Early Drla inlet resriction

[rjscustom]

I have been chasing jetting issues on my 2276 for quite a while. I have 45 dellortos and love the driveability but I cant get jetting sorted out. You can run as large of a main jet as you can find (200 or larger) and it still acts like it isnt enough fuel on top end. Changed pump to a mallory from air cooled.net with 3/8 line to the motor, good volume and pressure is good. Bought bigger needle and seats and Earls banjo fittings for carbs. Bolts are different in banjos, so of course I start looking  for a solution. That is when I notice the extremely small hole leading to the needle and seat it is smaller than than the seat. Has anyone else had problems with this ? can I drill them or just find later model lids. If budget allowed I would have already bought IDAs,at this point I am curious to see the difference with adequate fuel.

[Bruce Tweddle]

Now that you've seen the tiny hole in the carb, it makes you wonder why everyone parrots that you have to run a 3/8" fuel line, doesn't it?

Go ahead and drill it.

[rjscustom]

Thanks Bruce. Yeah it does, just trying to figure out how I have overlooked and never thought about checking that. Even after drilling the banjos. Should make a noticable difference.

[Ohio Tom (DdK)]

Try some 180 air corrector jets.

Weak top end can be due to many reasons.

[Bruce Tweddle]

If you can, post some pics for future reference.  There are 2 different styles of fuel inlets used on DRLAs, and the text doesn't really tell which ones you have.

[martin]

Can you try a wideband and see how the mixture is?

[rjscustom]

i have tried 180's and even tried 165's i had thinkining it would richen it upon top end. Didnt help much just created stumbles in cruise and mid range,especially on and off throttle. I have checked intake gaskets.I put update kits in them and that helped mid range alot, but not top end. I have gotten the inlets drilled and it seems to have made a difference but still have to play with jetting a bit. I should have posted some pictures of before and after but as usual, didn't think about until too late. The carbs are early Dellorto with the 7mm bolt in inlet not the later 12mm bolt. I did have the car on a chassis dyno and was 139 hp and 142 ft lbs torque but it was leaning out around 5000 (kind of spiking) then slightly back towards rich. i have never had an engine want so much jet
2276 9.5:1 compression
fk10
ultra mag 42x37 heads
1 3/4 berg heater exaust

[burnt63]

could you post some pictures of the "after". i have a set of early dells that i was thinking about doing the same to. thanks.

[rjscustom]

I am happy to.It will be the first of the week before i get to my shop so just check the post

[mmccarthy]

I am sure you already did it but make sure when you drill the passage out that the aluminum sealing washer is notched and aligned with the hole or it will partially block the enlarged inlet . I also removed the screen and used alcohol needle and seats , think they were 4.5 's I bought from Gene B when he was doing R&D on Dells.

[rjscustom]

Yeah the way the inlet was set-up could have been a little more efficient in design. I wasn't aware  that 4.5 inlet valves were available I thought the 2.5's were big. I am going to try and find a pair. I have gotten it back together and a few runs down the road and it feels better alot better on acceleration and on hills. The bigger inlet valves will probably help on all out top end. When I put the 2.5s in I had to drop the fuel pressure a bit,i guess due to the extra weight of fuel

[Bruce Tweddle]

When I put the 2.5s in I had to drop the fuel pressure a bit,i guess due to the extra weight of fuel

That's not why.  The same pressure acting on a larger needle area, causes more force on the needle.  That extra force pushes down on the float more, causing higher fuel level.

I recommend you try to work with the 250 inlet valves.  That's all you should need for 140 hp.  If you still see problems, there must be something else causing it.

If you do go bigger, go to a 300.  The bigger the valve, the less precise the fuel level is in the carb.  If there was no down-side to going big, even the smallest carbs would come with giant valves.

[rjscustom]

Got jetting situated still running 200 main and 180 airs but is running alot better all around pulls hard less stumble in between cruise and all on thro ;Dttle. Will post some after pics

[Ohio Tom (DdK)]

I run 2.0 inlet valves on my IDA's to 200hp without fuel starvation.
I really doubt that is your problem.
200 main jets sounds really fat too.

Honestly IMO you are barking up the wrong tree.
I have built many motors over the years and gone down similar paths.

You may be having limitations on top end due to poor flowing heads or floating valves. It's a bigger problem than most folks own up to.
The right heads make all the difference on top end power.
Valve float can happen really early depending on the cam used.

Also, your carbs may be the issue. A 2276cc motor wants big 48mm size carbs to pull much past 6,000rpm. A set of IDA's may be in your future.

Tells us more about the motor combo...

[rjscustom]

Cb ultra mag42x37 , cb650 springs chromoly retainers
9.5:1 compression
Fk 10 cam scat 1.4 rockers
Berg 1 3/4 heater box header w/2.5 magnaflow
 Also it is in a little heavier than stock car with wider than stock chrome stockies that are heavy (about 56 pounds each) so I know the engine is having to work harder. I have already ran a big vent on the fuel tank,and have3/8 metal line ran to the rear of the car.

[Bruce Tweddle]

Got jetting situated still running 200 main and 180 airs but is running alot better all around pulls hard less stumble in between cruise and all on thro.....

There are some that say the size of your main jet is related to how much hp your engine makes.  IOW, it takes fuel to make hp.
That being said, there's no way in HELL your engine needs a 200 main jet!
There is something else totally wrong with your engine/car that is being covered partly by that massive jet.

[martin]

I was told that bigger motors can need smaller jets due to the increased vacuum pulling more fuel out of the jet. A wideband sure would be nice to have.

[rjscustom]

Exactly my problem, i have never had an engine in fifteen or so years of playing with Volkswagons need such a large main jet to run. I put 170s in it and it runs terrible. No intake leaks plenty of fuel coming through the lines at the rear of the car. Even without the update kits still wants a big main jet . The engine made good power on the dyno, and the air fuel ratio was not out of line until top end it was going lean. The numbers i posted earlier were at the wheels. Can it be under carburation? maxing out the curcuits in the carbs?

[Ohio Tom (DdK)]

OK, you have answered many questions.
The motor sounds like a healthy build and should rip well.
To me the carbs are small and limiting the potoential of your motor.
That said, if you are still having a verified top end lean out. Then I would take a close look at your float heights. If the fuel level is too low, that can be an issue as well.
Beyond that and all else you have tried. I would say that you have reached the limit of what a set of Dells' can do. Both with flow restrictions and fuel metering limits.
I know the 48 dells had some "tri-jet" models that solved top end leanout. Still those carbs were only good for about 160-180hp.

your motor combo should push close to 200hp if jetted right and tuned.

 I stand behind my ealier comments about a set of IDA's in your future.
Fixes your problem and gives you a bunch more HP all at once...

[rjscustom]

That was pretty much my thoughts, just wanted to see if anyone had anyone any other suggestions.I appreciate all replies and input. I will post the results when i get to bolt some IDA's on see how they do.

[mmccarthy]

 Actually I liked my 45's better than my 48 tri jets, ran very crisp on the 2165 drag engine I had them on. What fuel pressure are you running and are you running the fuel transfer fittings or have you converted the carbs to the single line fittings.  I had separate lines going to my carbs from the fuel pressure regulator and had the pressure set to 3.5 lbs with the 4.5 seats if I remember correctly. The fuel pressure can be higher on the IDAs because of the ball style needle and seats which overcomes fuel volume , equal pressure smaller hole less volume of fuel. The only weak part to the Dells in my opinion was the size of the float bowls. The 48 IDAs needed to be modified by opening the other accelerator  pump hole up to increase bowl volume. Bruce could tell you more about all this than I can I am sure, but do not give up on the 45s.   Mike  

[rjscustom]

Not going to throw in the towel yet. I have seperate lines running to them, you can fee a noticable difference by opening up the inlets. It just acts like I am running off the inlet fuel to feed the main jet which may explain the large main jet. If I can get enough enough fuel fed into the carbs to maintain volume in the bowl I may be able to actually drop the jet size.

[rjscustom]

Who may have the 4.5 valves?

[screamingscotty69]

Or you could get a real car with a real motor.

[rjscustom]

Like a Honda. i assume

[screamingscotty69]

No a Nissan

[Ohio Tom (DdK)]

No a Nissan

LOL....

[Ohio Tom (DdK)]

REAL motor... LOL...

[Greg G]

what do the plugs look like if you do a high rpm full throttle push in the clutch shut off? i think you have too big of a jet. Try going back to the off the shelf 162air 162 main and see if it runs better.

[rjscustom]

I want that motor

[Ohio Tom (DdK)]

$8-10K and you can have one too...
LOL.. Merry Chirstmas...

[HBRag]

I dino'd a 2276 a few months ago, with Dell 45s. As a point of reference this is where I ended up;

Engine
Reworked CB Ultra Mag 44x37
9.3:1 compression
Web 86b cam Berg 1.4 rockers
A1 1 5/8" Sidewinder

Carbs
Late version DRLA 45s
Float 5/13mm
Inlet valve 250
38mm vent
60 idle
180 air
160 main
Fuel pressure 3.5 PSI

AFR 1/4 on idle circuit 15.6-15.8
AFT Full Throttle 12.9-13.1

Timing Mechanical Advance 28 degree, with CB Magnaspark Digital
Peak MAP ~68 kPA

It was putting out about 165 HP at 6500 when it tossed the fan belt. I am still messing with the timing curves, however it looks like a 57.5 idle jet is about right. I'm expecting the main to dial-in between the 155 and 160 range.