1992 f150 5.8l auto
Just installed my motor, and I thought this would work but....

The idle is terrible, and all over the place unless I retard the timing, and with it retarded it will not accelerate at all. I have been messing with this thing for a week with no improvement.

I have checked the firing order 10 times because it acts like its not right but it is.

With the timing advanced it idles terrible but runs like a jet on acceleration, but smokes black like one too.

With the timing retarded she idles good, but moans with no power at all.

Did I get to carried away with the cam, or is something else going on?

 

This is the cam specs

Adv. Duration:280/290
Duration @ 0.050" :214/224
Gross Lift:.472"/.496"
LSA/ICL:112/107

 

The LSA is is causing your issue. General rule of thumb for Ford Speed Density controlled engines is no less than 114. Yes, 2 degrees less is a huge difference. A custom tune may help, but that is going to cost you some $$, if your PCM is tunable at all.

Cut from the Summit Racing website:

Brand Lunati
Manufacturer's Part Number 11001LK
Part Type Camshaft and Lifter Kits
Product Line Lunati BareBones Camshaft and Lifter Kits
Summit Racing Part Number LUN-11001LK

Cam Style Hydraulic flat tappet
Basic Operating RPM Range 1,500-5,500
Intake Duration at 050 inch Lift 214
Exhaust Duration at 050 inch Lift 224
Duration at 050 inch Lift 214 int./224 exh.
Advertised Intake Duration 280
Advertised Exhaust Duration 290
Advertised Duration 280 int./290 exh.
Intake Valve Lift with Factory Rocker Arm Ratio 0.472 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio 0.496 in.
Valve Lift with Factory Rocker Arm Ratio 0.472 int./0.496 exh.
Lobe Separation (degrees) 112
Computer-Controlled Compatible No
Lifters Included Yes
Lifter Style Hydraulic flat tappet

 

ugh? It runs so terrible. I thought I would get by with it, but I guess not

 

Can I get the cam out of this thing without disturbing the ac core, or does it all have to come out

 

Yes the cam is your problem. What if any idle vacuum does it make?? With SD the idle vacuum has to be strong and steady which means the cam should have no less than 114deg LSA and no more than about 210deg duration at 0.050" and preferrable a little less than that, so advertised duration is also going to be down around 260deg. You could get away with a 112LSA cam but the duration specs have to be even shorter to compensate.. like 200deg or under at 0.050" lift. I believe you can just squeeze the cam out with the rad removed, the center brace of the rad support is the next thing in the way so the AC core doesn't factor in at all.

 

Ok. Band aid fix potential. This is how I got a lot of sd mustangs to run ok.

Get a big carb style fuel filter. Hook one end to the map sensor, and the other end needs a restrictor put in it (wooden dowel with 1/16 or smaller hole) and hooked up to vacuum.

I've put some big cams in before and they run crappy. But. You can go a little bigger vacuum can, with check valve to engine (sucks vacuum into the can but it stays in there) and then put the same restrictor in another hose (like above) but with a small small hose in it.

You want the vacuum to bleed out slow (for long accelerations) but you need it to hold the vacuum steady at idle.

This helps, but isn't a fix. Put timing to 6-8* and try it.

 

thank you so much for the quick response. I generally search before I ask, but couldn't find anyone dumb like me that had tried this cam. I was just so sure it would be close enough to work. LOL

Here is where I get confused.... i can't understand why it still runs bad when the map is unplugged.

I have worked on a bunch of these with various problems, and speed density can sometimes be so forgiving of false inputs. It just amazes me how such a small cam could turn these into a slobbering nightmare. BUT>>> this is the first experience with a performance cam. It reminds me of one with the cam timing off, but I took photos of the cam sprockets, and I can't look at them again. LOL

 

 

First thank you for taking time
I can tell vacuum is very low. I didn't have a vacuum gauge, but I felt of the map line, and it was pretty lame suction.
I am only asking this because I know you know, and I don't.....
I thought I would see a vast improvement with the map disabled, but it only improves for a second, or two,. Then it cops an attitude again, and goes nuts. It actually feels like it's dropping a cylinder, or two when the timing is advanced, to where it will run. When retarded it idles perfect. What exactly is going on when the map is disconnected, and it still is having a total fit.

 

What are you disconnecting on the map. The wiring or the vacuum line.
On a mass air setup you can disconnect one electronic element and get away with it. But not on sd.

Unhooking the vacuum line will make the ecu think you're accelerating. Less vacuum means enrich. Also less vacuum makes fuel pressure rise a little (42psi no vacuum or about 38-39 with)

Crack the throttle blade a hair with the throttle stop and retweak the tps. Maybe a little more air at idle will help

 

I will try that tomorrow. I was disconnecting the map wire part in hopes I could tune in limp open loop, but no success. I bought some vacuum hose, and fuel filter, and a shut off to try UNTAMND's suggestion also.

 

We ran a 351w from an 88 truck in a foxbody mustang with that cam with all of the truck computer and sd stuff, and it didn't idle worth a darn until it warmed up. Then it idled ok. But it never smoked or anything, it was just real choppy and if it was a DD it woulda been a pain, but its just a track car so it wasn't a big deal that it was choppy. But like you said, flew like a jet.

 

I thought I would get by with it, but not I guess

 

Tried the map trick, and that helped for sure, and that made the truck drive-able, but I can't imagine pulling a trailer with this like it is. On the track this cam would work great, but it is definitely too much for around town.Just a daily to, and from work truck, but I do pickup a car or truck occasionally with a trailer.
This truck has the e4od trans, and I don't feel like doing a mass conversion.

Soooo I ordered another cam, lifters, and will do this again. Grumble.... With the motor in.