Valve Train ?? More Dang??s

[SLESTAK75]

Just looking for opinions. It seems Uncle Sam may be feeling VERY generous this year (at least for me) So I am wondering what the consensus is on valve train. With larger cam would it be better to upgrade to stiffer springs or go for lighter Stainless Steel valves and Titanium retainers? I'm leaning toward the SS and Tit.
What say you??? And I have the A12 cam

[Masteryota]

Its really a give and take with valve train, stiffer springs will use some more power to overcome the pressure, but lighter valves almost require them, as it will rev a little higher than stock and you don't want any valve float at that speed either. Make sure you get under cut valves, as they will flow better and compliment your other mods. One thing to consider, is a 3 or 5 angle valve job, by a GOOD machinist, many machine shops claim they can do them, but I wouldn't trust most of them. If you are going this far, you might also want to wrap your head pipe with some header wrap to maximize scavenging effect off the exhaust valve. All this said, you might see a 5-10% increase in overall power and might want to consider a bigger carb, if not already done.

Of course, all this is in theory, and if applied incorrectly, can cause an adverse effect on power increase.

[bear]

Yea I hear ya "75" I might have a favorite "uncle" this year too!!!

[xlint89]

Not really needed unless you're riding around redline alot. And if that's the case, then all of the above would be a good suggestion.

[SLESTAK75]

I still have the stock CDI and I don't know if it has a limiter or not as my engine seems to rev pretty darn high and I have never noticed any sort of limited feeling. If it is limited I intend to keep it that way as I'm pretty happy with it as is. Had thought about a new CDI for the advance (run some higher octane) and just don't over rev it. Thanks for the feedback.

[Masteryota]

IMHO, I would upgrade the coil and CDI unit before doing anything else, there are CDI's out there with adjustable rev limiters and advance as well, but they will be pricey. If you do all the internal work and still run stock ignition components, you will be limited by them. Spend some change on a CDI first, and see how that feels, and a good coil as well, if not already done. Most of the reputable CDI makers limit the RPM to what they see as safe operating speeds, the cheapo chinese units may not have any of that.

[SLESTAK75]

Definitely already planned on getting coil and CDI. As well as UNI filter. I've already opened up the exhaust a bit. I was looking at the cheap Chinese CDI's but perhaps I will spend a bit more and get one with an adjustable limiter. So Master. Any opinions on the Valve Train?? I know that the whole package would be best but I will have to choose due to funds. I'm of the opinion that stronger springs will be harder on the valves, seats, rockers and all that good stuff; whereas, the lighter valves and retainers would allow the stock springs to do their job more effectively and actually reduce the strain on the previously mentioned parts.

[Masteryota]

Well, xlint said it best. opening up the valve train potential really only has a big effect on higher revving engines, and I think the safest on a GY6 is about 9k RPM. The biggest gain, would be from under cut, lighter valves. Lighter valves will free up some power, but if they are the stock size and cut, then they won't flow any better than stock. The racing head in your sig line, is it a 2 valve or 4 valve head??

Either way, it is imperative to get a 3/5 angle valve job done with new high performance valves, or they might not seal. No one thinks it will make a difference, but I have seen a few builders focus more on the valves and valve seats over the cam/head/rockers/ports, and they all have some of the strongest running small blocks I have ever seen, and they stay that way.

If I had to pick one over another, I would say valves for sure. Keep in mind, most of these mods result in increased air flow, and will require rejetting. Just the uni filter alone requires a bigger jet, so keep that in mind for your budget, too.

[Masteryota]

I would just like to add, I want my W-2 dangit!!

[SLESTAK75]

I think that because I'm not gearing the build toward a high revving engine I'm going to keep the stock valves and springs and put the titanium retainers in more for security than anything. And I have been trying to see if Kliff is still offering the big tamale. If he does not I will get a local machinest to do port polish and valve job. Thanks for all the input. The head on mine is the 2 valve big port.

[xlint89]

Tom Syc is really known for doing very good head work. Give him a shout.

[SLESTAK75]

Okay. Ill do that.