I have a nice 71, 4-spd, base motor car that I’ve been going through for about 5 years now and I want to finally do a bottom end rebuild and some performance work on that sluggish 270HP engine.

I enjoyed some nice HP and performance in the past with a 4-spd, 75 L-82 that I owned for almost 6 years and installed a set of Trick Flow Twisted Wedge Heads, Lunati 268 cam and topped off with a RPM Performer Intake. All but the cam, lifters, push rods and rockers were swap meet finds and that engine was pretty impressive if not just fun to drive.

This time I have a different focus and plan to do a bottom end rebuild on the original 2-bolt main block and limit the changes to a budget (reasonable cost) top end that will deliver significant torque, vice high end horse power. I learned a great deal when I studied and did the 75, L-82 top end but I’ve been poking around and doing more studying for a few years, and without spending the extra money for a 383 stoker kit or buying a crate engine, the quest becomes collecting the right Head/Roller Cam recipe that works best.

When you use different search engines on-line for this topic (building a SBC torque motor), you sometimes end up steered toward building a truck motor with low end torque and while that’s a really big part of the goal, I don’t want the motor to completely fall flat at 4K RPM, although I don’t plan to spin it up past 5K RPM that often.

Interested in some good feedback on this and if anyone has used or developed the best combination of heads and cam that deliver a good pull.

 

10-1, real good 180cc head, 268 to 270 type roller cam, same intake you had, mech fuel pum 650 DP or tuned Q jet, 1-5/8 primary headers will do the trick. Its all in the heads!
Prefer the afr 180s make real strong torque efficient chamber and good airspeed in the port
with a 5500 celing may want to consider a single pattern cam.

 

Dart 180 head with 64cc Chamber. Performer RPM non-air gap intake. 650 Holley HP. A four eyebrow replacement "TRW" piston (Speed Pro) at zero deck will give you 10.5 to 1.
Put this cam in it with a 1.5 rocker: https://www.howardscams.com/hydrauli...cams-111145-10
This should make about 425-430 ft/lbs torque from 3000-5000 rpm.......nice and flat......
Some are going to tell you to put a smaller cam in but with heads as good as these.....you can get away with more cam and not lose a shred of torque......
The Dart 180 as cast head is tough to beat horsepower per dollar.......I have installed a dozen pairs of these on 350's and it is like the head was made for it.
But......the jury may be out when I build this 175cc Trick Flow roller 355 this winter......stay tuned.

Jebby

 

I might suggest you take another look at the 383 stroker kit. It will cost you the same as a 350 kit and it will make a lot more torque. if it costs the same, it should not be a question. JMO.

 

Thanks much to all for the feedback..........................

So I want to stay away from the stroker kit because I am sticking with the 2-bolt main, original block and crank. Will probably need new relived pistons to be sure I have plenty of roller cam choice flexibility. I know stroke develops torque but it's a trade-off I have to live with unless the cost goes way up to splay the main caps or just get a new crate engine (EPM, ATK of BLUEPRINT).

Agree with all so far that the success stories for SBC low-end torque all include the same ingredients: a good intake runner size/flow rate, big intake valves and a good roller cam. Just looking for the best recipe/combo.

 

The 2 bolt block is good for 500 horse or more if you use ARP bolts.....I have done it many times. That said....a budget 383 balanced rotating assembly comes in at $1000 for everything. If you go with new pistons on your current setup.....you will need it balanced which closes the gap between using your old stuff and a new rotator. But there are other things to consider with a 383. Cam tunnel clearance need to be checked and a small base circle cam must be run if using a roller......
But the argument can be made that a well sorted 355 will be better than a decent 383 for torque.......it is only .270 of arm.
I think if it were mine....I would go with my 355 recipe, put Wiseco Pro-Tru forged pistons in it, and have it rebalanced....maybe add a set of Eagle SIR rods.

Jebby