1967mustang

ivehave had this 1967 mustang for about 4 years. been drving it for 2 year. and i need toknow what the REDLINE would be? it is a289 block with 302 heads on it. i am kinda guessing it is 5500 RMPs. i have never had it that high, becouse i dont no.


thx nick

my77stang

probably 5500 although you could get away with 6000. the weak point is the stock rod bolts (that are now 40 years old), and valve springs that are also god knows how old.

i wouldnt want to hold it at those rpms, but i would be comfortable bringing it up around 55 or 6 while running thru the gears.

Norm Peterson

From your other thread, I'm guessing that your 3-speed is a manual, and from that that your 289 has a two-barrel carb. In that case, it won't even want to go up to 5500 rpm, though you can make it wheeze its way up there if you're in a cruel mood.

I'm also assuming that you have no idea how many miles have been run up since the heads were swapped, or if the rest of the notor was even touched at that time.

If you're looking to upgrade the motor a bit to go with that 4-speed, you owe it to yourself to at least freshen the engine up (and replace anything that you find to be questionable or marginal once you've got it torn down).


Norm

Starfury

I definitely wouldn't trust the stock valve springs past 5200 or so, and probably wouldn't trust the stock rod bolts much farther than that.A failure of either could be just as catastrophic. In any case, the came dies off really quick after 5k so redlining it is going to be difficult without downshifting.

1967mustang

well i rebuilt the motor.new everything valves, valve springs.rods, pistons,ect.yes does have 3 speed manual. i did buy a 4 borg warner for it so ill be putting that in.i am hoping that be alot beetter onit so not turning 3000 RMP at 65. and easyer take off. and it has 4 barrol 650 holly .

Starfury

As I mentioned in my other reply, the 4sp isn't going to affect your final gearing. You'll still be turning the same rpm's in 4th as you are now in 3rd. It's a better tranny, no questions about it, but not for that reason.

Since you've already gone through a rebuild, redline is going to depend on how well you built the engine. What rod bolts did you use? What are the valve springs rated at? Did you have the rotating assembly balanced? Which cam are you running?

Also, you may strongly consider dropping to a smaller carb. 650CFM is huge for a 289 unless you're winding it to 8k or running 12:1 compression. You may be able to tune it to work ok, but you'll likely get much better throttle response and efficiency from a 500-550.

1967mustang

yeh no i get what you saying about 1 to 1 but it be easyer take off and such. i know i am going to have to shorten my drive shaft and all that. i used all stock parts. every thing is new but same spec was in 67. 289 block and pistons and rods. 302 heads and valves and springs. i havnt had any problems with the 650, it is littol slugish but i dont foul plug or anyting, it might allso be me lugging it with the 3 speed trans. i put 650 holly on it cuz it ws just good carb i had sitting around. another thing is when i doing 70 and i put to floor liek nothing there. yeh know? i wish now when had all aprt and out of car i went big with it. but now i want to put 351 in it. and i just got some factory header from guy i work with for it so that might help some.

JBradley500

you could probably run through the gears til 6000 without a whole lot of problems. i dont like to turn anything thats not racing over 5250 unless its a OHC. too much moving too fast for a stock build IMO. probably not making power anyways, just noise.

Starfury

An oversized carb is more likely going to run lean, not rich. There's not a strong enough vacuum signal to pull the proper amount of fuel out of the carb. This causes hesitation and poor throttle response. You can tune some of this out, but it's probably nowhere even close to being tuned for your engine as is.

With the factory rods and factory style rod bolts, I wouldn't try to push it past 5500. I still don't know what cam you have though, so no telling if it will even go that far.

There is no such thing as a 'factory header.' There are hi-po manifolds which were factory on K codes, but no headers from the factory.

67mustang302

Pushrod engines can turn insane rpm IF THEY'RE BUILT FOR IT. With stock parts and a stock spec cam, it's doubtful you're making any powerpast 5,000rpm so there's no need to turn it above that. And yeah, 650 is too large for a mild 289. You'll make more power with a 450 than with a 650. That's part of the reason it's sluggish off the line, and part of the reason there's nothing when you throttle it on the highway. It's not making effective metering signal cuz you're just not moving enough air through that carb. The gearing on the 3spd is actually better in 1st than on the Toploaders. It's a 3.03 1st as opposed to a Toploader which has a 2.78 1st. But the 2nd and 3rd gearing is a huge bonus, rather than having one long 2nd gear.