mopar performance red valve springs with stock 340 camshaft

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dbphemi

dbphemi

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Hear is a question i haven’t seen asked. I’m putting back together my mostly stock 340 engine out of my 69 swinger 4 speed . back in the 90s it had the mopar 292/508 cam with the recommended mopar red valve springs installed. i cannot recall the part number. I am planning on putting the stock 69 cam or possibly the regrind of the 68 4 speed cam. Can i use the mopar springs or should i purchase replacement springs? They do not have many miles on them but they are close to 30 years old .
 
You can get a new set of Comp 901-16's that should work nicely with that stock-ish cam for less than $80. I wouldn't mess with the old ones. They are stronger than needed and potentially questionable after sitting for so long.
 
I guess i’m willing to take a chance on springs because they were made in the usa back when aftermarket parts weren’t crap, lol.
 
I can’t find any info on the spring rates but i know they were much higher than stock. the engine easily hit 7000 rpm with these springs. i have to admit there is some sentimental attachment to them lol.
 
The DC/MP part# is P4120249, a direct replacement for the H.P.340 unit, p/n 2863439.
Spec. is 70# minimum at stk. installed ht.,
260# at .500" lift, rate is 386#/inch.
The 901 Comp spring specs are;
~90# minimum at stk. installed ht.,
260# at .500" lift, rate is 353#/inch.
The key with the Mopar units is to be sure the installed hts. are tight enough to achieve the seat load of 70-75#, shimming if needed. If those springs haven't gotten rusty or run overheated, & pass the load check they'll be fine. The Comps having a longer wire with less rate offer more seat load, by about 20#, for what You're doing either is fine.
 
Killer6 said:
The DC/MP part# is P4120249, a direct replacement for the H.P.340 unit, p/n 2863439.
Spec. is 70# minimum at stk. installed ht.,
260# at .500" lift, rate is 386#/inch.
The 901 Comp spring specs are;
~90# minimum at stk. installed ht.,
260# at .500" lift, rate is 353#/inch.
The key with the Mopar units is to be sure the installed hts. are tight enough to achieve the seat load of 70-75#, shimming if needed. If those springs haven't gotten rusty or run overheated, & pass the load check they'll be fine. The Comps having a longer wire with less rate offer more seat load, by about 20#, for what You're doing either is fine.
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thanks!
 
The DC/MP part# is P4120249 or the original 340 valve springs are very good. If you have them tested, they will probably still be within spec. I run used ones all the time, without problems.
 
i appreciate the help. this motor has been in storage for long time . It wants to run again!

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512Stroker said:
If the heads were stored off the engine as shown in your pic's I would not hesitate to reuse the springs. I would be alot more concerned if some springs sat compressed for a long period of time.
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they were on the block with no valvetrain to keep crap out of the cylinders. There hasn’t been any valvetrain since it wiped out a cam lobe in the late 90’s .
 
dbphemi said:
they were on the block with no valvetrain to keep crap out of the cylinders. There hasn’t been any valvetrain since it wiped out a cam lobe in the late 90’s .
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That’s good for the springs. Now why did the cam wipe a lobe out? May want to have the lifter bores checked and the side of the lifter shaved for oil…
 
dbphemi said:
I guess i’m willing to take a chance on springs because they were made in the usa back when aftermarket parts weren’t crap, lol.
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Why in the world did you ask for advice when your mind is already made up?
 
RustyRatRod said:
Why in the world did you ask for advice when your mind is already made up?
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asking for advice on if the springs work with stock camshaft, i know the springs are old because i put them on the engine. It also has stock valves too. If they won’t work with stock cam i will replace them. I really don’t want to replace chrysler parts with chinese parts if i don’t have too. i’ve been having a lot of problems with aftermarket parts i’ve bought for this car.
 
Scody21 said:
That’s good for the springs. Now why did the cam wipe a lobe out? May want to have the lifter bores checked and the side of the lifter shaved for oil…
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cam wiped out a lobe because a “missing “ coil terminal nut fell into the distributor hole when changing out to an electronic distributor and hit a lobe when the engine was running. luckily it just messed up the cam. i found the half chewed up nut when pulled the intake off to figure out why the lifter was ticking. dropping nuts in your motor is a bad idea , i don’t recommend.
 
dbphemi said:
asking for advice on if the springs work with stock camshaft, i know the springs are old because i put them on the engine. It also has stock valves too. If they won’t work with stock cam i will replace them. I really don’t want to replace chrysler parts with chinese parts if i don’t have too. i’ve been having a lot of problems with aftermarket parts i’ve bought for this car.
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Well lemmie ask YOU a question. Are the red springs single springs? If so, I'd run um.
 
there have to be quality springs made now , can't all be crap . I'm goingto rebuild my 1970 340 that has been sitting for 12 years engne has maybe 15,000 miles Ill have the springs checked if they are not close to perfect new springs it is , not like they are 100.00 a spring am replacing the cam as well with a comp cam 20-227-4 i think , nothing to radical.
Good luck with your 340 even stock they pull hard
 
Nat said:
there have to be quality springs made now , can't all be crap . I'm goingto rebuild my 1970 340 that has been sitting for 12 years engne has maybe 15,000 miles Ill have the springs checked if they are not close to perfect new springs it is , not like they are 100.00 a spring am replacing the cam as well with a comp cam 20-227-4 i think , nothing to radical.
Good luck with your 340 even stock they pull hard
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I’m most worried about the cam lifter issues everyone is having. my engine had less than a 1000 miles put on it before it went into hibernation. I’ll have everything checked by a machine shop before i put it back together.
 
dbphemi said:
I’m most worried about the cam lifter issues everyone is having. my engine had less than a 1000 miles put on it before it went into hibernation. I’ll have everything checked by a machine shop before i put it back together.
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i just had one of my 340 built no problems with cam or lifters , yet no miles jut dyno runs so far we will see in 2 weeks maybe it is sub par buidlers having trouble ? out of 20 builds so far have not seen any problems at my friends shop unless you count driver stupidity
 
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