JKNVA

I have a 69 with the original 350/300 in it and would like to get a little more out of it so I figured an intake and cam make the most sense. Engine currently has good oil pressure and runs well but isn't the best performer in the world. Here is what I know:

Unmolested 4 speed car with 3.36 rear end
Original block
186 64cc Heads (Most likely original valve sizes)
Original iron manifold with Q-Jet
Compression is 195 to 210 across all 8 cyls
Base timing should be 4 BTDC but is at set at 1 BTDC which was needed to prevent pinging on 100+ degree days with 93 octane and octane boost when I used to live in Dallas.
Mech and Vac advance amounts are unknown but functioning. Need to get an adjustable light.
Engine was likely apart before I got it 18 yrs ago since I can see RTV on the joints.
Cam is a complete unknown.

My goal is more bottom end neck snapping grunt. Do I have enough info here to pick parts or do I need to do some more digging? Is 200 psi normal for one of these engines? Seems like maybe not enough cam for the low clearance volume.

Thanks,

John

Little Mouse

Well you have plenty of compression. you will have to go
with a low rise manifold with your hood something like a
edelbrock performer. crane cams bluprinted version of your 300hp
cam that came in your car has this for specs.
rpm range 800-4500
.050 int dur. 195
.050 ex dur. 202
LSA 112
int valve lift .390
ex. valve lift .410
here are a some cams you can look at
crane Z-cam
power range 1600-5400 rpm
.050 int dur. 212
.050 ex. dur 218
adv int. dur 262
adv ex dur. 268
int. lift .446
ex lift .459
crane Z-cam
power range 1800-5800
.050 int. dur. 218
.050 ex. dur. 230
adv. int. dur 268
adv.ex. dur. 280
LSA 112
int. lift .459
ex. lift .486

The first cam would be more like what you want for good torque and more
mid range power, the second cam is getting more into an HP cam.
Part # for the first cam with cam and lifters # 113512
2nd cam and lifters part # 113522

JKNVA

Thanks for the recommendations. I will check them out.

John

johns73

You may want to look at the sticky post at the top of this page and do a performance tuneup on your car. That would be alot cheeper then spending alot of money and may get you closer to where you want to be. If that doesent work your only out $50 to $60. Bucks

JKNVA

Not sure which Sticky you are referring to. Only one I see performance related is the one on ignition and while things may not be perfect I am already retarded 3 degrees based on detonation with all new parts so I wouldn't think I had any hope there. Carb is rebuilt and and seems to be functioning well with no bad habits so I wouldn't expect a major improvement there. Am I missing something?

Little Mouse

If I remember right a 300 HP motor was a 10.1 comp motor
your readings seem high for that.

JKNVA

The marketing department sold it as 10.25:1 . Reality is probably a little shy of that. Any thoughts on why the compression is so high? I have verfied it using two different testers so the numbers seem real. My only guess was a low duration low lift cam during the rebuild.

Little Mouse

it would be hard to find a much lower dur cam then the factory used
in the 300hp engine int. dur. at .050 of 190. someone may have used a domed piston if it were rebuilt.. a cam with more duration like the
second cam would bring your comp down some, assuming you have
a very mild cam in it now.

moosie982

If he installs a hotter cam then he may run into problems with the valves kissing the pistons if they are pop-ups, wondering if the present cam is indexed properly ? Needs to be checked by someone with a bit of experience.......Peace,,,Moosie

Little Mouse

.460 lifts are very mild, domed pistons are cut to handle a lot more
lift then that.

moosie982

put anything done now is basically a shot in the dark or a pig in the poke,,, still should be investigated,,,Peace,,, Moosie