dsljunkie

Well I was doing a valve job on the truck ( last thing before the motor goes back in ;D) and I found out that I need ALL new valves :'(. My exhaust valves are bent and my intakes are getting marginal in thickness >.
First question: Where can I get a set of valves and is it worth going with something like titanium?
Second question: I talked to a friend who builds NHRA 1,500 +hp motors and he says I should under cut the intake to 20* and the exhaust to 30*. Has anyone done this? He tells me it will make everything flow better and dissapate heat better as well. He is a very reputible guy (several national championships have been won on his motors) and he is definately NOT trying to rip me off. I was just wondering if anyone had had any success with different grinds?
Thanks
Scott

thumper 549

what i do know is, What works in the world of racing dose not always to a lot not work out in the world of endurance. The gearheads have pit crews and endless amounts of $$$to fix replace or what ever.
so did i ans you question NO. in the world of diesel its a diff. world then gas...and its aLLLLLL a world of compromise. if you use a wide seat it cools the valve better but the seal is not as good and verse a visa...Now,, going way out here to the land of my opinion " I do not think you would be able to tell any diff. on a dyno or any other way if your seats were cut at 30 and 45 which i think there sopposed to be as oposed a much steeper angle to increase the flow and maybe swollow a valve. If you gained 20 hp and swollowed a valve in the next year- was it worth it??' I am sure you can order up valves out of any materal you want from race world some where.

Rolngthun

Most any good machine shop can help you out. It is very common now a days.
He is not referring to changing the main angle. He is refering to a multy angle job. Remember in the old days people talking about a 3 angle valve job? Well, now racers and performance guys use many angles.
It won't effect the longevity of your valves, unless they really mess up the machine work. You won't be able to feel the minute gains.
My concern would be; how did it bend the valves?

Mexstan

I agree with Rolnthun. I would first try and find the cause of the bent valves. I admit to not having experience with changing valve angles on a "normal" diesel day runner, but what experience I do have would make me very leery about changing the valve angles. My gut feel is to go with the factory angles. Any gains will probably be more theoretical than actual and then they could be offset by mechanical problems later.
If you do decide to change the valve angles please report back later and let us know the results, both good and bad.

JKE

which part of the valve is bent?

do you know what the angels are now? FYI - Be aware that both valves have underhead flats. the intake is 60 degree seat and the exhaust is 45. underhead design (intake valve) is usually dictated by the motor manufacturer due to intake design (air). I would be sure you know what you are doing.

Thin margin will lead to catastrophic failure and is a result of being reworked too many times or too much one time. This is also effecting your gauge to tip specification, web thickness and spring preload. You only have 0.005" worth of rework before you are out of specification. A certain seat surface finish must be maintained also.

Just letting you know, BE VERY, very careful. :-X

FWIW

John

ramguy

Multi angle Vave jobs;
Reduce the seal area to insure a good seal and is the primarary reason behind multi angle valve jobs. The problem with that is you have a much higher Pound/Sq. In. and this multi angle grind produces thinner edges on the valve which creats hot spots "burned valves". In summery the higher psi and the heat take away from the longevity of the valve job, "more frequent maint.".RACING!

ramguy

DF5152

y did u rebuild the engine in the first place?

dsljunkie

Ive heard a lot about multi-angle valve jobs and this is not what he is talking about doing. He is gonna go in and cut the valve seat in the head and match the angle on the valves.
By the looks of the exhaust valves its not hard to tell that they have been real hot. The stem on each ex. valve is discolered ( like a rainbow) at the base. They have not been seating right for a long time . I attribute most of this abuse and heat to the trucks previous owner, who by the way is the reason for my whole rebuild >.
The bottom part of the stem where the discoloration is, is where the valves are bent. The valve angles are: intake= 30*, exhaust=45*.
I am replacing my stock valve springs (both intake and exhaust) with the heavy duty springs for the 4k kit. These springs are longer so there is no need to worry about being a little out of spec.
Thanks for all the input guys 8). Im in the process of looking around for a set of valves so Ill have to see what I can come up with there. Right now the best price Ive found on a set of valves is ~12$ a piece. If I can come close to that price for a set of stronger valves from somewhere else Ill probably go with that.
BTW: I was very concerened with cratering a valve and that is the reason for going with all new valves. It would be awefully silly to go in this deep and waste it all on a 12$ valve . I have been assured that the .001 that will be taken off of the base of the valve will not effect is durrability 8), because that was the first thing that came to my mind as well.
Thanks again,
Scott

DF5152

well the old owner could ahve floated the valves and hit a few pistons. dont think the heat alone would do this unless he was over fueled and running way above max EGT. but this is not a common failure/problem.

thumper 549

valves are the major part of the eng and replacing them is not a bad idea.Be happy they are not porsche valves at 30.00plus per valve.
I guess i went off on the deep end at the top here ..you can multi angle all your surfaces away into a nice radi and not hurt anything (not your seal angle).
Most diesels like sodium valves-they carry away the heat to the guide better. Titain valves might take the heat better like s.s. but the transfer is not as good....the long term out come is I do not know

Mexstan

dsljunkie, the first thing that came to mind when you said that the valves had obviously not seated right for a long time was a problem with valve clearances. Do you know if the valves had proper clearance before you dismantled it? Is there any crud on the valve stems to hold them open? Also if the valves were held slightly open for any reason that would have degraded performance. The fact that the valves were held slightly open could I suppose have contributed to the overheating of the stems and also maybe if they got hot enough to cause softening of the metal, they could have got bent. But that is just conjecture.
I would still suggest that you think twice, no three times, before you consider changing valve angles. Just remember, these engines go for hundreds of thousands of miles and to my knowledge valve problems are way below average. In other words, if it ain't broke, don't try and fix it.

JKE

OK, valve seat insert...this could be ok if done properly. There are several different designs and I do not know which one we have. Some already have the second or taper angle and some have a venturi design. You have the angles correct. REPLACE all valves.

You had me worried when you stated the intake valve thickness was marginal. Sounds like you are fine with new valves.

Buy the valves from Cummins. These would not be aftermarket which will have wider tolerances than the ones you purchase from Cummins.

Hope this helps and things work out for you.

John

JKE

Getting new stem guides too right?

maybe a good idea.

John

dsljunkie

Ok... I talked ot my guy today and I got it all figured out . The intake and exhaust valves are the exact same as valves from a small block Chebby. So.. Im going with Manley intake valves and Fearra Special alloy for the exhaust. The Fearra are a very high quality valve and are made for tubo and super carged motors with nitro and beyond , so I figure these valves are way better than anything I could get from Cummins at about the same price 8).
Also: I was mistaken when I said he was changing the angle of the valve seat :, my appologies :-[. What he is going to do is back cut the valves and the head to match 8).
Thanks again
Scott

thumper 549

Well I do not want to sound like a knocker,but most of these eng. will out last a gasser valve job by 2 to 6 times...how do you improve on that????????
Like I said sodium think sodium think sodium -anyway let us all know how it all turns out and how much more torq. and hp. you get by doing this.
personaly I am not seeing the benifits ...yet??
P.s. what or did you do anything diff to your piston cooloing jets??