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98 Explorer 5.0L Valve springs and rocker arms?


New Member
January 15, 2011
Reaction score
City, State
Middle Georgia
Year, Model & Trim Level
1999 Ranger
I'm sure this topic has been beat to death, but I'm not having too much luck finding the answers.

Have a stock 5.0L from a totaled 98 Explorer that ran well before I pulled it. Was going into an 86 Ranger, now it's going into a classic car I don't own yet. Likely mid-late 60s Ford, maybe a Mercury? Keeping the Explorer EFI and 4R70W, so working on converting EFI to standalone (PATS already solved).

Right now I have a running engine, will not be going further into the engine than valve covers and oil pan if necessary. Cam swap would be nice, but not going to happen.

I understand that these engines suffer from valve float due to weak springs. If I installed better valve springs with the stock cam and stock rockers would I see any improvements in performance? Would I be able to rev higher, or is the cam still limiting factor? If so is there any more power to be had there?

I am considering 1.7 roller rockers. If I'm doing my math right the Explorer cam will provide a valve lift of .474 (E) and .447 (I). Based on that, I'm thinking this spring kit will fit my needs with either rocker ratio:

Valve Spring Kit GT40P w/ stock cam and 1.6 or 1.7 ratio rockers up to .515" Lift Max Output 1TS Turbo Supercharged Nitrous

I've read about clearance issues with 1.7 roller rockers and stock valve covers when used with larger cams ("E" cam and aftermarket). Given the lower lift of the Explorer cam, is there still a clearance issue? I'm also thinking about swapping to aluminum Fox Body valve covers for the looks, not sure how those clear either.

Has anyone here personally used Proform rockers in a non-race or close to stock application? Results?

Not going to spend a lot on roller rockers (or springs, but Alex's has good reputation) for this engine. If I can find a used set of Scorpion or Crane rockers in similar price range I'll get them, but I'm not going to wait long, otherwise I'll go with Proform. I average around 16K miles per year total and about 13K of that is my daily driver. This engine probably won't see 4K miles per year all street driven, those rockers might see 20K miles before the engine gets replaced. If one grenades I'll just be building sooner.

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