Competition Cams Valve Springs

[Dave Barbieri]

The machinist doing my head work gave me a call concerning the intake springs. For the heads we went with new valves, new springs and guide inserts. The seats were all in good shape and and not much material to be removed to make them perfect. Exhaust valves, springs, seals and retainers went together perfectly. When the valves are opened to spec height, the clearance between spring coils is perfect. The intake valves are another story - when opened to spec, the valve spring is almost coil bound. Not quite, but awfully close. Way too close to be good. Has anybody else run into this?

 

[icanfixall]

Not that I have ever heard about. Both the intake and exhaust valves are set to a specific depth in the heads. These are the specs.
Valve head recession relative to head deck
Intake ........0.042 to 0.054 inch depth in the head
Exhaust......0.051 to 0.063 inch depth in the head...

 

[racer30]

The valves only move .381 on a stock cam. If the machineist says thay are at coil bind he has the wrong springs or he has made a calc error. most springs can compress .450 or more before aproching coil bind. recheck the install hight and re-calculate. when using other than stock springs you need to check for install hight and shim to be correct, or cut the head for more room for the spring. don't panic re-check untill the error is found.

 

[Dave Barbieri]

Gary & Brad -

Thanks for the response. Gotta tell ya, I'm kinda stumped at this point. When I read thru the posts on CC springs, it was nuthin but good. No fitment issues, no breakage, no disasters. Coupled with the Typ4 Torque Cam, it's the perfect answer to more low-end GO. The machine shop has done my work for over 20 years. They're mighty good at what they do and they get it right. Plus, this isn't their first IDI. So when I get a message about coil bind concerns, my antennae go up right away. I'm headed over there this morning to see what's up. I have a 1984 Truck Shop Manual (Engine), so I'll drag it along with me and we'll compare their readings with Ford specs. I'd like to see valve head recession and spring height (1.798" I & E). I'm hoping it's something simple. We'll see.

 

[Dave Barbieri]

OK, here's the stock specs:

Valve Head Recession
Intake: .042 - .054
Exhaust: .043 - .055

Valve Spring Pressure (OEM)
60# at 1.798" (intake & exhaust)

Valve Spring Pressure (Comp Cams)
92# at 1.800" (intake & exhaust)

Valve Spring Assembled Height
N/A

Here's what we actually have:

Valve Spring Assembled Height
1.780" exhaust
1.677" intake

This height gives 124# of spring pressure on the intake valves when closed. That's over twice the stock pressure. Jeremy, the machinist working on the heads, is going to mill .060" off the intake spring seats/pads. This is still .040" less than spec'd, but it'll lower the seat pressure considerably.

I visited with the Navistar techs in Tyler and then went to Longview to talk to the folks at a machine shop that does a lot of IHC stuff. They were really great about taking the time to talk to me and go into their engine manuals to search out the info I needed. Well, neither IHC/Navistar nor AERA publish the installed height spec, or how much material can be safely removed from under the spring. When I asked what height they typically used as a standard when working with IDI heads, the supervisor grinned and said, "We never measure it." So, we'll see what happens with our .060 plan.

 

[Black dawg]

where did these valves come from, and are they down into the seat correctly?

 

[PwrSmoke]

What's the stem height and is it the same as the exhaust?

Have you compared keeper groove height on the new and old valves (or are you using the ones that were there)?

The AERA info I have says 1.8" installed height but with the notation "pads vary."

Are all the spring pads at the same level?

Also, the AERA info I have says closed spring pressure is 72-80# @ 1.798. 82.5 psi is what I got using the aftermarket Power Stroke springs @ 1.798"

 

[Dave Barbieri]

where did these valves come from, and are they down into the seat correctly?

Clevite intake and exhaust. Seat depth/valve protrusion is within specs.

 

[Dave Barbieri]

Comparing the OEM exhaust valve and the replacement exhaust valve, the distance between the valve head and keeper groove is the same. Yup, "pads vary". The casting distance between teh machined valve seat and the water jacket isn't precise. Jeremy is checking the pad height and I'll check with him tomorrow morning and see what he found. Gotta tell ya, I like AERA's data! The 90 pounds closed pressure is what Comp Cams advertises on the side of the box, and that means I'm looking at about 10 - 15 pounds more seating pressure than OEM.

 

[racer30]

Thats kinda what I was thinking, You should have no problems cutting .060 off. Somewhere there is a picture of a head cut through the center that shows the thickness of the casting. I bet there is plenty of room to cut more than that. I will be using the same size springs on my build with a J2 cam. I will keep an eye on the install hight now that you have had this problem, the J2 cam will compress even farther than the typ4 cam. I was told they swaped right in no problem.

 

[sassyrel]

Thats kinda what I was thinking, You should have no problems cutting .060 off. Somewhere there is a picture of a head cut through the center that shows the thickness of the casting. I bet there is plenty of room to cut more than that. I will be using the same size springs on my build with a J2 cam. I will keep an eye on the install hight now that you have had this problem, the J2 cam will compress even farther than the typ4 cam. I was told they swaped right in no problem.

a J2, is how diff, than a typ4????

 

[PwrSmoke]

Comparing the OEM exhaust valve and the replacement exhaust valve, the distance between the valve head and keeper groove is the same. Yup, "pads vary". The casting distance between teh machined valve seat and the water jacket isn't precise. Jeremy is checking the pad height and I'll check with him tomorrow morning and see what he found. Gotta tell ya, I like AERA's data! The 90 pounds closed pressure is what Comp Cams advertises on the side of the box, and that means I'm looking at about 10 - 15 pounds more seating pressure than OEM.

Isn't the intake the one with the problem? How did the keeper groove compare on it?

Also, when I did my heads, I tested my stock, original, 140K mile valve springs.... 77.8# seating pressure @ 1.8" average. When I did that, I wondered where that 60# @ 1.798 OE spec came from. Was it early engines or is that the minimum spec? Doesn't really say in the manual, it just lists that spec... though it does say in the notes "Service Limit- 10% loss of pressure." It's in my '86 manual and a later manual too. I checked about half my old springs and they were in the 77-79# range. AERA calls for 72-80# @ 1.8".

Anyway, I'm very curious what your problem will turn out to be so I'm hoping you'll keep us in the loop.

 

[racer30]

The typ4 cam has some changes to the valve timing with just about .012 more lift on the intake with .392 valve lift and 12* more duration. the exhaust has the same as stock lift with .380 but has 14* more duration. this makes more HP and Torq than a stock cam with most of it low end 1400 rpm all the way to 3600rpm The J2 cam is reground with more Turbo specific valve timing and lobe ramp rate to open the valve faster for improved flow. The complete valve specs are not public but the lift has been let out of the bag for comparison info. .406 intake .453 exhaust. the most important thing is the valve timing and increased duration make the cam pull hard from 1800rpm or so all the way to as far as you whant to spin your engine. I ran some computer sim runs to 5000rpm and the torq curve was almost flat from 3000 to 4400. We all know that fuel is the problem up high in the rpm range so the sim runs where for just to watch the air flow specs. even my sim said that the engine had to heavy of internals to spin that high. The typ4 cam has been proven to be a great performance cam in a DD Truck and towing power and loves all the little mods most guys put on there Trucks. The J2 cam is for those fokes that want to push it a bit farther in the quest for performance.

 

[Dave Barbieri]

Isn't the intake the one with the problem? How did the keeper groove compare on it?

Also, when I did my heads, I tested my stock, original, 140K mile valve springs.... 77.8# seating pressure @ 1.8" average. When I did that, I wondered where that 60# @ 1.798 OE spec came from. Was it early engines or is that the minimum spec? Doesn't really say in the manual, it just lists that spec... though it does say in the notes "Service Limit- 10% loss of pressure." It's in my '86 manual and a later manual too. I checked about half my old springs and they were in the 77-79# range. AERA calls for 72-80# @ 1.8".

Anyway, I'm very curious what your problem will turn out to be so I'm hoping you'll keep us in the loop.

Jim -

The spec I used came from my 1984 Ford Engine Manual. Since AERA and everyone else uses the higher number, it sounds like you're right. Ford changed a few things in production over the years. What stumped me was why my intake valves were nowhere close to the production spec. To get them to the .800", nearly .124" would have to be milled off the spring seat. Man, that's a LOT!! I compared several new intake valves to the OEM valves we were replacing. Distance from the keeper groove to the valve head was the same. No differences whatsoever. Weird.... Jeremy milled off approximately .070" from each intake spring pad, to bring spring height to 1.750" for each intake valve. I'm still .050" outside the spec, but I'm not willing to machine that much metal off the head. When I get the heads and valve gear installed, I'll check for clearance between the coils when each valve is fully open. We should be more than OK, I just like to double check.

 

[PwrSmoke]

Thanks for the update. You didn't say if the spring seats were the same one to another? In any case... another good IDI "watch out for this" thread for the brain trust.