Valve spring ?

86coupe · 07-14-2003, 06:58 AM

What problems can happen with valve springs that has lost 100 pounds of seat presure? car was going low tens now hi tens lost 5 mph and 5 tenths. anything else?

richd · 07-14-2003, 07:58 AM

You'll get valve float which would rob some power, not to mention the possibility that valve and piston may collide from the valve not retracting fast enough.

Here's the specs for spring pressure from the Ford manual:

Compression Pressure (Lb @ Length)
Intake 74-82 @ 1.78 to 211-230 @ 1.33
Exhaust 77-85@1.60 to 200-226 (doesn't say at what length, so maybe fully compressed? Non HO specifies 192-210 @ 1.05, maybe HO is at same length)

Free Length
Intake 2.02
Exhaust 1.79

Ah, I see that it says service limit is 10% pressure loss @ length. 100 lbs is close to 50% at short length.

Hope this helps,

Rich D.

86coupe · 07-14-2003, 10:41 AM

Thanks for the reply have you ever heard of weak springs killing your 60 ft.? Lets say you have cam that needs 330 seat pressure and it only has 180 but the car goes a 133 in the 1/4. then backs up to 128 after 6 passes. What do you think the perf. would be like with the right spring pressure? Just curious becuse i got screwed on a set of weak *** springs.

Coupe50h · 07-14-2003, 07:19 PM

my slipping clutch is hurting my 60's....

07-14-2003, 06:58 AM	#1
86coupe Registered Member Join Date: Jul 2003 Location: Maryland Posts: 7	Valve spring ? What problems can happen with valve springs that has lost 100 pounds of seat presure? car was going low tens now hi tens lost 5 mph and 5 tenths. anything else?

07-14-2003, 10:41 AM	#3
86coupe Registered Member Join Date: Jul 2003 Location: Maryland Posts: 7	weak valve springs Thanks for the reply have you ever heard of weak springs killing your 60 ft.? Lets say you have cam that needs 330 seat pressure and it only has 180 but the car goes a 133 in the 1/4. then backs up to 128 after 6 passes. What do you think the perf. would be like with the right spring pressure? Just curious becuse i got screwed on a set of weak *** springs.

07-14-2003, 07:19 PM	#4
Coupe50h Registered Member Join Date: Aug 2002 Location: SanAntonio, Tx Posts: 957	my slipping clutch is hurting my 60's.... __________________ X-Texas highway patrol ssp 1990 coupe - exploder Gt-40 iron heads, Explorer intake, 19 lber's. E-cam. crane 1.7 rollers. 190fp. 75mm maf. 65mm tb, tubular subframe connectors, mac cai, Asp crank pulley, T-5, king cobra clutch, flowtech 1-5/8 unequals, mac X-pipe Frpp driveshaft, lakewood Lca's. race weight 3,160 12.69 @ 107.35, 1.71 60' 26x8.5 drag's 3.90 gear 13.20 @ 106.91 - 235/60/15 firestones 2.3 60' 3.27 gear

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07-14-2003, 07:58 AM	#2
richd Registered Member Join Date: Jul 2001 Location: Edison, NJ, USA Posts: 125	You'll get valve float which would rob some power, not to mention the possibility that valve and piston may collide from the valve not retracting fast enough. Here's the specs for spring pressure from the Ford manual: Compression Pressure (Lb @ Length) Intake 74-82 @ 1.78 to 211-230 @ 1.33 Exhaust 77-85@1.60 to 200-226 (doesn't say at what length, so maybe fully compressed? Non HO specifies 192-210 @ 1.05, maybe HO is at same length) Free Length Intake 2.02 Exhaust 1.79 Ah, I see that it says service limit is 10% pressure loss @ length. 100 lbs is close to 50% at short length. Hope this helps, Rich D.