What is the installed spring height for M&A heads?

[evil666]

I would like to replace my valve springs on my M&A heads with competition cam 981 which have 105 lbs at 1.700 installed spring height. I just want to make sure that the installed spring height on M&A heads is 1.700. If I am not mistaken, the stock heads, champion and T/A installed height for valve springs is 1.700.
Thanks ahead of time for any advice I can get. I just want to make sure I don't put a valve spring with to much pressure and then I will chop my flat tappet cam.
Marco

 

[Nick Micale]

I would like to replace my valve springs on my M&A heads with competition cam 981 which have 105 lbs at 1.700 installed spring height. I just want to make sure that the installed spring height on M&A heads is 1.700. If I am not mistaken, the stock heads, champion and T/A installed height for valve springs is 1.700...................

The 1.700" install height may be close for an iron head, but the alum heads are much different and can be over 1.800", plus there are many other variables to consider.

Some of these variables are valve length, retainers and locks, spring locators and even the valve job itself.

To arrive at an accurate number, you must measure your existing set up.

 

[evil666]

Ok, thanks Nick. I guess I need to buy myself a tool and measure.

 

[dank GN]

Mine are installed at 1.8

 

[evil666]

Ok, here is some info I just found out about my heads. The installed height is 1.800". The valve springs are at 140lbs @1.800" and 290lbs @1.250. Now here is the problem, I am running an Erson 214/214 flat tappet cam with 1.60 roller rockers. The reason I want to change my valve springs is cause when I dynode the car it peaked HP at 4673 rpm. So here I am thinking that my valve springs are probably weak and the valves are floating and that is why I am peaking HP so low. After reading and doing some research and asking questions, I found out that if the valve springs are at 90 or 95lbs for my flat tappet cam get rid of them and replace them with fresh valve spring that have 105 to max, max 110lbs at installed height for a flat tappet cam. Now, I don't know if you guys get where I am getting at over here, but isn't 140lbs at installed height for a flat tappet cam way to much? With that much pressure, wasn't I suppose to chop the cam? What is the bad side on performance when you run a flat tappet cam with to much pressure? These heads were on a car that had a roller cam, and the guy who did the valve job on my heads removed the inner spring in the valve spring so I would be able to use them with my flat tappet cam and told me that with the inner spring removed I would be fine. With the inner spring in place the valve springs had 160lbs@ 1.800" and 400lbs @ 1.250".
These are some Comp Cam valve springs that I found to replace the ones that I am using right now, which one should I go for:
926-12
Installed Height (in): 1.800 in.

Seat Pressure at Installed Height (lbs): 109 lbs.

Open Height (in): 1.300 in.

Open Pressure (lbs): 317 lbs.

Or the
26915-12
Installed Height (in): 1.800 in.

Seat Pressure at Installed Height (lbs): 105 lbs.

Open Height (in): 1.200 in.

Open Pressure (lbs): 293 lbs

Here is a picture of my cam spec sheet if it helps:

 

[TurboBuRick]

Too much spring pressure would prolly wear the lobe out yet a higher tension spring will yield more power and rpm.

Sounds like perfect time to throw a roller cam in.

 

[TurboTdr3.8]

Here is a good site to explain about weak valve springs , http://www.aa1car.com/library/valve_spring_diagnosis.htm