#380 engine diagnosis help

Making sure I'm understanding what I'm seeing here.

Dual valve springs plus a flat-wound damper??? I'm only familiar with a single spring with damper, or dual springs with NO damper. Never have I seen all three on one valve.

Devon

 

I could see it possibly holding the valve from opening all the way but not from closing or sealing.

 

I see the same thing, I’ve seen triple springs but not the arrangement there

 

Comp cams 986-16 or similar... Used that set on low lift long duration performance cams with stock rockers in the past. Dual springs with a damper.

JW

 

IF that’s the spring and seal set up on the remaining 15 valves, I’d inspect ‘em.
If those seals were installed and the springs blindly installed I’d say more seals are ready to pop off, the spring/s are gradually pulling the seals off the guides, by rubbing on them and or destroying them.

 

Fred - did you do the rope, air, ???

 

Thanks Jim, I have a crane 850571 cam installed so would this make sense with this type of spring? I don’t have the original receipts from the prior owner outside of the cam card for the 850571 cam and a work order from 1987 saying they installed a hydraulic cam & kit with springs but did not saw what type.

 

Hi, Air.

 

Thanks Mark, To your point, I was thinking that I should replace all of them anyway. ?? 3/8 valve and my guide o.d looks to be .525. I called t/a since I couldn’t find a seal for this guide size and they recommended.

Product ID: TA_1433BV
.531"X.372" Viton Rubber Valve Stem Seals

 

Usually the guides are machined for .500 seals IIRC.
You may have to leave out the second spring and just run the outter spring and dampener if you don’t have the guides machined.

 

On YouTube vid of the valve, I don't like the valve's seat pattern. Looks rough and the seat in the head may be rough as well. Do a video of the exhaust valve on the best cylinder (or easiest one) to compare.
Exhaust valve sealing issue won't show on vacuum @idle reading unless it's so bad as to be a near-dead miss.
Suspect double springs+damper and exh valve seals is from shop/owner not knowing better... not the cause of this problem.
Mike

 

Got around to pulling head. #3 exhaust valve definitely leaking.

 

Put a straight edge across the valves. That seat surface is huge, looks like the seat is sinking. I bet your exhaust valves are all over the place.

 

I checked and the exhaust valves are ~ .032 taller than the intake valves.

 

I'd say its time for hardened exhaust seats. The bummer is you'll have to pull the other head.

 

So what’s interesting is that the seats were already replaced when they put-in the larger valves during original build. Passenger side head the same as drivers with exhaust valves taller than the intake. What I don’t know is if they used hardened seats. I’m planning on getting both heads redone so pulling other head was already planned.

 

Maybe they set the seats too deep in the head.

 

Thats strange they are all off the same amount. Sloppy machine work?

 

You checked WHERE?

Are the valve tips taller, or the valve faces? Makes a world of difference.

 

Heads back from shop. New guides, hardened exhaust seats, and guide seals. I had to replace #3 exhaust valve which started this project (bad seat and valve). Also replaced springs so now have correct ones for my cam. Making progress and slowly getting her back together.