No, they won't. Been there, done it. Oil pressure holds that lifter up, not a spring. Ran a cam so big I had to notch the pistons to make it work in my 318 and still used the stock lifters with the MOPAR performance springs rated for .600 lift. Used the Harland Sharp 1.7 non adjustable rockers on that build too with stock length push rods. I did run the upgraded retainers and locks.


No sewing machine noise from that engine's top end at all. Comp cams knows the specs on the stock cam, their cams are ground with the same base circle as stock, unless you go so radical they have to cut into the base circle to get a crazy high lift, or you regrind a stock cam for more lift. You can call to verify it with if you so desire.


I can't even believe you'd be able to find an aftermarket hydraulic roller lifter for the magnum engine with a .940" roller that isn't tied back to being an official MOPAR part. Why would anyone want to jump into the market of a niche engine that has been rendered obsolete by the corporation that designed it for a part that will see no gain over the stock part? Perhaps if someone designed a significantly lighter lifter that still maintained the stock lifter's integrity you might have a part that ten guys in the whole country are interested in who are seriously racing these engines and want to rev north of 6000 RPMs.

 

While I respect your been there done that didnt you have off-idle stumbling problems with your build. Dont remember if you fixed the problem or not then sold it shortly after but a lifter colapse would cause that problem. Didnt you have eq heads that are supplied with heavier springs so why change springs with such a small cam .488 lift and with 1.7 rockers .518 lift..eq's come with either .525 lift spring which is a good match to your cam or .580 lift spring or sum such. As far as notching the pistons you picked the 2.02 eq monster mags which severly decreased the p/v clearances thus the notching. Had you picked a stock sized valved eq heads you would not have to do all the extra work in notching the pistons plus the fact 1.92 would of been a much better match for the 318 and the small lift cam. hylift johnson lifters have supplied lifters for decades and so has rhodes you should have looked in to them. HYLIFT supplies a few diffrent lifter from oem replacements to stiffer lighter tighter lifters for these mag engines. YES LIGHTER...If your rev a hydro roller cammed magnum past 6k then solid lifters are the hot ticket. Hydro roller lifters just cant take the valve spring pressures required at that rpm. yes oil pressure adds a cushion but what holds the lifter up when the enginne isnt running? The internal spring will. If the lifter doesnt over come the springs pressure with the engine not running then there is bleed down, and a hell of a clatter at ever start up which is never a good thing. Dodge used a very soft valve spring(80 seat 200 open) for a roller cam that is which eleminated the bleed down at start. There will all ways be someone that has done it or dont like a product but the fact is if your going to swap a cam in a higher mileage engine or a rebuild, why skimp on the lifters and reuse the old worn out trash collecting lifters. Lifters are not that expensive considering the problems they can cause. Heres a link to hylift and a info to quote....[“R” designates lifters which have lower hydraulic ‘bleed down’, from 8 to no more than 20 seconds. “R”type lifters will provide a better idle quality when using a high performance camshaft.“S” designates ‘slow bleed’ and will have even lower hydraulic ‘bleed down’ than the “R” type lifter. Use of this lifter will eliminate the need for lash adjustment in a typical mechanical lifter application and will follow the camshaft profile translating all the lift to the valves. Type “S” lifters can withstand very high valve spring pressures, result in more power and higher RPM as well as reduce valve train wear compared to standard mechanical flat tappets.....This applies to roller lifters as well]....part#'s A-2269R A-2269S....r=race s=special. Also offer a direct shot oiling lifter as well as oem's.http://hylift.clickdriver.co/wp-cont...talog_2014.pdf

 

Erm, there isn't ANY bleed down in mechanical lifters, as there is no hydraulic component to them. They are solid..... therefore, nothing to bleed down.

 

The spring inside a lifter can't even resist your finger if there is no oil in it (like on a new one). It keeps the cup in contact with the push rod, and when the engine is off, it pushes down on the check ball to keep the lifter from bleeding down. If that spring didn't compress on a stroke, how would oil get pumped upward to the tip of the push rod that meets the rocker arm?

The cam was too big for the engine, as were the valves. I eventually wanted to stroke it hence the larger valves (buy heads once I could afford, deal with the shortcomings for now) , but a better deal came along for me and I let it go. It's not every day the Mrs. O.k.s a +400 hp car purchase, so I pounced.

I'm not so sure how much the larger valve contributed to the clearance issues. To be sure they did, but the larger valve is .100" in diameter, which is .050 for the radius, and the valve approaches the head at an angle that definitely isn't 90° perpendicular to the piston, so that total radius isn't a simple addition to the total lift.

The bigger problem that required notching was the crazy steep lobe profile I believe, got the valve too high, too fast for the flat top piston. But that crazy ramp up profile is part of the plus of running roller lifters.

Clearwater, the shop that sold the heads to me were nice guys to talk to, when I told the owner what my total lift would work out to and what the cam profile would be he told me the .525 springs would be borderline. The guys at bionic suggested I go for the MP .600 springs as the seats in the EQ heads wouldn't need to be altered and the MP hardened locks and retainers would also work no problem.

Johnson was the manufacturer of the MP lifters to my recollection, and Rhodes lifters were only recommended if low engine vac was a concern.

There are Chevy lifters that meet the general spec of Chrysler lifters save that the roller is much more narrow. I've heard of them being used in Chrysler engines as a suitable replacement lifter. I was warned against using them as the wider roller supposedly dispersed forces across a wider cross section of the cam lobe and that was better for cams with aggressive profiles. Never seen a known hylift lifter in person, but from that website you linked, it looks like one I bought from NAPA from their parts catalog that did indeed have a roller that was not as wide as a stock lifter. I recall that the amount of machined surface on the lifter that would actually contact the lifter bore was less on that NAPA lifter than the one I pulled out of my engine.

Never did figure out what was wrong with it before I let go of it. Could it have been a lifter? Maybe, but I would have expected to hear some engine clatter at start up, not a bad almost-stall-out stumble after a 20min drive. My feeling was either it was something electrical, like an over heating coil, or a trans issue that manifested when it warmed up, possibly a converter issue.