It's a fact: there exists a "potential problem" with any single coil spring. That, if valves' sole spring breaks, the valve is more likely to drop than not.

However, when valvetrain is set up properly, and with quality pieces, that failure potential is minimal; sorry no stats, JME.

** seems OP Dorian has now fitted his heads (of unknown pedigree/quality) with known quality (PAC) springs. Dunno 'bout the remainder of valvetrain ? If this were my project (it's Not), I might've opted for polished and/or cryo-treated pieces. However, I've no doubt those PAC beehives are a major improvement.

*** Same polish (e.g. REM) and/or cryo treatment can be applied to Any spring combo configuration; including single with flat damper.

 

I still don't think his idle (the original issue) will be any better with those springs

 

Running flat tappet "Z/28" springs with a roller cam is asking for trouble. The bee hive springs should help stabilize the valve train. Has to be better.

 

Not all, But Millions of Gen 1 sbc were equipped OE with OE roller lifters + OE springs w/ average seat pressure about 80 psi at about 1.700". Most open pressures about 200 psi at about 1.25". Easily fact-checked.
OE GM roller lifters are only a little heavier than OE hyd flat tappets; but are considerably lighter than most retrofit link-bar hyd roller lifters. No AI here.

Most Z28 springs are rated with higher pressure than that. Typically about 110 psi on seat at about 1.700" and about 285 psi closed at about 1.21". Like most things, Some Z28 springs are poor quality while others are very good. No AI here.

For decades preceding roller lifter era, Millions of OE Gen 1 sbc valve springs were the Single Coil with Flat Damper configuration, for hyd Flat tappets and ALSO had average seat pressures also about 80 psi. Most open pressures also about 200 psi at about 1.25". Easily fact-checked. No AI here.

FWIW - all those L31 5.7L & L30 5.0L Vortec motors: all of em, ALL iron-head Vortecs delivered with a True Single Coil spring with NO Damper and they ALL have OE Roller Lifters. No significant histories of dropped valves; certainly No more than earlier motors having Dampers. Those motors Continue in Current GM Powertrain production to this day as replacement engines and for marine & industrial applications. No AI here.

Depending on application (valve weight, lifter weight, rpm range) and setup, a good quality Z28 spring can support a peppier sbc than OE roller springs will. JME: a typical sbc Flat Damper Spring contributes Very little pressure.
Everything has its place; everything in moderation. No AI here. No stats either.

 

New aluminum pump. I could hear bearing grinding at idle.

Some engine enamel. Chevy Orange, of course.

Interesting- weep hole on underside reveals a leak.

New pump installed


With a bit of luck, a test run tomorrow or the day after.

 

soon as is possible, suggest remove all paint that may be on that lower rad hose spigot.
Paint will cause the hose to bond to pump; later (when you need to remove hose), that may give you grief.

 

Thanks !!!

 

We all know the drill.


Maybe will make things easier. I hope it sticks.


Here we go again.


Nothing unusual that i see. Dirt is an optical effect. It’s clean.


Looks fine. I checked the cam with a bore scope. Looks fine.


These look fine as well.


The only issue: several of the lifter plungers are stuck.

I am going to try to carefully unstick them.

 

I am not confident that the lifters will become “unstuck”. Several hours later, one pair is still stuck.

i have been reading up on my “high energy” Comp Cams lifters. Not unusual to fail out of box. (‘had these issues since day one.)

interestingly these lifters are no longer available. The next generation are called “Evolution”. Go figure !!!

Sigh. Expensive !!!

 

When hydraulic lifters are stuck internally, you must completely disassemble them and clean all bits with aerosol carburetor cleaner & compressed air. Reassemble internals with just enough AT fluid to coat surfaces (don't attempt to "fill" them). Do NOT mix any internal parts between lifters. Maintain each lifter and its parts as one discrete unit.

Top quality, New replacement retrofit link-bar roller lifter brands:
Gaterman, Iskenderian, Morel

yup, good quality valvetrain pieces are expensive

*I see evidence of scuffing on lifter bodies.
suggest you closely inspect & measure lifter bodies' external ODs and block's lifter bores' IDs
lifter bores can and do wear out.

 

I have 2 of these cams and one is brand new in the box if anyone is interested. it came in the never ran 406 I ought last year but since I had the same cam in my 355 I decided to go with the summit ls firing order cam that was slightly larger... It was pretty tame to me but I did have to change my adjustable distributor vacuum advance can because of the lower amount of vac and adjust my idle so it would stall in gear. I use enginetech retro roller lifters from rock auto... no issues but folks here will say they are junk just because of the cost. im 95% sure im running comp dual 986 springs.

Just an fyi theres another thread on here about this same cam idling too rough for someones liking... All I remember is it was a red car lol

 

Sadly, these are not rebuildable. Interestingly, the next generation is.

yes. I noticed the scuffing as well.

 

I have a set of used comp retro roller lifters like this with very low miles and the sides are very scuffed compared to the enginetech version I pulled from my 355.. Not really sure why but that and the fact that Id need to change my pushrods led me to reuse my enginetech lifters instead. I plan on using the comp lifters along with this cam in my 355 once I find a project roller for it and the th400 I yanked fro the c3.

 

That evolution thing is essentially an insert from an OE GM hyd lifter.

Newer Harley D are likewise.

Suggest purchase new Gaterman or Isky or Morel (not Comp). told ya.

I don't have Your lifters in front of me. And whether they can be rebuilt (or not) is not a certainty, either way.
But, I do feel confident advising you, that (unless the lifter is severely damaged/broken) the hydraulic part can be disassembled, cleaned, then reassembled; in much the same manner as a typical hydraulic flat tappet lifter.

As for the roller parts, it would likely require a dedicated jig/fixture to disassemble/reassemble and dunno if comp offers replacement parts for those specific lifters. Their bodies may be so damaged-scuffed to be not suitable for reuse; I have not inspected/measured.
--------------------------------------------------
OR try some of the Asian retrofit link-bar hyd roller lifters like augiedoggy got from RockAuto; Enginetech P/N RFC35016. A full set of Eight pairs are about $212 today.
----------------------------------------------
Regardless whose New lifters you settle upon; strongly suggest you disassemble, clean, reassemble as before.

And, suggest you pull cam from motor and place on a clean bench with bright light and magnification. Closely inspect for any damage to all lobes.

 

Well at least it sounds like you found a real possible source of your erratic idle issue.
A valve hanging open, or shut, or loose and clicking.

You'll get there.
I would go with what Rebel says, he has built far more engines than almost any of us.

I have heard of a lot of owner issues with hydraulic roller lifters, but never got enough information to know the reason why.

 

Yes, I suspect with a lot of patience and the right tools, these could be rebuilt in my garage. I can see the snap ring, but goodness the pry gap is ridiculously tiny. And with these plungers not budging, I have a little confidence that I can service all of these lifters.

Over 12 hours in paint thinner had no effect.

I do remember when I first installed these lifters and the roller cam, it was difficult to set confidently the lifter preload. Was this related to having the wrong springs on there? Who knows.

While I’m at it, I will pick up some valve spring seat locators and hopefully these are standard valve stem oil seals.

I also think there is too much bling under my hood. I rattle canned my intake manifold aluminum silver. Hopefully I can spray VHT Chevy orange engine enamel over that, after a very good clean and scrub

 

You probably need 1mm snap ring pliers and you need to roll the roller on a hard flat surface, they should roll smooth. If they don't you have brinelling which means the needle bearings inside are deformed or flattened and should be replaced.

 

I must say, this has been an interesting journey.

My frustrations with this engine have been with me since almost day one. It seemed plagued with performance issues.

I am convinced we are finally on to something. I do think the lifters failed out of the box… I don’t think the weak springs caused this - sure as hell did not help. The problem with new parts failing is you tend to question what you are experiencing and look for the suspected issue elsewhere.

These lifters, now no longer on the market, had a mixed track record on reliability and QC. That said, I’m only speculating on their share of responsibility.

I am not there yet, but I think we are on the right track to finally solving this one.

Further, I want to thank everyone who contributed to this thread.

Stay tuned. I expect to order parts still this week.

I am sure curious to see how performance will be affected.

Incidentally - the rollers on all were operating super smoothly. No complaints there

 

Many times, when having difficulty setting preload, that's because the hydraulic has become "full" of fluid/oil and cannot be easily compressed in a static motor.

perhaps review my comments on lifter reassembly; in p# 70 above.

No matter whose hydraulic lifters, no matter new or not, no matter which brand, again, I suggest disassembly, clean, reassembly (using only enough ATF auto trans fluid to lightly coat hydraulic bits & pieces).

 

interesting

The Evolutions are explicitly listed as rebuildable. .