Little Mouse

Whoever put thise springs in had no clue what he was doing. Im assuming tiu know for sure you have .505 lift on your cam.

Z06CE

.505 on exhaust
.500 intake
The exhaust push rods are not bent
Cylinders 1, 3, 5. and 2, 4, 6 intake rods are bent
Cylinders 7, 8 are good

Little Mouse

stock length valves in factory bbc use 1.80 install height you have at most .505 lift correct ? That gives you 1.295 left at most. Your machine shop has told you what they coil binded at 1.280 thats .015 left over. On a hydraulic its best to have .050 to .060 you can do less then that with a solid. Hydraulucs kind of all over the place compaired wiith solid. Its the damn oil and spring inside a hydraulic lifter. Even if your machinest was coil binding at 1.260 thats only .035 still not even enough comfort zone for damn lifter floating around all over the place in oil. Throw the springs in the trash they were never right. Matter of a little more time you would have had more bent pushrods. Whoever set the heads up was an idiot. Heavy 3/8 valve bbc valves you need 300 open even on that mild .505 lift cam. Install height 1.80 coil bind at 1.250 or slightly less they can put shim under them. That will increase mostly the install height pressure with the shim. If you dont feel you know how to do this. Have the machine shop set it up. Be nice to know how good your guides, seats and valves are whike he has it. You can pull your valves out 1/2 inch from the seat they should be very tiny movement at that, then pull them out an inch roughly they will get a hair loser. I suspect if there are miles on it you will find some valves will wiggle a hair more then others. As steel is much harder then iron it will be more guide where then valve stem where. My job early 70s was rebuilding heads at a 3000 sq ft machine shop that had two crankshaft grinding machines in it. Even an alternator generator shop.on the other side was a parts warehouse. We had valves in .001 to .003 valve stem oversize to try to patch things up. This was before the bronze guide was tge way to fis things. Sbc was the worst engine for guide where. Bbc no problem press in a new valve guide and it was fixed right. Ill bet i did sbc back then at a 10 to 1 rate to ford or chyrsler and they were sure wernt selling 10 chevy engines to ford. Damn chevy valve guides even thow im a lover if them the guides were crap. I always say the bronze valve guide was created to fix a sbc.

Little Mouse

If it will help you any further. You dont have heavy roller lifters with the flat tappet. Find springs with. 1.8 install height, 110 seat pressure, 300 open, a resonably good rate will cover everything else. Then 1.8 -.505 lift come up with .050 to .060 extra clearence so you wont coil bind again and dont go higher then .060 clearance. Thats another can of worms you dont want, besides the coil bind that bent your pushrods. Only good thing in this the coil bind problem, your pushrods were sacrifised but you wont have any valve or pistons problems from any possible contact. Have fun.

stingr69

Nice sharp looking Vette you have there. Going to be a lot more fun once you get it all put back together right.

derekderek

Nice all around spring for sub-.550 lift and sub-6500 rpm. Buy shims and 8 rotator eliminators. Then measure thickness of eliminators compared to rotators. https://www.jegs.com/i/COMP-Cams/249/911-16/10002/-1. .015 to .150 when stacked. https://www.ebay.com/itm/COMP-CAMS-4...AAAOSw9EJZt~2Q

Z06CE

Thanks, Bent push rods live in there LOL

Jebbysan

Yes....911-16 and the rotator eliminators....I agree with this.....

Jebby

jackson

may be as good or better than comp 911 but 2/3 $


https://www.summitracing.com/parts/r...0-16/overview/

https://www.racingsprings.com/index.php/catalog/product/view/id/3815/s/valve-spring/category/399/

SPECIFICATIONS

• Part#PAC-1900
• NameValve Spring
• Alt Part#PAC-1900-16
• DescriptionAMC and BBC Street Single Std. Hot Rod Valve Spring
• Outside Diameter1.500
• Outer Spring ID1.086
• Middle Spring IDN/A
• DamperYes
• Inner Spring ID0.996
• Install Height1.880
• Load at Installed Height98
• Spring Open Height1.300
• Spring Open Load316
• Recommended Valve Lift0.600
• Spring Rate (lbs/in)376
• Coil Bind (max)1.115

derekderek

I would rather see 120-130 installed pressure.

Z06CE

How is the is the installed pressure, installed height, open height, open pressure figured with the lift of the cam?
What determines the clearance to avoid coil bind?
How's is this set up?

derekderek

The pressure at installed height is a given. Then you have the lbs/inch spring rate, which is pretty linear. So 374 lbs/inch times .500 is 187 lbs plus the 122 at 1.88 equals 309 over the nose. (Max lift over nose of cam.)

derekderek

So same spring on .6 lift cam would have same closed pressure assuming same installed height and extra 37.4 lbs open pressure.

Z06CE

.
122 lbs is installed height at 1.88. Got that. Also the spring is rated at 374 lbs is that st bind?
What determines the cam can handle the load pressure at 309 lbs at full lift @ .500

derekderek

374 lbs/inch of spring compression. Dunno the unloaded length. Around 2.2 inch. If truly linear, spring is compressed .32 or .33 to get to 1.88 and 122 lbs pressure.

Pmillspa

I just briefly read this post and there is some good info and not so good. In my opinion, (I have built big blocks that have won championships in all forms of racing, 396 up to 745 ci) and with compound angles of the valve train, it is very difficult to set up when the history is not known, Has the block been decked, are the heads angled milled, is the can a regrind, just too many checks that can not be answered. I see your intentions and the thirst for wanting to know is there which is great! However it would be best to seek out the help of one person in the know and have them help you. This way you can enjoy a big block that way it was built for. Just my opinion...

derekderek

His valve geometry overall looks good. I am recommending he reassemble it with new springs and get closed spring height correct. Then run the car before deciding if it is worth 2k to redo the top end. But since they are 781 heads worth 300 a pair on ebay, once they come off it is difficult to justify spending money on them.

2mnyvets

I don't want to add to you woes, but why aren't 7 and 8 bent? Carefully check your cam. Three of my 4 lobes were wiped in the back end and my machinist told me the BBC had cam alignment issues. .

jackson

what he asked about 7 & 8

Z06CE

Your points are well taken. The issue is I don't know what has been done to the 427. I can't tell you at this point if I have hydraulic or solid lifters!
I know the lift of the cam and that's it. I know it has 781 heads, I know the block is original. I have measurements of the springs.. I talked height and I have .020 clearance to bind.
I will first proceed with a compression check, then remove the intake, measure the lift from the lifters, check lifers if there if there hydraulic or solid and inspect the cam. then remove the heads.