What does everyone think about this one?

I put a set of stock gt40p heads on a 351w. The heads have the stock valve springs which are set up for a roller cam from the 5.0 explorer applicaton. My 351w has a flat tappet cam. I think I'm getting ticking noises from the motor that sound like lifter ticks or somesort of valvetrain noise.

I don't think I have an exhaust leak and I even swapped out the injectors for another set, wondering if the injector noise could be the problem.

Valve spring specs for a roller cam seem to call for a higher seat pressure than a flat tappet cam. I wonder if the higher spring pressures could be messing with the non-roller lifters and causing trouble.

Otherwise, the engine runs well.

Does anyone know if it's definitely a problem to run valve springs designed for a roller hydraulic cam on a flat hydraulic cam?

The rest of the valvetrain is stock - stock stamped rockers, stock pushrods.
It's just a towing cam, nothing large or radical and it ran fine for years with the e7 (stock) heads that were on it.

Thanks in advance.

 

I didn't see where it said what lifters you're using....

 

It's not a problem with new lifters. Your old ones might not be up to the task of a heavier valve spring. You can isolate the noise by listening with a wood dowel aganist the area you think is ticking.

 

Thanks for responses.


Answers - they are basically stock flat tappet hydraulic lifters from FRPP. They have about 70,000 miles on them before the head change.

I tried isolating the sound as suggested with a stethascope and rod both. Two friends listed as well, it seemed like it was in the passenger front (5-6 cylinders) and the guys with the good ears thought noise was coming from under valve cover. I pulled that valve cover and bled the lifters down on the base circle of the cam to check the clearance between valve tip and rocker - all of the ones on this side were within spec for the clearance, so longer pushrod issue shouldn't be the problem.

 

Follow up - after doing lots of research it seems like stock ford valve spring pressures are about the same for roller cams as for flat tappet cams. I'm comparing specs for a 1989 351w (flat tappet) which calls for a 200# pressure at 1.2 inch spring height to a 1996 5.0 (roller cam) which also calls for 190-210# at 1.20 inches and a seat pressure closed valve (installed height) of 75-80. That's right from a Ford technical manual. Does this seem right to everyone - maybe I was off track thinking that the stock valve springs were significantly different from flat to roller.

Anyway, Does anyone know for sure that stock GT40p heads from explorer application came with valve rotators on the exhaust valves? I found several pictures of take off heads that look like they have rotators. Napa replacements call for shorter springs on the exhaust, which makes sense for a rotator.

I bought what I thought were stock heads and they don't have the rotators, so if all the stock heads came with them, that shows that I have unknown valve springs on these heads so without taking them off and getting them measured, I don't know what pressure they are putting out. They are single springs and don't look like anything fancy, but you obviously can't tell by just looking at them.

Sorry for long post.

As always, thanks for help/thoughts....

 

As far as I know the P heads used the same springs (yes, with exhaust rotators) as the E7s, which were used on both roller and non-roller applications.