valve, valve spring, retainer info

[dwg86]

I just wanted to pass along some info on valvetrain parts. I found my valve stems and guides were worn when I disassembled my junkyard 7120 head. So I decided to used sbc 1.94/1.50 undercut, swirl polished, EPN stainless valves. They were a lot cheaper than the mopar performance valves. I got them off ebay for around $60.00 (set of 6). Feedback was very positive about the quality of the valves (do a search on EPN valves). They are also the same length as the stock valves. Since they are 11/32 I just need to have the guides enlarged. I did notice the lock groove in the sbc valves is lower than the stock valves. I don't know how this is going to effect the spring installed height yet. I can get some locks that are +.050 if needed. Hopefully I won't need to have the the valve spring pockets machined.
I am using the Mopar Performance valve springs p/n P5249464 ($6.99 a piece from advance auto parts). If you go to advanceautoparts.com, click on "online shopping", and then enter P5249464 in the part search. It will show the price. You can also use this for price matching if you prefer shopping at Jegs or Summit.
I did some searching for valve spring retainers that would fit the 5249464 MP springs and 11/32 valve. Comp cams p/n 747-12 works... O.D. 1.400/ first step on retainer 1.050. The mopar springs are 1.420 O.D./ 1.050 I.D. on the outer spring. It fits great! Also these are 10 degree retainers. I will be taking my head to the shop soon to have the intake valve throats opened up to fit the 1.94 valves. Then I will do some porting, and then back to the machine shop for valve job and setting up the springs. I will let you guys know how this combo works when I am finished.

[kris]

Thanks for the info.


A search at Advance comes up with "no items found".
That is a good price, I think you got lucky.


k.

[dwg86]

I just checked advanceautoparts.com and it worked. You have to hit shop online. Another widow should open. Type in p5249464 in the search block. It shows $6.99, shipped in 3 days. I used this after I bought my springs from Jegs. I called Jegs and told them how to see the price of the springs.They matched the price and refunded me the differance.

[kris]

Much better, thanks !

k.

[seanyb505]

My machine shop advised against those springs, as they had double the recommended seat pressure for the 4.0.

[SilverXJ]

The MP 5249464 Springs? No they don't. At 1.64" they are only 113 lbs with a rate of 270

[gradon]

They would be the first springs I would consider for a cam w/ lift above .43"

[seanyb505]

Maybe I got shipped the wrong springs, but when they tried to install them they were way too stiff.

[SilverXJ]

Do you have the numbers he came up with?

[dwg86]

I bought the mopar springs because I felt the crane and comp cams recommended springs had too much spring pressure. I haven't had them installed yet. It's going to be a while before I do, but I will post the installed spring pressures.

[oletshot]

The MP 5249464 Springs? No they don't. At 1.64" they are only 113 lbs with a rate of 270

I don't know what the actual stock spring is rated at, but Sealed Power VS822 stock replacement valve springs are rated at 66lbs at 1.625" closed height. So the Mopar springs aren't quite twice the pressure but are close.

[dwg86]

The stock springs are rated at [email protected](installed), and [email protected](open) as per alldata.com. Averaged out would be [email protected] on the seat and 190lbs [email protected] lift(1.64-1.216=.424). So the stock springs are rated at 295lbs/inch. Crane recommends 96803 springs for their cams([email protected], [email protected], spring rate 330lbs/inch), and comp recommends using their 926 springs([email protected], [email protected], 415lbs/inch). So using the stock .424 cam lift as the standard, the spring rates would be as follows...
Stock [email protected]
Mopar [email protected]
Crane [email protected]
Comp [email protected]
If we increased the valve lift to...lets say .480, the results would be...
Stock [email protected]
Mopar [email protected]
Crane [email protected]
Comp [email protected]

Now me, personally, I liked the little higher seat pressure of the mopar springs with the lower open pressures, as well as stock 1.64 installed height. Also good for up to .525 lift and smaller diameter to fit closer to the original spring seat diameter. The mopar springs can be installed with no additional machining, because they have the same installed height as the stock springs. I think the Comp cams 926 spring rate is too high, especially for the cam wear problems that people have been having.

[SilverXJ]

The 2000 FSM says the stock springs are 71-79 lbs at 1.64 closed. 202-218 lbs @ 1.216 open.

[oletshot]

1994 FSM says stock springs are 81-89 lbf at 1.64" closed and 190-210 lbf at 1.216" open.

I'm wondering where the stock lift of .424" comes from? I've seen it referenced many times but my FSM says .253" lift at the cam and .405" at the valve and my micrometer confirms the .253". Just curious.

Seems to me, if your not sure if your valve lift warrants heavier springs, start with the stock springs (if all the spring pressure #'s are correct, worn stock springs may have more pressure than the Sealed Power replacements). If they float, it wouldn't be hard to put in the Mopar springs.

[dwg86]

The stock spring data I got from alldatapro.com. I used 1997 Jeep Wrangler. I just checked alldatapro.com for 2000 Jeep wrangler spring and cam specs. For the 2000 Wrangler it shows springs [email protected] and [email protected]. It shows cam specs as .4075 ex lift and .4145 intake lift. I got the .424 lift from the installed valve height 1.64, minus the open spring height 1.216 = .424. My mistake on the stock cam lift being .424. But using the formula, spring rate x valve lift + installed spring rate = open pressure....the calculated open spring pressures at .424 and .480 are correct. You can use that if you want to know spring pressures for any cam that you install. Given only open and installed spring rates you can still calculate spring rate...example [email protected] closed, [email protected] open. 1.64-1.216=.424 and 190lbs-65lbs = 125lbs. So the spring rate increased 125lbs for .424inch. 125 divided by .424 = 294.811...rounded up=295. You can check your math... spring rate x valve lift + installed spring rate = open pressure... 295x.424=125.08 125+65=190. That matches the installed [email protected] and open [email protected].