Broken valve spring

NvO

Member
Aug 14, 2015
47
Netherlands
After rebuilding my car for the last 5 years it broke a valve spring within 50 miles of droging it.

I bought the engine rebuild through eBay 5 years ago and cant contact the seller anymore.

The pistons used are unknown to me so i dont know static compression, engine parts i know :

1986-up 350 bored 030
Vortec heads 10239906
Edelbrock performer intake
650 CFM carb
1 3/4 primary headers

Current cam is a enginetech es1014r, 204 intake 214 exhaust at 0.50

Would like to change the cam for a better quality one, best a kit with cam lifters springs and locks

Any recommendations? I would like to change the springs with the heads on the car still anybody did this?
 

CorkyE

Veteran Member
Lifetime Gold Member
Nov 4, 2004
11,647
Ringgold, GA
Comp Cams, and maybe some others, have an online tool that will help you select a cam. You can call Howards and speak to one of their tech guys, I've done that before.

You can change springs with heads on and in the car. Some use compressed air to keep the valves up. I lower the piston, put about 18" of cotton rope through the spark plug hole, and manually turn the engine to where the piston has the rope pushed up against the valves. If you search UTube, you fine several videos on this subject.
 

tom3

Veteran Member
Aug 1, 1999
14,243
ohio
Replacing the springs is usually done with air in the cylinder - that I've seen. That cam is not much for performance for sure. Might have limits on valve lift with the heads if they have not been reworked. What transmission are you using? If the block has provisions for factory roller lifters that would really open up a lot of possibilities for a good street friendly cam with good performance.
 

NvO

Member
Aug 14, 2015
47
Netherlands
Ill look into converting to roller cam,

Perhaps somebody has experience with vortex heads and bigger lift cams
I would like to use :

Cam COMP Cams 12-240-4, 226/[email protected] , .480/.489 lift
Locks Comp 648-17 , 7° 11/32
Retainers Comp 787-16
Springs GM 12499224 Beehive

I was told with these springs/retainers there would be sufficient seal/retainer clearance. Perhaps somebody can conform?
 

1980RS

Veteran Member
Jun 17, 2006
5,993
MN
Ill look into converting to roller cam,

Perhaps somebody has experience with vortex heads and bigger lift cams
I would like to use :

Cam COMP Cams 12-240-4, 226/[email protected] , .480/.489 lift
Locks Comp 648-17 , 7° 11/32
Retainers Comp 787-16
Springs GM 12499224 Beehive

I was told with these springs/retainers there would be sufficient seal/retainer clearance. Perhaps somebody can conform?
Nothing wrong with that cam. Did you cut down the guide bosses before putting the valve seals on to see how much retainer to guide clearance you have? if not I would get that done first. I had one set of 906 Vortec heads that would take no more then .455 lift and just hit the guides. I run 062's with spring pockets cut and a milled down the guide bosses .100 tons of clearance. My cam is the Elgin 1165P .488 and .510 lift more so on the intake side as I run 1.6 rocker on the intake side. Spin my 406 to 6200 with no busted anything. Beware that GM and comp has had some crappy valve spring issues in the past, that's why I do not use comp anything now.
 

tom3

Veteran Member
Aug 1, 1999
14,243
ohio
Valve guide clearance is covered early in this huge Vortec info thread:
 

sandlapper

Veteran Member
Oct 9, 2020
1,188
SE CSA
Just because a kit has matched valvetrain parts ... that isn't the end ... YOU must either have an auto machine shop measure & set up valvetrain clearances or DIY. Many here will help guide you thru it once you commit to DIY.

Seems you may have a roller-ready block ... as said, good time to go with a roller cam.
Look at this selection of 4 step-nose USA billet steel roller cams; all 4 right at $270.

I haven't bothered to look up the comp cam, but most likely it's made on cast iron core, while likely selling for more than summit's more preferable ($270) steel piece. Just a name.
 

sandlapper

Veteran Member
Oct 9, 2020
1,188
SE CSA
A drop-in valve spring-retainer kit from Alex's Parts can be a good option which does Not require any machinework. Also, google "ghetto grind" for a DIY job using aftermarket "Z28" springs on Vortec heads.

It's an old wives tale that you MUST ALWAYS machine the guides/guide boss ... wrong. All depends on choice of retainer and springs. Some folk didn't confirm if their valve stem seals are firmly/correctly seated ... doing that may yield a lot more retainer-to-seal clearance.
 
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