I'm trying to decide if I want a roller cam setup in my Mark IV 454 Chevy for my muscle car. Lots of guys are saying "its the only way to go" and just as many other guys are saying "it will eventually fail".
so what's the deal?
My understanding is that due to the way lifters are lubricated and cooled (by splash), the roller lifters have little or no lubrication at times of low rpm, and thus not recommended for the street because they will "eventually" fail.
Almost every roller lifter I've seen out there has "needle bearings" surrounding the roller axle. However, the Isky EZ Roll lifters are different - they have a continuous single bearing - not needle bearings, but those lifters are new I believe and have not withstood the test of time for street applications.
I also learned that several lifter companies offer "pressure fed" lubricated roller lifters which take oil from the lifter bores. Yet, I still hear guys saying that doesnt work well either.
I've even had some guys tell me that there are ways to machine the block and lifters to promote better "splash" and lubrication for the roller lifters. Well I'm not doing that...........to much time and money and work. I'm not racing this thing, It's just a weekend warrior during the summer months and I don't want to "over engineer" this application. If it's a bad idea I'll just go with a solid FT cam and be done with it.
So............I need help from you guys to educate me on what the real story is and what I should do. Eventually I will have enough information and can make a educated decision at that point, but for now I feel like a dummy.
I don't know who is saying roller cams fail,but almost all new vehicles now come with roller cams.It is my past experience that when the factory tries something new and does not get good results they go back to what they had before. I don't see any manufacturers of new vehicles going back to flat tappet cams. My friends roller cam failed in her 2003 suburban,one roller lifter roller had slight pitting on it, but this happened at 386,000 miles. I dont think this should scare me away from roller cams. :thumbup:
I just changed my original post to note that this is for a Mark IV block. I'm sure the newer production blocks setup for roller cams have different provisions for lubricating the roller bearings. Don't know - just guessing.
I just changed my original post to note that this is for a Mark IV block. I'm sure the newer production blocks setup for roller cams have different provisions for lubricating the roller bearings. Don't know - just guessing.
The guys having trouble with solid rollers on the street are using a very aggresive profile with very high spring pressures. Combine this with a lot of idling and you will have lifter failure, especially if the lifter bores aren't square with the camshaft.
If you want to run a solid roller on the street, don't go too radical in cam profile and run sensible seated and open pressures when setting up the heads.
Factory roller set-ups last a long time because factory cam profiles and seat pressures are designed for longevity as well as fuel efficiency and performance.
The guys having trouble with solid rollers on the street are using a very aggresive profile with very high spring pressures. Combine this with a lot of idling and you will have lifter failure, especially if the lifter bores aren't square with the camshaft.
If you want to run a solid roller on the street, don't go too radical in cam profile and run sensible seated and open pressures when setting up the heads.
Factory roller set-ups last a long time because factory cam profiles and seat pressures are designed for longevity as well as fuel efficiency and performance.
please define "too radical" and "sensible" for me.
Is .600 lift "too radical" I dont' know? Is 600# open pressure and 225# closed pressure "sensible"? I don't know. Never done this before. I know the spring pressures for these roller setup are much more (like double) the spring pressures of non-roller setups right?
I have to ask-how often do you Bush Lifter Bores? I know that it's critical on high RPM engines, but on the Engines you build, how often do you find them out of Spec? I'm sure a lot of people probably don't look at this issue (or think about it)- just curious-
please define "too radical" and "sensible" for me.
Is .600 lift "too radical" I dont' know? Is 600# open pressure and 225# closed pressure "sensible"? I don't know. Never done this before. I know the spring pressures for these roller setup are much more (like double) the spring pressures of non-roller setups right?
This is a question I have also-I am looking at a Hyd. Roller for my 496 with a .610 Exh. Lift and wonder if it might be too big (for the required Spring Pressures)-
I have to ask-how often do you Bush Lifter Bores? I know that it's critical on high RPM engines, but on the Engines you build, how often do you find them out of Spec? I'm sure a lot of people probably don't look at this issue (or think about it)- just curious-
Most of the engines I build are warmed over stock or fairly mild street-strip mills. (Don't get me wrong, I have more than a few 8-9 second 1/4 mile drag car and circle-track customers) For this level of performance I don't see too many issues with lifter bore alignment. I have had only one customer with an issue that I attribute to a lifter bore alingment problem and that was with a 383 Dodge. If I built engines running .650" or more solid roller cams and such, I would probably get deeper into lifter bore work.
please define "too radical" and "sensible" for me.
Is .600 lift "too radical" I dont' know? Is 600# open pressure and 225# closed pressure "sensible"? I don't know. Never done this before. I know the spring pressures for these roller setup are much more (like double) the spring pressures of non-roller setups right?
For the street, I would consider up to .630" lift with up to 175lbs seated and 475 - 500 open to be OK. Anything more than that is not going to last forever.
This is a question I have also-I am looking at a Hyd. Roller for my 496 with a .610 Exh. Lift and wonder if it might be too big (for the required Spring Pressures)-
I just changed my original post to note that this is for a Mark IV block. I'm sure the newer production blocks setup for roller cams have different provisions for lubricating the roller bearings. Don't know - just guessing.
Not really, but the OEMs raised the height of the lifter blocks to increase body support for the lifter so it's less likely to want to tip from lack of support. This improves tracking of the roller on the lobe and reduces side loads being introduced to the roller's bearings, which they are not designed to withstand.
After market rollers in a non roller block have problems with the roller that looks like an oiling problem and can be helped with more oil on the roller but this problem really sources from:
1) Inadequate lifter body length support. The OEMs added from 3/8s to 1/2 inch of lifter boss length to their OEM roller blocks.
2) The tendency for hot rodders to run high spring pressures and aggressive lobe profiles doesn't help the problem either as this adds to forces trying to twist and kock the lifter body in it's bore.
3) Experience indicates to me that the aftermarket method of aligning pairs of roller lifters doesn't provide as much stability as does the OEM approach of milled flats of the lifter body riding in the broached hole of the retainer bar that is located by the bolt on spider. This proves to be a simple yet very durable method of alignment. Unfortunatly it doesn't retrofit well to non OEM roller blocks.
I have customers with 30,000 miles + on there solid roller engines, that do only street driving with them. It's like everything else in the engine building trade people have problems because they do not have the correct set up for what there doing.They read all the book and magazines ( that give incorrect information) and never ask some one that actually did the work.
As far as the lifter bore issue goes...
I have done maybe 30 blocks, all chevy, small and big blocks. I can tell you that some of the big block's through the 70's have some major issues with the lifter bore locations and perpendicularity. As Tom has stated, if you run a mild cam in one of these blocks the issues will never show up , but you start getting into 250@ .050 duration and above you will have problems. I did a big block once that had destroyed 3 cams in less then 500 miles. After i did the lifter bores, (and the last i herd about the engine) it had around 60,000 on it. No more cam issues. That was a flat tappet engine. When you fixture up the block and look at the lifter bores you think some times that they are not even going to tru up with the reamer.. They always do, but some are real bad.
Ha! You goose! You can spell perpendicularity but you can't spell ointment!
That's someone from Pennsylvania for ya!
tom
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