Mopar LA Cylinder Heads High Performance Bolt On Upgrade

Bolt on a pair of aftermarket small block Mopar LA cylinder heads from Edelbrock and you’ll notice the difference in power and performance without a doubt. With a few more simple bolt on parts as such as a camshaft swap, long tube headers, 4bbl carburettor, intake manifold, and roller rockers you can easily gain 100+ RWHP (150+ hp at the crank) over your current stock series v8 engine.

To find out what your current factory stock 318, 340 and 360 LA series engine made view the horsepower chart listed on the Allpar website here  https://www.allpar.com/mopar/318

No need to port your existing heads, swap out your pistons for high compression ones or even have your old heads milled for more compression. Simply make these few changes and run on premium 93 pump gas and call it a day. Follow along to find out exactly what to do. This can all be done without even pulling your engine from your car. You can even do it yourself if you wanted to.

Mopar LA Cylinder Heads Flow Chart Stock VS Edlebrock RPM

First we’ll take a quick look at how this is possible. We’ve borrowed a couple of flow charts from the Hughes Engines website. You can see the charts here along with many other Mopar heads flow charts, as well for future reference and research. http://www.hughesengines.com/TechArticles/1headflowchartscomparisons.php

We need to take into consideration that all things are not completely equal. Depending on the year of heads you have on your small block LA engine, the intake valves sizes were typically any where from 1.78 up to 1.88 inches in size. Only the 340 LA engines had the 2.02 intake valve sizes. You can see the chart here for more info on stock valve sizes from the Engine Labs website. https://www.enginelabs.com/engine-tech/

You can see from the description in the image above as to what heads Hughes Engines are referencing to. You’ll notice the ‘Stealth’ head porting service includes adding the larger 2.02 intake valves. Even so, if we take a look at the highlighted flow numbers in the above chart, the Stealth mod flows 218 CFM on the intake side. This is significant of course. When you consider the money you’d have to invest to have this done on your factory heads, you’d be spending the same money if not more than the cost of a new set of heads.

Now let’s take a look at the Edelbrock RPM LA heads flow chart from the Hughes Engines website.

As you can see the highlighted numbers show 249CFM with the Edelbrock aluminum cylinder heads. They are  not ported. You’ll also notice I’ve only focused on the .550 inch lift numbers. Edelbrock recommends the heads are suitable for camshafts of up to .575 lift.

When considering a higher lift setup it would be wise to consult either your engine builder, if you’re not doing the install your self, or contacting Hughes Engines via their website. Just to be sure you’re making the right choices to achieve maximum potential and that the setup will last.

With a 1.6 roller rocker ratio and depending on your cam of choice, you’d be heading into .600+ valve lift territory. If your using your factory 1.5 ratio hydraulic rockers, and want higher lift, make sure you do your due diligence first. Obviously when getting into the top end of the valve lift scale, you’re heading into 400+ horsepower in stock form with the performer RPM heads! If you’re building a killer street/strip engine then I’m sure you can see the potential here.

Cast Iron LA Heads Horsepower Numbers!

Ok so now that we have got the basic technical aspect out of the way, as far as the performer RPM heads go, let’s see some proof. I’ve included a video here put together by Richard Holdener. You’ve probably seen a lot of cool videos by Richard already. Perhaps you’ve seen this video before too.

The engine featured here is a 360 2bbl LA series engine. The heads used throughout the dyno test are the stock factory cast iron heads. Richard does give the heads a very mild port job. You’ll see all parts I’ve mentioned at the start of this article have been used as well. Including two different camshafts.

I wanted to highlight the potential that your stock cast iron heads do have. So if emissions testing in your state, city or country is an issue to overcome, fear not. The stock heads still perform very well. While watching the video though, consider what you have learned here, as far as the potential of what the Eddy heads have in them. Bolting on a pair of new Edelbrock heads is like bolting on a pair of ported big valve heads, but better.

Edelbrock LA Heads Product Description

A few features the aluminum Edelbrock Mopar LA cylinder heads have include

• Phospher-bronze valve guides
• Interlocking ductile valve seat (hardened and replaceable)
• Stainless steel high flow 2.02 inch intake and 1.60 inch exhaust valves
• 63cc combustion chamber
• 171cc intake ports
• Heat treated and machined steel retainers and valve locks
• Heavy duty valve springs suitable for up to .575 inch valve lift. For higher valve lift, more suitable springs are recommended.
• Stock location intake and exhaust bolt holes and flanges
• Stock spark plug location

You can use your stock cast iron intake manifold and exhaust if need be. Headers are recommended for better exhaust flow and increased horsepower. Better economy can also be achieved. Your stock valve covers can also be used.

As mentioned already, you can use your stock rocker assembly. You can also use your push rods as well. As long as they are inspected for any wear and measured for the correct length. Some after market heads require the use of roller rockers, as your stock rocker gear won’t fit on those particular heads.

Although this leads to an increase in horsepower too, this is an added expense when looking to purchase and install new heads for your engine. You can also use roller rockers on the RPM heads too. Perhaps the initial budget for roller rockers might be better spent on other recommended parts as such as upgrading to a better performing camshaft.

If you are upgrading the camshaft, look to buy the complete package. This will include the tappets or lifters, push rods, timing chain and timing gear.

Small Block Mopar LA Heads Conclusion

If 400+ plus horsepower is your goal for your Dodge 360 engine or your 318, as you’ve read and watched from the above video, this can be achieved on a budget. Simply bolting on the aftermarket heads after having them checked over will net you a good noticeable increase in power and performance too. Even if you kept with the 2bbl intake manifold and switched to a Holley 350 2bbl carburetor. Or the stock carburetor.

How much more you would gain will vary. As long as you have good compression, or as good as can be expected you will notice the difference on the street or highway. Remember in the video Richard says the stock compression in his 360 2bbl LA engine had about 8.2 to 1. I had to laugh a bit when he removed the stock air cleaner from the engine and made 5+ horsepower right off the bat! Switching to a K & N open style filter would bring similar or close results.

This was good to see right at the start. Then changing out the parts and testing on the dyno, we were shown increased results. A quick re-cap on the parts swap were:

1. Two different induction systems
2. Long tube headers
3. Two different camshafts
4. Ported heads
5. Changed from the 2bbl carburetor to a 650 Demon carby along with the bigger camshaft for the biggest horsepower gains

With the smaller camshaft and Quadra-jet carburetor installed, the engine was put back into Richard’s van. This was then put onto a chassis dyno where we saw an increase of 100 horsepower at the rear wheels over the factory stock 2bbl setup. As shown in the video.

So it really comes down to, ‘how far do you want to go?’ and what realistically fits your budget. Many of us tend to buy one item at a time and piece things together over time. On the other hand installing the new heads first allows you to keep driving the car, or truck or what have you, even if that means sticking with everything else you currently have for now.

My goal here is to show you what’s doable. It is relatively simple. At the very least you now have some basic knowledge that allows you to ask the right questions, when looking into purchasing some new heads for your beloved Mopar.

If you have any questions fell free to leave a comment below this article. If you’re interested in purchasing a new set of RPM heads for your small block LA engine, you might be interested in reading my review including the pros and cons of the Edelbrock aftermarket Mopar LA cylinder heads. You can find that info right here https://quartermileaddiction.com/best-small-block-mopar-heads-on-a-budget-build-review/