I’m getting ready to install a 97” big bore and head on my 2004 tc88 Electra glide. I’ve been looking at the S&s 551 and the Rocket 554. But curious to what everyone else is running and has experience with.

 

You need to do more homework. Those are two very different cams; the 551 intake closes at 19* and the Rocket 554 closes intake closes at 38*. You need to better understand cam profiles, compression and matching components to produce the desired results. Stock '04 valve springs will not accommodate lifts greater the .500".

If you want help from this forum, you need to provide more details about the build plan.

 

I thought that they would accommodate up to a.510" lift stock.. hence the 509 and 510 cams..

 

I’m not using the 04 heads. I’ve got heads off of a 07

 

.500" is what HD says but you are right. I have seen early springs accommodate up to .525" without coil bind but I know they will not accommodate the .550" lift the OP is considering. Now we get the rest of the story, the OP is using a set of later heads that will accommodate the higher lift so a moot point.

 

So valve lift won't be a problem but as I said in my previous, the two cams referenced in your previous post are very different profiles and you need to figure out which profile will provide the results you are looking for, i.e., which best matched riding style.