Mass Air Questions

'88 5FOX · Sep 7, 2010

I was on here about a week ago and was talking of a mass air conversion that I have now completely finished. I ordered a 70mm throttle body for it that will be at the house on wednesday. It acts like its not getting enough air is the problem. My question is what size meter do I need with #24 injectors. The motor has a cobra intake, now has #24 injectors, gt40p heads, 3.73 gears, and a five speed conversion if it helps with answers. Thanks.

rc5liter · Sep 7, 2010

is your current meter calibrated for 24# injectors ?

'88 5FOX · Sep 7, 2010

It's not, it is the stock size.

f8tlfiveo · Sep 8, 2010

Your meter has to be calibrated the same as yor injectors.. Just put the 19lbs back in they will work with your setup..you can get 300 hp out of stock injectors

jrichker · Sep 8, 2010

jeepguy00 said:
Your meter has to be calibrated the same as yor injectors.. Just put the 19lbs back in they will work with your setup..you can get 300 hp out of stock injectors

Good advice.

When you swap the injectors, be sure to replace the O rings & pintle caps.
Fuel injector seal kits with 2 O rings and a pintle cap (Borg-Warner P/N 274081) are available at Pep Boys auto parts. Cost is about $3 per kit.. The following are listed at the Borg-Warner site ( BWD - Home ) as being resellers of Borg-Warner parts:

Parts Plus - Premium Auto Parts & Accessories or Auto Value / Bumper to Bumper Quality Parts & Service - Home of the Aftermarket Auto Parts Alliance Group or Tires, Auto Parts Stores, Brakes & Automotive Parts | Pep Boys or Federated Auto Parts - Automotive Aftermarket

Most of the links above have store locators for find a store in your area.

Use motor oil on the O rings when you re-assemble them & everything will slide into place. The gasoline will wash away any excess oil that gets in the wrong places and it will burn up in the combustion chamber.

The pintle caps fit either injectors with a pin sticking out the injector end or 4 with more tiny holes in the injector end. The pintle caps hold the O ring in place and keep it from sliding off and into the manifold. If the correct pintle caps are used, they do not have any effect on the injector spray pattern or engine performance.

Heating the pintle caps in boiling water makes it much easier to install them.

NIKwoaC · Sep 8, 2010

Yea, you either need a "matched" meter or you need to have the car tuned so the computer recognizes the bigger injectors. You can't just mix-and-match injectors.

I vote for a bigger aftermarket MAF meter ("calibrated" for 24lb injectors), like a 75mm unit. The stock MAF meter absolutely chokes your intake flow.

f8tlfiveo · Sep 8, 2010

Just use the 70 mm unit off of a 94-95 mustang gt.. Setup for 19 lb injectors.. Unless your plans are for more than 300 hp 24's aren't necessary.

NIKwoaC · Sep 8, 2010

If he already has 24s, I don't see why he should go backwards. The 24s will allow him some growing room, and besides, a Cobra intake and GT40P heads are capable of high 200s or 300 rwhp (with the right supporting parts), which is ~325ish at the flywheel, so you'd be pushing the limit of those 19s.

'88 5FOX · Sep 8, 2010

That's the issue. I'm going bigger and I have 3 other cars to drive so this one can sit til I get what I need. From the answers I got either 70mm mass or one out of a sn95? right

f8tlfiveo · Sep 8, 2010

That meter from sn95 is for 19 lb injectors.. On another note my brother is running 19lb injectors with 332 hp at the wheels with no problems..so I know they are capable injectors.. But if you want to be safe go with the 24's I guess

NIKwoaC · Sep 8, 2010

jeepguy00 said:
That meter from sn95 is for 19 lb injectors.. On another note my brother is running 19lb injectors with 332 hp at the wheels with no problems..so I know they are capable injectors.. But if you want to be safe go with the 24's I guess

What fuel pressure?

f8tlfiveo · Sep 8, 2010

Stock regulator

'88 5FOX · Sep 8, 2010

The reason I have so many questions is because this is my first fuel injected car that I want to upgrade with. Should I just get a 70mm mass air and see what happens.

NIKwoaC · Sep 8, 2010

jeepguy00 said:
Stock regulator

What is the exact setup? Because I'm beginning to think this is hocus pocus.

'88 5FOX said:
The reason I have so many questions is because this is my first fuel injected car that I want to upgrade with. Should I just get a 70mm mass air and see what happens.

There is no "see what happens" with modifying EFI. You either do it right, or your car doesn't perform as well as it should, OR, worse case, you kill your engine.

Either get a '94-'95 70mm unit and go back to 19lb injectors or get an aftermarket MAF that is "calibrated" for 24lb injectors. This is all assuming you are actually using a mass air computer (e.g. A9L).

madspeed · Sep 8, 2010

GOOD POINT, are you using a mass air computer? ie A9L??

'88 5FOX · Sep 8, 2010

I have an 88 foxbody. Car came with an automatic AOD trans and original 5.0 Ho. I spun the front main bearing, and front rod bearings. Coulndn't turn the crank anymore so I replaced the motor. Ran it with the motor like that for a while, 89 motor. Trans started slippin from the previous owner dragging the car. Pulled the transmission and converted it to a five speed. I naturally liked the 5 speed better so I rebuilt the AOD. Three weeks ago the fuel injectors started leaking. For monies sake I rebuilt them with new injector kits. Didn't fix the leak so I replaced the injectors with #24 injectors because I was told by someone who obviously doesn't know what they were talking about that it would work. They were the same price as stock injectors. Before the leak occurred I put a gt40 intake and heads on it. As I said before I plan on going bigger so I got bigger injectors. Car didn't run well because it was flooding so I got a conversion list from a site on the internet and followed it to a tee. I got the mass air harness and a 91 GT computer, to my understanding that is a mass air computer, if not somebody tell me, may be my problem also. I still have the problem because according to the guys on here it all has to be calibrated. None of this I knew, hence the problem. I don't want to go back down and buy stock injectors because that is that much more money that I could just spend on making my set-up work.

madspeed · Sep 8, 2010

Just pickup a 75mm MAF that is calibrated for the 24lb injectors from the classifieds for like $50 and youre good to go!

NIKwoaC · Sep 8, 2010

madspeed1 said:
Just pickup a 75mm MAF that is calibrated for the 24lb injectors from the classifieds for like $50 and youre good to go!

+1, a 91 GT computer is mass air, so you should be set once you get a calibrated meter!

madspeed · Sep 8, 2010

Heck ill sell you my chrome bullet 75mm that is cald for 24lbers if you can find me a pro m 77mm

'88 5FOX · Sep 8, 2010

Thanks for all the info, if it wasn't already sold there was one on craigslist in greensboro, NC. I was looking at it but didn't know if I needed it. Its gone now, sorry.

Mass Air Questions

New Member

New Member

New Member

My wife likes my spool and blow-off valve.

StangNet's favorite TOOL

中國製造

My wife likes my spool and blow-off valve.

中國製造

New Member

My wife likes my spool and blow-off valve.

中國製造

My wife likes my spool and blow-off valve.

New Member

中國製造

Colonel Mustard

New Member

Colonel Mustard

中國製造

Colonel Mustard

New Member

Similar threads

Privacy & Transparency

Privacy & Transparency