289 improvement ideas

Cdaniel

Founding Member
Nov 29, 2001
220
0
16
Arizona
What I have: 289 C code with about 40k on a stock rebuild that was bored .030 over.

What I'm thinking about doing:
Basically a 4V carb and dual exhaust keeping the stock appearance, heads and exhaust manifolds. Possibly add headers, but doubt the heads will flow to make it worthwhile.

Worth the trouble for a little extra power?
Are the stock 2V heads a restriction for a 4V?
Is there a mild cam improvement worth doing?
 
  • Sponsors (?)


the stock heads an handle a decent amount of power, though at some point they do become a restriction. that said a 4V carb upgrade, use the performer rpm or weiand stealth intake manifold and a 600 cfm carb, i prefer the edelbrock 1406, but there are a number of good carbs out there to use.

dual exhaust is great, add a set of tri-y headers to round out the exhaust, they are designed to operate in the mid ranges and will add power to the engine.

for a cam upgrade, look at cams that operate in the 1000-5000 rpm range. that is where your engine will operate about 80% of the time.

remember shelby used the stock heads on the GT-350s, even the race cars, though he did port them for racing, and the shelbys dominated their class in SCCA racing, sometimes even beating A production cobras. so since oyu are not going to make around 400hp, your stock heads will do just fine.
 
  • Like
Reactions: 1 user
Thanks. I've been looking at the edelbrock carb intake package deals. Seems like a good way to go. Maybe add their cam as well. This engine has never been very smooth at idle since new and I've always suspected the generic stock cam might be at fault. I just finished a compression check and all is good internally.

Any experience with tri-y header install and fit? Pain in the keester?
 
i havent put my tri-ys in yet, but i think they will fit better than the 4-1 tubes i had in the car, and they fit pretty well. as for your not so smooth idle, you might have a vacuum leak in the stock engine, rather common issue as the intake gets a bit loose over time. i have had that happen a few times over the years. it stopped when i went with fords suggestion of torquing the intake to 30ft/lbs, and changing the pattern i used to torque the intake down, starting with the four corners in a criss cross pattern, then using the stock ford pattern to torque the intake down. that prevents the inner bolts from loosening up when the outer bots get torqued down.
 
the cam manufacturers tend to be conservative when recommending cams, personally i would go with either the 260h or the 268h grind. i think for your application the 260h would do you just fine. the 252h is perhaps a tiny bit better than stock.
 
Thanks. I have a 260h comp cam in an SBC stroker for a 4x4 rock crawler with efi and it's great for that.

For the mustang it's just needs a little wake up, but I want to maintain a civilized idle.