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Time for valve guides, and a few upgrades while I'm in there
C6 Corvette ZR1 & Z06General info about GM’s Corvette Supercar, LS9 Corvette Technical Info, Performance Upgrades, Suspension Setup for Street or Track
Time for valve guides, and a few upgrades while I'm in there
A little history. I bought the car used, about 26,000 miles with the heads addressed by the previous owner using parts that seemed logical and ones I would have chosen myself. That is one of the reasons why I bought this car. The heads were AI 280cc milled for 12.0:cr, CHE bronze guides, stock intake valves, hollow Ferrea exhaust valves, BTR 660 springs, titanium retainers, smallish custom ground 232/246 .639/.639 115+3 camshaft for drivability and still enough performance to manage a 164.47 1/2 mile speed. They lasted about 9000 miles, most of which were tuning and higher rpm miles I must admit. During a Corvette Club Cruise one of the members noted that I have excessive smoke from the exhaust at high rpms. That prompted me to do a wiggle test which I could wiggle the valves with the springs still installed. I removed the springs for cyl #2 to get some sort of measurement, mainly because I wanted to use the spring compressor tool I just paid $200.00 for. The measurement at the top of the intake valve was about 0.019" and the exhaust was 0.006".
Simulation picture of valve measurement:
Valves removed
These Vampire lineman pliers worked like a champ removing the valve seals with a little help of a panel pry tool.
Exhaust valve and some wear. It weighed 87.88 grams dirty. Ferrea F2242P hollow valve.
Close up of the exhaust valve wear.
Stock intake valve. It weighed 79.38 grams dirty. I like the dirty numbers because that is the weight the engine will see.
This is the frightening part. The marks you can see toward the shiny center part you can feel with your thumbnail and are actually cracks in the valve. It wasn't long until this intake valve was about to drop. There were several like that and one that still looked perfectly new. Go figure.
I'm not here to bash anyone or give negative press. Personally, I would have chosen the exact same parts as the previous owner did as stated earlier. I think AI did an outstanding job with the port work and these heads were run hard. I have many log files where rpms actually hit slightly above 7500 on several occasions.
I'm going to try a different combination which I have partially decided upon and still figuring out. I noticed during tuning that the camshaft seemed to be holding the car back a bit so I'm excited to get a chance to change that. I see the COPO 427 later version has a redline of 8000 rpms and the modified version even higher. I will be looking closely at these parts.
This is not going to be an all out rebuild so definitely not as exciting as some of the posts to follow. I will be concentrating on a good match of parts for a nice weekend cruiser and bruiser with occasional track time at various events. This car will need to be an all around performer.
Last edited by MickVette; 10-23-2018 at 08:11 AM.
Reason: edit
I hit quite a few steps backwards lately (I might mention some of that later after I get past those hurdles) and finally I feel some of the dark cloud being pushed aside.
I was originally just going to use Manton pushrods but after working with them and sorting things out I almost feel part of the family. They encouraged me to do my own research, never once pushed their products, in fact I didn't even know they made rockers when I was measuring pushrods. I am so happy with the quality and look of these Manton rockers and anodized valve covers, I had to share...they just arrived 9:20 this evening and I'm too excited to sleep right now.
If you want to add another quality company to work with like HPR, add Manton to the list. I'll let the pics speak for themselves.
Next hurdle will be getting a 0.500" pushrod to work with these heads.
Looking back I wish I would have gotten Katech ti/mo intake valves. Looks like the ticket if you run bronze guides. If you’re still considering titanium I would look very closely at those.
Looking back I wish I would have gotten Katech ti/mo intake valves. Looks like the ticket if you run bronze guides. If you’re still considering titanium I would look very closely at those.
Actually, the heads are on the way to Katech right now, shipped yesterday. Going with ti/mo intake and exhaust, 1511 springs, ti retainers and new bronze guides. Those were a few parts I did decide on.
Good thing you inspected the heads when you did! Have you decided on ballpark cam specs yet? I have a very similar sized cam and I think it has been holding my setup back a bit as well-230/246 .644/.631 115. Pat G spec'd me a cam and I've been tossing around the idea of AI's porting program but I'm still waiting for a reply to an email I sent more than 2 wks ago. I don't track it or do any straight line events yet but I do drive the **** out of it on the street when I can. Sorry for the partial hijack and good luck on the rebuild.
Good thing you inspected the heads when you did! Have you decided on ballpark cam specs yet? I have a very similar sized cam and I think it has been holding my setup back a bit as well-230/246 .644/.631 115. Pat G spec'd me a cam and I've been tossing around the idea of AI's porting program but I'm still waiting for a reply to an email I sent more than 2 wks ago. I don't track it or do any straight line events yet but I do drive the **** out of it on the street when I can. Sorry for the partial hijack and good luck on the rebuild.
Jesse
I paid to have two cams spec'd out by the Guerra Group, bought Desktop Dyno 5, plugged in my own known results with my current camshaft and started comparing 18 camshafts that interested me in a spreadsheet. Turns out my current camshaft is pretty healthy until higher rpms. Most of the camshafts I was interested in gave up a lot of low rpm torque in favor of decent high RPM horsepower gains. To my surprise the Katech K501 did great with the AI port flows and was a nice compromise for my goals of an everything car. It only gave up about 6 lb*ft of torque just above idle and surpassed my old camshaft around 2500 rpms with good HP gains at higher rpms with the ability to rev out better. I don't have my desktop dyno with my right now so no exact numbers to reference.
No hijack at all. This was a big part of my calculations and time spent deciding which components to choose. They all have to work together. If I would have chosen a different camshaft I might have chosen different valve guide material, valves, springs and company to go with. Totally relevant in my eyes.
Mine peaks at about 5k and falls off noticeably after 6k rpms. Otherwise it pulls hard everywhere. The K501, BTR 3 and Titan 3 by Cam Motion were three I narrowed it down to before having Pat at the Guerra Group spec me one. Surprisingly, the cam he came up with has very similar specs to those three and essentially identical overlap-18.
Mine peaks at about 5k and falls off noticeably after 6k rpms. Otherwise it pulls hard everywhere. The K501, BTR 3 and Titan 3 by Cam Motion were three I narrowed it down to before having Pat at the Guerra Group spec me one. Surprisingly, the cam he came up with has very similar specs to those three and essentially identical overlap-18.
After looking at 18 different cams that I was interested in, I was able to start grouping them together and really start picking them apart on the Desktop Dyno. You just have to find the best match for your goals. No cam is perfect so areas that I am willing to deal with may differ for you. Tuning plays a big part too. I work with Tampa Tuning to get me an awesome tune with a great starting point, then take it over from there but keeping Tampa Tuning in the loop as I modify parts to work together better as I see weaknesses in the combination trying to maximize each part. I have 129 tunes on my own from trying different combinations and all sorts of ideas.
The Titan 3 wasn't on my radar. I'll have to put that one in and see how it does. It looks like it would handle a slightly heavier exhaust valve quite well with the .639 lift and longer duration. Everyone knows the B3 is a beast but you give up some low end torque. I like rolling out of my driveway, smacking the throttle and annihilating the tires from barely above idle. I don't think the B3 will do that without a little clutch work.
Just wanted to add...holding the intake and exhaust valves in my hand I wasn't expecting the hollow exhaust valve to be so much heavier than the intake. I guess it is almost 10% heavier, but what a difference just holding them both and moving them around. I was trying to imagine how difficult it would be to control the exhaust vs the intake at 7000+ rpms.
Yeah the B3 may give you that 600whp (in STD anyways) a lot of people seem to be chasing but I wouldn't want to give up too much down low either. Need to find a nice happy medium.
... and now your adventure begins. Your experience is why I wanted all new valves expecting the old guides were shot (14 of 16 were) and not wanting to run old valves in the new guides. Good choice on the head work and parts.
On the torque side, I went from AFE/Pfadt 1 7/8" Try Y's to 2" ARH headers and picked up over 50#-ft. of torque at 2500 RPM, some power and torque up top.
... and now your adventure begins. Your experience is why I wanted all new valves expecting the old guides were shot (14 of 16 were) and not wanting to run old valves in the new guides. Good choice on the head work and parts.
On the torque side, I went from AFE/Pfadt 1 7/8" Try Y's to 2" ARH headers and picked up over 50#-ft. of torque at 2500 RPM, some power and torque up top.
Thank you Dave,
I followed your build pretty closely since we seem to have somewhat similar expectations from our vehicles. I think you have a solid plan and like the direction you take. I have the Kooks 1 7/8" merge collector headers. I'm sure the 2" would be better but I'm going to be broke for a while so they will have to do for now. I still have suspension and freshen up, the rear and transmission and torque tube and motor mounts.....and more and more. Haha!
I followed your build pretty closely since we seem to have somewhat similar expectations from our vehicles. I think you have a solid plan and like the direction you take. I have the Kooks 1 7/8" merge collector headers. I'm sure the 2" would be better but I'm going to be broke for a while so they will have to do for now. I still have suspension and freshen up, the rear and transmission and torque tube and motor mounts.....and more and more. Haha!
Yes, to run seriously with the Z's is lots of $$. I just play, not compete seriously, and it's still $$ but I really like have a car with these capabilities and then using them fully. I am running Faberge billet engine mounts. I noticed bringing the car home from CPR yesterday that I get a nice hands massage, none of that in our other two cars with electric power assist steering!
Mine peaks at about 5k and falls off noticeably after 6k rpms. Otherwise it pulls hard everywhere. The K501, BTR 3 and Titan 3 by Cam Motion were three I narrowed it down to before having Pat at the Guerra Group spec me one. Surprisingly, the cam he came up with has very similar specs to those three and essentially identical overlap-18.
I just plugged that Titan 3 camshaft into the desktop dyno and it performed like a K501 shadow. It was right there the entire torque and hp curves. 2 avg hp and 2 avg torque within each other. If I were using a heavier exhaust valve with moldstar 90 guides I think the Titan 3 would be the better choice. With the titanium exhaust valve I feel the K501 is the better choice. Again, this is just a Desktop Dyno induced guess and there are so many other factors to consider.
Yes, to run seriously with the Z's is lots of $$. I just play, not compete seriously, and it's still $$ but I really like have a car with these capabilities and then using them fully. I am running Faberge billet engine mounts. I noticed bringing the car home from CPR yesterday that I get a nice hands massage, none of that in our other two cars with electric power assist steering!
Now that is getting the total "feel" for your car!!!
They do have a lot in common and all three perform within 3 avg HP and 2 avg Torque of each other on the Desktop Dyno. I think it comes down to personal preference. All three suppliers(designers?) of these camshafts provide great products, fantastic customer service, and are very helpful on the phone.
I'm a spreadsheet geek and love to calculate things. I like the K501's higher intake lift which calculates to a slightly higher choke rpm using this calculator: http://www.wallaceracing.com/machcalc.php
I do realize the other BTR3 and Titan 3's slightly longer intake duration totally equaled things out. The lesser duration of the K501 might be the make or break if piston to valve clearance becomes a potential issue.
Last edited by MickVette; 10-26-2018 at 09:39 AM.
Reason: correction 113 K501, addded info
They do have a lot in common and all three perform within 3 avg HP and 2 avg Torque of each other on the Desktop Dyno. I think it comes down to personal preference. All three suppliers(designers?) of these camshafts provide great products, fantastic customer service, and are very helpful on the phone.
I'm a spreadsheet geek and love to calculate things. I like the K501's higher intake lift which calculates to a slightly higher choke rpm using this calculator: http://www.wallaceracing.com/machcalc.php
I do realize the other BTR3 and Titan 3's slightly longer intake duration totally equaled things out.
See, and I prefer the lower lift numbers of the BTR3 and Titan 3 because if I'm using the OE rocker Arm's, I'll have less degradation of the wipe pattern with those two versus the K501. If the Titan 3 was a shadow of the K501, and that power band was the most attractive to me...I personally would go Titan 3. Just my 2 cents...
Great thread but also depressing to see that almost anyone that checks their "fixed" heads after 10k miles needs to do a rebuild. Seems like there really isn't a true fix yet...
Great thread but also depressing to see that almost anyone that checks their "fixed" heads after 10k miles needs to do a rebuild. Seems like there really isn't a true fix yet...
there is...katech (wcch with katech spec valves) or ahp.
10-23-2018, 08:03 AM
Time for valve guides, and a few upgrades while I'm in there
