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· Registered
24 Posts
Discussion Starter · #1 ·
Looking for suggestions on upgrades please.
(and apologies - i know this question will have been asked several times in similar fashion)

I have a fairly stock 289, which is still getting hot on the passenger side. I've got the citric acid flush left to try, but pretty sure i've narrowed it down to being related just to that head (whether the passages are all blocked up or something). Judging by the oil condition when i got the car, i dont think the PO was that into changing fluids. :/

Oil pressure is also quite low when hot - at idle, the needle is barely lifted off the stop. It's about 1/4 way up the gauge when cruising, and 3/4 of the gauge when cold and first started.

So, im thinking some worn bearing shells probably cause of this. No knocking, but thinking still due a rebuild. Also, get a reasonable amount of breathing out the rocker cover filter.

So, thoughts while i'm at it, is that maybe just replacing the heads is the way to go.

Current specs are:
Stock 289, with Edelbrock Performer intake, and Edelbrock AVS2 500 CFM carb. "High rev" hydraulic lifters, uprated springs (inner & outer), new Cloyes timing set, and changed the cam (which was meant to be a Performer, but got something different - but is about 1-2 levels above stock). Standard exhaust headers, with 2" dual exhaust. Stock C4 trans, and stock rear axle/diff.

Not after anything too fancy - just street use for a bit of fun, and a bit more noise/choppier idle.

After suggestions, please, for suggested mods? I.e. new heads (or should i just strip and completely refurb my stock heads?), plus cam (i'm not against changing this again), and others?
I'm allowing for crank grind, new bearing shells, cylinder bore hone (probably), and set of rings (hopefully dont need new pistons), new oil pump. Would i need new push rods?
And ideally, i guess i should change stock headers (and hopefully could just change the headers and adapt my current dual exhaust to mate up to the new ones).

Probably budgeting around 2500. I know heads would eat quite a lot of this, hence the question about refurbing current heads. But if i'm wasting my time doing anything else until the heads are changed, then maybe budget needs to increase a bit..

Any thoughts/suggestions greatly appreciated.

Many thanks in advance.

· Registered
24 Posts
Discussion Starter · #11 ·
Most people here will suggest not wasting money on the OEM heads and replace with some flavor of aluminum heads.

If they are the early small chamber heads I would suggest some good exhaust port matching and cleanup, screw in studs, and a decent set of roller rockers. Additionally, I would increase the valve sizes.
Thanks. Port matching and a good clean seems to be a common theme. Does increasing valve sizes not require quite a lot of machining work? Probably pushing toward different heads in that case?

On the stock heads, there are small coolent passages that run around each spark plug. I found this on a set of 1970, 351W iron heads. They were all clogged shut with sediment and rust. I worked at clearing those passages out and over a perion of a week or 2, I got them all opened up.
Will have a good prod and clean.

Mike, tell us what year your engine is.
Sorry - yes, this would have been useful info. 1966.

f you plan on keeping the 2 inch dual exhaust, don't bother changing the exhaust manifolds, its already choked off.
Fair comment. What size would i need? Sounds like headers and exhaust will be one of the things to change..
It would be nice to know what cam you have now, before recommending others.
I'll try dig the specs out.
How about testing the oil pressure with a trusted mechanical guage, and then a leakdown & compression test ?
Yes. Will do that and report back.

These gauges are notoriously inaccurate. I'd like to see a real number. Factory spec is minimum 25 psi @ 2000 rpm hot. So, a hot idle would be pretty darn low.
Will get some numbers a report back.
The Edelbrock Performer is no better than the stock iron manifold. That carb is fine for a mild cam. High rev lifters are no harm, but no help, since you don't have a high rev setup. I don't know what "levels" means. To me, two levels above stock is the Cobra LeMans cam, which you assuredly do NOT have. Give us some numbers. 2" exhaust is fine if you are not going out on the track. Heck, the 67 GT500 428 dual-quad engine came with 2" exhaust. The C4 is going to need some help with shifting, perhaps the K code shift servo. If you still have the 2.78 rear, it's killing your performance.
I would say cam similar to the Edelbrock Performer cam, but will find the spec sheet for the one i have. "Levels" was just one of those things to describe the increments between stock and mild, i think. I will look into the C4 work. What makes the stock rear so bad / why was it sold if so bad? What would be a suitable replacement?
Take some advice from an old guy who can still hear. Loud exhaust doesn't make the car faster. It just pisses off the wife, girlfriend, and neighbors. And a choppy idle means the engine was not planned carefully.
Agreed. It's just a bit too quiet / family runaround sounding at the moment :L
While I have the C3OZ-6250-C mechanical cam in my own car, mechanical cams are not for everyone. The C9OZ-6250-C hydraulic cam provides very similar performance.

For this upgrade, you will need:

C9OZ-6250-C camshaft
Cobra or Performer RPM intake manifold
Autolite, Summit, or Edelbrock 600 cfm carburetor
14" open air cleaner
Distributor recurved to BOSS 302 specifications
Dual valve springs (recommended)
Screw-in rocker studs (recommended)
Heads port-matched to exhaust (or aftermarket heads)
289HP exhaust manifolds or headers

This combination has been dyno tested at 323.5 hp @ 5300 rpm.

Nothing else is required. No whiz-bang million volt coil, 10mm wires, etcetera.
I will look into the above. But ideally with keeping my current intake and carb, and just accept that it wont hit the same power you have.

So, it's sounding like a good clean of block and heads. Strip bottom end and inspect. New bearing shells, hopefully just a crank polish. New piston rings as a minimum, and maybe pistons depending if the bores need boring/honing. Keep stock heads, with new set of valves. Port match the exhaust. Cam tbc. And change headers/exhaust system for a bit more air flow...

Many thanks all.
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