How much is too much lift for Cathedral port heads.

[Ziegelsteinfaust]

I am back on the LS swap bandwagon, and have a few questions.

When my TH700r4 died. I knew it killed my 383 LT1's thrust bearing. Well it wore quite the groove in the crank. While staying with a carbuerates 383 LT1 was fine when it was a cheap rebuild. It is now not so much with needing a new crank. Plus controls for the 4L80E I have too. The 350 in my truck is for my Camaro so it is not a waste. As the 383's plan was a rebuild, and back in the truck.

I plan to run home ported cathedral ports, cleaned up tbss intake, and a 230 duration cam roughly.

With 600 lift cams being everywhere, and after watch Richard Holdner on YouTube nursing a knee injury again. Are they a good choice for DD? Or should I stay safe and get around a 550 lift. Or are today's springs good enough for 100,000 mile reliability.

[LS short box]

I've run a couple of LS1's with around .600 lift with no issues. Use good springs and push rods. Some add a trunion upgrade for the rockers. Double check your push rod length.

[AussieinNC]

Grab yourself a beer (or a coffee) and read this excellent article.

https://www.lsenginediy.com/best-cam...iv-ls-engines/

It gives you a good overview of which cams work best with what and the presentation is easy to understand.

0.600 lift is achievable, but its not all about lift. Consider LSA (Lobe Separation Angle) for drive ability and torque creation.

Remember, HP doesnt move the vehicle, Torque does. and the lower rpm the torque comes in the more driveable the vehicle.

There are various vids on youtube that match the sample low LSA cam against several altered LSA cams, each with the same lift, going from starting point of 108 in stages to 116.

The 116 may sound "nice and lumpy" but is drops nett HP and torque down from the 108.

[Ziegelsteinfaust]

I have 4.88 gears, and run 32" tires. So I can afford to loose some tq if it gives me some faster rpm gain. Typical cruise rpm is 3000.

Depending on what lsa/duration magic a fuel injection system will easily tolerate. Since this will be my first fuel injection project. I don't want to set the bar to high. Depending on Holley vs factory computer which is a better all in option when I start going for the expensive items. I want to run a 110lsa which should be smooth enough for fuel injection, and not limit realistic rpm capabilities.

[MySons68C20]

My son runs this BTR stage 3 cam in his 86 K10 truck (see link)....5.3 LM7 w/cathedral port unmodified heads, flat top pistons and Edelbrock Pro Flo 4 fuel injection. It pulls well to 6k and has a nice lope at idle.

https://briantooleyracing.com/btr-ca...r31824100.html

[LS short box]

I always thought a LSA of 114 would have a smoother idle? 108-110 LSA would have more chop at idle?

[Ziegelsteinfaust]

Originally Posted by LS short box

I always thought a LSA of 114 would have a smoother idle? 108-110 LSA would have more chop at idle?

That's what I thought with duration being equal. As it can add chop in of itself

[Paul Y]

Check out the latest set of videos from Richard Holdner.

https://youtu.be/qDZOM-m_xTY

He tests the BTR Truck Norris cam against the new Sloppy Best Cam. Think you will be happy with either but the BTR had a little more bottom end at the sacrifice of some HP up top, the Sloppy cam was the opposite.

Let’s us know what you decide on!

P.