Hi Folks, I found a AMC 401 that I am going to rebuild. I am trying to decide between the Edlebrock Performer and the Performer RPM heads. Emissions legal isn't a problem but they are designed to run in different RPM ranges. It's going in my CJ7 and it will be used both on and off road. I am running headers and a Non EGR Manifold. I haven't decided on a cam or compression just yet as I need to figure out which heads I want to use. Any thoughts on the value of the exhaust crossover ports on the Performer head vs the Non crossover port on the RPM heads? The Performer heads were designed to run with the Performer Manifold and the RPM range is from Idle to 5500. The RPM setup uses the RPM manifold and is designed to run from 1500 to 6500. The RPM set up will pull more HP and TQ but at a much higher RPM. Any preferences or opinions out there would be a great help. Thanks, Jack
All builds revolve around intended usage.
If your building a sand drager or a pit bogger, your build will be completely different from a rock crawler, technical wheeler, or even a DD.
I would be hard pressed to think about replacing heads unless your working on a high end RPM machine. Any gains for a pleasure wheeler would be lost, along with a ton of money.
Most folks who build a DD, usually find the most happiness building toward a low end torque curve or a mid range HP engine. Neither of these builds require extensive modifications and usually revolve around the "big three" (cam, intake, and carb). A mild bump up in compression can help as well. I like to keep things running on pump gas so that is something else you may think about.
My personal opinion is this...
If you're thinking about spending the money on heads, you want to make a little bit of power. If that's the case, you're going to want a "little more" after some time frame. I'd personally go with the RPM's in case you ever want to do a little more in the future.
All the pieces come into play to make it work, but the heads are where your power lies if it's all done right.
However, if you're thinking you want to make 300HP, you can easily do that without spending the money on heads. It's really going to come down to what kind of power you're looking to get?
434 pump gas SBC with an NX/HVH plate system
th350/Coan 5,000 converter/Dana 300 tcase
Dana 30 front with 4.56's/Dana 44 rear with 4.88's
Dissenting opinion here. Aluminum heads will allow 10.5:1 compression on pump gas, and to me, that alone justifies spending $200 to $300 more than an equivalent set of iron heads. You also loose 60 to 70 lbs of weight. As for the Performer vs Performer RPM's, I have been running the latter on a sbc in my flatty for almost 10 years and can say there is no downside to not having that heat riser crossover. I suspect the emissions are more when cold but that's about it. I have experienced nary one problem with cold weather operation and it does get cold in Montana.
You will obviously need to nail down what compression ratio you want before ordering. At least for Chevys, there are several cc chamber options along with the straight or angled plug option. For the cost, the RPM's are a really decent buy. I don't know what the budget for this build is, but those heads work really well with a roller cam with steep ramps. You can get a lot of lift with a short or moderately short duration cam. The 381 sbc in my 3B has had a Comp roller since 2008 and IMO, cat's meow.
1955 CJ 3B, 381cid sbc (441cid all aluminum sbc coming soon), AGE M22W, Teralows, Warn OD, OBA, Premier Power welder, Warn 8274
1968 CJ 5, factory 225" w/ headers/450 cfm Holley, T86AA, Belleview winch, Warn OD
2012 Wrangler Rubicon Unlimited, Warn 9.5 xp-s winch