So exactly what technique are you suggesting (on a car set up like his), for street driving around town from a dead stop, or worse yet starting uphill?
I know of only two approaches - either slip the hell out of the clutch, or rev it up to about 3 grand and side step the clutch.
Neither one is very sensible for durability.
IMHO an axle ratio change is the best approach.

 

I don't believe the OP knows what ratio he has. So to conclude a gear change will solve the problem is premature.

He did say he "thinks" it's a 3.08. If so then yes going to a 3.70 or lower would help. Down side is freeway driving will be painful. He posted issue "starts and stops". What's the stopping issue?

My 64 L76 had 4.11s. Great up to about 60 and freeway driving was not fun. Just installed a close ratio TKX and now it's the best of both worlds.

1st need to determine what he has before deciding on what changes to make. Without an OD tranny I'd go with a 3.55.

 

Well maybe, but your wording was crude and fairly insulting.

That said, a personal experience helping a fellow with his fuel injection persuades me that you could be on to something:

A fellow with a '63 FI car came to me complaining of an off-idle bog. I made some tweaks and he did a test drive. Nope. Still bogs. More tweaks and another test drive. Still bogs.

Finally I did what I should have done at the beginning.... I got in the car with him and had him demonstrate the bog.

What I discovered was that would just let out the clutch without giving any throttle. RPM would drop below 500 (Duntov 097 cammed engine not happy) and only then he would give throttle. At that low of an RPM, there was nothing the engine could do. So I taught him how to drive and, amazingly, the bog disappeared. He left happy.

So, bottom line, you might be right but it would pay you to re-consider how you express your thought.

 

[QUOTE=Vega$Vette;1604574003 Down side is freeway driving will be painful.... Great up to about 60 and freeway driving was not fun.[/QUOTE]


Thats largely subjective....I drove my L76/3.73 car from VA to TX this past spring, cruising around 70 the entire way....zero issues. It might be more annoying with side pipes, but with the rear exit exhaust, it was perfectly mellow at just under 3K RPM.

 

Grumpy in traffic & hard to get going??
Im not being a smart ***, but it may be helpful if u could try & help us understand exactly what is happening in stop/go trafffic & getting it to go above that ?

Does it bog like the gas pedal feels rubbery? Does the motor not rev right away, does it buck, does it throw u forward first before it puts your back into the seat?
This would help us understand.
I own a 65 with a original 327/365 solid cam, 4:11 rear gears idles around 900-1000 (reading it off the gauge cluster tach), this car was all new to me I’m constantly in traffic with this car I just need to feather the gas some walk the clutch out & its off & running no hesitation/bog/chatter I’m on the gas pedal & its looking for 2nd. Gear it just flat out wants to go.

Again, I’m not being a wise guy.. I would make sure your carb. (Accelerator pump etc. is working correctly), I also would recommend to make sure you timing & advance (vacuum & mechanical) is working correctly I was cleaning my engine this spring & found the vacuum hose off the distributor was cracked/ruptured (that cured the erratic idle rpm more than normal:-) & carb. pop I was getting intermittently at times ). Spray some carb. Cleaner around the base of the carb, intake bolts vacuum hoses (Brake Booster & rubber vacuum hose if u have power brakes.

This engine should only need a little more idle rpm than others & a little feathering of the gas pedal coming out of a stop other than that hold on.. Please go over the engine & see if all (carb. & Distributor) is all working its a fun engine for sure..
Good Luck
Let us know
Chalie

 

70 mph with 3.73 and 26" tire is 3375 rpm. not just under 3000.
You would need a different rear end gear or a 30" tall tire to get under 3000 rpm at 70 mph

 

I had a 64, L84 with 3.55 rear gears, it required a little finesse when dead starting on a hill but, other wise was a good all around combination. This even provided more than 25 mpg when driven on thei hiway.

 

I could not explain it any better than this, the L76 to me is the best sounding hardest running small block ever. Spool it up and let it rip. You need 4:11’s to take advantage of the motor.

 

Maybe just over 3K......tach was bouncing all over the place as the whole cluster needs a rebuild....either way, GPS on the phone confirmed 70mph cruising and it was just fine.

 

His 215/70R15 Avon CR6ZZ tires have an inflated OD of 26.9" that equates to a loaded revs per mile figure of about 775, and the actual axle ratio is 3.70.

Revs @ 70 = 775 (3.70)(70/60) = 3345

Duke

 

Thanks for all of the replies. I went out and drove and measured 60 mph on the gps at 2800 rpm, assuming my tach is correct. 24.5 inch tire. 1:1 ratio in 4th gear.

Going back to my high school math

2800 rev/min x (Pi x 24.5)/rev x 1ft/12in x 1 mi / 5280 ft x 60 min /1 hr = 203 mi/hr / actual 60 mi/hr =3.4 gear ratio

Answering the question about what 'grumpy' is I have to apply a lot of throttle and slip the clutch to get it going, like starting out in a higher gear. The engine really starts making a lot of power above 4k pulls hard. I think the engine will die if you just let the clutch out in gear without throttle. (need to try again.)

That just makes it a pain in start stop traffic. Haven't driven in traffic for years but it will start to heat up and has even backfired before, but i can't remember if that was before i rebuilt the carb and fixed various other issues.

Anyway, it seems this is a very large cam, so it is probably the gearing. Did GM make a ratio near 3.40 for this car, 3.42?

Tim
Timz06 is offline Report Post

 

no 3.40, but did make a 3.36

 

Yes, 3.36 was pretty common. But probably not common with the L76.

Ted

 

Close enough.

If OP has the 365 HP engine with a close ratio 4-speed and 3.36 gears, he will generally be MOST UNHAPPY driving around town. Highway is okay. Stop and go a pain. He should switch to at least a 3.70 or 4.11 gears, if around town cruising is the main driving.

Larry

 

Having an original close ratio (2.20) first gear and a 3.36 axle are the exact reasons I switched to a Tremec 5 spd trans. Now I can idle it off the line if I want (or really light em up!) and have an OD 5th gear good for 2000rpm at 70 mph.

Its the" best of both worlds" for my situation!

 

5 speed would be nice, want to keep the car original, and i already changed the clutch that was a rough job getting the trans out without cutting up the exhaust! Tim

 

ha ha you are pretty funny. I burned up my first clutch in a 77 280z in 1984 that is when i started working on cars and learned how to drive. I am an instructor for most of the big track day clubs and raced a 2002 Corvette in Nasa ST2 for about 5 years, i know how to drive a manual transmission, even heel and toe downshift, can you believe?

I have a 2008 z06 that will start out in 3rd gear on flat pavement by just releasing the clutch, no throttle, so I am just trying to get an idea of how these cars are supposed to drive, since I have never driven another.

Thanks for your feedback! Tim

 

Pacha, that is a cool pic. I bought my 64 because of my dad (also a Vietnam vet),

he had a 63. Here is a pic of him and my grandfather in 64. (Sorry digressing from the thread.)

 

A car from the factory with a 365 h.p. engine would have com with a close ratio trans and 3.70 rear ratio. They don’t have a very low 1st gear and are really designed for road racing where you want to keep the rpms up with a lot of shifting. Things change in 50+ years so check your trans to see if it is a CR or WR. If it is a WR it will have a lower 1st gear and you would be OK with a 3.36 rear end.
Back in the day one of the catch phrases was “it has a close ratio tranny” most guy had no idea what that meant but thought it was cool.
For best all around driving I prefer the WR. I have one of each in my two midyears.