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If I had the 3.42 or 3.55. I would have chosen the .82 for sure.
Or if my HP/TQ came late to the game like a high revving small block (that should get some comments...lol) |
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I get you. I was just fun'n about the small block.
My cam is not radical, builder concurs. He says even lumbering along at 1800 rpm shouldn't be a problem. |
Do you have the cam specs handy?
Believe it or not, you can have a mild cam but still have a lot of overlap, and it's common for both off-the-shelf and custom hydraulic roller camshafts. The hydraulic roller for the FE is a catch-22.....you either have a cam that's a little lazier with a greater amount of overlap, or you have a cam that's more aggressive with less overlap. If you have the aggressive cam, then you're automatically down 20 hp to a similar camshaft with a less aggressive lobe, and you have valvetrain/lifter noise. If you have the lazier cam, then you're up horsepower, but you have a good bit of overlap that needs to be managed and your engine will buck at low rpms, even with a low duration. It's taken me quite a few years to find out which lobes offer the balance of those two situations. If you have the cam specs, including advertised durations, .050" durations, the LSA, and where it's installed, I can tell you if you'll have issues. |
I do not have it with me, I will check it when I get home and let you know
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OK, Brent, here is the came. Pond 427, stroked to 482.
@.050. int open 7.5 BTDC - close 46.5 ATDC - lift 108 - duration 234.0 EX open 50.5 BBDC - close 9.5 ADTC - lift - 112 - duration 240.0 |
Got advertised durations?
Pretty mild so far though... The .050" duration is only 10 degrees off from a 482 I built to tow a 10000lb travel trailer.... |
Of course, you only need less than 20HP to keep your Cobra rolling along a flat plane at 75MPH, and only two or three times that if the plane is inclined (upwards, obviously:p). To really enjoy the .64 TKO, you have to live in an area where the highway cruising speed matches up with the product of your engine's quietest RPM, your differential ratio, and your tire size. The .64 is not for racing, nor even aggressive acceleration. It is for quiet cruising, but you have to do your homework and make sure it will work for you. If it does, then you'll love it, and if it doesn't, then you'll hate it. But, even if you make a mistake in the choice, it's not the end of the world. The transmission only weighs 100 lbs. and is not that hard to pull. You and a strong son can pull it, drop it off at the transmission shop for a gear swap, and then put it back in if you find you don't like what you have.:cool:
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FWIW, I thoroughly enjoy my TKO 600's .64 overdrive. I also have a Pond based 482. The first 4 gears provide all the performance I need with the 5th gear providing the perfect overdrive. I also have a 3.25 final drive. I wouldn't swap it for a .82 overdrive, even if the change-out was 100% free.
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My only reservation will be track days. I can see that. But that may only be 3-4 times a year. Yet any drive into town, is 45 minutes at 70-75 mph
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Thanks Brent. I also appreciate your help and parts with Bud and my engine. It pulls good vacuum for my power brakes too.
And when I say track days, I mean road course, not drag. And spirited driving, not competition. If the course has long straights that could be a problem for the Cobra, I'll take my GT 500 |
I have a BOSS 302 with about 425 hp. The rear end is 3:31 and the original
TKO has a .63 overdrive. The cam is a mild solid roller with very similar specs. It is essentially a 4 speed with a genuine overdrive gear for the occasional peaceful freeway jaunt. The 5th gear could just as well be a button on the dash! I would guess I use 5th less than 5% of my drive time. Where I drive I hardly even use 4th gear! |
I agonized over the gearing decision when planning my build. 3.31 or 3.54? .82 or .64? I spread sheeted it to death and wound up choosing 3.54 and .64 as I drive it in town about 90% of the time. I never use 5th until on the highway, where it cruises at 70 mph/2000 rpm. There is about a 500 rpm drop between all gears except 4th to 5th, where the drop is about 1000 rpm. Since a Texas highway speed limits are 75 and everyone drives 80, this combination is perfect for me. If I had planned to race the car, I would have gone for the .82 OD.
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My cam is similar to your's but I only have 347 cid. The 482 cid will tame that cam a bunch. I trust Brent, so you will be good. I suggest, that if you have never drove anything with a 1.0 4th and .64 5th, you drive one and see how you like it. There are people who like it, and you may be one of them. You certainly have the engine to pull it off.
I hate it. It reminds me of shifting from 1st (super grandma) to 2nd (road gear) in a model T Ford. Well to be honest the 1-2 shift in a Model T is way worse. The big step in gear bugs me, but that isn't what I hated the most. I drive on back roads and stay away from traffic most of the time. I almost always had my wife with me. 4th the pipes was to loud to talk over at 55 mph and 65 -70 mph was too fast for the roads and the wind becomes to loud even though you cannot hear the pipes. Most of the time I ended up driving 45 mph to talk. Then a car would come, and I couldn't drive that slow. The lower rear ratio, allows me to run in 5th at 55 mph, but I cannot let it drop much lower. Now 4th make the pipes too load at 45 mph. So it sill isn't perfect, but much better. |
I don't understand
I put 42,000 miles on my small block 354 with two different trannies both with .64 OD. Cruise at 1,300 rpms in 5th with no trailer hitch jerk. 4,000 miles on Hodges 408 with 3550 .64 OD. 1,500 rpms in 5th., no problem. A couple of thousand mile on Lainhart's 1965 KC 427/487 620 hp 3550 .64 OD. You can cruise at 1,800 in 5 th with no jerking. Coach's KC 428/461 TKO 600 .64 OD 1,800 no jerking. Coach's Unique with a Pond's KC 482. He bought a TKO 600 with .82 but after a few months bought the parts and swapped out for a .64 OD. Cruises at 2,000 easily. Now, none of these motor would pull from 1,300 - 2,000 if you stomped the gas pedal to the floor very quickly. But down shift to 3rd or 4 th and you're off like a missile. All of these motor were build with a lot of low end torque. Easy to cruise at low rpms. If you want to see videos of these cars cruising at low rpms just email me. We would laugh at how low I could cruise. Got to be a game on the back road to see how far I could go in 5th. Dwight |
These engines are not 2017 Mustang engines with EFI and variable cam timing. They are old-school V8's with lots of horsepower. Lugging one down to off-idle rpm's, whether or not they will do it, is not good for the engine and is opening the engine up for detonation or spark knock that you can't hear in a car that's open to the air and has loud exhaust. I would highly discourage anyone to see how low you can pull one down while driving. "Stomping the gas pedal to the floor very quickly" from 1300 rpm is a good way to damage an engine.
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My car came with a 460 and 3550 big input tranny originally. I'm installing a 700+ hp approx 650tq 545bb and have already bought tko 600 w/.82 od. After talking to Cobra Valley guy I was told to stay with the 3550 with upgraded shifter because tko 600 can be difficult to shift and 1st gear has a tendency break. I have a 2450.00 tranny and not sure whether to use it.
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