AZDoug

Anybody have teh lobe spread/overlap on this hyd cam?

This is where I am going with this:

My 327 motor ahs 11:1 pistons.

When I had the old camel hump heads, with the 64 CC chambers, it would ping on 92 octane.

When i put the 64 CC Bowtie heads on, the ping went away, most likely due to improved combustion chamber design, maybe.

I am really looking at an LT1 cam with a 1.6 intake rocker, as I do like the low speed torque, i don't really like buzzing around at 3K RPM everywhere, and like to be able to literally cruise at 1200 RPM if need be, and hit the gas and it goes, like I can now.

I am trying to figure out if I will get a premature ignition problem with the LT1 cam, by trying to get a feel of how the present L46 cam and the LT1 cam compares on overlap to see if I may not have a ping problem using these heads, with the LT1 cam.

Also, I do have knock control/ignition retard on my EFI, so the engine won't self destruct if I get a knock problem, but I still would prefer not to have to use that safety valve.

Thanks,
Doug

KyleDallas

This list has many factory GM LSA's

http://www.kendrick-auto.com/chevrol...y_cam_spec.htm

AZDoug

Got it, thanks,

Looks like my 962 cam has a 114 LSA.

Doug

Injected Stingray

If your Bowties are Aluminum that would also keep the detonation down due to the improved heat dissapation.You can run about 1 point higher compression with aluminum heads over cast iron all things being equal.

AZDoug

Iron heads.

Unfortunatly, I did not CC the heads when i did the porting and combustion chamber work. I didn't hog the chambers, but I cleaned them up, as they were pretty much raw castings in the ports and chambers, needign a lot of work around teh valve guides and intake runners to clean them up, and the chambers needed cleaning up .

Doug

KyleDallas

I think your headflow cfm @ lift is one of the big pieces of the puzzle..
knowlng what your heads flowed at certain lifts would help you in
cam selection.

Chevy Bow Tie Phase II CCM-184cc port

177/119- .300 lift
205/123- .400 lift
225/123- .500 lift
210/127- .600 lift
209/127- .700 lift

Original Bowties Heads 1st edition- 171cc port

212/145- .500 lift
211/147- .600 lift

(sorry, my data on the original Bowties is incomplete... it's all
I have... If I had to guess, I say .400 lift flow is 200 to 210)

I've got some data on head porting that indicates the most effective
aspect of head porting is the pocket port.... which conenctrates on
minimizing or eliminating the valve guide boss that causes obtruction
in the port leading to the chamber.... minimization or elimination of
the valve guide boss typically results in an extra .010 cfm of flow..
...theoretically, enough flow to give you an extra 20 hp...

On the 1st Edition Bowties... this would mean 222/155 cfm @ .500 lift
... 221/157 cfm @ .600 ...

well speced and assembled engines can produce 2hp per cfm.. so
pocket ported, with a good cam and intake tract... about 444hp is
the goal.

It's pretty rare that heads flow better at .400 than .500.. so your lift
sweet spot for flow .... from the sporatic info here would be .500 to
.550....
I can't remember if you are running headers Doug... if you are running through the manifolds I'd say Aaron would have better info...and suggestions...that's where he has spent his time.

AZDoug

I have the phase II Bowties, and I cleaned up the valve guide bosses a lot, used pics of known racing heads that worked, as an example.

Headers, yes, free flow exhaust, yes, expansions chambers prior to the Borla muffs.

See my new post about an experiment i did today.

Doug

aaronz28

doug, removing all that material likely bought you quite a few CCs.

i can speak from experiance that true 11 to 1 and an LT1 cam will not work well with 92 octane.. with optimal timing

Good luck

A

KyleDallas

Bowtie Phase II's are advertised with a 64cc chamber.