Gun Jam

Hello

right now I have heads that are cast iron and stamped 289. I dont know what the PO did to them if anything (certainly not ported or polished) I dont know much about the cam nothing useful thats for sure. It is perhaps an edelbrock street performance cam and it does have a nice lope.

Right now I make about 225 RWHP at about 3000 to 3500 rpm (I have my dyno sheet here some place) I also get 16mpg at 75 mph @ 75deg f on level freeway.

I would like to add a bit of hp and torque without giving up too much fuel economy (more efficient system if possible) by switching to aluminum heads and maybe a matching cam if that's required. This is my daily driver so the new system must be reliable and not be a complete gas hog.

If I could get 290 to 310 RWHP and still maintain 16ish mpg at cruise speed and not give up that old sKl lope I would be real happy.

what are some ideas?

Thanks

-Gun

groho

Logically speaking, because the 289 heads are smaller runners, int and exh valves, they can't push the fuel of a larger head, so theorically, the 289 heads are more in line with what you describe; MPG. It might be cheaper to port and rebuild your current heads, and even rejet (one step smaller) your carb than it would be to change heads +/-$1000. Remember, larger runners, larger int and exh valve means more fuel/air, less MPG. As my brother used to tell me, you can't have both MPG and power, its one or the other. Ya...sure, it may say 400hp from a 5.0L at 24 MPG....but I don't care what anyone says..you can't push 400hp and expect to get 24MPG..

Gun Jam

I would think that there should be something close to what im after. I was hoping I could improve efficiency with a modern head.

I manged to bend a push rod which ended up causing some damage to a valve stem end where the rocker rides. If I have to pull the heads to replace the valve I was hoping to not have to reinstall them and get something more modern.

I figured 290ish rwhp was still pretty streetable for a 289...new heads and perhaps a matched cam is the wrong way to achieve that?

Thanks

-Gun

rmodel65

how about getting a set of GT40's and porting them yourself or getting Thumper of Orange park to do them that would put you in the power ranger youre looking for

Gun Jam

Gt40s are going to flow better than say doing the same thing to the heads I have now?

Starfury

I don't see see the point in putting a lot of work into factory heads. By the time you rebuild them, install larger valves, and work the exhaust ports a little, you're getting close to a set of aluminum heads that will still flow better out of the box.

That said, if you can get away with minimal work to your existing heads and open up the exhaust ports a little, they're probably going to be the most efficient you can get without going to a fast-burn head (like the GT40P or GT40X heads). Unfortunately, GT40P swaps are a royal PITA due to the spark plug angle change, and GT40X heads are overpriced for what they are. Remember, cast iron retains heat better and provides for a more complete burn than aluminum, which transfers heat so well it quenches the flame front in the chamber. Good for preventing detonation and removing excess weight, not so great for combustion efficiency.

If you do go with a modern aluminum head, stick with something small, like Edelbrock Performers (not Performer RPM's), and keep runner size down. Smaller runners = higher port velocity = better throttle response and fuel efficiency.

A small cam designed for low end torque will get you the best fuel efficiency and driveability to go with whatever heads you use. A custom cam would be ideal, but Comp cams has a good selection of off-the-shelf cams that would work well for what you want.

Still, don't expect to pick up 75hp out of heads and a cam. Realize that you may even be stepping up your combustion chamber size, depending on your existing heads, which will drop your static compression.

guitarman376

I would say go with the gt40 heads if you can steal some for cheap. I couldn't justify buying aluminum heads for a mild 289. Roller rockers would add some "free" horsepower, perhaps ignition upgrades could do the same (I am unaware of what setup you are running), maybe a phenolic spacer under the carb will keep the air charge cooler. Just ideas...

guitarman376

But yea I wouldn't expect the 75hp increase you want.

Gun Jam

Hey thanks guys for the help.

Starfurry could you post a link to a set of aluminum edelbrock heads that are similar to what you described?

What about a roller cam setup are they too much trouble... are the power gains minimal?

What about the kits that edelbrock has available? They have cam,intake,and heads??

Finally gt40 heads are a simple swap but not gt40p? what does the p designate?

Thanks

-Gun

Starfury

The P heads have relocated spark plugs and an improved combustion chamber for better combustion efficiency. Unfortunately, this requires special headers on classic mustangs to keep the tubes away from the plugs. The GT40X heads are still of the fast-burn combustion chamber style, but they have standard plug locations. Unfortunately, they usually run the same as better flowing heads like Trick Flows and Edelbrock RPM's.

A roller cam would get you a significant increase in power without sacrificing efficiency. It would allow you increase lift and duration @ .050" without increasing valve overlap, providing you a good idle and a broader power band. However, roller cam conversions tend to be expensive. In addition to the more expensive cam and lifters, plus the spider assembly, you'll also need screw-in studs and improved springs to match the cam (don't rely on the springs that come with aftermarket heads). Still, it's an option if you have the money.

I don't like the Edelbrock packages because I don't like their cams. I much prefer the comp cams grinds, which are plentiful. Edelbrock only has a couple grinds to fit everything out there.

I'll see what I can find for heads out there...