Joined: Sun May 06 2007, 10:35AM
Location: State of Denial
Posts: 81
I think I'm going to run an RV cam as suggested prior. I'm going to borrow a friend's book on cam timing to further narrow down what is needed.
The Comp cam grind looks like it's out.
The primary issue with engine design or modification is that there has been so many combinations tried that it's hard to discern what is truth and fantasy.
The key to sort through all the fog and romance of engine building is to look at the key research done by testing labs and use thermodynamics and physics. Physics of fluid dynamics, physics of liquids, physics of combustion.
Of course personal experience backed up by hard fact is a power resource to draw upon. My personal experience in physics and actual mechanic work on engines from lawn mowers to massive diesel electric generators has been a great library. However, this does not mean I ignore the counsel of others. "There is wisdom in a multitude of counselors", is a saying I've lived by for a long long time.
Joined: Thu May 01 2008, 11:15AM
Location: Chicago,IL
Posts: 2868
I guess the thing I look at with that intake too is that it's what, a 30yr old design, and nobody has done anything like that in a dual plane carb intake again. The theory has translated to very cool variable intake tract stuff in the last 10yrs in OEM engines, but that intake just doesn't seem to cut it. That intake was developed long before the sophisticated modeling tools that are available today to know whether it would work.
Joined: Thu May 01 2008, 11:15AM
Location: Chicago,IL
Posts: 2868
another thing to think about here is the open chamber heads. I don't know what your budget is and how extreme the plan is, to just try to optimize a few things for a few bucks or a full on budget to see just how far you can push mpg? A set of closed chamber heads or some quench pistons to allow the motor to behave more like a modern, quick burn engine would yield a lot of benefit I would think.
Joined: Sun May 06 2007, 10:35AM
Location: State of Denial
Posts: 81
I agree on the head issue. Something with more quench would be better, but I am running on a budget right now and would like to use stock parts as much as possible.
Intakes and carbs are tolerated by the purists it seems. I do know that Mopar had some great head designs in the 60's, like the 452 castings and these can be obtained on classifieds for a song.
I would install an RV grind cam (or a magnum cam for a bit more fun, both are pretty mild and make great street motors) an Edelbrock Performer intake, factory HP exhaust manifolds and 2 1/2" dual exhausts (with an H pipe) and you would have a nice low-mid rpm torque monster that is still easy on the gas.
My 68' Newport came with a 383HP and 3.23 gears, and got 17mpg on the highway. It now has reworked heads with great big valves, Edelbrock performer intake, Comp Cams XE268H grind cam, and a 2 1/2" TTI exhaust system. It easilly runs over 100mph in the quarter and still gets 16 mpg (but only nine in city traffic). The torque this thing produces makes driving tons of fun, and it surprises lots of unsuspecting Mustang GT owners.
Joined: Sun Feb 26 2006, 08:46PM
Location: Kingston,Ontario
Posts: 5622
Krautmaster,I looked at the Comp Cam specs and state "Requires machining on cylinder heads" Did you have to do any work to the heads to accomodate the XE268H? I have a 750 Eddy,factory 301 intake,HP logs,2.94 gears and will be using a 2200-2500 stall convertor. I am also looking at the regular 268H cam as well. Thanks
<span class='smallblacktext'>[ Edited Wed Jan 14 2009, 09:26PM ]</span>
This cam grind looks pretty good. Has a good duration, is close to the stock Magnum grind (which is what I'm looking for), and works with a 750cfm carb which I have on the car now.
I'm also planning on the dual exhaust route as well, probably not much bigger than 2.75" tubing because of room. I had thought about a header system, but all the headers I have run were really loud and tinny.
Joined: Thu May 01 2008, 11:15AM
Location: Chicago,IL
Posts: 2868
I have that very cam in my 383 right now. It is a good, mild cam, worked with a stock stall just fine when I had the 727 in the car. I also went 13.20 @ 102 when I had it in a different 383 with a torker and 750 holley and 3.91's. I got 19mpg with the 2bbl, 2bbl cam, and 2.73's @65-70mph. It dropped to 15mpg when I did 4bbl, 268H, headers, and 3.23's. Was a lot more fun to drive though.
68Cbarge wrote ... Krautmaster,I looked at the Comp Cam specs and state "Requires machining on cylinder heads" Did you have to do any work to the heads to accomodate the XE268H? I have a 750 Eddy,factory 301 intake,HP logs,2.94 gears and will be using a 2200-2500 stall convertor. I am also looking at the regular 268H cam as well. Thanks
Those are footnotes refering to having the top of the valve guide boss being cut down to accomodate #925 dual valve springs, but you can use their #911 springs with no mods. All of those other notes also refer to only when using other specific parts (like note 37-adjustable valve train req. when using #867 lifters). The only things you need to use this cam are the #911 valve springs and # 822 lifters. But I also put in the special valve retainers and locks, a set of magnum pushrods, and a double roller timing set. Just put all the pieces in and go fast!
<span class='smallblacktext'>[ Edited Thu Jan 15 2009, 10:01PM ]</span>