Here are my first thoughts:
Looking to build a high torque street machine. 72 Supreme, 3.42 gears, TH350 with a Hurst Dual Gate.

Have a stock block with only 42,800 on the odo....YES...42,800! Still have to tear into it, but I'm going off the assumption that there is little wear for the moment.

Up the CR to 9.5:1 with a piston change
Stock 7A heads with a little porting...nothing ridiculous
Edelbrock 3711 Performer intake
Rebuilt Stage 2 Quadrajet
Comp hyd roller cam XR262HR
-Duration@.050 210/216
-Seat to Seat 262/268
-Lobe centerline 110
-Int centerline 106
2800 stall convertor
Long tube headers
Dual exhaust with an X pipe

What do y'all think? Am I on the right path? I figure this will give me lots of low-mid torque and somewhere around 310-330 HP. Sound correct?

 

One thing to consider is dynamic compression with that cam (at 9.5:1 compression). It may be okay, but it's a little tight on the intake closing event, and that will push dynamic compression a bit higher. This is important with regards to running 87 octane pump gas, but you'd have to check (see link below). You can drop the compression a little or run more duration in the cam or run 93, and that would fix it, but I'd let others chime in before making the call. I only mention because I have to run 93.

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

 

Why the 3711 intake? that's an EGR piece that you wouldn't need for your build. 2711 is more appropriate IMO - no EGR provision so nothing to cover. As to 3.42 gears - nice for low speed street performance but probably too high for road trip duty - I had 3.23 gears in a prior 72 Skylark and it already hit 3k rpm by 60mph on 245-60-15 tires. Stage 2 Qjet might be rough on your running idle but if you want the one I recently bought from Quadrajet Power I'll make you a deal. Used it for tuning my built 350 but couldn't get it to idle well enough for my taste. I run a Howards street performance cam and F2320 flat top pistons in my '72 Cutlass 350 now, 2711 intake, fully rebuilt 7a heads and a 2300-2600 stall, with 3.08 Posi out back. Performance tuned (but essentially mild) Qjet up top. It idles, pulls strong and rpms only at 3k by the time I hit 70mph.


also, don't assume your block will be all that clean inside - mine was only 53k but probably as cruddy inside for NOT having been driven as a high mileage motor would have been for age wear/tear.

 

I took that into consideration already. Planned on running on 93. By my calculations, the DCR will be 9.052:1 with this set up.

 

You are right on the intake. I got them mixed up, As for the gears, with stock tire sizes I should be running 2811 RPM @ 65mph according to an online calculator I came across. Haven't done the math by hand yet though, so maybe it's wrong. How do you like the 3.08? I may take you up on the carb.

 

3.08 is a good compromise between stock 2.73's that came out and the 3.23's that I previously ran. with the other ignition and powertrain mods I've made the car still has a strong pull from idle all the way up the dial. Compression is 9.5, great vacuum and I run 92-3 pump.

 

The 2711 also doesn't have a provision for the hot air choke whereas the 3711 does. Not an issue if you want to convert to electric choke, but if you use the hot air choke then the 3711 is the one you need.

 

Nope, you won't hit your target with that combo.
Your cam is too small, the 2711/3711 is a bad choice and I'd swap the Qjet for something better. And why would you buy a carb with idling issues, just sayin.��
You need about 8-10 degrees more cam, an Edelbrock 7111 intake and as stated, 9.5:1 or better static compression.
A couple of things, a small cam does NOT guarantee low end torque. And the 2711/3711 intake is a waste of money for the desired hp.
As I've mentioned a hundred times, you need the right overall combination to make good torque where you want it.

Hope this helps.

 

Correct me if I am wrong, but wouldn't bumping the cam up 8-10 make the torque curve steeper and move the peak torque up the RPM scale. My first goal is to get the proper cam and build off that. My reasoning for this one is that (according to the info at Comp) is that it has a broad torque curve on the low end. If I were to bump it up 8-10 wouldn't it steepen the curve and move the peak up the RPM scale? If that is the case, would I notice a big difference?

 

Generally speaking yes.
But in order to make hp and tq you need airflow. With the heads you're using you'll need more cam than what you planned to in order to even come close to achieving your goals. And remember, your tq PEAK may rise with more duration, but there's also an excellent chance the entire tq curve will fatten. I did a SBO stroker (375ci) a few years back. With 9.0:1, a 216/221@.050 hyd roller, bowl blended 7a heads with 2.00/1.62 valves, an RPM intake and 750 carb it made 323hp measured, about 360hp corrected. But it made nearly 400lbft of torque by the mid 3000's. My own 350 makes about the same numbers with 9.7:1 and a 222/230@.050 hyd roller. Tq PEAKS at about 3600-3800 but pulls very strong from just off idle all the way to 6000.
My point? You'll need the airflow, and/or displacement, to make your tq and hp goals, plain and simple.

 

Thanks for the info. That sounds like what I am looking for.

 

So the XR276HR would be a better choice?
Dur@0.050 of 224/230

 

Kind of, but a bit more lift would be beneficial. What is Comp getting these days for a roller cam and lifters? I might be able to save you some $$$.

 

Looks to be around $835.00 at Summit for the cam and lifters.

 

$795.00, shipped. But you'll need a cam button either way.

 

This is my point. Notice the low rpm torque numbers, almost identical between the two camshafts. And there was a 35* difference in the cams.
But also notice the entire tq curve was fatter. You need airflow to make hp and tq.
Yes they raised the compression, but the increase in cam size would've pretty much had the same effect no matter.

Hope this helps.

 

This is where I'm at now. Ran some cam simulations on some software and I am pretty pleased with this one. Of course, real life can often be very different. Any thoughts?

INTAKE DURATION 219 ⁰ @ 0.050"
EXHAUST DURATION 233 ⁰ @ 0.050"
INTAKE CENTER 105 ⁰
OVERLAP 6 ⁰
LOBE SEPARATION 110 ⁰
INTAKE LOBE HEIGHT 0.317 in.
EXHAUST LOBE HEIGHT 0.317 in.
INTAKE OPEN @.050 4.5 ⁰BTDC
INTAKE CLOSE @.050 34.5 ⁰ABDC
EXHAUST OPEN @.050 51.5 ⁰BBDC
EXHAUST CLOSE @.050 1.5 ⁰ATDC

 

Sounds just slightly larger than the cam in my engine, which is actually fairly mild (UltraDyne .485/.485, 217/221).

 

More duration spread and less lift than I would do but........