Comp Cams 31-255-5

[qdeezie]

Hello,

I own a SD 1990 F150 with the 5.0L engine. I'm hoping I can reach out and get some help from the Bronco family regarding my camshaft selection.

I recently rebuilt my engine and I am pretty much convinced that my camshaft selection was very much the wrong selection. It looked good on paper, but in practice, it's a different story.

The camshaft I'm currently using is 35-512-8 by Comp Cams. My engine is doing everything but running properly. It's surging, bucking, running pig rich and shutting off. It was running fine prior to the rebuild with the stock flat tappet camshaft. I am seriously considering going with a 92-93 F150/Bronco stock roller camshaft due to the specs being pretty much the same as the flat tappet camshaft that was originally in my truck.

So, with me recognizing my camshaft selection was not the best of choices, I truly do not want to go back to the stock camshaft seeing everything I've done to the engine. I am not looking for the baddest truck alive, I'm pretty much just wanting a torquey, reliable build that I can hook up and tow with from time to time.

At this point, I need a roller camshaft that will play nice with my SD because I don't want to upgrade to MAF.

What I am considering is getting Comp Cams to custom grind a roller version of the 31-255-5 camshaft.

In your opinion, would this be a wise thing to do?

If I'm not providing sufficient information, please let me know. My mods are in my signature.

And I want to add that I am using the 1-3 firing order with the 35-512-8 camshaft, but I'm very much open to going back to the old 1-5 firing order.

[sackman9975]

Originally Posted by qdeezie

At this point, I need a roller camshaft that will play nice with my SD because I don't want to upgrade to MAF.

Why not go with the stock HO roller cam? It's a favorite around here.

[qdeezie]

Mustang HO or Explorer HO?

[sackman9975]

Mustang.

Here's a quote from the "how to pick a camshaft for EFI" thread

Originally Posted by Fireguy50

For a good fuel injection truck cam:
intake duration @ 0.50" should be kept at or under 210
Gross valve lift should be kept under 0.500
Lobe seperation should be at or above 114°

Good 5.0L/5.8L (302/351) EFI hydraulic flat tappet cams:

Comp Cam 35-255-5
* Duration at .050 in.: 210 / 214
* Gross valve lift: 0.478 / 0.485
* Lobe separation: 114°


Edelbrock 3782
* Duration at .050 in.: 210 / 216
* Gross valve lift: 0.469 / 0.484
* Lobe separation: 116°


Crane Cams 444232
* Duration at .050 in.: 206 / 214
* Gross valve lift: 0.448 / 0.464
* Lobe separation: 114°


Best 5.0L/5.8L (302/351) Roller EFI cam:
89-95 Mustang 5.0L HO
Ford Part numbers: E8ZE-6250-CA / F1ZE-6250-AA / F4ZE-6250-DA
* Advertised Duration: 276 / 266
* Duration at .050 in.: 214 / 210
* Gross valve lift: 0.444 / 0.444
* Lobe separation: 115°


Good 7.5L (460) EFI cam:
Comp Cam 34-255-5
* Duration at .050 in.: 212 / 219
* Gross valve lift: 0.490 / 0.495
* Lobe separation: 114°

-------------------------------------------------------

Stock 302
* Duration at .050 in.: 210 / 211
* Gross valve lift: 0.421 / 0.447
* Lobe separation: 116°

Stock 351
* Duration at .050 in.: 206 / 221
* Gross valve lift: 0.440 / 0.450
* Lobe separation: 115°

Lightning
* Duration at .050 in.: 198 / 208
* Gross valve lift: 0.416 / 0.445
* Lobe separation: 114°

96-01 Explorer 5.0L HO roller
Ford Part numbers: F4TE-6250-BA
* Advertised Duration: 256 / 266
* Duration at .050 in.: 186 / 197
* Gross valve lift: 0.422 / 0.448
* Lobe separation: 116°

Stock 460
* Duration at .050 in.: 193 / 206
* Gross valve lift: 0.438 / 0.459
* Lobe separation: 111°? (unsure at this time)

-------------------------------------------------------

Linkbar lifters can be used to retrofit a roller cam into an older block

[qdeezie]

Ok, I will try to look one up. I think I saw one from an 86 Mustang for sale somewhere. Your help is greatly appreciated!!!

[qdeezie]

I just looked again and saw that it says 89 to 95 Mustang. I'll look around a bit more.

[TS 90F150]

Originally Posted by qdeezie

Ok, I will try to look one up. I think I saw one from an 86 Mustang for sale somewhere. Your help is greatly appreciated!!!

Originally Posted by qdeezie

I just looked again and saw that it says 89 to 95 Mustang. I'll look around a bit more.

86-88 cams would be essentially the same. They are more sought after by "factory class" racers as the profiles are slightly more agressive.

With that said, I run a 5.0 HO roller cam in my GT40X headed 5.8. The cam provides excellent power from 1400ish rpms up, but is a little soft from off idle to the 1400ish.

In other words, I don't agree with the thread linked above. Sadly I based my cam selection on this, the $ of a proper mass air conversion, and the fact I could get this cam cheaply off the Corral.net.

I am pleased overall with its selection but do think better options are out there. I am not one of those guys that never see over 3000rpms in my vehicle. I am sure those guys would hate the HO cam choice.

hth
tim

[qdeezie]

I privately wonder is there a company that can figure out or has figured out the SD truck camshaft riddle and produce a decent SD custom ground camshaft that would work well for a truck.

After I sell the 35-512-8 camshaft, I'm going to call around and see if there are any SD roller cams with the 1-5-4 firing order or someone that can custom grind one and stand behind their work if my factory computer decides to disagree.

In the meantime, I decided to go with the 92-93 roller camshaft for the sole reason of it being the safest bet to get my truck back on the road.

Currently, I am in the process of tearing my truck engine down currently and hope to have the camshaft installed over the next few days.

[qdeezie]

I figured I'd come back to give the latest news for the sake of formality. The camshaft was not the issue. I got a bit stubborn and it paid off because I did not want to pull that camshaft out.

I had everything on the engine professionally cleaned with the exception of the upper intake and that was where the problem was. I "cleaned" it previously but I needed to take the cleaning part to the next level.

1) The vacuum tree on the upper intake was stopped up, so I took that off and let it soak in parts cleaner.

2) I sprayed the upper down with purple stuff (full strength) and took it to a heated car wash and sprayed the #$%^ out of it. All kinds of chunks of carbon/sludge came out. Now I actually see bare metal on the inside of it.

3) I ran a dedicated vacuum line to the MAP sensor. I accomplished this by routing the PCV fitting in the rear of the upper intake to the MAP sensor and I tapped a hole in the side of the upper per the Ford TSB and ran the PCV to that and capped off the now unused ports on the vacuum tree.

I used two brass fittings from Home Depot to adapt the 3/8 PCV fitting in the rear of the intake to the 1/4 fitting on the MAP sensor. I also used 1/4" and 3/8" radiator hose to ensure that I won't have to deal with hoses collapsing.

The result: A smooth running engine and all kinds of low end torque. It's definitely fun to drive. I am currently using Stock GT40 heads, but I can't help but imagine how strong the engine would be with aftermarket heads, so I'll be swapping out the heads sometime down the line.