Hello my 2 pence on C C THUMPER cams we have tried these cams in our engines as customer requested we use one in there engine in the exact same engine we build ... our 355 SLAYER roller engine when thumper cam installed with pretty much the same lift & duration we use .
The Thumper cam BHP & torque results fell way short of our STD hyd roller cam we use output... prox BHP loss @ - 25/30 ... prox ft lbs torque loss @ - 30/40..... but hey the idle was LUMPY
A comp cams 265 'dual energy' or 268 'high energy' or 270 'Magnum' cam will work nicely for you.
265 = good everyday performance with std cyl heads & exhaust. Very strong midrange with a lopey idle.
268 = good street performance with std converter choppy idle.
270 = high performance, biggest cam with std converter but works better with 2000+ converter. Likes headers and mild rough idle.
I'd look at the 265 or 268 if I were you.
Thanks. had a look at the 268 and it seems to be the one im going to get.It comes with new tappets also which is good also.
I forgot to mention i have block hugger exhaust manifolds
Good choice, depending on your budget I'd strongly recommend fitting new appropriate valve springs as well as yours will be tired and the higher lift will need a stiffer spring to control it properly.
While the springs are off fit new valve stem seals - cheap and will give your engine a new lease of life for starting (no oil contaminated plugs) and stop any smoke on startup. This can all be done with the heads still on if you feed about a metre of rope into each cylinder via spark plug hole (keep some hanging out!!!!) and hand crank the piston up against it.
Luckily i have no smoking problems or oil consumption but if i am going at this i Will do as mush preventive maintainence as possible.
That's for the advice.
Turns out I may have a cam already installed but must take some measuments first
I am renewing and upgrading the ignition ie leads,plugs,dist cap and accel module first
thanks all for the advice and technicaltom for calling over to look at my engine and give some great advice and a nice guy too