slade69

Does anybody here know what are the stock cam specs for -69 2bbl 350 cutlass engine?

joe_padavano

P/N 400084
36 deg overlap
250/264 intake/exhaust advertised duration
.400/.400 lobe lift

slade69

Thanks Joe!
I'm trying to find a cam, that will noticeable improve my 350 overall performance, but still work with stock converter and gearing, power brakes etc...
If anyone has good ideas or even experience with good results....Also the cam/compression ratio info would be interesting!

cutlassefi

Compression should be right about 9.0:1.
Are you staying with the stock exhaust and current intake setup?
I can help with a cam if you're interested but your ultimate goals would help.

slade69

My goal is a fun/comfortable summer daily driver with some extra grunt over stock. Stock converter/gearing/350 trans will be kept, so low and mid range torq is preferred over top end. Original #5 heads with slight mods will be kept. Air bumps will be removed but not so sure about filling the heat risers, because car will be used under 10°C temperatures also. 2711 intake will be considered, also Hooker 1 5/8 primary headers.

Fun71

And if I remember correctly, 186º/204º duration @ .050" lift, 109º LSA

slade69

Whoa! That's really mild! Those "vintage" ramps are really slow.

slade69

What do you guys think about Comp Xe262HR cam? Will it be good for daily 350 summer driver with stock converter and low gears? Cr 9,0-9,5 to 1.
Is this cam what can be considered as a modern, agressive ramp design with much "area under curve"?
Would it work fine with ex. manifolds? Intake will be Performer.
Target is +300 real world hp.

Fun71

The Comp website shows:

.475/.480 lift, 262/274 advertised duration, 218/224 duration @ .050" lift, 110° LSA

That is close to the UltraDyne cam in my 350. I have a Performer RPM, headers, 2500 RPM stall converter, and 3.23 rear gears. If it were me, I would go with a slightly smaller profile, such as something around 210º @ .050" lift.

pmathews

Make sure that you check the dynamic compression before settling on a cam (ask me how I know) -> http://www.wallaceracing.com/dynamic-cr.php

Fun71

So, how do you know? I'm always interested in other peoples experiences with cams.

pmathews

On my recent 330 High Compression (10.25) build, I overshot the compression, I wanted 10:1 but ended up with 10.4. My CompCams 265DEH probably would have been fine at a slightly lower compression, but the intake timing on the compression stroke is too early, and this causes more dynamic compression.

The result is that I have to keep a very close eye on detonation. I run 93 octane with 32 degrees total (12 initial). I would love to run 36, but I don't want to run octane boost all the time. For a while, I was running 28 total and it was overheating a bit (timing retarded), but I retuned the carb to run a bit richer, and that allowed me to use more timing.

Longer term, I could swap the pistons, but I had my rotating assembly balanced, and I don't want to risk losing that investment. I thought about adding a thicker head gasket, but that leads to quench issues making detonation worse (not better). I know that's counter-intuitive, but I've done the research, and that's not a viable option.

I could polish out the combustion chambers to lose a few cc's, but I'm afraid that I would nick a valve seat, etc...

The best option is to swap the cam. I could have avoided this mess if I had checked dynamic compression before I bought the cam.

Better yet, just get one from 'cutlassefi' (see above). He's an Olds guy and can get you a custom grind. I wish I had done that, but at the time, I was an Olds newb.

Hope this helps

johnnyjaws

go with a comp cams 262 or a 264 and u can use the same pushrod and rockers

DoubleV

Take it for what it's worth but the Voodoo cams were specifically designed to out power the Comp Xe cams all while being more quiot. If that is indeed the case I don't know why there are so many people still wanting to use an Xe cam....

rubeng442

Do you know at what lift?

rubeng442

They are much more well known. Comp Cams did a stellar job marketing them.

slade69

Thinking between these two:


http://www.compcams.com/Company/CC/c...csid=1182&sb=2


And
https://www.lunatipower.com/Product....d=3204&gid=289


SBO 350, solid main web block, Probe -3cc pistons, SBC Rods, #8 heads milled / ported with new stock size valves.
Cr 9,1 - 9,5
Stock low gears
Stock converter
Performer intake (2711)
Manifolds/ headers not decided yet


Aiming for +300 real hp and flat torq curve.


Comp would be the easy choise because of better availability, and they also sell nice kits inluding lifters, springs, retainers etc. to match.

slade69

This showed 9,06 dynamic cr and 186,6 psi of cranking pressure. Is that ok or not? Those numbers tells me nothing.

rubeng442

From what I've read 9.06 DCR is considered a bit high for an older combustion chamber iron head. Most recommend low 8's. But more than that I think your cubic inches and compression ratio increase would do well with a cam in the 264 to 272 range.

captjim

This is one reason why the cam should be chosen last, after the cr is measured exactly. Dynamic compression ratio calculators are only educated guesses, there are many factors which can affect the true cylinder pressure. The best bet, IMO, is to use experience and/or existing builds as a model.

Also on the quench thing, this is often mentioned. Due to the shape of the combustion chamber on an Olds engine, the quench area is VERY small, especially with a dished piston, using a thicker head gasket has less affect than it would on other engines. In a perfect world, sure, get everything where you want it and .040 piston to head. But, if you need to lose a little compression, adding a bit of thickness will have very little effect, IMHO.
BTW, you could also change the cam timing to reduce the cylinder pressure, I'm sure you know that, just thought I would mention it for those that do not.

slade69

I'm not really sure about this dcr- calculator:


http://www.wallaceracing.com/dynamic-cr.PHP


It tells me I should have about 8.7:1 Static cr to get recommended 8,25 dcr. In other words it tells me to lower my CR from original 9:1, if I go with Comp 262 Hydraulic roller. Can not be right.


Is there somewhere information available from Comp what CR they recommend with each of their cams?

captjim

Better to ask an experienced Olds builder, who knows what works and doesn't in Olds engines, IMO

rubeng442

I don't think you are using it correctly. First determine your actual static compression ratio, THEN worry about the DCR.

To determine your SCR you need to know your heads final combustion chamber volume, head gasket bore dimension and compressed thickness, bore, stroke, piston dish volume, and piston to deck height dimension.

slade69

I assume there are some experience in this forum also. I live in
Finland, no Olds experts engine builders here.

pmathews

Agree 100% on getting a good static compression ratio before using the dynamic calculator. It's just a tool, real world experience is more reliable. The tool can help you narrow down the choices, I would use it for that purpose, to steer away from the bad combos.

From what I understand, the 31 degrees ABDC on the XR262HR cam is going to create too much dynamic compression. For comparison, my 265DEH ABDC is 58 degrees. Try adjusting the ABDC number and it should help you stay away from problem cams. Others can provide much better advice when you narrow the selection down a bit. I'm guessing the hydraulic vs. roller ramps are very different in spite of the similar duration, and that adds an additional variable.

Like folks said earlier, there are some really good experts on this site, I don't rank (haha), but I can share

Thanks Jim on the quench thing, now I feel better about trying a thicker head gasket.

With regards to CompCams, it was an arbitrary decision, my builder prefers them. Once again, if I had to do this all over again, I would let cutlassefi pick my cam. Not trying to advertise for him here, but I've been reading his posts and he's dead on. Let the pro's do what they do best. There are lots of smart folks on this board.

slade69

At least in that calculator the inlet closing degrees are the biggest factor, and of course an engine can not build any compression before valves are closed.
It would be interesting to now the original inlet closing degrees?
I would like the idea of using roller cam and roller rockers to minimize valvetrain frictions, and in the other hand benefit rollercams faster opening and closing ramps(more velocity with less degrees). Also, I don't want the hassle of tappet cam broke in procedure. With roller it's also possible to use modern motor oils without worrying about zink.

RocketV8

The problem is these cam specs are incorrect:

http://www.compcams.com/Company/CC/c...csid=1182&sb=2


The valve events are noted as @0.006" but it sure looks like @0.050" events to me. Compare to ICL and duration and you get the picture.


This calculator needs seat-to-seat numbers, not @0.050":

http://www.wallaceracing.com/dynamic-cr.php

slade69

Thanks! You are right! This explains the odd results from this calculator!

pmathews

Good catch RocketV8

I rechecked my cam card, and it's accurate, but the XR262HR is definitely wrong:
http://www.compcams.com/Company/CC/c...csid=1182&sb=2
http://www.compcams.com/Company/CC/c...csid=1179&sb=2

I recalc'd the XR262HR with a 57 degree ABDC, and it's now showing 8:1 dynamic which should be really safe on pump gas.