valves

[amcinstaller]

ok, ive heard people are using the sbc 2.02 and 1.97 valves in the heads of their strokers. i have a few questions about this:

1. i was researching on summit racing and see that the sbc valve stems are about .002" skinnier and 0.056" shorter than the jeep style. im guessing this is nothing to worry about?

2. if someone was to use these other valves, what other adaptations should be made (different valve springs, etc.)

3. any specific heads to use for this?

[dwg86]

When changing the Jeep valves is you will most likely have to change the springs, retainers, and locks. The Jeep valve has a round groove in the valve where the lock goes, and the lock has an 8 degree angle. The valve lock groove on the Jeep valve is closer to the tip of the valve. That also needs to be taken into consideration.

For example, I needed new valves for my stroker head. I bought SBC 1.94/1.50, 11/32, undercut, swirl polished stainless valves for my 7120 head. They were a lot cheaper than buying stock Jeep valves, and I can just have to guides opened up to the 11/32 valve(saving a little money on buying new guides). They SBC valves are really close in length to the stock Jeep valves, but the grooves are lower on the valve stem. So I had to buy +.050 locks to move the retainers up on the valve stem. This puts the retainers real close to the original retainer height. I am using Mopar performance P5249464 valve springs. They install at the same 1.640 height as the stock springs. I am using comp cams 747 retainers(10 degree) and comp cams 614 (+.050) super locks.

By using Chevy valves(being LS1 or standard SBC) you will have more choices on valve springs, although some machining on the head will be required. If you stay with the stock jeep valve, the only performance spring that I know you can use will be the Mopar P5249464. Mopar performance sells an 8 degree 8 mm retainer(part number P4452032) that will fit the P5249464 Spring, and the spring installs at the stock 1.640 height as the stock spring, so no machining is required. The mopar spring is good for up to .525 lift and has a 270lb spring rate installed at 120lbs(good valve control without excessive spring rate.

I will post some pictures comparing the stock Jeep valves to the SBC valves tonight after I get home from work.
I hope this helps a little.

[dwg86]

here are some pics of the valves. If you click on the 1st picture, it makes it bigger and you can see the round groove of the stock valve compared to the SBC square groove.

DSCN2013.JPG

[dwg86]

Valves with springs. I made a mistake on my previous post. The locks are comp cam part number 614-16(+.050)

[dwg86]

BTW, those are the intake valves.(stock Jeep 1.92 vs SBC 1.94)

[amcinstaller]

alright, so if im reading this right, ill need to buy the springs to match the valve i choose, and if i choose sbc valves, i may need some machine work to the head. i guess what kind of machine work are we talking about with the sbc valves? how big of valves have people gone in the 7120 heads?

thanks for the quick response dwg! very helpful for me

[dwg86]

Well, you need to buy springs that will match the cam. But with the stock Jeep valves, you are limited on the springs that you can buy. With the stock Jeep valves having a round groove and 8mm stem, there aren't any aftermarket locks available with the round groove and 8mm stem. Also the stock jeep retainers and locks are 8 degree. Aftermarket locks and retainers are either 7 or 10 degree. If you could find an aftermarket spring that you could use the stock retainer and lock on that might be an option. I haven't found any aftermarket spring that will work. The stock jeep valve stems are 8mm in diameter. Aftermarket locks are for 11/32 or 3/8 and some for 5/16 stems.

If you are using the stock valves, the best spring to use on a performance cam for the Jeep is the Mopar performance spring(my opinoin). It installs at the same height as the stock spring. The retainers that are made for the spring are made for a 8mm valve stem withan 8 degree lock. There is no machining required to install them. They are good for up to .525 valve lift, which is good for most cams that are made for the jeep 6. And with a 270 lb spring rate...thats not too excessive for a flat tappet cam, but still would have good valve control.

If you are using a different valve...For example the SBC standard valve, the bowls will have to be opened up for bigger valves, the guides opened up or changed for the larger stems, and depending on what springs you use, the spring seats machined to accept whatever springs you use (spring diameter and spring installed height). Oh yeah...Valve length needs to be taken in consideration for proper valve geometry. You might want to talk to a good machinist to find out what they would reccomend for your aplication and pocket book.

[amcinstaller]

ok, so im thinking that i will use the comp cams 232-4 cam, so ill need to get spring pressures to match that cam, which my machinist will be able to figure out or will know. im also planning to open up the valves a little bit, so ill need to machine the valve bowls for the larger valves, (which i knew) but ill need to as well machine the spring seats to accept whichever springs end up getting used. cool, thanks!

other than that, find valves with similar stem height.

[dwg86]

Don't buy the K-kit(the one with all the springs, retainers, locks) if you decide to use the stock valves. That kit is made for the amc 258(11/32, square groove valve). I also don't like the springs that comp says to use with that cam. It has a 328lb spring rate. I think that's pretty high for a flat tappet cam(with all the cam failures). Crane cam has a pretty good instruction sheet in thier on-line master catalog for choosing a valve spring and learning about spring rate and how to calculate the open spring pressure for the lift of the cam you are using.

[jeep7081]

I know topic is old, but I used the search button

Can I get part numbers or years used?

LS1 Valves
+.050 locks
LS1 springs (installing a Comp Cam "231")

Thanks

[str8-6]

Mopar performance sells an 8 degree 8 mm retainer(part number P4452032)

Checked that part-number on Summits web-page and there it's said to be a retainer for 7 degrees locks,is that correct or has Summit scr*w*d the numbers up?