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Discussion Starter · #1 ·
I'm going to be revving my 331 to about 7000 after I get it rebuilt. Things i'm upgrading to are 1.7 rockers, beehive springs, and a single plane manifold. I have a 282S Comp solid lifter cam with 236 @ .050 and .528 gross lift and .510 net lift (.018 valve lash). I have 1.94 and 1.6 stainless tulip valves.

My 972 Comp springs have 124 lbs seat pressure @ 1.800 and 281 lbs @ 0.510 lift (308 lbs/in). I was revving the engine to nearly 6800 with these springs. My lift will increase to .543 with the 1.7 rockers. I could possibly reuse these springs (bind at .605 lift), but i'm just not sure if they are up to the task.

Comp has several new beehives. I'm looking at the older 26918, and some of the new beehives.

I know I can call Comp to get a recommendation, but I want to ask you guys.

What I am not sure about is how much open pressure I need with the beehives. I understand that I can use less pressure and still get as good or better valve control with beehives as compared to traditional springs.

Here is the pressure of each spring i'm considering:

26918 130 lbs closed, 300 lbs open (313 lbs /in)
26986 123 lbs open, 275 lbs open (280 lbs/in)
26995 137 lbs closed, 289 lbs open (280 lbs/in)
26915 105 lbs closed, 275 lbs open (313 lbs/in)
26915 121 lbs closed, 291 lbs open (.050 less installed height)

They all have 1.800 to 1.700 installed height so I can use them with shims without modifying my heads. The 26986 and 26995 have nearly the same identical bottom diameter as the 972s that I have now. The others are narrower at the bottom (not sure if I need to machine the head for these).




_________________
Tracy Blackford: Corona, Ca
'65 FB Mustang 331, 282S cam, ported 351W heads. T5z, 3.50 9" posi.
346 [email protected] on a warm spring day (335 RWHP SAE corr.)


<font size=-1>[ This Message was edited by: blkfrd on 10/21/06 1:29am ]</font>
 

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any machine work been done to the heads... the spring seat area? What hardware is being used there..shims cups?

26995 137 lbs closed, 289 lbs open (280 lbs/in) sound like a good bet
I believe they are supposed to fit in a stock llocation with very little finagling
 

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The 26918 would be good for you. The 1.7 rcockers are a waste of money. I am surprised your engine is happy when you rev it up to 6800 because you cam is pretty small for that size engine. The higher ratio rockers will LOWER you rev limit by 300-500 rpm, Keep that in mind. JOE SHERMAN RACING
 

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Discussion Starter · #4 ·
On 2006-10-20 15:02, BIGJOE wrote:
The 26918 would be good for you. The 1.7 rcockers are a waste of money. I am surprised your engine is happy when you rev it up to 6800 because you cam is pretty small for that size engine. The higher ratio rockers will LOWER you rev limit by 300-500 rpm, Keep that in mind. JOE SHERMAN RACING
It will?...yikes, that's not good. I have never heard that 1.7 rockers can have that effect? I get peak HP at 6400 now. Yes, that cam and this engine loves to rev! Are you saying that my HP curve will shift to the left and peak HP will move down 400 rpm or so or are you saying the valvetrain limitation will drop 400 rpm?

Don't know if it makes a difference or not, but I bought Probe's shaft mount rocker system with 1.7 rockers. They were not a lot of money more as compared to a nice set of 1.7 full rockers.
 

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Joe,
Does the 1.7 rockers lower the powerband, or just make the valvetrain less stable and you lower the max RPM before valve float?
 

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Both.-Only a small percentage of engines respond to the higher ratio with more power. Most LOOSE up to some point (5000-5500) before they show a tiny gain (5-10 HP)The 1.7 would move the HP peak UP, but the valves will float at a LOWER RPM than before. Approach with care. JOE SHERMAN RACING
 

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Discussion Starter · #7 ·
On 2006-10-21 10:08, BIGJOE wrote:
Both.-Only a small percentage of engines respond to the higher ratio with more power. Most LOOSE up to some point (5000-5500) before they show a tiny gain (5-10 HP)The 1.7 would move the HP peak UP, but the valves will float at a LOWER RPM than before. Approach with care. JOE SHERMAN RACING
OK...now i'm with you. Your initial reply had me puzzled. I agree with what your saying. I'm doing the 1.7s because it's a simple mod. I don't expect more than 10-11 HP gain from the mod if that.

As far as springs go, that's why i'm asking for advice on them. I want to get a spring that is up to the task. 26918s sound like they might be the way to go, but I have to machine the heads to make them fit (they have smaller diameter). Thanks

I'm going to give Comp a call to see what they recommend. They advertise the 26986 as the beehive version of the 986 dual spring. The 986 is the spring that is recommended for the 294S cam...one step up from my cam and essentially the same lift as I will have with my 282S and 1.7 springs. This is the spring I would have used if I were staying with a traditional spring. I'm curious if they recommend the 26986 because it has almost 20 lbs less open pressure than the 986 would have. Maybe beehives do require less spring pressure to do the same job. The 26986 will fit without any machining to my heads.

_________________
Tracy Blackford: Corona, Ca
'65 FB Mustang 331, 282S cam, ported 351W heads. T5z, 3.50 9" posi.
346 [email protected] on a warm spring day (335 RWHP SAE corr.)




<font size=-1>[ This Message was edited by: blkfrd on 10/23/06 9:18am ]</font>
 

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Have you got screw in studs? Are you using rail type rockers?
Paul
 

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Discussion Starter · #9 ·
Called Comp Cams. They said the 26986 would be a great spring for my engine. I asked about the lower 275 lbs of open pressure as compared to the 972s I have now or even the 986s (dual spring) which would be about 291-292 lbs open. They said the beehives work great with lower pressures and they are more efficient especially as the lift increases. So 26986 it is.
 

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Discussion Starter · #10 ·
On 2006-10-23 01:24, PaulS1950 wrote:
Have you got screw in studs? Are you using rail type rockers?
Paul
Not any more (have shaft mount now) and No
 

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Discussion Starter · #12 ·
On 2006-10-23 15:52, n2omike wrote:
I believe Joe Sherman knows far more than any Comp tech. I'd listen to him.
It's really not that at all. My decision is based on several things and not just the Comp tech.

The spring Joe recommends requires some machining to my head. The 26986 does not, and it is advertised as the beehive version of the 986 dual spring (a step up for me and is designed for a more radical cam than mine). Comp has several articles on their web site pulled from various publications. Two articles use the 26986 spring. One of them is a small block 383 chevy that has a cam and lift similiar to mine and larger heavier 2.08 valves. The engine produced excellent power to at least 7000 rpm (my intended redline) w/o valve toss. The 26986 is one of Comps new beehives.

I respect Joe's opinion and I even sent him a PM on the subject. If I can use a spring that does not require machining, then so much the better.

_________________
Tracy Blackford: Corona, Ca
'65 FB Mustang 331, 282S cam, ported 351W heads. T5z, 3.50 9" posi.
346 [email protected] on a warm spring day (335 RWHP SAE corr.)




<font size=-1>[ This Message was edited by: blkfrd on 10/24/06 8:01am ]</font>
 

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Discussion Starter · #13 ·
What the heck!?!? My car in my sigpic just turned into a funky metropolitan!
 

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in 5.0 mustang &sf they are building a stroker small block using comp cams beehive 26120-16 going to rev to 7k I think... using afr 205 heads...
 
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