68 289 More Power!

6mustang8 · Sep 27, 2008

I've driven a 68 289 2v stock engine for awhile and finally have some cash to upgrade a few things. I don't want to go wild but I'm looking for more power and a great sound. Its a 1968 with A/C and power steering (info for headers). On the intake I was thinking of a 570 cfm street avenger on a weiand stealth. For the exhaust I want to change the the manifold w/ single exhaust to something like Dougs tri-y's to an H - dual exhaust with dynamax muff's. I was thinking 2 1/4" would be plenty for this set-up. Does this sound right for intake and exhaust to match? Will the power steering or A/C cause problems for the headers? BTW I'm not planning on doing any mods to the engine itself, just the add-ons. I'm fairly new to this so any help would be great!
Thanks

68conv4sp · Sep 27, 2008

I had essentially the same motor. The 68 has 63cc combustion chambers, thus low compression - 8.7:1. I did the extrnal mods you have described with little effect. Then I added a moderate cam (Crane w/ .469 lift) and alum edelbrock heads (60 cc). That made a HUGE difference. So, as a package i have tri-ys, 570 Avenger, cam and heads. The Tremec 5 speed and 3.55 diff capitalize on the mods, and the tires will spin in second. Its like being in high school w/ the car I always wanted. My only second guess is that I should have stuck with the Edel 500 cfm carb. It was smoother at low rpms, and only slightly weaker at the top end.

D.Hearne · Sep 28, 2008

6mustang8 said:
I've driven a 68 289 2v stock engine for awhile and finally have some cash to upgrade a few things. I don't want to go wild but I'm looking for more power and a great sound. Its a 1968 with A/C and power steering (info for headers). On the intake I was thinking of a 570 cfm street avenger on a weiand stealth. For the exhaust I want to change the the manifold w/ single exhaust to something like Dougs tri-y's to an H - dual exhaust with dynamax muff's. I was thinking 2 1/4" would be plenty for this set-up. Does this sound right for intake and exhaust to match? Will the power steering or A/C cause problems for the headers? BTW I'm not planning on doing any mods to the engine itself, just the add-ons. I'm fairly new to this so any help would be great!
Thanks

Do just what mods you listed and then add a Comp Cams 268H cam, new lifters and valve springs(if you've still got the originals on the heads, otherwise if the springs are fairly new, leave em be) The 268H will compliment the compression ratio.

S-Car-Go · Sep 28, 2008

Sounds like a good plan, but what trans and gears do you have?

6mustang8 · Sep 28, 2008

Everything is original to the car: C4 transmisison with 2.79 axle ratio. 8.7:1 Compression. I just now have $$ (lol w/the economy) to change some things. I don't want to go wild, just add a few mods for sound and response. Maybe later I'll add new headers etc at a second stage, but I think I could alsob swing adding a new cam.

6mustang8 · Sep 28, 2008

Also, I'm looking at Tri-y's or hedman long tube headers for AT. Would I be limiting myself in the future with the hedman long tubes since they are for AT? Sounds like it.

D.Hearne · Sep 28, 2008

The auto trans headers will not work with a manual trans with the stock mechanical clutch linkage, if that's what you thinking of.

S-Car-Go · Sep 28, 2008

Personally I'd take a stock 289 with an OD trans (AOD or T5) with some gears over a warmed up 289, a C4 and stock open rear end.

If it were my car, I'd stick a T5 in there, run the exhaust (inc headers) around the new trans, then do the rear end, then worry about the motor.

68 289 More Power!

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