Rev limiter and Timing Questions for the Caddy

Ricky B

Ricky B

Wiiide Open
Joined
Mar 20, 2005
Location
LKN - Tha Dirty Mo (Mooresville, NC)
info on my setup is a 76/75 (not exactly sure) 500 Caddy with the early 70's heads (bout 13:1 compression I believe), edlebrock intake manifold, block hugger headers into 3" pipes strait out the back, Holley 770cfm Truck avenger Carb, running 100 octane gas.


Anyway, I have two questions/concerns

First is that I'm not sure where to put my timing, this is a first time experience for me running a high compression motor and high octane gas, Currently its set 3 deg advanced at idle, but my exhaust is so loud I can't really advance the timing by ear and tell when it starts to spark knock so I'm not sure where to set it.

Second question is I'm about to install a manual valve body in my tranny so I can hold gears when I'm hammering down in these offroad competitions, especially in the mud drags I need to be able to keep my wheelspeed, thats what killed me at the Sparta Mud Bog, couldn't hold lower gears. I'm also wanting to install a rev limiter so I don't hold the gear till my motor blows At what rpm should I set the rev limiter at? Bearing in mind my bottom end/valvetrain/cam are all stock as of now.

Thanks guys, I posted this over in the mts Caddy 500 specific forum but arn't getting any response so figured I'd ask u guys see if you have any info/tips :driver:
 
I've never had an issue with a stock VB not staying in the gear you put it in?
 
A basic shift kit will give you the 'manual' override to hold it in any gear WHEN you manually shift it into that gear.. IE you put shifter in 1 and it will stay there. A stock VB will eventually shift, its just a matter of, if the motor will run that high or not.

RPMs. Was the bottom end balanced? With the stock valve train I'd keep it under 4500 to start with and see how it does...

Timing... I'd go read up on how guys are tuning the older big blocks like the Pontiac and olds 455s. They will likely be similar in the timing/tuning enough to give you a decent starting point..
 
yager said:
A basic shift kit will give you the 'manual' override to hold it in any gear WHEN you manually shift it into that gear.. IE you put shifter in 1 and it will stay there. A stock VB will eventually shift, its just a matter of, if the motor will run that high or not.
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oh ok, so I guess I don't need a manual valve body then, whats the purpose of a manual valve body when you can just do a shift kit?

yager said:
RPMs. Was the bottom end balanced? With the stock valve train I'd keep it under 4500 to start with and see how it does...
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idk the bottom end is all stock I havn't touched it, I'f i nail it it'll get to 5 grand maybe a little over, I've never held it long enough to find out, I have read that the stock valve train isnt the best thats my main concern for failure if i overrev too long, so yea I guess I'll go with 4500,

yager said:
Timing... I'd go read up on how guys are tuning the older big blocks like the Pontiac and olds 455s. They will likely be similar in the timing/tuning enough to give you a decent starting point..
Click to expand...

aight, if it helps the distributer/coil/etc is exactly the same as a chevy 350, as a matter of fact the one i have on there now is the accell coil/dizzy/wires setup that was on my old 350
 
Call the CAD Company, i'll try to dig up there info tomorrow.

I KNOW that the stock rods WILL FAIL if revved over 6k for any period of time. But if you are running stock valvetrain, then the weak point is the springs. 4500-4800 are about it for the stock springs/cam.

I'd go with 4500 to be safe, and to keep it from grenading if held there for any length.

I'll try to get in touch with my buddy at the engine shop that I help out a while back, see if he offers any guidance, and see if I can find the number to the CAD company.....they know there stuff about the 500.

p.s. sorry I havent call you back yet, just been busy workin on my jeep, anytime I'm not actually working. Check out my build page, its in truck gallery "YJ Buildup"
 
you talkin bout this place: http://www.cad500parts.com/

I woulda called them already but I kinda feel bad calling a place for advice and not buying anything, lol.

4500 sounds like a good point to set it then, I knew I had read that the stock valvetrain was kinda weak, that is my main concern when I'm sittin there nailing it in a mud pit especially when i get the kit to hold her in gear.

Rods fail at 6grand huh . . . . maybe thats why I bent two rods a lil while back, had both of em in Z shapes :shaking::lol:

no biggy on the call, was just trying to get back to you, I'll check out the build thread :driver:
 
Go with a rev limiter that has plug in pills for the rev limit set. The ones with knobs can get bumped and moved up or down without you noticing.
 
snappy said:
Go with a rev limiter that has plug in pills for the rev limit set. The ones with knobs can get bumped and moved up or down without you noticing.
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Dangit those are like 60/70ish bucks more :rolleyes:

You're right thou, would suck to find out the hard way that it moved on its own, cause I know when I'm hammering down I'm not gonna notice if it changed.

Also need to figure out how to waterproof it . . . .
 
jrraw23 said:
you talkin bout this place: http://www.cad500parts.com/
I woulda called them already but I kinda feel bad calling a place for advice and not buying anything, lol.
4500 sounds like a good point to set it then, I knew I had read that the stock valvetrain was kinda weak, that is my main concern when I'm sittin there nailing it in a mud pit especially when i get the kit to hold her in gear.
Rods fail at 6grand huh . . . . maybe thats why I bent two rods a lil while back, had both of em in Z shapes :shaking::lol:
no biggy on the call, was just trying to get back to you, I'll check out the build thread :driver:
Click to expand...

thats the people, called them a while back just to pick their brain a little, and they were a great help, and didnt mind helping
 
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