Stock cam about tune was able to increase timing by at least 15 deg through 2000 rpm to 3000 rpm. But listen for pinging
Harland Sharp Roller Rockers
- Thread starter TonyO
- Start date
So your seat of the pants gains were RRs PLUS tune, right? I mean, there was no tune on it before you swapped on the RRs.
Don't forget, the change in ratio changed the effective cam profile. So his seat-of-the-pants feel was from a change in effective cam profile, a change in tune and timing.
Full roller rockers would net no significant power differences in something making the power of a 4.0. IIRC the guys on engine masters showed no power change from a stamp steel rocker vs full roller rocker on a 500 hp engine.
They have a rather limited lifespan compared to stock rockers correct? Like 20-30k? I almost got some harlans but didn't for that reason
I started with the tune but with the rr was better. Still say rr was the best add on. I also have 62mm tb. Stock intake. For 180k motor sure is strong up to 3500.
Yep, and that's why I asked what cam. I think the increased ratio would make a more noticable difference on a stock cam with a stock head than people realize because the stock cam is so dinky. A larger aftermarket cam is probably already getting close to if it not exceeding the practical flow of the stock head so it doesn't help much more. Enough difference to notice seat of the pants power though still surprises me. I was trying to chalk that up to the tune but it sounds like he had already put more timing into it before the RRs as well. I run 1.65 ratio RRs myself but have a lot else going on so it's not apples to apples.
Different platforms have different results. Some gains can be had simply from a lack of deflection in the stock stamped rockers at higher rpms in some applications. I think I remember seeing a 4.0 dyno shoot out showing just that somewhere. I'll see if I can dig it up.
MFMauceri
New Member
Did you have to cut the baffle out of the Valve Cover to make them fit?.. There's a debate whether doing this will foul the PCV valves.
MFMauceri
New Member
MFMauceri
New Member
I'm going to concur they DO bring engine noise down a bit.
Mine went in as part of an engine overhaul where many new parts (OEM and After-Market) got installed, so I can't pinpoint which ones may have positively affected what or to what extent... But on the whole, I basically have a new 4.0L powerplant in a 20-year-old jeep.
There are different opinions on pairing valve cover options:
1. Get a taller after-market one.
2. Cut out the top baffle plate inside the stock cover to accommodate the HS rockers' height.
3. Rubber mallet the top plate to pick up the tink bit of clearence you'll need to keep the OEM cover.
I cut my out the top baffle plate but have since leaned that this will probably send oil into the PCV system. Any thoughts out there? In hindsight, I think the rubber mallet may have been the the best low-tech option, but would incur a lot of trial and error.
There's also a valve cover spacer.
If you want the baffle back, you have two options; 1 - OEM cover with spacer or 2 - taller aftermarket cover with baffle.
Joedert
Member
4.0l harland sharp Roller rockers were a hard no for me. They don't last anywhere near as long from what I've gathered.I have stock rockers with 200k on them in great shape with my comp cam.
Joedert
Member
Yes my research says about 50,000 mi. In a V-8. I’m doing Less rpm so probably more. My TJ is a 2004 I bought new. It has 78,000 now. And I put 3000mi on it in the last 5 years. So they will never make it to 50,000. But I will say the 1.7 do make a difference.
So long as people are aware they aren't reliable it isn't an issue. I've read as little as 20k miles on the harlands. I've done that in a couple years