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https://www.ford-trucks.com/forums/1...-a-poco-4.html Stock springs are rated around 90lb/in as I recall, by 100-125k they are down in the low 70s...at correct install height (yes I tested too). Account for valve and seat wear, they have pathetic seat pressure. Some of mine we calculated were in the low 40s. Yes, low 40s. I was able to spin a bunch of mine BY HAND. My heads are clapped. Hell, I gained about 60psi on No 8 after springs, go figure.
Basic arithmetic reveals that boost multiplied by the valve diameter area shows how much force is acted upon the backend of the valve. Even 15psi on the stock weenie, 1.65"? valves, reduces the seat pressure like mad. Really, no shocker why so many 7.3s are complete dogs. Never, ever under estimate the power gain or loss via the cylinder heads. Hell, I believe the late John Lingenfelter said 'all the power is in the heads'
Furthermore, the 910-16 set is around $90. Add shims and stem seals, you are under it for sub $200 plus beers. Not the worst job, but not the best.
https://www.ford-trucks.com/forums/1...-a-poco-4.html Stock springs are rated around 90lb/in as I recall, by 100-125k they are down in the low 70s...at correct install height (yes I tested too). Account for valve and seat wear, they have pathetic seat pressure. Some of mine we calculated were in the low 40s. Yes, low 40s. I was able to spin a bunch of mine BY HAND. My heads are clapped. Hell, I gained about 60psi on No 8 after springs, go figure.
Basic arithmetic reveals that boost multiplied by the valve diameter area shows how much force is acted upon the backend of the valve. Even 15psi on the stock weenie, 1.65"? valves, reduces the seat pressure like mad. Really, no shocker why so many 7.3s are complete dogs. Never, ever under estimate the power gain or loss via the cylinder heads. Hell, I believe the late John Lingenfelter said 'all the power is in the heads'
Furthermore, the 910-16 set is around $90. Add shims and stem seals, you are under it for sub $200 plus beers. Not the worst job, but not the best.
see this seems like something that will have a domino effect of “while I’m in there” mods lol
Like Hitman X said these spring with miles suck, i could literally push my valves with one thumb yes not a whole lot of pressure left on my old engine at 800k+ new engine received 910 with correct shimmed height. With my 160/0 stock SD turbo with billet wheel I make 20 psi on factory tune if I drive it hard, before on old engine with stock turbo with billet wheel and my 160's I was lucky to see 15psi on factory tune at WOT.
I wanted to do springs when I did injectors. But I was lazy, next time the engine is opened up I plan to do them. My behemoth needs all the go power I can get.
Alright I’m convinced. After I finish putting my fence and AC in at the new house I’ll open up the valve covers. Might as well just do the SD UVCH at the same time as the springs. Since I’m concerned about the injector o rings I’ll do those as well. No idea how old these GPs are so I’ll probably do them too. Might as well just open it up one time and do everything
I use the OG valve cover plugs. Alliant has a depin tool, AP0010...I wonder if you can just depin the OE plugs and plug them into SD plugs. That way one does not have to make all those splices. I did springs/pushrods, valve cover gaskets with harnesses, injector seals, and GPs I think too at once. Weekend job for sure or do one bank, then the other if you do not have a spare vehicle.
Remember, there is a tiny buttplug on the back side of the heads for the oil rail under the valve cover. Pull that and let it drain before pulling injectors, then pull No 7 and No 8 first. Twill keep most oil in two holes.
Last I checked, I do about 15psi on stock tune/90cc sticks. Unsure if I ever rechecked after the HPOP swap. I even found better drop in springs for my 4.9 903-12 from Comp.
Just today I found that CNC fab offers springs in stage 1 and stage 2. I'm no spring expert though if these would be good or to stick with the tried and true Comp 910s.
Got me. They are probably made by a cam company to CNC Fab's specs. For most, the 910s are fine. They do between 132-136lbs on the seat at 1.750-1.760" with the stem seal (also has shim, keep this in mind). I think I used a touch of bearing grease to keep them together after measuring.
I use the OG valve cover plugs. Alliant has a depin tool, AP0010...I wonder if you can just depin the OE plugs and plug them into SD plugs. That way one does not have to make all those splices. I did springs/pushrods, valve cover gaskets with harnesses, injector seals, and GPs I think too at once. Weekend job for sure or do one bank, then the other if you do not have a spare vehicle.
Remember, there is a tiny buttplug on the back side of the heads for the oil rail under the valve cover. Pull that and let it drain before pulling injectors, then pull No 7 and No 8 first. Twill keep most oil in two holes.
Last I checked, I do about 15psi on stock tune/90cc sticks. Unsure if I ever rechecked after the HPOP swap. I even found better drop in springs for my 4.9 903-12 from Comp.
Originally Posted by Hit Man X
Got me. They are probably made by a cam company to CNC Fab's specs. For most, the 910s are fine. They do between 132-136lbs on the seat at 1.750-1.760" with the stem seal (also has shim, keep this in mind). I think I used a touch of bearing grease to keep them together after measuring.
Oh, much easier to do the springs when injectors are out. Use the little hole in the cup for a dowel rod to find TDC on each hole. Simple!
Thank you for the tips!
Originally Posted by Khan
Just today I found that CNC fab offers springs in stage 1 and stage 2. I'm no spring expert though if these would be good or to stick with the tried and true Comp 910s.
Hmmm definitely worth looking into. I wonder if there is any negative impact of running the stiffer springs if you aren’t running crazy power
Shimming IMO is required. I know some folks drop 910s in without shims, but its a waste as seat wear is different on each valve.
Exactly. Mine were all over the place. All the intakes or all the exhaust were right about the same, 0.110" of shims needed. Tellin ya, may pull this mill. Do serious head job. Balance rods with ARP fasteners, balance that to the crank and polish it. ARP main studs, align the mains, zero deck. Hone it, reuse pistons. Motor on, probably easy 150k of trouble free driving.
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Tellin ya, may pull this mill. Do serious head job. Balance rods with ARP fasteners, balance that to the crank and polish it. ARP main studs, align the mains, zero deck. Hone it, reuse pistons. Motor on, probably easy 150k of trouble free driving. 