Big Block Valve Spring Help

[ykf7b0]

I have 915 big block heads and I'm looking for valve springs that would support .516 lift. I have a 484 lift hydraulic flat tappet MP Purpleshaft cam with 1.6 rockers necessitating something other than the MP 3690933 springs rated for .510 lift max. The choices are confusing to me when lift is not mentioned but spring diameter is. Thanks!

 

[lewtot184]

yep, it can be confusing. edelbrock springs can cover a lot of ground and will fit as a general purpose spring. the stock retainers don't always work well the 1.50 and larger diameter springs. installed height should be measured along with retainer to seal clearance with those iron heads. if you have single groove valves there can be more options with retainers and valve locks. be sure the locks match the stem diameter and retainers.

 

[ykf7b0]

I have Manley 10 degree retainers (23635) and Comp Cams 10 degree single groove super locks (612) with Mopar Performance 2.14 and 1.81 valves and are also single groove. I just need the springs to complete the set-up.

 

[lewtot184]

I have Manley 10 degree retainers (23635) and Comp Cams 10 degree single groove super locks (612) with Mopar Performance 2.14 and 1.81 valves and are also single groove. I just need the springs to complete the set-up.

do the edelbrocks.

 

[ykf7b0]

do the edelbrocks.

Which ones? I would like to have something that works with the locks and retainers that I have.

 

[lewtot184]

Which ones? I would like to have something that works with the locks and retainers that I have.

the ones used on the rpm heads

 

[ykf7b0]

Based on what I have found those RPM head springs have lots of seat pressure @ 140 lbs closed and 335 lbs at .550 lift. According to most I should limit the seat pressure to around 120 lbs and the open pressure to about 300 lbs with a hydraulic cam. Would those RPM head springs not be better suited for a solid lift cam? Correct me if I'm wrong because I am just beginning to learn about this spring stuff. Thanks lewt!

 

[lewtot184]

Based on what I have found those RPM head springs have lots of seat pressure @ 140 lbs closed and 335 lbs at .550 lift. According to most I should limit the seat pressure to around 120 lbs and the open pressure to about 300 lbs with a hydraulic cam. Would those RPM head springs not be better suited for a solid lift cam? Correct me if I'm wrong because I am just beginning to learn about this spring stuff. Thanks lewt!

adjust the installed to 1.90. + .050" locks can help. there are other options that i use but i don't know where to buy my "favorite" springs. there is a crane option that requires shimming. it all depends on the installed height your working with.

 

[IQ52]

Your retainers https://www.summitracing.com/parts/man-23635-16 are not a good fit for the Edelbrock spring https://www.summitracing.com/parts/edl-5792 . If you are trying to keep to the spring pressures you have listed, the Comp Cams 950-16 dual valve spring https://www.summitracing.com/parts/cca-950-16 will fit the retainers almost perfectly, be about 120# IH and 300# @ .500" lift. Also, according to the Manley catalog the 23635 retainer is +.060" installed height so be prepared to do some shimming if necessary.

More specifically, your retainers were designed for the Manley 22406-16 valve spring https://www.summitracing.com/parts/man-22406-16 .

 

[ykf7b0]

I just talk to Tech at Comp Cams and he has suggested I go with their 911-16 springs. I am getting lost in all this. IQ, I know you do lots of head work and maybe lewt does too. What springs would you guys use if you had factory heads (915)'s) with a MP 484 cam with 1.6 roller rockers (.516 lift)?

 

[IQ52]

How are the 915 heads built? Do they have bronze guides installed? What kind? Are the spring pockets machined at all? If the stock valve guide spring pocket boss has the spring locator machined away you will need spring locators. Do you have a picture of the spring pockets in the heads?

There is of course lots more to this than just buying springs. The 911 springs will work for your cam, but not properly with your retainers as the spring locating part of your retainer is to small in diameter to properly control the spring. When I recommended the 950 springs I forgot to consider that the spring seats in your heads, if still stock, would need to be machined for the dual springs. You can use the 911 springs, with stock spring pockets, but I would purchase the Comp Cams 741-16 retainers,
https://www.summitracing.com/parts/cca-741-16 to go with them. You can still use the 10 degree locks you have with the Comp Cams retainers. Even with the 911 springs you may have to machine the valve guide boss to give you enough retainer to seal clearance.

 

[ykf7b0]

I'm not sure what exactly was done to my heads as it was almost 20 years ago but I have to believe they are pretty much stock except for the bowl porting and being cut for larger valves. The MP 933's were installed at that time as well so this is why I don't believe anything was done as far as machining. Thanks for the recommendation IQ!!! I appreciate you!!!

 

[ykf7b0]

the ones used on the rpm heads

I spoke to Dwayne Porter about these springs and he says they will work fine for my set-up. A FBBO member offered me a set with retainers and locks a good price and I took him up on them. Thanks lewt for the recommendation it was appreciated!

 

[383man]

I ran the Comp single spring with the dampner on a mild 383 with 452 heads and stock valves. They worked good for years on it as I had the MP .484 cam in it. I raced it a little also over the years and drove it alot on the street. It ran 12.30's which was good for as mild as that 383 was. Ron