Roller cam conversion or new engine

[PlayingWithTBI]

It's geared toward not tuning it all which is asinine no matter what you drive.

^^^This - what's the fun in that?

 

[Pro439]

^^^This - what's the fun in that?

The biggest problem is that the hydraulic roller cams have a limit as to how big you can run because the spring psi will work against the hydraulic psi and collapse the lifter. The 3 cams I have are cast so I don’t think they would hold up to a mechanical roller lifter. In general when you run a low lsa the cam manufacturers want stall converters, headers and lower gears and say it does affect vacuum. So anything that uses vacuum will be affected and unless you have the ability to program the computer I don’t even know if the factory setup will run with a 102 - 110 lsa or more than 230 degrees of duration @ .050. Because the factory setup is geared towards meeting emissions and not anything else. That’s why the ls engines are such a big deal. But to me they’re not a small block or a big block

 

[Supercharged111]

The biggest problem is that the hydraulic roller cams have a limit as to how big you can run because the spring psi will work against the hydraulic psi and collapse the lifter. The 3 cams I have are cast so I don’t think they would hold up to a mechanical roller lifter. In general when you run a low lsa the cam manufacturers want stall converters, headers and lower gears and say it does affect vacuum. So anything that uses vacuum will be affected and unless you have the ability to program the computer I don’t even know if the factory setup will run with a 102 - 110 lsa or more than 230 degrees of duration @ .050. Because the factory setup is geared towards meeting emissions and not anything else. That’s why the ls engines are such a big deal. But to me they’re not a small block or a big block

LS motors use the exact same lifters as Vortec rollers. And LS motors use a higher ratio rocker, which works more against the lifter to collapse it. And LS motors run 230+ cams all day long. . .

 

[Pro439]

True but the induction angle is more conducive to air flow. And I am going by what the engine builders who have tested the bigger lift cams are saying about lifter collapse. I also believe that because of the straighter induction angle the ls can get away with more w/o it affecting it like a 23 degree setup

 

[Supercharged111]

True but the induction angle is more conducive to air flow. And I am going by what the engine builders who have tested the bigger lift cams are saying about lifter collapse. I also believe that because of the straighter induction angle the ls can get away with more w/o it affecting it like a 23 degree setup

All I really know about the 2 as it pertains to bigger cams and airflow is that it seems to be more common to run over .600" lift on an LS application. Never really thought to ask why as I don't have an interest going that big in my own small blocks as they are in heavy trucks that need some low end to get moving. Every setup is different though, and engine builders are not always engine tuners, so they have to trust that whoever is tuning it (assuming holes don't get burned in pistons) knows what they are doing. If they don't (but they think they do) and drivability suffers, what gets blamed?

 

[Pro439]

Whoever picked the parts out. Which is exactly what I’m doing with a big block build. Because the heads flow so poorly it’s not much different in cost to go with a small port aluminum head and be able to run a little more compression. My target is to have good power between 2 & 5,500 rpm. I don’t care about anything less than 2,000 as you’re normally just putting around. The 383 I put together I couldn’t find a set of heads I really liked except for the small port bowtie heads. I wasn’t about to spend the money on screw in studs bronze guides guide plates valves seals on a stock set that are prone to cracking and have close to the same money in them This engine should make good power in the same rpm range. I got the rod ratios where they need to be and both engines are internally balanced I’m still waiting for the crank trigger from FAST as they have been back ordered since covid. I’m really interested in seeing what I’ve done makes them run. I’ve never had either sized engine before. 355’s and 357 and 400 small blocks is all I’ve ever messed with. Tuned a couple big blocks but never ran 1

 

[shovelbill]

Whoever picked the parts out. Which is exactly what I’m doing with a big block build. Because the heads flow so poorly it’s not much different in cost to go with a small port aluminum head and be able to run a little more compression. My target is to have good power between 2 & 5,500 rpm. I don’t care about anything less than 2,000 as you’re normally just putting around. The 383 I put together I couldn’t find a set of heads I really liked except for the small port bowtie heads. I wasn’t about to spend the money on screw in studs bronze guides guide plates valves seals on a stock set that are prone to cracking and have close to the same money in them This engine should make good power in the same rpm range. I got the rod ratios where they need to be and both engines are internally balanced I’m still waiting for the crank trigger from FAST as they have been back ordered since covid. I’m really interested in seeing what I’ve done makes them run. I’ve never had either sized engine before. 355’s and 357 and 400 small blocks is all I’ve ever messed with. Tuned a couple big blocks but never ran 1

Do you have a build thread or plan on one for that engine? I'd like to follow along.

 

[Pro439]

No I haven’t. I didn’t think it was anything special. If I can’t get a crank trigger I may have to come up with something for the stock trigger and sensor

 

[shovelbill]

The biggest problem is that the hydraulic roller cams have a limit as to how big you can run because the spring psi will work against the hydraulic psi and collapse the lifter. The 3 cams I have are cast so I don’t think they would hold up to a mechanical roller lifter. In general when you run a low lsa the cam manufacturers want stall converters, headers and lower gears and say it does affect vacuum. So anything that uses vacuum will be affected and unless you have the ability to program the computer I don’t even know if the factory setup will run with a 102 - 110 lsa or more than 230 degrees of duration @ .050. Because the factory setup is geared towards meeting emissions and not anything else. That’s why the ls engines are such a big deal. But to me they’re not a small block or a big block

I'm not intimately familiar with the oiling systems of SBCs, but why would a roller lifter collapse under the proper spring pack? I do understand the vacuum issue with car/truck engines.

 

[Pro439]

So when you get up into the big cams they use a lot of seat and open psi on the valve springs. As you up the psi it over comes the ability of the lifter to stay pumped up. Yes a high psi oil pump helps but it still is not enough