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Thank you for posting that. So many people think ls7 lifters are some huge upgrade, and they are really just stock replacement
They are indeed a stock replacement lifter. Though, they are still a good lifter choice for 90% of the Chevy builds out there. But if you're expecting some mechanical wizardry out of these things, you're going to be disappointed when you find out that all it does is ride a cam lobe up and down.
Originally Posted by G Atsma
Though I heard they are an improvement over what came before them.
That they are, which is why they made their way into every production V8 after the LS7 debuted, and eventually took over as the sole replacement part.
The main complaints come from the people who didn't change their pushrod length to offset the added cup height.
It still applies to LS7 lifters since they were designed to have a wide preload range. However, blindly throwing in factory stuff and assuming everything is good is never a great plan. For instance, on the 5.3 I put in my dad's 64 Impala, the factory pushrods were too long putting the preload around .090"-.100". I stepped down to 7.350" pushrods to knock .050" off. This was with a factory block, heads, cam, gaskets, and LS7 lifters. Some times the tolerances just stack that way.
If people are throwing just one LS7 lifter in as a replacement on their engine and don't check the pushrod length, they could be inadvertently running a pushrod that is too long. On the LS engines, this will affect preload. On LT1 and SBC engines, it will affect the rocker's sweep pattern over the valve.
Oh yeah I get that you SHOULD measure every time, but I was just wondering if, when GM went to LS7 lifters, they changed pushrod length. It appears not...
I'm currently running a set of the Rhoads vari duration hydraulic flat tappet lifters in a 69 Camaro with 406 small block. I went from liking them, to disliking them, to liking them again in about a 1.5 year span. The dislike came after getting a souped up Holley 830 cfm carb added along with a dyno tune. Tuner marveled how clean it pulled even at 6500 rpm. I wondered why he ran past even 6000 rpm with a flat tappet hyd cam. A few hundred miles after the dyno session, I got a bad lifter knock. Checked all of the usual suspects and the valve train checked out OK. At that point, I figured that I had a bad lifter or a wiped lobe on the very inexpensive Summit cam. With 1.6 ratio roller rockers, lift was .497 on the intake and .519 on the exhaust. 224/234 114lsa. Also has Trick Flow 195 "as cast" cylinder heads with their valve springs.
Didn't touch it for almost a year. Started it up to pull it out of the garage and get it prepped for surgery. I noticed right off that the valve train was totally quiet. WTF. Ran the snot out of it and couldn't make it make noise. Just ran like I knew it should. 18" of vacuum, perfect manners, and it pulls HARD from idle 'till I lift. Usually about 6000rpm. So, at this point, I'm again liking the Rhoads lifters.
Well, I sent Howards Cams an email and link to this thread inviting their input, and have had no response. So I'm guessing they are either too busy with SEMA and PRI coming up or simply do not want to talk about their product here. THere was no consensus over on a race engine forum, some had success, some had power loss.
It appears that to work well the lifter bores should all be perfectly straight (aligned), round, and have identical clearances. Then, the correct size bleed off hole in the lifter would bleed off duration until rpms forced the lifter to simply pump up and become more like a solid lifter. Therefore a well made set of hyd rollers with variable duration may well be worth trying if we were prepared to blueprint and rebush the lifter bores to exact tolerances. I'm prepared to do that and budget allowing try back to back pulls comparing to normal lifters
Well, I sent Howards Cams an email and link to this thread inviting their input, and have had no response. So I'm guessing they are either too busy with SEMA and PRI coming up or simply do not want to talk about their product here. THere was no consensus over on a race engine forum, some had success, some had power loss.
It appears that to work well the lifter bores should all be perfectly straight (aligned), round, and have identical clearances. Then, the correct size bleed off hole in the lifter would bleed off duration until rpms forced the lifter to simply pump up and become more like a solid lifter. Therefore a well made set of hyd rollers with variable duration may well be worth trying if we were prepared to blueprint and rebush the lifter bores to exact tolerances. I'm prepared to do that and budget allowing try back to back pulls comparing to normal lifters
That makes sense!
I wonder if Nikasil or similar coating on blueprinted & rebushed lifter bores to reduce friction would be a good thing or a wild card with Rhoads lifters.
It would but that is old tech. I'd use superfinishing on the lifters then stealth coat them ( a low friction dry lubricant using nanoparticles) and stealth coat the bushings. Both services are available locally to me and the top racing guys are doing this now though not telling anyone - worst kept secret though because word is out lol.
It would but that is old tech. I'd use superfinishing on the lifters then stealth coat them ( a low friction dry lubricant using nanoparticles) and stealth coat the bushings. Both services are available locally to me and the top racing guys are doing this now though not telling anyone - worst kept secret though because word is out lol.
Oh, that sounds like some sweet technology
Thank you for sharing!
How expensive is superfinishing & Stealth coating a set of lifters & bushings? That seems like a very trick set up.
I read where superfinishing can increase the working life of a gear by up to 4x. That seems like the ticket for cam lobes and lifters, piston pins and so on.
Here are prices in New Zealand dollars, USD are likely similar. This is for superfinishing work. The stealth coat is applied by a liquid medium making it easy and cheap to apply, so the costs would be mainly the expensive ingredients in it (I have no price list for the coatings yet but expect it to be a lot cheaper than super finishing which is time intensive.
Here is a pic of a crank they did - the super finishing gives it a mirror appearance, then the coating gives it a matt finish - but the combination leads to a much more slippery/harder wearing piece
Thank you! I had never heard about that, as I TRY (lol!) to stay informed.
I have in the past considered Rhoads lifters to be snake oil, but this makes them more legit!
10-17-2018, 11:49 AM
