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4.10 vs 4.56 - Don't want a soggy bottom end

I have used a cam practically exactly like that in a similar engine, heads were 882 so less power overall. Truck was a 72 k20 had 31 inch tires and 410 gears so pretty deep, same carb same intake etc. pretty close besides the tires you are running, I had to bump stall to 2200 and I felt that wasn't enough IMHO.. and it made really decent power for a practically stock sbc 234whp and 289 tq at the wheels.

If it was me I would go 456 because that cam makes good torque but not right off idle like an rv cam but it was much better all around than an rv cam motor. it makes power all the way to redline. makes a good sound, mpg wasn't that good but 2800 at 70 isn't great either.. I towed a lot with that truck and never felt that I was underpowered. Also the main reason I cammed up to that is because on the freeway my rpm was higher that 2500 anyway so why choose a cam that is loosing tq and not one that is making it and has more left??
I also chose it because when your truck has to shift into 2nd on a hill (heavy load) it would pull because it has some breath left.. rv cams tap out way sooner than this did. it pulled 4krpm all day no problem..

https://www.youtube.com/watch?v=2uA8VOdHZ2A
 
sreidmx said:
I have used a cam practically exactly like that in a similar engine, heads were 882 so less power overall. Truck was a 72 k20 had 31 inch tires and 410 gears so pretty deep, same carb same intake etc. pretty close besides the tires you are running, I had to bump stall to 2200 and I felt that wasn't enough IMHO.. and it made really decent power for a practically stock sbc 234whp and 289 tq at the wheels.

If it was me I would go 456 because that cam makes good torque but not right off idle like an rv cam but it was much better all around than an rv cam motor. it makes power all the way to redline. makes a good sound, mpg wasn't that good but 2800 at 70 isn't great either.. I towed a lot with that truck and never felt that I was underpowered. Also the main reason I cammed up to that is because on the freeway my rpm was higher that 2500 anyway so why choose a cam that is loosing tq and not one that is making it and has more left??
I also chose it because when your truck has to shift into 2nd on a hill (heavy load) it would pull because it has some breath left.. rv cams tap out way sooner than this did. it pulled 4krpm all day no problem..

https://www.youtube.com/watch?v=2uA8VOdHZ2A
Click to expand...

Glad to hear that. Aren't 882s the camel hump heads?

2200rpm?? Really that high? Do you remember the specs on that cam? What transmission?
 
No they are stock truck heads with big chambers but the quench was tight and the block was decked so I think I was 9-1 or 9-3:1 ish so similar compression. And the highest stock truck converters are 18-1900 rpm anyway so 2200 felt stock it might have been 19-2100 but stall isn't a definite number anyway it's estimated. With the stock 1972 converter it would drag way down and not idle in gear so trust me get a looser converter you will thank me later
 
Look at the centerline and lsa for that voodoo cam, prolly less Than 110 lsa can cause stinky exhaust. But I'm not familiar with their specs, might be similar to the Comp Thumper cams with higher duration and less lsa and centerline which gives a rougher sounding idle but again not sure.

I'd contact lunati and talk to them.

Depending on how you are going to use the truck I'd be carefull on going to high on the stall. (Heat kills)
 
sreidmx said:
No they are stock truck heads with big chambers but the quench was tight and the block was decked so I think I was 9-1 or 9-3:1 ish so similar compression. And the highest stock truck converters are 18-1900 rpm anyway so 2200 felt stock it might have been 19-2100 but stall isn't a definite number anyway it's estimated. With the stock 1972 converter it would drag way down and not idle in gear so trust me get a looser converter you will thank me later
Click to expand...

Did you do much towing or slow speed creeping in the truck with that stall? If so, did you ever notice any excessive heat?
 
blazer74 said:
Look at the centerline and lsa for that voodoo cam, prolly less Than 110 lsa can cause stinky exhaust. But I'm not familiar with their specs, might be similar to the Comp Thumper cams with higher duration and less lsa and centerline which gives a rougher sounding idle but again not sure.

I'd contact lunati and talk to them.

Depending on how you are going to use the truck I'd be carefull on going to high on the stall. (Heat kills)
Click to expand...

Yeah, I'm going to do a lot of asking around to see if I can come across anybody that did any work with trucks that had 2000+ stalls. I think 2000 would be OK for minimal towing but I've never had high stalls so I don't know from experience. I do know I shouldn't have to worry about heat from cruising speed since I'll have the 4.56/TH350 combo. I'm sure I'll be over 2k at 50+ mph
 
LSA on the Voodoo 60102 is 112. I've been told the 60102 needs about 9.5:1 or higher to reach full potential. I should be around 9.7:1 to 9.9:1 with a .015 shim gasket. Quench will be approximately .040 give or take a few. I feel pretty good about the motor minus the dish pistons but it's just a fun truck and quench and compression should be good so I'll be ok with it.
 
I didn't have any issues with the Trans overheating, horses some times require frequent backing and slow going and I never had an issue, the comp cam was extreme 4x4 cam and its on a 111 lsa so the lunati should be a tad better at idle my truck had long tubes and an h pipe which made a big difference in torque. I wouldn't hesitate to do the same combo again it's a very good engine across the board and very flexible.
 
What are your plans with the truck?

I would swap cams.

It's too bad you don't still have the TH700R4.

Normally with your TH350 I would say 4.10's, but with that cam, you are probably going to want 4.56's.

Martin
 
I believe I had that exact same cam in my truck! I loved it, I thought it was great. It sounded great, but still had a good idle still, and the power band was pretty wide. For me it made power from 1600-5400ish. My motor had very similar specs too with a .030 over 350, dished pistons, 9.4 compression, 180cc aluminum heads, Weiand intake, and a Demon 650 carb.

My truck has 35s, SM465, and 4.10s. I found that taking off from a start I'd have to feather the gas a little more than the factory 305 it had before. But it'd take off and pull hard once over 2000 rpm. When I towed my boat (5000lbs) I'd really have to work the clutch and gas to keep it from bogging when trying to take off. However once I reached the power band its like it wasn't even behind me. Honestly I never really thought twice about it but some deeper gears like 4.56s would have helped with my takeoff. But really, my biggest problem was the wiiidddeeeely spaced gears and the slow shifting on the 465. That's not much of a concern for you though.

Despite those problems I still swapped cams to a bigger Lunati hydraulic roller. Now my low end hasn't changed much but now I can my pull hard to 6000 rpm! :saweet:
 
Good to hear that with a similar cam. I ordered the 4.56s so after I get everything buttoned up, I'll try to choose stall wisely. Sreidmx makes me rest easier with his experience with the 2k stall. I don't see this cam needing anymore stall than 2k especially going to 4.56s. I'll still do more asking around and research though. I figure it can only help.
 
Yea do some reading and talk to the cam company they can make a better recommendation.
 
Lets break this down a bit simpler.

You are running 2 sizes larger than the stock tires that came on your vehicle. You also added some weight with those big tires.

Most would agree around here that a STOCK K20 or K30 with the usual 4.10 ratio that most of those trucks came with, with the stock 31" tire is about right as far as a balance between power and revs on the highway, regardless of OD or not.

So.... to get back to that same 4.10/31" ratio that works so well, you would have to go to a 4.88/35" combo. Factor in the extra rolling mass of your tires and your cam (which I think is a good choice for a cam) and a 5.13 ratio would likely be a good choice.
 
Truck has 4.56s front and rear now. Haven't started the engine build yet. Money, or the lack of it, put that on hold. I was hung go on stroking it to a 383 for a couple months. Now I'm back to just doing the top end.

I picked up a 700r4 from an 89 burb. I'll have it rebuilt and then do the swap. My low end is noticeably better but cruising 55-60 is not so cool. I don't like the engine at that rpm for 30 minutes straight when I'm going to town. I can almost physically see the gas needle dropping.

Dropped over 2k in the rear axle. Yukon parts are expensive. Just used Summit brand gears in the front and replaced axle seals while I was in there.
 
I think you'll be happy with the 700r4. It lets you run a deeper gear yet still keep the highway manners civil.

I used a Comp 4x4 extreme cam that lists about a 1000-5200 powerband, vortec heads, a Howell TBI, 33's, and 4.10 gears. The truck moves very nicely around town, barely have to use any pedal to get it going. It's no drag racer, but it always feels like it's got plenty of power, and seldom sees 4k rpm. After about 3500 it's more noise than speed anyway. It cruises easily on the highway.

I think most often you see under-gearing, because everyone wants the lift and tires, but a lot of people don't want to change gears, and everyone goes bigger with tires at some point. I never liked the idea of weak acceleration and poor fuel economy from inadequate gears.
 
Well I'm having a hard time letting go of the 383 idea but I just don't have the cash, plain and simple. I've beat to death cam choice over on hotrodders.com but I'm just going to throw the Lunati 60102 in there and let it go. Not a torquey RV cam but it will work well with the modified Vortec heads and I think the 4.56 gear will help it get to 1500 rpm good enough. A lot has come up financially since I started this quest and I've got to pull the flaps out on the truck project.
 
It may be cheaper to do a LS swap.... I'd do that before going 383
 
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