CanadaGrant

What you are saying kind of makes me wonder why Comp Cams would say you MUST use aftermarket springs in even their .500 lift big block cams. When I installed a Comp XR270HR with about that lift in my bone stock 69 427 that at the time had never been rebuilt I measured the original springs prior to removal just to see. They were within .010 of coil bind COLD with a .500 lift cam. I would never run stock springs with anything like this.

Z06CE

I'm pulling the friggin heads

CanadaGrant

After seeing the valve stem head in your last pic, it's a good decision. Figure out what's in there, fix it and go with a matching complete setup that will work for you and what you want. You can get a complete kit from any of the cam manufacturers and it's kind of a fun project.

Little Mouse

its not all about the lift in modern cams the ramp rates on them are worlds quicker then the old days requring better overall rate in the springs, reason they dont want you running the old tech springs with modern cams. But at .505 lift no chance of retainer hitting a guide, coild bind or valve to piston problem. Best bet pull the heads off and know whats going on eliminate that as any problem. Other owner may have simply over reved the hydraulic cam muliple times for all he knows. Any 4 hydraulic cammed car 4 speed even auto or a boat should have some form of rev limiter.

Little Mouse

In 1973 i ordered a new 73 vette LS4 454, 4 speed with no a/c or power windows did get the leather seats. Hot rodder ive always been a/c extra weight. Well at 4000 miles still in warrenty i was not putting up with that slug. Pulled the engine out 2 bolt block only thing really used again. The cam i put in it was a sokid lifter crower 310/320 duration 560/580 lift used factory chevy bbc springs it was basicly good for 7600 rpm with the now rectangle port heads a tarantula single plane 850 dp holley. My point is tge chevy springs worked fine with what was cinsidered a fairly radical cam back then. Could i use those springs on a modern flat tappet cam of those specs today. Not even a chance. Cams like comps extreme, lunati vodoo todat are trying to come as close to roller ramp speeds as they can get and there not going to last long term. Have to have far better overall rate springs to even try ti make them work regardless of amount of lift.

Little Mouse

Back to my fathers mercury and all 16 unbrella seals crack up from oli heat and in the pan and pump screen. He had some luck the crank was not damaged but the bearings were. Nice cold winter in little rock arkansas in a car port freezing are **** off changing the main and rod bearings.

derekderek

The other thing with OE springs. They were 40 years younger. That 40 years was spent compressed too. I wouldn't trust them on a .480 lift truck cam. Now, if pulling the heads, these are 454 heads. First you check the stroke and make sure this is a 427, not a 454. Then you post pics of the piston tops. We are looking for dome size, numbers and evidence of valves hitting. I don't think it is necessary. I think you need springs, seals and pushrods. This engine was overrevved. Quicky valve test. Lay heads on exhaust ports. Fill intake ports with water. Flip over. Fill exhaust ports with water. Once heads are off and pistons are figured out, you may want to consider different heads. Current heads could be near perfect. Also could be 150k on a truck and lapped and new seals by a backyard a-hole and have shot guides. Pull the springs and check them yourself.

OMF

Well, I just spent the morning reading this thread, and rather than giving you my 2 cents on what to do ( these guys ^ are giving good advice) I'm just going to welcome you to C3 ownership! Working on your C3 is just part of it...enjoy!!

Z06CE

Thank you, and I thank everyone for there input.
I'll be hitting up for opinions for the best head gaskets, intake gasket, valve seals... etc.
I might as well get the intake powder coated to clean things up as well, freshen up the engine compartment while I have all the accessories off.
I'll take pictures of before and after.
Jackson.... I have done a leak down check. All looks good. Before I take the heads off I will do a compression check.

In

jackson

What about the 0.020" ... sum total or NO?

Z06CE

I don't know what is meant by sum or total.

I took the valve springs to XCH. He measured the spring at total bind and measured at 1.280, then measured spring @ .500 compression. Measured 1.260... Difference is .020. This was done on a spring compressor with indicators.
Thanks.
Mike

jackson

So ... it's now clear ... you did Not check or measure for coil bind ON MOTOR with pushrods & rockers all assembled ... while rolling motor thru to Valve Full OPEN position ... then visually inspecting any gaps between any coils and then measuring any and all gaps ... and then adding the total of any & all meaurements to become a SUM TOTAL.

Sometimes there's NO gap at all so 0.000"
Sometimes there's only one gap between and it's x.xxx" = total clearance
Sometimes there's two gaps (or more) and then it's x.xxx" PLUS z.zzz" = SUM TOTAL

root cause may never be determined with certainty ... but given what the shop measured on bench ... probably coil bind

stingr69

Total valve bind clearance is .020" which is somewhere around .004" per coil, static. The general rule is .060" total minimum coil stack clearance or about .010" minimum clearance per coil so these springs are being loaded very tightly. Some strange spring motion happens when the engine is revved up and the springs begin to oscillate up and down. The solid stack "weight" of the valve train load can get very high when the coils are too close together at higher RPM. Still need to check everything in the rest of the valve train but spring application, installation and condition needs careful attention.

The bent push rods may have saved the rest of the engine.

suprspooky

Well, you're at about the point I was two years ago. I pulled my Tri-power off in prep for new AFR Alum. Heads to become pump gas friendly. Found a worn cam, from there it turned into a full upgrade.

I will be interested to see if you did contact pistons (hopefully all will be savable), if you end up putting AFR's (or other aftermarket alum. heads) on it, check for temp sender provision. I also had to modify an aftermarket Alternator Bracket as the GM piece was cast Iron and not bendable, the aftermarket was steel so a little heat and a big wrench got the bolt hole to line up.

Good luck and take breaks often (it'll save you from rolling it into the street and setting it on fire, oooh I was close last fall).

derekderek

Get the spring height back to 1.88 or 1.9 and you are gonna be at 1.35 or higher full lift. And comp 911 go to 1.20. .170 is plenty of breathing room. If they are setting up too low without shims, and with eliminators replacing the rotators, the valve retainers can be replaced with taller ones. valvetrain needs set up anyway. Put it together and run it. Let the car decide what to make you spend money on next.

derekderek

Did you get your hands on a borescope? Did you get a look at pistons and chambers? And mebbe run scope down a couple intake ports looking for bowl work.

Z06CE

Derek... I did but I couldn't see crap in the cylinder with the bore scope. I was only able to get pictures of the lifters.
When I take off the intake I will see the intake runners. When I take off the heads I will see the cylinders and pistons, but before I remove the heads I am doing a compression check. I have to reassemble the springs. push rods and rockers.
I know you guys are wondering whats taking so long but I have a business that I run. Also having a 90th birthday party on St Patty's day for my dad that I have been busy with.
That Work crap gets in the way.

Z06CE

Little Mouse

this is not enough you need .060 clearence. I dont know what kind of spring other owner did. But this has caused your problem.

Little Mouse

Your old springs should have been set at factory 1.80 install hight your cam is lifting to .505 1.80 - .505 = 1.295. Your machinist was coil binding at 1.280 or was it 1.260. At 1.280 thats only .015 ckearance to coil bind. If its 1.260 .035 to coil bind.on a hydraulic .060 good amount but no more. I did not look at all these posts. Coil bind bent your pushrods. Get some springs with 1.80 install height with 1.225. That gives you .575 or 1.200 plenty of room for to be shimmed up the right amount. Springs in hydraulic flat tappet 300 open presure plenty and a decent rate in case its a fast rate open cam. I have doubts it is at that low of lift number.