Have a question. I have a 3.4 pr set up with a 260H cam and want to know if I can change my 1.5 rockers to 1.6 roller rockers without changing the stock springs?
1 - the higher ratio rockers will wear the guides more quickly, if you care
2 - don't ask this sort of question on a forum, inquire directly from the vendor that made/sells the bits you have in the engine. Even if someone says you can get away with it doesn't necessarily mean that it is a good idea.
3 - the 260 cam is pretty useless - not much better than stock. The 272 is much better for a modestly improved engine.
I'm interested in roller rockers that fit underneath stock valve covers as a possible fix for my rocker ball wear problems... so do let us know what works out.
1 - the higher ratio rockers will wear the guides more quickly, if you care
2 - don't ask this sort of question on a forum, inquire directly from the vendor that made/sells the bits you have in the engine. Even if someone says you can get away with it doesn't necessarily mean that it is a good idea.
3 - the 260 cam is pretty useless - not much better than stock. The 272 is much better for a modestly improved engine.
Well your not much help lol. 260h can with 1.6 rollers is basically 272. So answer me do I need to change the springs ?
I'm interested in roller rockers that fit underneath stock valve covers as a possible fix for my rocker ball wear problems... so do let us know what works out.
One of the reasons why I switch to full roller ones...and why I made my aluminum valve cover spacers so they don't hit the valve covers...
If it's the Crane 260-1, then no. You'll bind the springs. It's why (IMHO) most people go for the 260 instead of the 272. If it's the Comp 260, then... I'm not sure. It depends upon the lift numbers. (The Crane 260-1 uses "staggered" lift numbers. .427/.454, I/E . I believe the Comp is "square", but I'm not sure of the lift numbers.)
One of the reasons why I switch to full roller ones...and why I made my aluminum valve cover spacers so they don't hit the valve covers...
How is it that ball pivots didn't work out for you (or for me), but they work for thousands of other engines? Were we doing something wrong?
I saw your spacer thread. Do you have extras for sale (just wondering)? I also saw other threads where people installed roller rockers beneath stock valve covers, so I guess the necessary clearance depends on the specific roller rocker that you buy.
[This message has been edited by pmbrunelle (edited 07-05-2020).]
I used the Crane 272 on my 3.4 build and not only did I need new springs, I had to have both exhaust and intake spring pads machined down to avoid binding problems. I was very careful to communicate to the shop that it needed to be verified, as I had read multiple horror stories of people only swapping springs and then finding out the pads were too high from the factory to avoid binding when they wiped the cam.
I'm with Raydar, the virtue of the 260 is being able to run it in an otherwise stock engine. I feel like the 272 is still quite mild in a 3.4 but I love how it performs. My head machine work was $600 for the complete rebuild, so it isn't cheap, but I like not having to worry.
Originally posted by BillS: the higher ratio rockers will wear the guides more quickly, if you care .
That can be fixed very easy. The reason it wears is becasue the higher ratio changes the angle. If the guides are modded by elongating the slots you'll be fine.
[This message has been edited by La fiera (edited 07-05-2020).]
I used the Crane 272 on my 3.4 build and not only did I need new springs, I had to have both exhaust and intake spring pads machined down to avoid binding problems. I was very careful to communicate to the shop that it needed to be verified, as I had read multiple horror stories of people only swapping springs and then finding out the pads were too high from the factory to avoid binding when they wiped the cam. .... the virtue of the 260 is being able to run it in an otherwise stock engine. I feel like the 272 is still quite mild in a 3.4 but I love how it performs. My head machine work was $600 for the complete rebuild, so it isn't cheap, but I like not having to worry.
My head work, including the spring pad work and the porting, was ~$800. But the finished result (a 3.4) was almost as fast as my 4.9. Minus the tractor tendencies, of course.
[This message has been edited by Raydar (edited 07-05-2020).]
Originally posted by pmbrunelle: How is it that ball pivots didn't work out for you (or for me), but they work for thousands of other engines? Were we doing something wrong?
I saw your spacer thread. Do you have extras for sale (just wondering)? I also saw other threads where people installed roller rockers beneath stock valve covers, so I guess the necessary clearance depends on the specific roller rocker that you buy.
Well, with a full roller setup, you no longer need guides... To me it's not about just what works...but what works better. I have about 10 sets left at $125 shipped in the US. My 1-off pair that I started with was >$400 so when they worked, I knew I'd need 2 more sets for myself so I ordered a full sheet's worth to get the costs down. I use the Summit aluminum narrow body 1.6 full roller rockers. I also use the 10mm->3/8" adapters from Crane that are typically a special order since these rockers come with a 3/8" nut. https://www.jegs.com/i/Cran...71/99148-16/10002/-1
It ends up being pricey but I have no performance complaints...
I forget the Summit Part # ... either SCC-SCP1088 or SCC-SCP1074
[This message has been edited by lou_dias (edited 07-06-2020).]
To answer the original question, upgrading the rocker arms will require upgrading the valve springs, for a couple reasons. The increased lift will bind the stock valve springs. Plus it will cause valve float at a lower RPM. However, a set of aftermarket valve springs can fix that. For example, the Comp Cams #980 springs will work. They're a drop-in replacement for stock valve springs, that can handle more lift. Plus they're a little stiffer than stock, which will help prevent valve float.
Side note: One of the reviewers on that web page said you have to do a bunch of machine work to install them on a 60-degree V6 head. I don't know where he got that info. The installed spring height is 1.7" stock! No machine work necessary. With the stock retainers and locks, coil bind will be at approx .550" lift, which gives you a safety margin.
[This message has been edited by Blacktree (edited 07-06-2020).]
To answer the original question, upgrading the rocker arms will require upgrading the valve springs, for a couple reasons. The increased lift will bind the stock valve springs. Plus it will cause valve float at a lower RPM. However, a set of aftermarket valve springs can fix that. For example, the Comp Cams #980 springs will work. They're a drop-in replacement for stock valve springs, that can handle more lift. Plus they're a little stiffer than stock, which will help prevent valve float.
Side note: One of the reviewers on that web page said you have to do a bunch of machine work to install them on a 60-degree V6 head. I don't know where he got that info. The installed spring height is 1.7" stock! No machine work necessary. With the stock retainers and locks, coil bind will be at approx .550" lift, which gives you a safety margin.
so just so im clear, these springs with a 260H equivalent cam and 1.6 roller tip rockers and I should be good? so if I have the 260H cam and these springs already installed, just swap the 1.5 rockers for 1.6 roller tip and im good to go?
