Ford Mustang Forum banner

Status
Not open for further replies.
1 - 19 of 19 Posts

·
Registered
Joined
·
47 Posts
Discussion Starter #1
I have a 90 with a 331 stoker, .512 lunati cam, AOD and a 4.10 posi rear end. Motor has a 70mm trhottle body, 24lb injectors, systemax upper end with alunimum heads and a 73mm red tube which was calibrated to 30 lb injectors due to the previous owner ruinning nitrous. I didn't want to beat up my new motor so I decided to not run the nitrous and install the 24 injectors. I went to the 1/4 mile dragstrip and ran consistant 13.50's at about 102 mph with 2.07 60 foot times. I was very dissapointed. I think it is time to do a chip or dyno tune or tweecer program or QH by Moats. Can anyone share with me the best solution at a realistic price. I think I have a mid twelve car just need to get the electronic tune to make it all work. Anyone have any suggestion for a low tech old guy? Thanks in advance for your responses. RG
 
R

·
Guest
Joined
·
0 Posts
the first question i have is what have you done with regards to the suspension.....

based on you 60' time that where the problem is .....

also what tires are you using and is there any work done to transmission.......


its not always the amount of the engine has its how much get to the ground
 

·
Registered
Joined
·
47 Posts
Discussion Starter #3
Car has subframe connectors, HPM lower arms with sway bar and solid upper arms. Tires are drag radials. AOD has been beefed up changes to the servos, valve body and kevlar bands. Convertor is a 2200-2400 stall. Tire spin is minimal. Car has good weight transfer. Off line engine acts like part throttle (bog) for a moment then accelerates good. Cars then pulls well in first and second and third until over 5000rpm then seems to max out on pulling power. Thanks for your reply. RG
 

·
Registered
Joined
·
304 Posts
i would think that the bogging your talking about would be timing related
 

·
Registered
Joined
·
1,241 Posts
you need to get it dyno tuned. it would prob take that bog away.

with that set up, you should def be in the high 12's, low 13's at the least.

he said he had 4.10s
 

·
Registered
Joined
·
5,170 Posts
Pull the codes and make sure everything sensor wise is fine. Whats fuel pressure? Whats timing? ANd I also think you could use a higher stall(3000)... If its falling off at 5K Im thinking not enough spring to control the valve train properly(floating valves). What heads exactly?
 

·
Registered
Joined
·
47 Posts
Discussion Starter #9
*Heads are the Holley stystemax with springs that handle .550 lift cam. I guess they could be weak.
*Timing set at 12 with 38 total at 2000 rpm. Has MSD distributor and coil. No MSD box yet.
*Fuel pressure set at 38 pounds but I don't have an exterior guage to read on the track.
*24 injectors not calibrated to the sensor. How do you calibrate?

Thanks RG
 

·
Registered
Joined
·
60 Posts
I can guarantee that you are running very rich at WOT. I bought the quarterhorse and love it. If you are good with math and computers then go and tune it yourself. If not, get it tuned professionally.
 
R

·
Guest
Joined
·
0 Posts
*Heads are the Holley stystemax with springs that handle .550 lift cam. I guess they could be weak.
*Timing set at 12 with 38 total at 2000 rpm. Has MSD distributor and coil. No MSD box yet.
*Fuel pressure set at 38 pounds but I don't have an exterior guage to read on the track.
*24 injectors not calibrated to the sensor. How do you calibrate?

Thanks RG
There is the problem.....

you need a calibration tube for the 24's
 

·
Registered
Joined
·
47 Posts
Discussion Starter #12
Reggie,
do you think this engine setup would ahndle the 30"s that were calibrated to the current tube? Or should I just pop for the the new tube?
rg
 

·
Registered
Joined
·
5,170 Posts
*Heads are the Holley stystemax with springs that handle .550 lift cam. I guess they could be weak.
*Timing set at 12 with 38 total at 2000 rpm. Has MSD distributor
Dont let the "Springs good to .550 lift" confuse you. That doesnt mean that its still controling the valves properly at high RPMs. The amount of free spring and open/closed pressures are whats important. To me when they say "springs good to XXX lift. That means at XXX lift, you are safe from coil bind. Doesnt mean they are optimal
 

·
Registered
Joined
·
5,170 Posts
Not suggesting it, just stating the fact about Springs vs lift numbers. Look at it like this. Say you have a 1.850 closed hieght. And coil bind is 1.200.

Sooo.... You have a .512 lift cam

1.850-.512= 1.338 thats puts you with .138 of free spring. So the spring can dance around and cause valve float. THis is assuming the spring pressures are adeqaute also. Keep the free spring below .080 and you should be good. These are examples by the way. If you could post up your spring spec it would be more accurate.
 

·
Registered
Joined
·
47 Posts
Discussion Starter #16
89 COUPE,
If I take the valve covers off and take a feeler guage to each valve spring with the valve open and have more than .080 clearance between the coils I should be clear of coil bind. But still have to make sure the valve springs have the proper spring pressure. It's my understanding that the FMS roller lifters are good to 6000 rpm.

thanks
rg
 

·
Registered
Joined
·
5,170 Posts
The spring specs would be best for me to give you a better answer.

But to answer you question....You would want to be AT .080 or slightly under that. But even if you are at that mark, if the spring pressures are off its not going to matter. Im no Cam expert so i cant suggest what springs you need, Its best to get a reccommendation from a Local cam grinder for spring pressures. The feeler gauge method will work.

If you have a dial cailiper, you could use the depth measuring part of the caliper to measure the valve closed hieght, then roll the engine over while monitoring the caliper readings. When the reading stops decending you are at the open height, the difference between the 2 would be total lift. Then measure between the coils. That would be the free spring. Some guys run as close as .030 from coil bind, those guys are more experienced. For the novice guy like me and most others its best to stay close to the .080 mark.
 
R

·
Guest
Joined
·
0 Posts
Reggie,
do you think this engine setup would ahndle the 30"s that were calibrated to the current tube? Or should I just pop for the the new tube?
rg
if the car is tuned it most likely would be ok with the 30's

but my gut feeling tells me you should spring for the tube....
 

·
Registered
Joined
·
47 Posts
Discussion Starter #19
Thanks you all for the response. I have a few things to do now. I'll let you know how things go once I make the changes. Budget a bit tight currently so it might take the summer to get ur done.

thanks again for the help
rg:bigthumbsup
 
1 - 19 of 19 Posts
Status
Not open for further replies.
Top