I'm building a 3.4 push rod with a 272 cam. The cam specs show recommended cruise rpm between 2600 and 3000. I was originally going to mate it to an F23, but with this info, I'm thinking to keep the 85 4speed Muncie?
From ari web site : "Crane PowerMax H-272-2 216 228 272 284 .454 .480 112 112 Good idle, daily usage, and off-road, towing, performance, and fuel efficiency. Increased compression and gearing advised. 2600-3000 cruise RPM, 8.75-10.5 compression ratio advised. Basic RPM 2000-5000."
I would still go with the 5 spd. While you may not be in the ideal sweet spot for the cam, you will get better mileage and the motor will last longer. You can always downshift to 4th to be in the same rpm range as your 4 spd would be. Just think of 5th as overdrive and use it accordingly. Cams don't really have an "off and on" rpm range. With the 112 LSA I think the cam will be very streetable and won't mind cruising in 5th on the highway.
Thanks for the input. I'm on the fence because I LOVE the Muncie 4speed but would definitely enjoy the modern feel of reverse synchronization, positive gear engagement, and a fifth gear. Did i mention that i love the 4speed Muncie? It's got four perfectly placed gears (with 14" tires) and just feels good when shifting. Gosh. I just don't know what to do.
The cam and trans choices went together nicely. It's turning about 2650rpm at 70mph. I haven't completely dialed in the vss signal yet, so i might be off a couple mph. But so far, That rests very well in the snap-neck performance range without being totally wound up. Thanks for everyone's advice!
[This message has been edited by f85gtron (edited 09-06-2016).]
Yes, bringing it to rfth! Yes, The f23 5 speed is now my preferred transmission in the fiero. Now I just have to find a shifter gate map to replace my old one. Don't want the valet to get confused
I had that same cam in my 3.4 but with the auto trans. I think in the th125 3k at 65 mph and I later switched to the 4t60 and dropped to 2k at 65 mph. This probably don't help you at all but I figured I'd throw it out there.....
If you use the Muncie four speed and the 2.8 l V6 engine, you can expect 3400-3500 rpm at 70 mph based on my F308 replica car. I think that the 3.4 tach reading would be similar.
I gps'd it today on the hwy. 75mph is sitting at 2900rpm on the f23. Has plenty of power to spare still. I was concerned that 5th would be too tall for this combo, but it feels just about perfect....or at least close enough! Very pleased indeed. Nelson, are you gonna make rfth this year??
You should easily be able to keep it up in range on RFTH.
