinto so in this case, it will stay a gain of 2 Bhp and you loose all the benefit of the 32/36.

On 6 cylinders or V8 (using one throttle for 1 bank of cylinders) I do see increased power when I open the chokes of the 38DGAS and in this setup the carburetor is working ver well. Despite it is no progression carburetor as a Holley 4 barrel, for low powered V8 (V6) it is working great and easy to setup. I bore them 2mm over and have a special cutter to make a new radius turn on the choke

**Graham** · 11-02-2023, 17:30

Dirk has already covered this, but heres my version of the same test

https://youtu.be/GMyfJ7Ix8qE

**Miniliteman** · 11-02-2023, 22:57

The narrowest place where the air (or air/fuel) enters the engine determines how much power the engine can make. Think of the restrictor in rally-engines or the airbox entry on F3 engines. The DGAV has 26 and 27 mm throttles, the DGAS 27 and 27 mm. So there is very little differences, hence similar power from both carbs.
The drivability of the DGAS can be improved on a Pinto by fitting different idle air bushes. Companies like FastRoadCars sell already modifies DGAS carbs for use on the Pinto.

**Graham** · 11-02-2023, 23:12

Originally Posted by Miniliteman

The narrowest place where the air (or air/fuel) enters the engine determines how much power the engine can make. Think of the restrictor in rally-engines or the airbox entry on F3 engines. The DGAV has 26 and 27 mm throttles, the DGAS 27 and 27 mm. So there is very little differences, hence similar power from both carbs.
The drivability of the DGAS can be improved on a Pinto by fitting different idle air bushes. Companies like FastRoadCars sell already modifies DGAS carbs for use on the Pinto.

agreed, but the whole point is dgas on a pinto doesnt make more power unlike so many say

**katana** · 12-02-2023, 13:10

Your description of 'what everyone said in the past' was so true - it was almost tuning law, if you wanted to retain a downdraft carb on a Pinto, fit a 38 off of a V6 - makes loads, bolt on!
Those back to back run overlays are almost within the tolerance of output capture by the software - less than a hp. Lets hope that myth now dies a death! And considering the 'standard' state of Junkyard Dog, that cam and tube exhaust do make a nice enhancement compared to Ford's quoted output of 105-108hp back in the day!
The only problem with your videos that I have is . . . . . . . . . I want more LOL!

**Graham** · 12-02-2023, 14:28

Originally Posted by katana

Your description of 'what everyone said in the past' was so true - it was almost tuning law, if you wanted to retain a downdraft carb on a Pinto, fit a 38 off of a V6 - makes loads, bolt on!
Those back to back run overlays are almost within the tolerance of output capture by the software - less than a hp. Lets hope that myth now dies a death! And considering the 'standard' state of Junkyard Dog, that cam and tube exhaust do make a nice enhancement compared to Ford's quoted output of 105-108hp back in the day!
The only problem with your videos that I have is . . . . . . . . . I want more LOL!

yeah junk yard dog is certainly fairly strong for what it is, even though its blowing a bit of smoke out the crank breather and the oil pressure is getting a bit marginal at high rpm, it doing ok,
with a standard cam, cortina exhaust manifold and system it made 104bhp, ok no air filter or cooling fan so it was making give or take a fraction ford standard power for a non RS engine which was 99/100 bhp. For any given spec that engine has always gives a strong torque figure, whether thats down to having an injection head or not i dont know.

next installment will be just that, standard with cortina exhaust, upgrade to ashley exhaust, carb rejet, cam swap and finally 40 dcoes from memory it finished on 123bhp

**onecamohv** · 14-02-2023, 22:45

I love your YouTube series for the simple fact you seem to be debunking tons of cast in stone 'tuning' must do's since the year dot.

Fit a bigger manifold, that thing is tiny! = Nope

Fit a 38 dgas, 32/36 is crap = nope

40's and 45's are the same if the chokes are the same! = Nope

Keep it up love it

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