Built 273, what sure grip ratio with a A833 3.09 first gear
65 barracuda formula S streeter built 300 hp 273
9.5 compression 920 heads
ld340 intake manifold intake ports matched to heads
holley dp 650
1 5/8 semi fender well hooker headers
2.5 head pipes to flowmasters,
a A833 4 speed 3.09 low first gear
3.55 rear gears
Erson solid cam short dur. high lift. 510 lift , 286 duration advertised , 2000-7000 rpm range
72*overlap. Pretty snotty cam for a 273 teener. built similar to the 66 d-dart or 65 golden commando's barracuda "gold fish" specs .
Question is :
would there be any advantage going to a 3.91-4.10 rear gear ratio.
The starter gear with the present 3.55 ratio is 10.9 . 26" tall tire being used . I have to shift pretty quick with a 3.55 gear already.
4.10 would be Really be quick and has no advantage IMO . I'd like to take it on the freeways with 26" tall tires . It's not a race car by any means .
what are your opinions ?
video of 273 with open headers
www.youtube.com/edit?o=U&video_id=Lur52zZxN9Y
Thanks .
4.10 would be Really be quick and has no advantage IMO
With a 3.09 I sortof agree in as much as first gear is concerned, and that is very application specific. Where the pay-off is with performance gears, is threefold;
1) the engine blasts thru the gears quicker, reaching the shift-rpms sooner.
2) it will usually go thru the powerband twice on a zero to 60 mph run, putting more average power into the effort, and therefore should be quicker.
3) for a streeter, you can put your 2-1 downshift in the right place in your powerband to annihilate cars with mismatched and often, bigger combos.
4)But yes, hiway use is the sacrifice we often have to make.
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For me, #3 was most important. I have a bigger engine but the point is the same. I wanted the 2-1 downshift to be at 32mph +/- 2mph. And my engine made peak power at about 5700(292/292/108 cam). Peak torque came in at about 4200. So in my naivete, I installed the 3.55s, giving me about 3600@32 mph with 28s, and the 2.66 low gear. And as you know 3.55s are a reasonable hiway gear. The thing is, my engine is too big, too powerful for the corner-carver type suspension it has, and so when I floor it, it instantly spins, and if I keep it floored it will not stop until I let up, which was near- speeding anywhere in Manitoba. I could easily give up a lot of camshaft, and so I did.
I swapped in a 270/276/110 that power-peaked at about 5000, torque-peaked at about 3600. So now with those same 3.55s, and on the 2-1 downshift, the Rs were still hitting 3600....... so it worked great! Except getting off the line with a 2.66x3.55= 9.44 starter gear and 28" tires was not making me smile. But I had 2 outta 3 so I drove it like that for a couple of years.
So I had the bright idea of installing a 3.09od box, and a GVOD to be used as a splitter, and gearing it to trap at 62mph, in first-overdrive. Daymit this was 3.55s again,lol. But now with the 3.09 low, the starter gear was 10.97 and that little 223*@.050cam pulled that easy. The 2-1 downshift was now 4200 at 32, and I just hit the splitter when it nosed over, and so now I was spinning all the way to 62 again....... and cruising at 65= under 1600. whoot! The bonus with that combo was; 32mph in second gear was a tic under 2300...... so I could sneak up on anybody, and shock the brown out of them tuner bums.
The downside was the ratios in the od box were too far apart and I was pretty much forced to always split gears and that got old in a hurry. I tried some other chunks to try and mitigate things but in the end I ditched the od box.
Long story short; What rear gear
YOU run
is up to you. Not everyone wants a tire-fryer right out of the gate. Nor wants a 2-1 blast-off. nor a 1600rpm cruise. If you like 3.55s and your engine likes 'em, let it be so.
At one time I had almost every chunk from 4.88 down to 2.73s, all lined up ready to go, and three different 4-speeds, plus an automatic, and a back-up 318. And I did a lotta lotta swapping. In the end, the 3.55s are back in there....... probably to stay,lol.
