Wierd popping noise...

[WayFast84]

I broke another rocker arm stud today. It's the exhaust on cylinder number 4. Last time it was the exhaust on number 8. This time it wasn't making a clicking a noise like a bad valve tap it was making a popping noise. I did not break a push rod either. What can be causing these damn stud's to break? I should replace all of them with ARP's. Even though they already are ARP's....

[BarneyMobile]

Something isn't right in your valvetrain if you keep breaking rocker studs. Is your valvetrain stock? How are you adjusting your valve lash?

[LTb1ow]

Did you just find pushrods and use them?

[Tru2Chevy]

Originally Posted by BarneyMobile

Something isn't right in your valvetrain if you keep breaking rocker studs. Is your valvetrain stock? How are you adjusting your valve lash?

No, he's got vortec heads on a 400 block, and aftermarket valvetrain.

Not sure on the details, would prolly help if he posted them though.

- Justin

[LTb1ow]

You know your not supposed to tighten those nuts on the studs all the way, right?

[//<86TA>\\]

definatly an issue with setup, and/or pushrod length

[WayFast84]

Originally Posted by LTs1ow

You know your not supposed to tighten those nuts on the studs all the way, right?

I don't have any info on the springs except they are good for .600 lift. I have chromoly push rods and roller rockers.

a local racer who happens to own a shop has been working on the car so I haven't had anything to do with any of the valve lash or anything for that matter.

Maybe I need to mount my rocker arms differently? Pedestal mount? what else is there?

[LTb1ow]

Can you look at the one valve stem that has no rocker on it?



Is the pattern on it anything like that?

[S.J.SLEEPER]

rocker ratio?
hydraulic or solid lifters?
pushrod length?

if you want help, need to give some specifics !

[WildBillyT]

On topic please. This is the tech section. Not the lounge.

[WayFast84]

Originally Posted by S.J.SLEEPER

rocker ratio?
hydraulic or solid lifters?
pushrod length?

if you want help, need to give some specifics !

1.6 rollers
Hydraulic
stock sbc length chromoly push rods.

[LTb1ow]

And how high do you rev it?

What kind of lift does the cam have?
What kind of lift are the springs good to?

[WildBillyT]

Originally Posted by WayFast84

1.6 rollers
Hydraulic
stock sbc length chromoly push rods.

WF:

Odd question. Have your Vortecs been modded to run a higher lift cam?

[WayFast84]

I went threw the vortec head thread on nastyz and I don't know how my retainer to guide clearance. Could this be the reason?

Originally Posted by Dirt Reynolds

Mike - thanks for the sticky.

I'm sure anyone interested in Vortec heads will find this thread to be quite useful and informative for their own Vortec engine build and questions concerning using the same. The idea is for anyone with Vortec experience and/or info to post here in this thread so as to pool our Vortec knowledge. Anything Vortec-related is welcome.

So -- without any further ado, I'll start things off.


What exactly are "Vortec heads"?

Beginning in 1996 to '00, L-31 Vortec heads were installed from the factory on GM truck and van 350 engines. These newly designed for 1996, state of the art heads are made from cast iron and replaced the former swirl-port TBI heads that had been previously used on the GM truck 350. Instantly the HP rating increased 55HP to 255 HP primarily from the power of these cylinder heads.

What makes Vortec heads any different from other GM steel heads?

Pretty much everything. Beginning with the intake port, which is 170cc with a cast-in 'ski jump' on the port roof which is there to increase port flow velocity, port flow was designed to be high in the .300"-.500" valve lift area to make power with relatively low-lift truck camshafts. The bowl area is wide around the guide - much wider than the old 'camel-hump' heads from back in the day - and the intake valve seat has a 3-angle grind from the factory. The intake valve is also back-cut as is the exhaust. The exhaust port, considered to be the "weak" part of the otherwise steller-flowing Vortec head, actually does not flow that bad but because the intake port is so good, responds better to port work than does the intake and there is a strong feeling in some camps that these heads make best power with a split-duration camshaft because of this aspect. The exhaust valve seat also comes from the factory with a 3-angle grind and back-cut valve (except as noted below). The combustion chamber design was a radical departure from anything GM cast in iron prior to the introduction of these heads, and is of a 'double-quench' design. Highly efficient, best power is made with 32° total timing, although these heads can make power with timing reduced to 29° when used with short-duration camshafts.

How many versions are there of 'Vortec' heads?

Realizing that today, several manufacturers have tooled-up their own reponses to GMPP's highly successful debut of the L-31 Vortec for the budget small block crowd, thus far we have several versions to choose from in the performance aftermarket:

GM L-31 Vortec
GMPP 'small port' Vortec Bow Tie
GMPP 'large port' Vortec Bow Tie
GMPP 'Fast Burn'
Edelbrock E-Tec 170
Edelbrock E-Tec 200
Dart Vortec replacement head
RHS Vortec
EQ Cylinder Heads Vortec

L-31 Vortecs -- there are two castings with two versions of one of these castings (#906). The two castings are the #062 and #906. The #906 is the same as the 062 with the exception as noted below. Using the 906 heads myself, I can safely say do not worry about any percieved weakness in HP potential in comparison to the 062. They both make the same amount of power. The 062 is the head you will get when buying the Vortecs from the dealership/GMPP.

• Vortec heads were designed based on the 1996 Caprice 9C1/Impala SS LT1 cast-iron head castings. The only difference is the water jacket revision so these heads could be used on conventionally-cooled small blocks. The 1996 LT1 cast-iron head was the highest-flowing LT1 head used by GM. These heads outflowed the Corvette/f-body aluminum LT1 heads reportedly by 20 cfm on the intake side. The cast-iron head was in development 6 months longer than the aluminum head and during that time GM engineers tweaked the ports for the additional flow.
• Two Vortec castings were used from 1996-99 on GM CK trucks ('00 in vans) and SUV's utilizing the Vortec 5700 350 engine. The #906 and #062. The #906 casting head was available in two versions. One has an Inconel exhaust seat with a single angle grind, and the other has the conventional 3-angle grind on the exhausts as per the #062. The #906 with Inconel seat does not intrude into the exhaust port. It was used primarily on the HD and 1-ton truck applications where sustained towing of heavy loads & weight up inclines could cause eventual damage to a standard induction-hardened exhaust seat from excessive heat.
• The only difference between the #062 and #906 Vortec head is in the exhaust seat of the HD/1-ton truck #906 version, as described above. The #062 has a 3-angle grind on a standard induction-hardened seat, as does the non-HD #906 head. The 062 does flow slightly better on the exhaust side at low lifts but the advantage over a 906 is very slight. They both utilize back-cut exhaust valves. They both have 3-angle grind seats on the intakes with back-cut intake valves. Both heads make the same power in stock form.
• Vortec heads were used exclusively in trucks and SUV's. No passenger cars were equipped with these heads.
• Stock out-of-the-box Vortec heads have approx. 480HP potential naturally-aspirated. Fully race-ported flowing 275 cfm @ 28" water with 2.055/1.60 valves, potential is approx. 580 HP. There are reports of some shops getting close to 300 cfm out of these heads in fully-ported form.
• Retainer to guide clearance is the primary Achille's Heel of the Vortec. For valve lifts above .460" they need to be checked for R-G clearance. This varies from head to head. Some find they can get .480" and slightly more valve lift fine. Others will find .460" about the limit. Always check R-G with any performance cam above .460".

Great, I'm interested in Vortec heads, but am concerned about retainer to guide clearance. What can be done about this, and, are there any places I can buy Vortecs already modified for use with high-lift camshafts?

Good question, easy answer.

Scoggin-Dickey sells Vortec heads already correctly modified for use with high-lift performance camshafts. They also sell a complete kit which has the modified Vortecs, intake manifold (Edelbrock Vortec), rocker arms, etc to basically bolted on your existing short block.

Sallee Chevrolet has an interesting solution to this problem (from their website):

The Sallee Chevrolet solution is to use Crane Cam’s 10309-1 drop-in valve spring and retainer kit which is good for .550” lift with no machining. The installed height for this Crane Cams kit is taller and the lower part of the retainer is shorter. The “AVERAGE” clearance between the retainer and seal is .575” for this kit. We have found that some of the Vortec heads, coming from the factory, do not have the valve seals driven on all the way. You need to check that they are before installing this kit. If they need to be driven on all the way, we have found that a 3/8” drive - 1/2” socket fits the valve seal just about perfect.As with all modifications to performance engines though, you should always measure to assure that there is proper clearance and fit.

Comp Cams sells a tool that will cut down the size of the Vortec valve guide and is around $50 or so.

Another method is the infamous Vortec retainer "ghetto grind". If the camshaft being used only requires a stock 1.25" diameter single-wound valvespring, it is possible to only need to grind off approximately 3/32" off the bottoms of the stock Vortec retainers with a grinder or on a grinding wheel to achieve enough R-G clearance to run up to approximately .530" -.540" safely. I must caution here that R-G clearance must ALWAYS be checked to verify that there is in fact enough clearance - also include allowing for coil bind. One other thing - you must remove the dampner in this modification. Don't worry -- the stock Vortec valveguide being much larger in diameter than other SB heads will act as sort of a dampner and I never noticed any RPM issues related to lack of running one when I did this mod. Although myself and others who have done it this way have had no problems, I must caution this basically for those on a strict budget and cutting down the guides either with the Comp tool or at a machine shop is the best way to go. However, I'm of the opinion that since it works well within the noted constraints, then you're really only out your time to grind down the retainers. The choice is yours.

More to follow.

[Tru2Chevy]

Matt, where did you get your heads, and what do you know about what was done to them?

- Justin

[WayFast84]

I got them from jegs and had them machined by Larry Hansen. I was told to use the comp springs in the thread but now I remember that when I gave the springs to Larry to use that he said something was wrong with them so he put in a different set... That's why Im thinking it has something to do with retainer to guide clearance...

[sweetbmxrider]

http://forums.hotrod.com/70/7400302/...sbc/index.html

[WildBillyT]

WF:

What cam are you running? R to G clearance is why I asked, but that could be a longshot.

[WayFast84]

234/244 @ .050" .488"/.510", 114 lsa

[WildBillyT]

Measure your R-G clearance.

[Pampered-Z]

You want to make sure the rockers are riding on the top of the valve stem and not making contact with the retainers throughout the range of travel. If the rocker is making contact with the retainer you could cause all kinds of damage. Look over the spring retainers closely, the rocker arms should only make contact with the top of the valve:

http://www.97transam.com/harold/IMG_0274_pic.jpg

The retainers should show no wear marks that would show the rockers are making contact with the retainers.

Take ALL the pushrod and roll then across something flat ( piece of glass. mirror etc ) and make sure they are truely straight.

Your cam with 1.6 Rockers is 545 lift. If those springs aren't set right you are probably going into bind?????

Just because the springs are capable of handling 600 lift, doesn't really mean they automatically will. They need to be set up for that lift, and this is done with the install height. using certain locators/retainers and even cutting the pockets and each spring installed needs to be shimmed to the proper install weight.

If the springs are set too tight you could then be going into coil bind. You would need some pretty serious spring pressure to cause this type of problem, and that would more likely show up as lifters colapsing. Although that should be ruled out just yet?

To me, my first guess would be coil bind, this does sound like what is happeneing if you are breaking pushrods and pulling the studs out of the heads.

My advise, check the springs for coil bind, Drop in a solid lifter, run each cylinder up to where each valve is at max lift and check for coil bind.

[WildBillyT]

Originally Posted by Pampered-Z

You want to make sure the rockers are riding on the top of the valve stem and not making contact with the retainers throughout the range of travel. If the rocker is making contact with the retainer you could cause all kinds of damage. Look over the spring retainers closely, the rocker arms should only make contact with the top of the valve:

http://www.97transam.com/harold/IMG_0274_pic.jpg

The retainers should show no wear marks that would show the rockers are making contact with the retainers.

Take ALL the pushrod and roll then across something flat ( piece of glass. mirror etc ) and make sure they are truely straight.

Your cam with 1.6 Rockers is 545 lift. If those springs aren't set right you are probably going into bind?????

Just because the springs are capable of handling 600 lift, doesn't really mean they automatically will. They need to be set up for that lift, and this is done with the install height. using certain locators/retainers and even cutting the pockets and each spring installed needs to be shimmed to the proper install weight.

If the springs are set too tight you could then be going into coil bind. You would need some pretty serious spring pressure to cause this type of problem, and that would more likely show up as lifters colapsing. Although that should be ruled out just yet?

To me, my first guess would be coil bind, this does sound like what is happeneing if you are breaking pushrods and pulling the studs out of the heads.

My advise, check the springs for coil bind, Drop in a solid lifter, run each cylinder up to where each valve is at max lift and check for coil bind.

A small side note-

WF, if you pull any lifters out, put them in baggies and label them with the cylinder number and if it's an intake or exhaust lifter. Since your cam is broken in you can't swap them around.

[WayFast84]

I am not taking this motor apart. I cant do it. I'm gonna go to the shop and talk to the guy who put it together the last time and get a rough estimate on diagnosing this problem will cost...

[LTb1ow]

Dude, all you have to do is pull the 12 or whatever bolts to pull off the intake. The rocker is already off anyway so thats easy enough, borrow a solid flat tappet lifter from that friend of yours and check it out. Simple, and much cheaper than having the whole valvetrain fail on you.

[WildBillyT]

Originally Posted by LTs1ow

Dude, all you have to do is pull the 12 or whatever bolts to pull off the intake. The rocker is already off anyway so thats easy enough, borrow a SR lifter from that friend of yours and check it out. Simple, and much cheaper than having the whole valvetrain fail on you.

SR lifter? I hope you don't mean solid roller. His engine is a flat tappet.