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Discussion Starter · #1 ·
Just installed AFR 165s, GT40 intake, F303, 190 lph pump, 24lb injectors. THe car runs but misses and vibrates at low rpms. Timing is set at 14 and firing order is correct. The car has even less power than before. Fuel pressure is about 36 with the vaccum line connected. Any help is greatly appreciated.

Thanks
 

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see if I can throw a shot in the dark here.

How did you install the cam? straight up? did you degree it at all?

Also what type of RollerRockers are you using? 1.6 or 1.72?

If you are using 1.72's there is a possible chance that you may have hit the valves on the pistons and bent them slightly.. I've seen cars run after this happens and run like,, well you know

The timing or spark plug wires can be in the wrong order also.. are you sure they are the right way and not the Non-H.O. way

Brad
 

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first thing I'd do is verify compression on ALL 8 cylinders.
 

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Discussion Starter · #4 ·
The F cam was installed straight up and I am using FMS 1.6 roller rockers. The distributor is correct and the wires are correct. Timing is at 14 degrees and the fuel pressure is at 36 with the vaccum line off.
 

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Yeah compression test it. Are you sure the Roller Rockers where installed right some may be hanging open if installed too tight? Good Luck.
 

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Try more fuel pressure. I just did the mods in the sig on my car a couple of weeks ago. Had the stock pump in when I first drove it (had a new, no time to get it in) I thought it wasnt any faster. Put in the 190lph pump and upped the fuel pressure and it made a night and day difference. Good luck, I know it's dissapointing at first if things dont go how you wanted.
mike.
 

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Discussion Starter · #7 ·
The rockers are correct. I had to install 1 thick shim for each one. There is no free play in the pushrod but I can still rotate it by hand.
 

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Discussion Starter · #8 ·
How much pressure. I was running 36 with the line connected and someone told me that was way too rich. What do you think?
 

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ohh, so you installed it straight up?
that means you degreed it and installed it on a 114 intake centerline. i presonally would not have put that cam there, i think it needs a bit more retard than that. i would have just lined up the dots if i were you.,....


anyway, here is yer prob. you have two plug wires crossed up.
13726548 counter clockwise.
 

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are they adjustable ped. mount rockers or non adj.?
 

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Discussion Starter · #12 ·
As far as the cam I installed it with the dots facing each other. I am using a ford Motorsport multi position chain and the crank gear is in the correct position.
I was thinking, I did the heads, cam, intake, and throttle body. All this is bringing in more air. Should I increase the fuel pressure???
 

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MenolaLX said:
Should I increase the fuel pressure???
are you running a pro-m 75 bullet, for some reason i had to adjust my fuel pressure to 46 to get best results, i guess it depends on who/when/how calibrates it atleast that's what the guy at the dyno told me, he's seen some combos run as high as 50+ psi, speaking of dyno, you should dyno your car, it's by far the best way to tune your car, you can even calculate optimum shift points for best et's
 

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I just got mine running the other night and I'm having a stumling problem as well. I know mine is a lean stumle though. The more fuel I give it the better it's idling and driving at low RPM's. I just kept turning the screw on the fuel reg. until it started to smooth out some. I pulled my plugs yesterday and they looked like they just came out of the box. Must've been pretty lean at idle. She ran hard at WOT though and my stumble seemed to clear up at 2500 RPM's. Keep messing with it and it'll come around.
 

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Discussion Starter · #15 ·
I am running a Pro M 75 mm meter. I did not have much time to work last night but I did pull 2 plugs on the drivers side and they were very clean. No sooty deposits. I am thinking I need more pressure. I hope this is right. I am going to increase the pressure tonight and see what happens.
Would a lean condition cause missing at low rpms. Also at higher rpms it kind of flattens out and what little power it has drops off.
 

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Discussion Starter · #17 ·
not really they were a little noisy when I first started before the oil got to them but they are pretty normal now. YOu think there may be a problem with them?
 

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if they are ped mount they can be trickey to adjust my book says after you feel a little drag spinning them with your fingers you should go about 1/2 turn more of corse that is with the cam lobe down /shim acourdingly
 

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the pedistal mount rockers i had before i just torqued them down 25#s, i tried to do what your doing and the car wouldnt run
worth a crap.
 

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Any updates? I'm running 40psi for now. I'm going to the dyno today though to get it tuned.
 
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