[goatman65]

Originally Posted by screamingchief

Exactly what valve springs are you using on those 6X heads?

What pushrods??

Stud girdle???

The 290b6 should pull strong to 6000+ no problemo.

Also,was that cam degreed when it was installed?

With the 6X heads and the compression your running,you really dont wanna go any bigger than that 290b6 cam.

Also,what sorta exhaust are you running,tight LSA cams absolutely abhor restrictive exhaust tracts,a restrictive exhaust system can cost big chunks of power with the tight LSA cams.

Can be lots of reasons for what your seeing,just gotta work thru the usual suspects in a logical way to eliminate any & all possible issues,it's a process,and it can be tedious at times,but you gotta expect to put in some work to reap the gains.

As for a SR cam to replicate the 290b6 when you upgrade the heads,here's my choice:

Brand & part no.:Comp custom high tech .420" SR lobes #51-000-5
Grind & lobe no.: AKA: the 290b6 roller "clone" cam. ( lobe # 4009/4023)
Tappet type: Solid Roller Tappet
Spec = intake/exhaust: (notes)
Adv.duration = 290°/304° (I/E split = 14°) (note: rated @ .020")
Dur. @ .050" = 254°/266° (I/E split = 12°)
Dur. @ .200" = 171°/180° (I/E split = 9°)
Lobe lift = .420"
Lift @ 1.5 rr = .630"/.630" (Gross lift) (To get Net lift subtract lash below)
Lash =
106° LSA = 106° ICL = 106° ECL

Seat events:
IO = 39° BTDC
IC = 71° ABDC
EO = 78° BBDC
EC = 46° ATDC
OL = 85°

Events @ .050":
IO = 21° BTDC
IC = 53° ABDC
EO = 59° BBDC
EC = 27° ATDC
OL = 48°

Compare that to the 290b6:

Brand & part no.: Comp Cams Part no.51-659-5 . (catalog grind)
Grind & lobe no.: Grind no.290b6 (lobe #6061/#6013)
Tappet type: Solid Flat Tappet
Spec = intake/exhaust: (notes)
Adv.Duration = 290°/304° (I/E split 14°) (note: rated @ .020")
Dur. @ .050" = 255°/266° (I/E split 11°)
Dur. @ .200" = 160°/172° (I/E split 12°)
Lobe lift = .360"/.356"
Lift @ 1.5 rr = .540"/.534" (Gross lift) (For Net lift subtract lash)
Lash = .026"/.028"
LSA = 106° ICL = 106° ECL = 106°

Seat events:
IO = 39° BTDC
IC = 71° ABDC
EO = 78° BBDC
EC = 46° ATDC
Total O/L = 85°

.050" events:
IO = 21.5° BTDC
IC = 53.5° ABDC
EO = 59° BBDC
EC = 27° ATDC
O/L @ .050" = 48.5°

Does'nt get any better/closer than that!

What's the diffence you ask???

Look at the additional lobe lift and the .200" duration numbers and you'll see.

And that SR cam will absolutely love better flowing heads!!!

But I'd definitely work with the current combo some more before making that leap.

Sooner or later though,those trips wont be able to keep up.

Bret P.

Springs are comp #995.130 closed,334open @ .550
Pioneer pshrods 5/16.I cant find the length.I had to get longer than stock because the lifter plunger was down in the body further than on the comp lifters that i was using with previous cam.
No stud girdle.Comp guide plates,7/16 studs.
Cam was not degreed.I'm suspecting this 'could be' a contributing factor.I run an E-brock geardrive with a 3 keyway crank gear.VERY hard to see the lightly stamped markings for +4,-4 or 0.There is a good chance i might have used the wrong keyway and installed it 'retarded' *4.
It does pull to 6000 and beyond with no problem,it just stops making power at 4900.
I'm replacing my 1-5/8 headers with 1-3/4.

I run 6x heads to keep a 'stock' look and i didn't have money at the time for alum.heads.I think to get low 11s/hi 10's the KRE heads would help a lot.