So I swapped to my racingbeat dellorto carb again. It was just rebuilt, the jets are correct and the tuning is set to racingbeat suggested.

I also have an uprated fuel pump with more than enough flow regulated to ~3psi.

Stock exhaust for now unfortunately.

So heres thats going on currently. Engine is fully warm, it idles like crap, pulls like hell right up to 60, then hits a brick wall. The car will not pull past 60, no matter whether I'm in 3rd 4th or 5th. The engine sounds like its REALLY struggling at the 60 mark too. Had it backfire once (i think, it was pretty quiet though)

any ideas? Could it be something as simple as intake spacers that I dont have on mine?

 

Sounds like fuel starvation or ignition breakup.

What's the condition of the fuel filter?

 

Replaced 3k miles ago

 

3psi is less that the pump for the stock nikki carb. and that struggles to keep up. up the regulator to 5 or so psi and see what happens

 

Agreed...I had a dell in my 83 and the regulator was set at 5.5. I have a nikki in my glc and it lives happily at 3.5 psi.

 

secondaries not opening

 

What secondaries? Its a 2 barrell lol.

So I should ignore the people saying "anything more than 2.5 will flood the needle seat"? What I was told is its all about flow rate. And psi does not equal flow rate.

 

holley floats can handle up to about 8 psi by themselves. im not sure about dells, but my OER which is almost the same thing, can handle 5-6 psi just fine. i can leave the pump running all day and it wont flood. not sure what the peak is for the floats.

 

On a Dell anything more than 2.5 PSI will cause erratic idle and poor tunability. Been
there done that and can even demo the affects for the disbelievers. Each carb has
its own requirements for fuel flow. A Dell is not a Weber or Mikuni or a Holley for
gods sake. Each has their own fuel psi and gph sweet spots and they are all
slightly different.

It sounds like you are not getting the gph you need and thats why it stalls out
around 5 or 6K (just a guess on the rpms).

If its idling poorly it could be the 3 psi, turn it down to 2.5 psi. BTW, how do know its
at 3 psi? Do you have a reliable guage? I use a liquid filled 0-15 Summit guage and
its not very accurate down that low. I basically adjusted the psi by listening to the
idle.

What regulator are you using? If its one of those dial type Mr. Gasket hunks of junk.
Throw it out. I tried one and it severely affected the performance of my Dell. I'm
using a simple Holley deadhead regulator with my Carter 4070 fuel pump and all is
well.

Did you rebuild it? What kind of kit did you use and how did it look when you
opened it up?

 

It idles well, it smells a bit rich but idles really smooth and steady. Starts well too.

And its not starving for fuel around 5-6k. Like I said no matter whether I'm in 3rd 4th or 5th gear, it will not pull past 60. Thats why I am so befuddled. If it was related to engine speed I'd at least have somewhere to start looking.

Yeah its a holley low pressure reg and a carter fuel pump, rated for 72gph. I can't remember the name of the gauge but its a really nice liquid filled one.

And it was rebuilt by a shop that works on old jensens and other euro classics, many with dells. They rebuilt it with a dell kit and cleaned it out. I also blew compressed air through all the jet passages after wards just to be sure.

 

if it cuts out related to vehicle SPEED, then its probably a fuel delivery issue TO the carburetor.

i would start with a volume/flow test. take the fuel line off the carb, and put it into a container that is fuel safe, and you can measure the amount in it. i have a juice container one of my lady friends gave me, its great, its marked every 100cc (and if she knew what i was using it for...)

so anyways, put the fuel feed hose in the container, secure or hold the container, and run the fuel pump.

mazda's spec for the P port is 1500CC in 30 seconds. my carter pump does about 1300CC in 30 seconds.

the FSM has a spec too, although off the top i'm not sure what it is.

if you don't get enough fuel VOLUME you can't drive 55!

 

So whats the fuel volume needed for a dell 48 o a stock port stock exhaust 12a? I'm so ready to ******* get rid of my car right now. Its been 3 years of bullshit no matter what I change

 

the carter pump you own, should do more than 1200cc/1.2L in 30 seconds. if it does not, you have a problem in the fuel delivery system. 1200cc is more than enough. with that, you can cross that off the list and move on to other stuff.

and as to that other stuff, part of modifying the car is actually having to tune it, and most of that is ust going down the list of things, like the fuel system, and verifying that they work.

i did the same with my car, it ran like a$% with the jetting mazda lists for my motor, i went thru the fuel system, ignition (i had a couple of ignitors go bad), and then each carb jet; idle main and air. it was one step forward two steps back for a while, but eventually i found what the engine wanted, and now it really runs nice

 

Looks like its pumping out 900CC in 30 seconds. Cause bumping up my psi give it more flow possibly?

 

I highly doubt your car would drink nearly 2 litres of fuel per minute at 60 mph.

My gut says you probably have a teeny needle valve and seat in there...


If its not the needle valve and seat I would be looking at your ignition system.

Also, racingbeats jetting suggestion isnt always perfect.
Their suggestion for my weber wasnt even close to what ended up working best.
You should be able to make it over 60, but I wouldnt use their suggestion as anything more than a starting point.


Good luck, and dont give up on the 7! Youll be more than happy when you get it all figured out!
Just hang in there, and keep at it!

 

pm sent

 

Just so you guys know Jon (Funk73) shot me a text saying its running well past 60 Mph now

He increased the fuel pressure and it runs fine now.

 

it means you fucked up but seriously, fuel issues and be sure to check for bindings and such (to ensure that it is capable to open 100%)

 

Yup bumped up the fuel pressure and I've tested it up to 80mph. Seems to be pretty good, little lagg in pull up top in the rpm bank but I'm sure some of that is down to the lack of header. I'll have to check out the needle seat though for sure.

 

Sounds like you got it licked. So now you know you can't trust that guage for much.

I adjust the pressure by having it set too low and cranking it up a little at a time
while the car is idling. When I hear the idle speed up I then back it down a touch
and leave it. Thats the pressure it likes. It appears to be between 2 and 3 psi.

My gauge is like yours probably, a fluid filled 0-15 psi. Its kind of accurate cold but
once it gets all hot under the hood it shows zero or barely any pressure and I
knows it lying becuase the car is running good. Someday I need to spring for the
ReSpeed 0-5 gauge.

 

Adjust the FPR but as soon as the gas starts seeping thru the carb (dripping thru the barrels), back off. I only use the F/P gauge for a second opinion

 

+1

I think my gauge is just en expensive plug for one of the outlets on the regulator

 

+1

 

cool! see you did something, and it made the car run better. don't be afraid to play with it, you can always go back

 

I've been following this post because I have a Dell ready to install.....with all the trouble Funk's been having, I've had second thoughts (I even took pix of everything getting ready to sell).

Glad to see you've gotten it sorted out.

Now all I have to do is grow a pair....and take the plunge!