What size Hankooks do you run on the '61 ?

 

I believe I did point out your "errors" : I asked earlier you why you were no longer fond of the GM cam when you talked so highly about it "spanking" the XE262 cam.
I commented why have you reversed your position on both cams ?

Seeing you are making such an issue of it : I will think about getting rid of the GM open gasket and plugging the EGR passage connecting the two sides of my "stock" GM EGR style Q'jet intake.
I run the stock 300 hp base cam so don't know if it this should /will improve anything : mileage or bottom end ?

 

Yep the good ole 5 speed : 1 gear to many !
Either : useless overgeared 1st gear or undergeared 5th overall ratio, take your pick ! LOL

 

Go 3.7 or 3.9 to 1. I truly beleave that this would be the best enhancement to your driving experience. I also thank that advancing the cam would help but in my opinion the cam is crappy and if your going to pull the timing cover you might as well pull the hood, radiator and intake and just change the cam. Go gears. If you do decide to Change the cam, research is best friend, I say 262, Gruber says 270 and there 5 or ten other cam recommendations, Google vortex combos with such and such cam. See what ya come up with. I get kind of obsessive on my projects, if it don't work for me I'll spend every idle moment thinking about what I did or didn't do. Call comp, lunati and iskedarian, email Chris straub all for recommendations. Like I said gears, if you can pull your own diff this would net the off idle torque your looking for in my opinion.

 

rear of my 61 has 235/75/15 hankooks. BIG-AZZ tires! 28" tall that makes the 4.11 rpm like a 3.70
i ordered them for the rear of my 72, but the date code was 2 yrs old so i rejected them. they would make the 3.08 like a 2.54 i wasn't 100% sure it could spin 'em, so i got 225/70/15 Falkens, which are nearly 10% taller than original, and make it like a ~2.87. spins 'em just right
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300hp base cam is tiny, little or no overlap. But EGR is bad imo.
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Yet another cam choice could be BEST for OP. Solid magnum 270S. 224/224/110 .020" Lash
I met some Comp guys at the circle track trade show. Back then my 61 had a 3.36 rear, and for that rear and a CR 2.20 1st,they both said i'd love the 270S. The OP should try it!

 

Really? What is your opinion on a 6 speed or the new C7 7 speed manual?

 

I agree with this - with a well-built hobby car, a 6 speed is pointless. The point of gears is to overcome motor difficiencies, if the motor has a wide power band - then what's the point of the extra weight and complexity.

however, in an econobox with a sweet spot of maybe 250 rpms, then as many gears as you put in the car is good.

heck, old semis had 13,15,or 16 speed road rangers because the power band was so narrow on the old diesels - do we really need to go back there?

and I do think the 7 speed is ridiculous.

- experience is from a 2006 GTO with an 6 speed, and my 4 speed Skylark then Corvette

 

don't quote me on this, but i heard the C8 will have 10 speeds, and pedals for great mpg!

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I checked out the 2012 Camaro. At 1st I thought, WOW the V6 is OVER 300HP it must be plenty quick. BUT if u are going 50 in 6th, it takes really really long to speed up to 70, like 15 seconds So it really doesn't compare with the torque of a 350. Guys that like lots of downshifting will love the v6, i guess.

 

I like having a close ratio 4 speed with a 10.93 to 1 launch, 1 to 1 4th combined with my 4.11 for 1/4 mile type acceleration then a .80 and a .62 od to enable decent highway cruising and mpg. The 6 speed OD final drive ratios are 3.28 to 1 in 5th and 2.54 to 1 in 6th. An overdrive trans is the most popular major upgrade here and, if you talk to those that have done it, the very best upgrade they have done. I think it would be the best option for the op but a rear gear change is cheaper and if he does no highway cruising the rear gears are the economical, easier fix for him.

 

Why do you want my opinion ?
You're smart enough without further input.

I don't know a thing about the C7 - could care less.

 

Right.

 

You've both overlooked my experience with the 3.70 rear and the factory 4 speed and its 2.54 first gear:

So, you're suggesting I start out in the 5 speed's even lower 1.99 second. I'm pretty sure that's a bad idea given how the car reacted with the m21's 2.54 first. No, my 3.70 reared car needs a much lower gear than the factory 2.54. I'm hoping with the 3.37 first in the five speed there will be some wheel spin but I'd bet it won't be excessive with the present 295/50 15 rear tires.

Remember I'm planning on building a similar motor to the OP's and he's complaining about the off the line slow acceleration. I had a 70 Torino with 3.89 rear gears and 22 inch tall tires which is the equivalent of a 4.95 rear gear with 28 inch tall tires such as on the Corvette. With the Torino's 2.78 first that was an overal first gear ratio of 13.76. Did it spin excessively? Yes, but not so much so that it didn't love driving it or was ever tempted to start out in second. It had a 6000 rpm 351 cleveland which didn't produce much power below 2500 rpm but came on real strong at higher rpms. I'm looking to duplicate that motor's performance with my 350.

In the Corvette with its 2.54 first I find I'm revving the motor a lot faster than I'd like and riding the clutch to get it moving from a stop and I find it really annoying to initially get it moving - it needs a lot more gear for my taste. And with the 3.70 gears in my Corvette I'm revving at about 3000 rpm at 60MPH - also very annoying. The .67 5th gear in the Keisler trans brings this down to 2000 rpm, a lot better for crusing and a lot better for gas mileage.

So, no offense guys, but I'm going with my opinion on the five speed, not yours and I think its ideal for my heavy corvette with the planned low torque 325 -350 gross hp 350.

 

I agree. For me the factory M21 four speed is simply inadequate at both low and high speeds. I can't wait to get my five speed installed.

 

What 63 mako is pointing out here is that he gets his cake and gets to eat it too.
He's got a 600hp tire burning 1/4 mile monster of a machine from 1st through 4th gear. Then he also can take it on a trip get 25+mpg and cruise at 1800 rpm with that tall 6th gear. I'd say that is the best of both worlds.
I know I'd like to take my vette on a couple trips but I have to factor in that at 2800 rpms to do 70ish mph I don't think that it will be too enjoyable after a couple hours and that's with a 3.08 rear. So with 3.55, 3.70 or 4.11 I don't think you'll be going very far or for very long without earplugs and a fat wallet for fuel. So I see the sense in a 5 or 6 speed trannie. I like the idea and will probably go that route myself eventually.

 

priya
i think the 5 spd will be lots of fun. mainly because of the tires. i know how they feel as i had 275/60/15 on 10" when i bought it. Think of it as a mini-big-foot those 4x4's with 5'tires need a blower just to get moving
Truth is, to keep your license, need to keep speeds down. 30mph in 1st, lots of grins, no ticket! That's why i didn't mind going to 4.11, the 3.36 was good for 60+ in 1st, and the speed limit is just 45.

 

I worked it out before I bought the 3.37 first five speed, If I remember correctly with the 3.37 first and 3.70 rear I'd be doing 39mph in first at 6000 rpm versus 44 mph in first at 6000 rpm if I'd have gone with the 2.87 first five speed. Based on that the 3.37 first didn't sound too short for me plus I am trying to emulate the performance of my Torino which I thought was an absolute blast to drive.

 

1974 i started out with a 1970, 237hp, R600 mack that had a 5 speed manual had several of them. Pulled as much as 120,000 gross loads on a haul in texas. It had a 900 rpm powerband 2100 down to 1200rpm, other engines used about 500 rpm. Power bands on old diesels were not always narrower back then i don't know of current engine that uses a 900 rpm drop but they do run as low as 1600 rpm as the top rpm. The older engines ran 23lbs of boost todays engines are using 35lbs of boost. You have heard of compacted graphite iron blocks that make iron chevy blocks twice as strong that nascar uses. Well the new pacar diesel engine blocks are now compacted graphite.

Ive had 5,6 speed macks, 9, 10, 13, 15 speed road rangers. A 15 speed is nothing more then a 10 speed with 9th and 10th reversed in the shift pattern making its 10th gear higher. Then it has a deep reduction that only works in the lower 5 speeds of the box has nothing to do with the upper five gears. only time anyone uses the deep reduction is for the lower first gear if you take it off road. The 13 speed has a spliter that you only split the top four gears on it , otherwise its just the 9 speed and can just be shifted as a 9 speed. Drivers almost always drive it as a 9 speed then only split the top 9th gear for the extra 13 percent of overdrive the spliter gives it.

The 5 speed mack only has about 10.1 low gear not really enough to go off highway with. The real stump pluller is the 6 speed mack transmission it had 18.1 low gear and a 36.1 reverse gear. for instance a 13 speed has a 12.5 low gear and about the same for reverse. The 6 speed mack had a .250 wall thick driveshaft that was also another 1/2 inch bigger in diameter, huge u joints to match it. The roadrangers all of them i mentioned use .135 wall driveshaft smaller by 1/2 dia driveshaft. After a driver twists the tube one you take it to a driveshaft man have him do a .180 wall tube shaft for it. Ask me how i know had more then a few drivers and diesel trucks. Lots of experience trying to gear something right to do the job.

Since the begining of time with GM any smaller performance engine got more gearing at first in the rear end now these days with more gearing in the transmission.

Chevy just droped the cu. on the C7 therefore it now gets a 7 speed manual and 8 speed auto to make up for its downsized engine. I'm sure they could get away with less if they still made 454 size engines. I ordered a 73 with 3.36, 2.20 low M21 with the 454 no a/c extra weight i did not need lol. Sure it worked with 454 cu but even then it was no drag machine lol. I'm thinking the OP has a tiney 350.

 

I spent a summer working construction jobs for a contractor whose butt lips were so tight he squeeked when he walked - all of our trucks were 50s vintage, no suspension detroit or cat diesels.... even with the splitter you couldn't shift fast enough on a hill to stay in the power band - but oh could you be noisy while going bicycle speeds

I've no inside GM design knowledge, but I'd bet the 7 speed is so the displacement on demand can stay active longer. The motor is the same size - 6.2l


Matt - drive a 3.6 VVT motor - they're pretty amazing in the torque department. It's why I choose it for the Fiat build.

 

Have a 1978 Mercedes Unimog. 40 HP deisel engine, 20 forward gears, 14.5 x 20, 42" tall tractor lug type tires, 4 wheel drive. top speed 55 MPH. It isn't fast but it will pull anything. Gearing makes that 40 HP seem like 300+ when you hook it up to something.

 

I spent 28yrs owning, driving, working on construction trucks. mack suspensions, four springs, walking beams to air ride suspensions. owned mack, cummins, detroit, cat. engines.

The 7.0 liter is gone more trans ratios the new help.

Put a 2 speed powerglide or 3,4 speed see what a dog the v6 becomes same with modern V8s. Cadillac, mercedes, lexus, bmw huge 500 cu. engine vipers. 6, 7, 8 speed transmissions.

Cu. or gearing or better yet both. Unfortunatly the OP passed on a cheapest of options a 3.75 stroke when rebuilding the engine.