piratebaseball

Hey guys,
Hopefully I'm posting in the right sub-forum. I have a 67 camaro that I built a 427 for with a set of Lingenfelter ls7 cnc heads. After cruising a couple of weeks ago, I dropped a valve. Block just needs to be honed, but a piston and rod are gone. From the research I've done, it seems that almost all ls7 heads have valve issues. Does anybody have any experience with trick flow or mamo ls7 heads dropping valves or getting excessive play in the valves? I've searched and couldn't find any negative complaints against those heads like I could all the rest. Cam is a 238/252 .651 lift if that matters. Just looking for feedback before I make a decision to keep and rebuild with a set of heads that will not give me reliability problem or sell everything and go in a different direction.
Thanks!

Unreal

Yes those heads have the same potential issues. If I was doing heads on a setup like that, I would call SPS or RPM and get heads through them. Either way LS7 heads need inspection and maintenance.

subfloor@centurytrans

Based on past experience, I would be really surprised if the cylinder wall where the valve dropped is fine. I ended up thinking this even before I also saw it took out both a piston and rod too.

piratebaseball

The cylinder wall is is ok. This is a 5.3 block with the Darton sleeves from Texas speed. It occured cruising around at 35 mph and it only knocked the cylinder wall in a couple of places The knicks are small enough that you can barely feel them with your finger nail. I'm going to have the cylinder and area magnafluxed just to be sure, but I was really lucky in the carnage.

subfloor@centurytrans

Gotcha, I didn't see that mentioned earlier which is why I brought it up.

piratebaseball

After reading about the problem with ls7 heads, I'm part scared to go back with them. The other option would be to get a good set of ls3 or ls9 heads and put those on top of the 427 with a supercharger. Thoughts?


Here is the damage to the bottom of the head where the valve dropped.

Unreal

What are the goals and use for the car? That will determine what works best. If you need a high NA high RPM engine, the ls7 ports can't be beat and you will give up some power going to other ports. If you are doing a blower, or don't mind losing 20-30rwhp, then ls3 style heads can be a great choice, or even going to a cathedral style head depending on what you want.

If you want the advantages of the ls7 head, run a more robust set of valves, and inspect often for wear/damage and replace as needed. If the extra power is worth the potential of pulling heads every 15k miles, then keep the ls7 style heads. If you don't want to deal with that, then some nice ls3 style heads are a great option. Understand that pushrods, rockers, intake, etc etc will all have to be changed.

subfloor@centurytrans

Get the valve guides done and use stainless steel exhaust valves and you should be fine. I regularly spin my motor to 7500 at the track, and that's with stock rocker arms and pushrods too.

piratebaseball

The car is not a track car. I want to take it to the track every now and then to have fun, but the main objective is a streetable fun car that can cruise on the highway and run at the track. Speed, my goal is to run 10's in the quarter in a car that is streetable. I think I may be leaning more towards supercharging it with ls9/ls3 heads just because I can run a smaller cam which will allow me to run a smaller stall torque converter.

I bought the heads from a guy off of LS1 tech and he said they had 6k miles on them, but just had a machine shop go through them. They have GM titanium intake valves and Manley Stainless Exhaust valves. I was running morel lifters and stock ls7 rockers with the trunion upgrade. I put less than a thousand miles on them before this happened.

piratebaseball

Dan_the_C5_Man

This looks like an intake valve failure.. Pretty rare to have that happen in 7k miles.. Maybe the original owner meant "heads have 30k miles on them but I've only owned them for 6k miles".

Unfortunaley, unless you personally validate LS7 heads yourself, "..had a machine shop go over them" has little to no value...

Check the heads and see what the guides look like (wiggle test).

Glad you escaped this failure with as little carnage as you did - a small miracle.

Your build seems perfect for a set of AHP heads - check them out.

MTPZ06

Keep that can NA IMO. LPE CNC'd teh heads...I wonder if the assembled the heads? They use the soft OE PM composition guides...and I'm not aware whether they send out the OE Ti intakes to be tumble polished.

In any event, I second Dan's AHP recommendation...with MS90 guides.

KurtsZ06

That is one beautiful Camaro, sorry to hear of your valve failure.

piratebaseball

Thank you sir. Kind of the reason I was asking to see if Trick Flow or Mamo heads are having the same problem or are prone to valve issues. Eventually, I want to drive the car down Route 66 or take it on the Power Tour Long Haul and I can't be in the middle of no where and a valve drop.

Pb82 Ronin

I haven't seen any examples of the Trick Flow casting having any valve issues like the OEM GM casting does. That being said, the TFS castings are relatively new to the market, and the customers running them are probably just now reaching 1-2K miles on them...so the data pool is relatively small. Trick flow also has their own valve train to go with their heads...and they flow GREAT numbers. In my opinion they make a great "bolt-on" that won't require that "wiggle-test every 10K miles" like the OEMs do...at least at the moment they don't appear to.

mykream

As unreal stated above, I would go with SPS or RPM to take care of the heads. Never know what you'll get with one of the other shops mentioned...

MickVette

Here are my titanium intake valves 8000 miles after the previous owner had the heads "done". Notice the cracking on the stems. I had one intake valve that looked in almost new condition and was the only one in spec. I guess that one was replaced and the rest were reused. I got lucky and caught this in time with a failed "wiggle" test. I had the valve guides replaced along with coated titanium intake and exhaust valves. My plan is to keep the LS7 set up and make checking the valve guides "wiggle" test part of my oil change. The bad ones were bad enough I could feel the valve move in the guide without removing the valve springs. I did remove the valve springs and verified once I felt play.

I don't think I'd give up on the LS7 heads if you are mechanically inclined and include checking the valve guides as part of regular maintenance. If you are not mechanically inclined, a different head might be a better choice.

OneMeanZ

This right here is what has gotten me thinking about using Katech for LS7 head repair. Using their Ti/Mo intake valves with the bronze guides seems like it may help this issue. This is what scares me about reusing intake valves.

Must_Have_Z

Katech recently posted here about the package they offer for LS7 heads, and the initial results are very promising. They're worth a look.

piratebaseball

Thanks guys for all the advice. I saw an amazing deal come up on a ls9 supercharger yesterday on eBay and I jumped on it. I'm going to rebuild my 427 bottom end (5.3 block with darton sleeves), throw on a set of Trick Flow GNX 255 heads, and put the ls9 on top. I'll be able to run a smaller cam for better streetability, a lower stall (I hated the 3400 as sometimes the car wouldn't move at idle), and make 850 horsepower and not stress the blower. It should be a more reliable set up. I loved the power of the ls7 heads, but I think all of them are a ticking time bomb.