Help! Can't remove valve keepers

[Mark E.]

Re: Help! Can't remove valve keepers

Thank you Joe!

[Chris H.]

Re: Help! Can't remove valve keepers

Mark. I was in a similar predicament a few years ago with my ‘69 L71. The thread is in the archives. I’d post it but doesn’t work with my smart phone. Short story is I wound up going with a Crane Cam spring, retainer package and Felpro umbrella seals.

Well now I’ve got a new problem and my original flat tappet cam is worn out. I measured the lift on all the lobes and some are worn up to 40%. So after much thought I’ve decided to make the switch to a roller cam. Don’t mean to hijack this thread but I thought it might be interesting to folks about our antique valve train and modern alternatives.

[Mark E.]

Re: Help! Can't remove valve keepers

40% is a lot of wear for 14,000 miles. What do you think caused it?

[Chris H.]

Re: Help! Can't remove valve keepers

Here's the old thread.

https://www.forums.ncrs.org/showthread.php?115471-69-L71-Valve-Spring-Retainer-Recommendation&highlight=odyssey

What started me down this road originally a few years ago was oil smoke in high vacuum situations, such as lifting off the throttle. Replaced the umbrella seals with no effect. Next on the cause list was sure sign of worn valve guides. Why were the guides worn? Because of broken valve springs ( at least 3 valves ) so common in the 1st design big block springs. The good news is that my motor never dropped a valve and lunched itself.

So, a few months ago I finally decided to pull the heads and have them rebuilt, new guides, pocket porting etc. Before I took the heads off I decided on a whim to check the cam lobe lift using a dial indicator on the pushrods. The results were a shocker. As to why the cam wear, I don't know. Modern low ZDDP oil? Did something happen before I bought the car at 14,000 miles? Crud in oil passages from car sitting for 30 years? I can only speculate.

Regardless, the plan now is to pull the motor and doing a complete rebuild. At first I was just going to put in a flat tappet L71 cam and call it a day. But then I started doing research on roller cams and their aggressive lobe profiles. The two main benefits are more power (average) and reliability. No more worrying about ZDDP and wiped cam lobes. The only down side is cost as rollers require a brand new valvetrain.

[Joe L.]

Re: Help! Can't remove valve keepers

Mark. I was in a similar predicament a few years ago with my ‘69 L71. The thread is in the archives. I’d post it but doesn’t work with my smart phone. Short story is I wound up going with a Crane Cam spring, retainer package and Felpro umbrella seals.

Well now I’ve got a new problem and my original flat tappet cam is worn out. I measured the lift on all the lobes and some are worn up to 40%. So after much thought I’ve decided to make the switch to a roller cam. Don’t mean to hijack this thread but I thought it might be interesting to folks about our antique valve train and modern alternatives.

Chris------


Like I've said many times before, I would never build another engine with a flat tappet cam (even though I have many NOS examples [none for sale]).

I never liked the concept of flat tappet cams from a time WAY BEFORE roller cams came into general use.

[Mark E.]

Re: Help! Can't remove valve keepers

Here's an update-

I replaced the early style springs that were installed with OEM style VS-708 springs, installed new OEM style umbrella seals from Fel-Pro to the original valve spring caps... all as suggested by Joe. I also got a variety of spring shims to set spring height for all 16 valves.

The engine now runs like a champ and I feel better about its reliability. Thanks for your help guys!!

It's really not a difficult job to replace valve seals, springs, and related hardware with the engine in the car. If you do this, I recommend getting two special, yet inexpensive tools: a screw-on type valve spring compressor and a spring height micrometer. The job would have been virtually impossible to do properly without them. I discovered every spring had a 0.060" shim under it even though valve height varied by 0.027" across the 16 valves. Now all valve spring heights are within 0.003" of spec.

It feels like I picked up 30hp (although fresh plugs and points probably made a difference too ).

The photo below shows the old hardware. All but one of the old positive-type seals on the exhaust valves were in pieces; the intake seals looked ok.

IMG_20200302_154123816.jpg

[Joe L.]

Re: Help! Can't remove valve keepers

Here's an update-

I replaced the early style springs that were installed with OEM style VS-708 springs, installed new OEM style umbrella seals from Fel-Pro to the original valve spring caps... all as suggested by Joe. I also got a variety of spring shims to set spring height for all 16 valves.

The engine now runs like a champ and I feel better about its reliability. Thanks for your help guys!!

It's really not a difficult job to replace valve seals, springs, and related hardware with the engine in the car. If you do this, I recommend getting two special, yet inexpensive tools: a screw-on type valve spring compressor and a spring height micrometer. The job would have been virtually impossible to do properly without them. I discovered every spring had a 0.060" shim under it even though valve height varied by 0.027" across the 16 valves. Now all valve spring heights are within 0.003" of spec.

It feels like I picked up 30hp (although fresh plugs and points probably made a difference too ).

The photo below shows the old hardware. All but one of the old positive-type seals on the exhaust valves were in pieces; the intake seals looked ok.

[ATTACH=CONFIG]98636[/ATTACH]

Mark------


I do not understand why this engine ever had the old style single valve spring with damper. 1970 big blocks were equipped with the dual valve springs with umbrella shield attached to the valve spring cap.

Also, most of the valve seals you have pictured are definitely not original to the engine. That may have been when someone retrofitted the springs you found on it. These were likely not even GM springs. The valve seals are definitely not GM.

[Mark E.]

Re: Help! Can't remove valve keepers

Joe,

You had a good theory in a prior post: during the rebuild, positive seals were installed. For these to fit required the old style springs.

[Joe L.]

Re: Help! Can't remove valve keepers

Joe,

You had a good theory in a prior post: during the rebuild, positive seals were installed. For these to fit required the old style springs.

Mark------


The original umbrella seals worked very well, I don't understand why someone thought they needed to install positive seals. Plus, they apparently used the "el cheapo" non-Viton positive seals. In addition, one of the valves has the 1965-69 style umbrella seal.

[Mark E.]

Re: Help! Can't remove valve keepers

Mark------

The original umbrella seals worked very well, I don't understand why someone thought they needed to install positive seals. Plus, they apparently used the "el cheapo" non-Viton positive seals. In addition, one of the valves has the 1965-69 style umbrella seal.

Joe,

Good eye.

I purchased the car in 1990 with 96,000 miles showing. The PO overhauled the LS5 himself in a barn a few months before because it was "smoking". New rings, bearings, cam, lifters, timing set, seals; cylinders honed, valve job with new guides. Original pistons, rods, rockers. I'm not sure what was done to the crank. A patched hole in the AC evaporator housing is testament to his struggles during R&R. I bought it against my better judgment since it had its original engine, a 4-speed and virtually every option... and I liked the color combo. Definitely an emotional buy.

Little more than a year later, May 1991, I took the '70 on a road trip from Dallas to Bowling Green via Atlanta (to rendezvous with my brother in his '85) for the factory's tenth anniversary. On Friday, May 31, about 40 miles from BG on State Highway 231, the breakdown was about to happened. The AC worked valiantly yet in vain on the 102 degree day while the engine struggled to maintain 210 degrees indicated. We placed bags of ice on the floorboards to protect our feet from the oppressive heat radiating from the big block. Cruising at about 70 mph, the engine suddenly let loose with a loud, repetitive banging. Rod knock? Spun bearing? ... No, more similar to the sound of a collapsed lifter but louder. Oil pressure was lower but still above 10psi. I pulled to the side of the road and removed the right valve cover. To my surprise, I discovered the top of the #2 exhaust push rod broken off. I was somewhat relieved to see the lifter remained in its bore sitting above lobe lift.

In the middle of nowhere on a hot day with no help in sight (pre-cell phone days), I decided to nurse the car into BG. Those last 40 miles took over two hours as the car limped down the highway with the AC off to ease the engine's burden. The local Chevy dealer couldn't work us in until Monday, so they referred me to Lindsey Automotive, a small shop down Scottsdale Road where the owner was also the lead mechanic. He did a compression check, replaced the valve seal, push rod, rocker arm then changed the oil and filter. The repair cost us two hours and $85. He was the saint who saved our trip.

I'm happy to report we made it to the factory festivities that weekend. The assembly line was loaded up with ZR-1s for the special occasion. The pride of the line workers was apparent: They demonstrated the smoothness of the LT-5 by balancing a quarter on its plenum during initial start up. And in the corner of the factory, they revealed an inventory of new Gen 2 LT1 engines awaiting 1992 production.

This is a long story to explain why #2 exhaust had a different type of valve seal. Years later, I discovered push rods of two different diameters in the engine. So even though it runs great today, this original 1970 LS5 engine somehow survived a barn style overhaul in the '80s.

[Dick W.]

Re: Help! Can't remove valve keepers

Mark------


Absolutely YES. Several sharp, HARD raps. You're not going to damage anything.

Before you compress the springs

[Joe L.]

Re: Help! Can't remove valve keepers

Joe,

Good eye.

I purchased the car in 1990 with 96,000 miles showing. The PO overhauled the LS5 himself in a barn a few months before because it was "smoking". New rings, bearings, cam, lifters, timing set, seals; cylinders honed, valve job with new guides. Original pistons, rods, rockers. I'm not sure what was done to the crank. A patched hole in the AC evaporator housing is testament to his struggles during R&R. I bought it against my better judgment since it had its original engine, a 4-speed and virtually every option... and I liked the color combo. Definitely an emotional buy.

Little more than a year later, May 1991, I took the '70 on a road trip from Dallas to Bowling Green via Atlanta (to rendezvous with my brother in his '85) for the factory's tenth anniversary. On Friday, May 31, about 40 miles from BG on State Highway 231, the breakdown was about to happened. The AC worked valiantly yet in vain on the 102 degree day while the engine struggled to maintain 210 degrees indicated. We placed bags of ice on the floorboards to protect our feet from the oppressive heat radiating from the big block. Cruising at about 70 mph, the engine suddenly let loose with a loud, repetitive banging. Rod knock? Spun bearing? ... No, more similar to the sound of a collapsed lifter but louder. Oil pressure was lower but still above 10psi. I pulled to the side of the road and removed the right valve cover. To my surprise, I discovered the top of the #2 exhaust push rod broken off. I was somewhat relieved to see the lifter remained in its bore sitting above lobe lift.

In the middle of nowhere on a hot day with no help in sight (pre-cell phone days), I decided to nurse the car into BG. Those last 40 miles took over two hours as the car limped down the highway with the AC off to ease the engine's burden. The local Chevy dealer couldn't work us in until Monday, so they referred me to Lindsey Automotive, a small shop down Scottsdale Road where the owner was also the lead mechanic. He did a compression check, replaced the valve seal, push rod, rocker arm then changed the oil and filter. The repair cost us two hours and $85. He was the saint who saved our trip.

I'm happy to report we made it to the factory festivities that weekend. The assembly line was loaded up with ZR-1s for the special occasion. The pride of the line workers was apparent: They demonstrated the smoothness of the LT-5 by balancing a quarter on its plenum during initial start up. And in the corner of the factory, they revealed an inventory of new Gen 2 LT1 engines awaiting 1992 production.

This is a long story to explain why #2 exhaust had a different type of valve seal. Years later, I discovered push rods of two different diameters in the engine. So even though it runs great today, this original 1970 LS5 engine somehow survived a barn style overhaul in the '80s.

Mark------


Pushrods used for big blocks over the 1965-74 period were 5/16", 3/8", and 7/16" OD depending upon year and engine application. However, the pushrod guides were also specific to each of those sizes. Did the engine have two different size pushrod guides installed? These guides each serve two pushrods. So, if there are different OD pushrods installed, they should not be served by the same guideplate.

[Mark E.]

Re: Help! Can't remove valve keepers

Mark------


Pushrods used for big blocks over the 1965-74 period were 5/16", 3/8", and 7/16" OD depending upon year and engine application. However, the pushrod guides were also specific to each of those sizes. Did the engine have two different size pushrod guides installed? These guides each serve two pushrods. So, if there are different OD pushrods installed, they should not be served by the same guideplate.

All the guides are for the larger OEM push rod (I don't remember which, 3/8" or 7/16") but some of the push rods were a smaller diameter (they had different style tips and color too). It worked, but probably not well. Now it's running new push rods, rockers, adjusting nut with ball, springs, keepers and seals.

Thanks again for your help, Joe. You identified the engine had the wrong springs and seals (probably from the PO's barn overhaul), and recommended which parts were required to make it right.

[Joe L.]

Re: Help! Can't remove valve keepers

All the guides are for the larger OEM push rod (I don't remember which, 3/8" or 7/16") but some of the push rods were a smaller diameter (they had different style tips and color too). It worked, but probably not well. Now it's running new push rods, rockers, adjusting nut with ball, springs, keepers and seals.

Thanks again for your help, Joe. You identified the engine had the wrong springs and seals (probably from the PO's barn overhaul), and recommended which parts were required to make it right.

Mark------


Your engine originally used 3/8" OD pushrods. The 5/16" pushrods were used only for early 1967 L-36/L-68 and all 1973-74 LS-4. The 7/16" pushrods were only used for L-88 and ZL-1.