340 X Head Valve Options

[SheSaid]

Hello FABO,

Getting ready to pull the heads off a 69 340 motor with stock original X Heads and I wanted to rebuild the heads to go back on the motor with a 400-425 HP street/strip target. I wanted to take my time, do it right, and employ all the tricks of the trade to get the most out of this motor. Had a few questions about valves, valve jobs, and eventually some street porting.

Let’s just start with valves

1. Has anybody had any experience cutting a 30 Degree face angle like in the below Mopar Muscle article?

http://www.moparmusclemagazine.com/techarticles/engine/mopp_0001_360_engine_head_porting/index.html


Now, I know the stock tulip valves will not work, but I was considering changing the valves anyway to a flat head style with 5/16 guides like brand X guys use. The article says that you can only do this if you are changing the valve size, so if I go from a 2.02 to a 2.05 would that work? Also I plan on installing hardened seats so would that allow me to switch to the 30 degree angle?

2. Assuming I could cut a 30 degree angle on the valve seat, what would be a good flat head style 5/16” stem valve? I would like to run a solid cam with adjustable 1.6 rockers and still fit under stock valve covers, so would I need a valve longer than the stock unit cut the stem to the same install height? I was thinking like something below:

http://www.summitracing.com/parts/PAR-8483/

Now I know changing from a tulip to a flathead valve will increase compression. Also the 5/16 stem would flow better than stock tulip 3/8 stem. Would there be any other advantage? And does anybody think for a 400 hp target is all this worry about the valves worth it? Or should I just get a traditional 3 angle job at 45 degrees and reuse the stock valves and get on with the next step in the build...

Thanks All!

 

[1wild&crazyguy]

Hello FABO,

Getting ready to pull the heads off a 69 340 motor with stock original X Heads and I wanted to rebuild the heads to go back on the motor with a 400-425 HP street/strip target. I wanted to take my time, do it right, and employ all the tricks of the trade to get the most out of this motor. Had a few questions about valves, valve jobs, and eventually some street porting.

Let’s just start with valves

1. Has anybody had any experience cutting a 30 Degree face angle like in the below Mopar Muscle article?

http://www.moparmusclemagazine.com/techarticles/engine/mopp_0001_360_engine_head_porting/index.html

Now, I know the stock tulip valves will not work, but I was considering changing the valves anyway to a flat head style with 5/16 guides like brand X guys use. The article says that you can only do this if you are changing the valve size, so if I go from a 2.02 to a 2.05 would that work? Also I plan on installing hardened seats so would that allow me to switch to the 30 degree angle?

11/32 +.100 over standard small block chevy valves are a common upgrade and the valves are cheap. The guides 'since already needing done' will be changed to a bronze press in style ..and NO u do not have to go bigger than the 2.02 head diameter u have now. As for the 30% seat angle , that is supposed to fatten the low lift numbers from actually giving more area between seat/valve at the same lift as a steeper 45* cut...but they say a 30* seat does not last...i think from the way it's hammered with a poorer cleaning ability in comparison to a 45*..so it go's away faster. something to google...i remember pontiac liked to use 30* cuts.lol

2. Assuming I could cut a 30 degree angle on the valve seat, what would be a good flat head style 5/16” stem valve? I would like to run a solid cam with adjustable 1.6 rockers and still fit under stock valve covers, so would I need a valve longer than the stock unit cut the stem to the same install height? I was thinking like something below:

http://www.summitracing.com/parts/PAR-8483/

Now I know changing from a tulip to a flathead valve will increase compression. Also the 5/16 stem would flow better than stock tulip 3/8 stem. Would there be any other advantage? And does anybody think for a 400 hp target is all this worry about the valves worth it? Or should I just get a traditional 3 angle job at 45 degrees and reuse the stock valves and get on with the next step in the build...

Thanks All!

The tulip vs nail head has to do with the underhead of the valve, the factory used a tulip...and the other manufactures as well as after market used the nail head. Less valve under head equal more bowl volume in a way and is lighter weight, just to start.

 

[1wild&crazyguy]

something i forgot about the 2.02/2.05 valve idea 'but was enlightened by a friend' , how many valve jobs have these heads had?

Would you be ok with doing hard seats on the intake as well?

 

[SheSaid]

I was actually thinking hardened seats on both, just to be safe. So yeah a 2.05 would still fit I would think. I am just really curious if this 30 degree face angle can be done. Supposedly its better than the 45 degree angle at low lift, which I am thinking about topping this thing off with the Eddy Air Gap and want the broadest average torque curve I can get and still build a valve train that can handle 7k rpms.

I have seen some 2.05 nail head valves but none of them are the stock mopar length... a stock chevy is too short, the plus .100 is too long. Would that throw off my rocker geometry? How easy is it to cut the stem to length?

Thanks wild&crazyguy, I was hoping you would chime in on this...

 

[SheSaid]

Oh and I am almost 100% sure these heads are cherry, but will find out soon this weekend

 

[66fs]

As I understand it, generally, 30 degree seats flow better at low lift and 45 degree seats flow better at higher lifts. Pontiac used 30 degree seats from the factory but was generally a low RPM torque monster.

 

[1wild&crazyguy]

I was actually thinking hardened seats on both, just to be safe. So yeah a 2.05 would still fit I would think. I am just really curious if this 30 degree face angle can be done. Supposedly its better than the 45 degree angle at low lift, which I am thinking about topping this thing off with the Eddy Air Gap and want the broadest average torque curve I can get and still build a valve train that can handle 7k rpms.

I have seen some 2.05 nail head valves but none of them are the stock mopar length... a stock chevy is too short, the plus .100 is too long. Would that throw off my rocker geometry? How easy is it to cut the stem to length?

Thanks wild&crazyguy, I was hoping you would chime in on this...

If you do the hard seats on the int...then u can stay with the 2.02 'if u want'
The concern about that was that if the heads had been recon'd already and more than once with a 2.02.. that another new seat cut for a 2.02 would be sinking the valves, which with these heads and others..'hurts flow'

The +.100 chevy valves are fine, they will need a rocker arm,shaft, and will have to cut stem height down till the wear/sweep pattern is correctly narrow/centered, the problem starts when u need more than 1.80 installed spring height with standard shaft location 'and that usually comes by means of pop up locks/retainers'...at that point 'without machining down spring pads/seats' u end up with the stem at or below the top of the lock..lol
I ended up at 'i think it was' 1.78 installed height max and went with shims to just be at 1.75 and used standard manley retainers and locks. I ran 1.80 with pop ups before, but it takes just the right seat depth for the valve's lock grooves to be just right so that u can use the pop up locks and still get very close to the center/narrow sweep pattern on tip.

 

[SRT_DSTRHOLC]

I have some 1.92 valves if your interested just a FYI.

 

[cudamark]

With the horsepower goal you have, I would use the factory valves and specs and spend the money you saved somewhere else. If you're trying to squeeze every HP out of it, that would be a different story....but then....with max HP as a goal, I would get some aluminum heads for it and have them worked.

 

[SheSaid]

Pulled the heads, intake, and carb today. Came across a surprise. A broken retainer! This could have been really bad!

Also found double valve springs??? not sure if I am going to reuse these...

Tons of oil residue in every chamber. I think the rings are shot.

 

[66fs]

Looks like aluminum retainers. Throw them in the recycle bin. It also looks like they were hitting the rocker arms. Get some new steel retainers and locks. Then double check everything. I bet he was down on power for some reason...

 

[1wild&crazyguy]

ur burning oil too.

scrape the pistons before assembly, the guides in those heads must be pretty shot to hell.

 

[pishta]

3rd pic looks like your chambers are about an inch deep! Its only the head gasket that gives that effect. The "double" springs you mention are probably just spring dampers , every 340 head I have seen has had them. Exhausts get the hardened seats, intake is not an issue. Have you looked into 7mm magnum valves? Do they make a 2.02? Or even back cut Manley valves?

 

[70aarcuda]

you can use chevy valves...2.02 +.100 and 1.60 +.100 11/32 stems...

also if you want to go oversize...2.05 and 1.625 both +.100...

 

[moper]

For what you are doing, the 30° seat is a waste of shop labor. And you wont get a 30° seat to run that great at high rpms becuase the valves tend to bounce. Least, that's what I'm told. 400hp is your goal. Have the heads done, stick 2.05" intakes in there so you're not worrying about seats, and you'll have just as much flow area from .000 to .050 as the 30° seat give you for a lot less money and I'll give anyone $100 if they take it for a ride and say it's sluggish from "too large a valve". Those heads with a hydraulic cam and real compression can make 400hp with no porting or mods at all. Least that's my opinon anyway.

 

[SheSaid]

3rd pic looks like your chambers are about an inch deep! Its only the head gasket that gives that effect. The "double" springs you mention are probably just spring dampers , every 340 head I have seen has had them. Exhausts get the hardened seats, intake is not an issue. Have you looked into 7mm magnum valves? Do they make a 2.02? Or even back cut Manley valves?

Yeah the gasket was just coming off the head.

I have not found the 7mm magnum valves. I was looking at a few used NASCAR valves. They are also 7mm, but i guess the way they are made they need replaced often. Racing parts are not street parts.

 

[SheSaid]

For what you are doing, the 30° seat is a waste of shop labor. And you wont get a 30° seat to run that great at high rpms becuase the valves tend to bounce. Least, that's what I'm told. 400hp is your goal. Have the heads done, stick 2.05" intakes in there so you're not worrying about seats, and you'll have just as much flow area from .000 to .050 as the 30° seat give you for a lot less money and I'll give anyone $100 if they take it for a ride and say it's sluggish from "too large a valve". Those heads with a hydraulic cam and real compression can make 400hp with no porting or mods at all. Least that's my opinon anyway.

Yeah Moper, the more i dig into this whole 30 valve face thing the more i am moving past it. Same problems raised here, flow well at low lift but do not seat well at high rpm or flow well, also weaker.

Currently I have cooked up another idea. It is a little out there so I want to check a few things before posting and looking like a total a$&.

 

[SheSaid]

you can use chevy valves...2.02 +.100 and 1.60 +.100 11/32 stems...

also if you want to go oversize...2.05 and 1.625 both +.100...

The Chebbie valves are on the table. But I want to try something different...

 

[SheSaid]

Took the heads apart. Looks like one of the sources of the oil consumption were these stem seals.


View attachment 2012-02-29 20.05.08.jpg

Also found that the “double springs” are actually double springs. These are not the stock 340 springs are they? The have a main spring, a damper, and then a second spring.


View attachment 2012-02-29 19.44.45.jpg

The retainers are all junk. Again, this could have been bad.


View attachment 2012-02-29 20.33.49.jpg

Also, looks like these heads have been off the car, maybe a cam swap. There were shims under the springs and the stem seals are different than stock ones I have seen in the past. Does not look like a valve job was done before though.


View attachment 2012-02-29 20.34.14.jpg

 

[SheSaid]

So I may have stumbled on a way to get bigger, lighter, stronger valves in my X heads. They are also cheap, very cool, and not Chebbie.


HEMI VALVES!!!


View attachment hemi_6_1_srt.jpg


I bought a brand new complete valve set on ebay for a 6.1L Gen III HEMI. The set costs less than $100 after buying multiple sets with a friend. That is less than $100 for brand new intake, exhaust, springs, retainers, locks and seals! It’s worth a shot!


So valves are valves, and springs are springs. Turns out the new 6.1L HEMI valves are very similar to stock X head valves, and stock 6.1L HEMI springs are very similar to Comp Cams high performance springs used for big lobe cams. And they look great!

 

[SheSaid]

Stock Tulip Intake Valves


Length: 4.9815”
Head Diameter: 2.0185”
Stem Diameter: 0.3735”
Weight: 136.2g

 

[SheSaid]

Hemi Intake Valves


Length: 4.9650” -0.0165
Head Diameter: 2.0755” +0.057
Stem Diameter: 0.3130”
Weight: 87.9g

 

[SheSaid]

Stock Tulip Exhaust Valves


Length: 5.0110”
Head Diameter: 1.6145”
Stem Diameter: 0.3400”
Weight: 105.7g

 

[SheSaid]

Hemi Exhaust Valve


Length: 4.9220” -0.0890
Head Diameter: 1.5960” -0.0185
Stem Diameter: 0.3120”
Weight: 79.6g

 

[SheSaid]

Stock Retainers: 11.7g
Hemi Retainers: 8.6g

Stock Locks: 3.7g
Hemi Locks: 2.2g

Stock Springs: 104.6g
Hemi Springs: 99.8g

Total Stock Weight: 361.9g
Total Hemi Weight: 275.9g


Nearly 24% lighter.