1965 Mustang I6 upgrade??

[juanmullen]

I have a '65 Mustang with an I6. I would like to get a bit more power out of the engine without actually changing the engine. It is the original and I don't want to change it. Also, is it normal for the 3 speed tranny to shift gears at what sounds to be a pretty high RPM? How feasible is it to bore out the engine and how large can I go? Would a performance carb be worth it? How much would new headers, exhaust piping and muffler help if at all? Thanks for your help.

[Tony H]

They're good stong engines, its a real shame there isn't more aftermarket for them. Their main problem is their breathing ability or lack there of (log intake). So yea, headers and a carb increase will help a lot.
These are educated estimates, your results could vary either way. Your stock motor makes about 85hp at the wheels. Just installing headers (duel 2" single 2.5"), a new carb such as the progressive Holley/Weber 5200 (270cfm), and an ignition upgrade (duraspark or pertronix) will get you about 125hp at the wheels. See what I mean about breathing?
This is where I'm at right now as I like my 25+mpg.
160 net hp at 4800 rpm with a bigger cam, direct mount 500 Holley or Weber 38/38, and a set of headers, Clifford port divider, late model log head port and polished (these heads have a bigger intake valves but milling is needed to bring your cr back up). Basically doubleling your current power, so yea I say they are worth it.
This is just to give you an idea of what is possible:
Go an even bigger cam, get some better in duction in the form of an import Argintina head, OR 2v Aussie head, (these engines are much more popular overseas) or a bolt-on 3 triple SU carb set,--- there could be 210 hp at 5500 rpm with ease. The exhast becomes the limiting factor here, and the cam must be specialised to allow good flow to balnance the intake flow.
By spending a LOT of money, you could get up to 245hp. Aussies do figures like this regularaly with their little 202 Holdens.

Nitrous oxide and Turbo are also great ways to add power but its still fairly new gound with these engines.
You should be able to bore the block same as any engine. Pistons might be a problem but they are the same as the ones in a 2.3 so it might not be so difficult.



http://www.fordsixparts.com/
This guy sells a lot of parts he imports from Australia.

http://www.stoveboltengineco.com/index1.htm
Sells that Holley/Weber that is so popular


You may want to look into installing a T5 from a 4cyl fox body.

[juanmullen]

Thanks for the info. Two more questions, what is a log intake and how will a larger cam help to increase power?

[Tony H]

The log intake is just a term used to describe the stock intake on these engines. They're cast on the head and kinda looks like a log. The cam shaft effects how far the intake and exhaust valves open and how long they stay open. Generally the more agressive the cam, the more hp (sacrificing some torque) and rougher idle.

[juanmullen]

Thanks again, I may have more dumb questions later.

[Tony H]

No problem, there really aren't any dumb questions when you're learning. So go ahead and ask anything. You may be interested in this book http://falconperformance.sundog.net/ It gives good information on basic upgrading on these engines (mostly little or no cost ideas/tricks). It doesn't cover the imported parts or t5 swap, because it was printed in 2000 and all that stuff has just come out in the last few years. Still a good source.

[juanmullen]

I looked at those sites and they brought another question to mind. I am taking the car in to have the carb looked at (it is leaking a bit), if I pay the money for a nice performance carb now, can I later change the intake/exhaust manifold and headers without messing up the tuning on the carb? In other words in what order should I make these upgrades?

[Tony H]

Forgot to mention it, but for some carbs you will need to hunt down a distributer from a 68 or later 200 for the duel advance (these still contain points which wear and will hurt your performance, the pertronix ignitor replaces the points). 76 and later had Dura Spark II. Both are good anyway, even if the carb doesn't need it.
Now back to what you asked about, retuning is always a good idea when changing something. If your mechanic is cool about it, get him to show you how its done (some don't want to of course). Its fairly simple, just hard to describe while not pointing it out. That book I posted devotes 3 pages to it. I really recommend it.
If you're on a budget, you could just start out with just headers, they make a good foundation for upgrades later. (A lot of people add an exhaust port divider between the 3rd and 4th ports which are conjoined. Clifford Performance claims a 10% hp increase with only only the adaptor with the STOCK manifold. I have my doubts about that, but it can't hurt to install one.)
On the top side, you won't see much difference switching to a later model intake without moving up to a better carb first (it can only take in what the carb provides). Clifford performance makes a kit with a carb, linkage, adaptor, and air filter, Down side is that its like $500. I bought a H/W 5200 with adaptor (may to fabricate a plate to make it work) for $80. I have to fabrictate new linkage and get an air filter but its a lot cheaper that way.