Hello everyone, just bought a 93 notch with a built 306, gt40 iron heads, ported cobra intake, x cam, 70 mm throttlebody, 75mm mass airflow,4.10 gears, new wc t-5. The rear, tranny, and engine hav 2000 miles on them. It has stock injectors, stock fuel pressure regulator. I know Dugans Racing built this whole car for a guy then the guy got divorced and I got a really damn good deal on this car. I own a drag car (bracket) that runs in the high 7's (1/8) and this car feels like it pulls stronger. I wont take it to the track until I can find two old wheels and a set of slicks so I dont have times for it yet. What do ya'll think the car will run and what about this fuel system?
Do I need new injectors?
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slow5poh
Senior Citizen
Black 93 Fox
Active Member
Don't be too quick to go to 24 lb injectors. At 38 PSI, the 19 lb injectors are good for 300-320 flywheel HP.
With non ported GT40P iron heads, I doubt that you are making more than 300 flywheel HP.
Play with the fuel pressure and you can tell if larger injectors would be helpful.
At 62 PSI, 19 LB injectors will flow 24.2 lbs.
Get one of your buddies to ride along with you. Find a level stretch of road where you can do some testing. Don't choose a speed range that will make you shift gears, the shift quality & speed will affect your results. Use 2nd or 3rd gear and do a run from 2000 RPM to 5800 RPM. Call out the RPM as it increases and have you buddy record it and the elapsed time. If you have one of those cheap digital watches like I do, a stop watch is built in. Start the fuel pressure at 36 PSI, vacuum off and make a run. Turn it up to 37 and make another. Be sure to reconnect the vacuum every time you set the pressure. Keep turning up the pressure and making runs until you notice a drop off in time. If your bud was careful to record the results, you'll have a nice chart to use to find the optimum pressure.
With non ported GT40P iron heads, I doubt that you are making more than 300 flywheel HP.
Play with the fuel pressure and you can tell if larger injectors would be helpful.
At 62 PSI, 19 LB injectors will flow 24.2 lbs.
Get one of your buddies to ride along with you. Find a level stretch of road where you can do some testing. Don't choose a speed range that will make you shift gears, the shift quality & speed will affect your results. Use 2nd or 3rd gear and do a run from 2000 RPM to 5800 RPM. Call out the RPM as it increases and have you buddy record it and the elapsed time. If you have one of those cheap digital watches like I do, a stop watch is built in. Start the fuel pressure at 36 PSI, vacuum off and make a run. Turn it up to 37 and make another. Be sure to reconnect the vacuum every time you set the pressure. Keep turning up the pressure and making runs until you notice a drop off in time. If your bud was careful to record the results, you'll have a nice chart to use to find the optimum pressure.
Thank you for everyones help. I have a three gauge pillar pod with oil, water, and fuel pressure.i have noticed that at most of the time it is sitting at 30 psi. I know this isnt right but it has the stock regulator, if I put on an adjustable regulator, can I regulate the pressure up to the higher thirties or do I need to solve the problem with low pressure first? This car was a converted 4 cylinder car that Dugans built but I dont think is the stock 4 cylinder pump. Because this car has everything. 8.8 rearend and braided fuel system and all. Im not new to cars but I am new to some of the mustang stuff.
I have built many a chevy, including Ls1's and god knows how many LT1's TPI and all. But I am now an Allison transmission tech so now auto is my hobby and diesel is my job. So some of the mustang and ford stuff is a tad different to me. thanks again to everyone for the help.
Daniel
I have built many a chevy, including Ls1's and god knows how many LT1's TPI and all. But I am now an Allison transmission tech so now auto is my hobby and diesel is my job. So some of the mustang and ford stuff is a tad different to me. thanks again to everyone for the help.
Daniel