Overdrive and camshaft selection - Chevelle Tech
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post #1 of 240 (permalink) Old Mar 26th, 19, 4:10 PM Thread Starter
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Overdrive and camshaft selection

I haven't had a stick with a big cam in my car before. I have always had 3 speed autos built to handle the power.
Being that I am changing over to a t56 magnum, I have been thinking about how my build might work with over drive.

I feel like it should work fine, but I want some additional thoughts.

489 big block
Jegs 290 heads
Isky SFT cam
250/256 @ .050
.605/.620 lift (lash is I believe .016 and .018)
108lsa
edelbrock proflo 3 fuel injection--xt manifold(able to adjust cruise A/F ratio and have it currently set at 14.8)
long tube headers-2 inch primary/3inch exhaust
3.73 rear

I bought the magnum so I can have the benefit of both over drives as I do interstate and back road driving primarily. I take beach trips/trips down south and soon trips up north. Usually they are about 200 mile stretches.

My goal is to keep the engine sitting around 2000rpm. I currently have a th400 with a 3500 stall so I have never really gotten to experience that. At 75 right now the thing sit around 3800 on the free way. I feel like the converter slips quite a bit.

Would my cam work in this situation?

Planned cruise speeds:
55 in 5th(.8) would be 2000rpms

65 in 5th(.8) would be 2400
65 in 6th(.63) would be 1800--might work?

70 in 5th(.8) would be 2500
70 in 6th(.63) would be 2000

75 in 5th(.8) would be 2700
75 in 6th(.63) would be 2200
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post #2 of 240 (permalink) Old Mar 26th, 19, 4:13 PM
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Mr Bill
 
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Re: Overdrive and camshaft selection

So how does the engine act now at 2000 rpm ?

Bill Koustenis
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post #3 of 240 (permalink) Old Mar 26th, 19, 4:18 PM Thread Starter
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Re: Overdrive and camshaft selection

Quote:
Originally Posted by BillK View Post
So how does the engine act now at 2000 rpm ?

It seems fine, usually the converter flashes passed that. I usually cruise at 2500rpm and up. I am not sure if the stall is causing an impression that it works great at that RPM.

Note: The only stick car I have owned was a tacoma 4 cylinder with a grabby clutch and honestly it was fun to drive.
I have driven a few stock camaros(2010+) but that is basically it.
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post #4 of 240 (permalink) Old Mar 26th, 19, 4:53 PM
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You’ll be fine unless your tune is not good.

255ish at .050
640ish lift
107 separation
502 big block


You won’t accelerate up any hills in 6th but will easily maintain speed and do a steady pass.

1968 Beaumont
502 big block
Stock looking, definitely not stock sounding
HP and ET not determined yet!
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post #5 of 240 (permalink) Old Mar 26th, 19, 5:45 PM Thread Starter
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Re: Overdrive and camshaft selection

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Originally Posted by GoFast Beaumont View Post
You’ll be fine unless your tune is not good.

255ish at .050
640ish lift
107 separation
502 big block


You won’t accelerate up any hills in 6th but will easily maintain speed and do a steady pass.
That works for me!
Do you happen to have any videos of your car driving??

Tune should be spot on with the fuel injection.... plus I can always change it to work.
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post #6 of 240 (permalink) Old Mar 26th, 19, 5:50 PM
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Chris
 
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Re: Overdrive and camshaft selection

Out of curiosity, how tall are your tires?

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post #7 of 240 (permalink) Old Mar 26th, 19, 9:39 PM
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Chris
 
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Re: Overdrive and camshaft selection

I have an 80E and is fine with my SR 262/269 at .050" in LU but have steeper gears.
I'd also be careful with your ignition advance while in od/lu.

73 nova,3515#(all steel)Pump gas!(91octane)406ci N/A, best 1/4,1.45 '60,[email protected],10.6 @ 122.38, short shifting,NO tuning!


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post #8 of 240 (permalink) Old Mar 26th, 19, 10:22 PM Thread Starter
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Quote:
Originally Posted by -SS454- View Post
Out of curiosity, how tall are your tires?
28 inches(28.4 to be exact)

Quote:
Originally Posted by WHT/73 View Post
I have an 80E and is fine with my SR in LU but have steeper gears.
I'd also be careful with your ignition advance while in od/lu.
I hear you. Don't want it to ping like crazy. What's the size of your cam?
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post #9 of 240 (permalink) Old Mar 26th, 19, 11:13 PM
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Chris
 
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Re: Overdrive and camshaft selection

I have a 230/[email protected] HFT 461 BBC with a T56 Magnum, 3.31 gears. 26.6-28" tall tires. I have a FiTech EFI as well.

I can low load cruise at 1200-1300 rpm when it just starts to complain. I think 1800 rpm won't be a problem for you.

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post #10 of 240 (permalink) Old Mar 27th, 19, 12:08 AM
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Re: Overdrive and camshaft selection

Mine doesn't like being below 1700 cruise rpm. It will start to buck below that. The t-56 Magnum is a very nice transmission, so you'll find the right gear. I have problems at 35mph. At 35, it seems too high for 3rd and to low for 4th. My exhaust is a little loud, so I try to keep it down in town, and third gear seems too loud.

I love the way my car drives with the t-56 Magnum and the hydraulic clutch. I'm sure that you won't have any problems.

502, 600hp, hydraulic roller cam 238/[email protected] .680/.650 110LSA, Holley MPFI, hydraulic McLeod RST twin disk clutch, 4.10 gears, and 28" tires.

'69 Chevelle SS ("NOT" ON THE ROAD NOW!
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Engine parts: (Heads, cam & lifters from Lewis Racing Engines)
ZZ502 Short block
AFR 305 CNC 106cc Chambers 8002 springs
Bullet HR ADV Dur 295/297 238/242 @ .050 .680/.650-110 LSA-108 ICL Morel lifters
Holley Avenger MPFI
612HP/594TQ
T-56 Magnum trans with hydraulic McLeod RST
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post #11 of 240 (permalink) Old Mar 27th, 19, 12:10 AM
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Re: Overdrive and camshaft selection

Quote:
Originally Posted by tacomatrd View Post
28 inches(28.4 to be exact)


I hear you. Don't want it to ping like crazy. What's the size of your cam?
262/269 @ .050, 110, .630 net lift. 10.5 compression.
My timing was locked out at 36*

73 nova,3515#(all steel)Pump gas!(91octane)406ci N/A, best 1/4,1.45 '60,[email protected],10.6 @ 122.38, short shifting,NO tuning!


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post #12 of 240 (permalink) Old Mar 27th, 19, 1:01 AM Thread Starter
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Quote:
Originally Posted by -SS454- View Post
I have a 230/[email protected] HFT 461 BBC with a T56 Magnum, 3.31 gears. 26.6-28" tall tires. I have a FiTech EFI as well.

I can low load cruise at 1200-1300 rpm when it just starts to complain. I think 1800 rpm won't be a problem for you.
Dang you can get it that low?? I thought about going to something with 236/242 and 0.600 lift but we will see.

Quote:
Originally Posted by MarkP View Post
Mine doesn't like being below 1700 cruise rpm. It will start to buck below that. The t-56 Magnum is a very nice transmission, so you'll find the right gear. I have problems at 35mph. At 35, it seems too high for 3rd and to low for 4th. My exhaust is a little loud, so I try to keep it down in town, and third gear seems too loud.

I love the way my car drives with the t-56 Magnum and the hydraulic clutch. I'm sure that you won't have any problems. <img src="https://www.chevelles.com/forums/images/smilies/thumbsup.gif" border="0" alt="" title="Thumbsup" class="inlineimg" />

502, 600hp, hydraulic roller cam 238/[email protected] .680/.650 110LSA, Holley MPFI, hydraulic McLeod RST twin disk clutch, 4.10 gears, and 28" tires.
Interesting. I'm excited to get it in. I don't care about loud, but in your case what is the issue? Just the lug going to 4th?


Quote:
Originally Posted by WHT/73 View Post
Quote:
Originally Posted by tacomatrd View Post
28 inches(28.4 to be exact)


I hear you. Don't want it to ping like crazy. What's the size of your cam?
262/269 @ .050, 110, .630 net lift. 10.5 compression.
My timing was locked out at 36*
Oh heck I should be alright then
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post #13 of 240 (permalink) Old Mar 27th, 19, 7:27 AM
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Re: Overdrive and camshaft selection

For sure. [email protected] on a 439 ci and it can easily cruise at 2200-2000 rpms. Not much below tho. These are PERFORMANCE cams , so trying to run it at 1700 rpms is simply not happening. Here, vacuum advance is your friend, as full mechanical advance is not all in yet.
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post #14 of 240 (permalink) Old Mar 27th, 19, 9:58 AM
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Re: Overdrive and camshaft selection

I'm still fighting mine. 55MPH is 1700 RPM and it bucks quite a bit at that speed. 60 MPH is around 1800 and it's better but it really needs 1900 + RPM to smooth out. That's also with my small 770 carb. The QF 950 is worse. The cam in it now was supposed to fix the bucking issue but it's no better than the other one. I think to run overdrive it will take something no bigger than 230 duration on at least a 110 LSA to make it nice at low RPM.


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540 BB
10 to 4 comp.
Brodix Race Rite BB-2 Plus heads
Edelbrock RPM Air Gap
Quick Fuel 950 CFM Carb
Lunati Voodoo HR 231/239 @ .050, 600/600, 110 LSA
Johnson 2116 BBR lifters
Hooker Super Comp 2" primary headers
Tremec TKO 600 .82 overdrive
3.73 Posi
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post #15 of 240 (permalink) Old Mar 27th, 19, 11:34 AM
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Re: Overdrive and camshaft selection

Quote:
Originally Posted by tacomatrd View Post
Interesting. I'm excited to get it in. I don't care about loud, but in your case what is the issue? Just the lug going to 4th?

Yes, it lugs it down. I just seems too low rpm. I made some changes to the EFI to smooth it out some, and it does run much better, but it still seems too low of rpm at 35 mph in 4th.


Quote:
Originally Posted by William Hennke View Post
I'm still fighting mine. 55MPH is 1700 RPM and it bucks quite a bit at that speed. 60 MPH is around 1800 and it's better but it really needs 1900 + RPM to smooth out. That's also with my small 770 carb. The QF 950 is worse. The cam in it now was supposed to fix the bucking issue but it's no better than the other one. I think to run overdrive it will take something no bigger than 230 duration on at least a 110 LSA to make it nice at low RPM.

The beauty of the t-56 is 5th (.80) OD. At 55mph, I'm running right about 2200 rpm in 5th, which is about the same cruise rpm at 70mph. Since the speed limit is only a suggestion, I can bump the speed up to 60mph in a 55mph zone and run 1800 rpm in 6th, which seems smoother. Going slower than 55mph in a 55mph zone is out of the question! A 3.73 rear gear would make it a little more comfortable to drive at 35, 55, and 70 mph, but I still want to have fun at the track occasionally so I'll keep my 4.10 gears for now.
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Engine parts: (Heads, cam & lifters from Lewis Racing Engines)
ZZ502 Short block
AFR 305 CNC 106cc Chambers 8002 springs
Bullet HR ADV Dur 295/297 238/242 @ .050 .680/.650-110 LSA-108 ICL Morel lifters
Holley Avenger MPFI
612HP/594TQ
T-56 Magnum trans with hydraulic McLeod RST
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