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  1. #1
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    Valve Train Noise

    I have installed a Comp Cams HRT stage 1 cam in my 05 Magnum RT. I also installed 6.1 springs, pushrods and new seals. It runs but I have a good bit of valve train noise, definitely more than before the cam was installed. The original cam was in perfect shape so I wasn't worried about a stuck roller senerio that causes the dreaded "hemi tick". It is a high mileage car with about 165K on the clock so I'm now wondering if I made a mistake by not doing the lifters while I had it down. If I do back in I'm going to go back with non-MDS lifters and block offs for the solenoids. Thanks in advance for any advice or opinions.

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  2. #2
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    Just curious, how do you make sure the valve adjustment is correct on these engines when there is a cam change? Are longer or shorter push rods available? I'm ignorant of how to do this.

  3. #3
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    Nov 2016
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    Hopefully Hemisary will chime in. I am not intimately familiar with Gen 3 hemis, just a professional engine builder. I think the 6.1 springs and pushrods were a mistake. I think the 6.1 exhaust valves are longer, and either the intake or exhaust valves are lighter. I put a stock 6.1 cam in my 250K 05 magnum and used PSI springs, I think numerous 1511. You need to be very careful mixing and matching parts. Did you check the valve train geometry?
    Also the hemi tick is not from bad lifters, it is because the lifters are fed from the rocker shafts, through the pushrods to the lifters. An easy fix for the hemi tick would be a set of Johnson side feed lifters (big bucks) and elimination of the MDS (which would not work with the lifters anyway)
    The fix to your problem may be as easy as changing exhaust pushrods. Although I am not confident with the choice of valve springs. Parts need to be matched more than mixed.
    Tom

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  4. #4
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    Quote Originally Posted by 2005rtmag View Post
    Just curious, how do you make sure the valve adjustment is correct on these engines when there is a cam change? Are longer or shorter push rods available? I'm ignorant of how to do this.
    You can get pushrods in any length you wish. Manton makes good pushrods, as well as trend. I do not know for sure, but would suspect that about .040 preload in the lifter would be about right. The way to be sure you are on the base circle regardless of how extreme the cam is as follows. When the exhaust is at peak lift, the intake on that cylinder is on the base circle, and when the intake just starts to close, the exhaust is on the base circle
    Tom

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  5. #5
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    Did you measure to find the correct pushrod length? I put a 6.1 cam/eagle heads/cosmetic gaskets/shimmed 6.1 springs in my 06 RT. It was a lot of extra work but I measured to find correct pushrod length. I ended up having to use custom length pushrod for intake and exhaust.

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    2006 Dodge Magnum R/T: K&N CAI, SRT headers, Magnaflow 3" cat-back, 180 degree t-stat, Diablo Trinity T1000, 300 SRT rims.

  6. #6
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    Quote Originally Posted by ChoochG View Post
    Did you measure to find the correct pushrod length? I put a 6.1 cam/eagle heads/cosmetic gaskets/shimmed 6.1 springs in my 06 RT. It was a lot of extra work but I measured to find correct pushrod length. I ended up having to use custom length pushrod for intake and exhaust.

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    ...I ended up getting all the pushrods from Summit

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  7. #7
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    Where you got the pushrods is irrelevant. The length is what is needed. You need to measure the geometry and get the length that is needed. On shoe type rockerarms the contact should start inboard of the center of the valve tip, then cross center, and finish on the outboard side of the tip the same amount as it started on the inboard side. You need to do this with checking springs so that you do not collapse the lifter. Once you have the length that works, you add the amount of preload you need (checking springs will not load the lifter at all), and just order the length pushrods you need
    Tom

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  8. #8
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    Thanks for the input so far. I had done some research prior to doing this swap and there are several folks that have done the same setup I'm running with a few different aftermarket cams, Comp 260 and 216 were mentioned. That being said, there also some folks saying the 6.1 springs are too stiff on the the 5.7 heads. A couple of other folks mentioned using the Manley 6.1 pushrods. Lots of different opinions... I may contact tech support at Comp and run this by them also since I'm running the newer HRT series cam.

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  9. #9
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    Quote Originally Posted by cthomas157 View Post
    Thanks for the input so far. I had done some research prior to doing this swap and there are several folks that have done the same setup I'm running with a few different aftermarket cams, Comp 260 and 216 were mentioned. That being said, there also some folks saying the 6.1 springs are too stiff on the the 5.7 heads. A couple of other folks mentioned using the Manley 6.1 pushrods. Lots of different opinions... I may contact tech support at Comp and run this by them also since I'm running the newer HRT series cam.

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    I have cams in all three of my Hemi's and the only ones I get a little valve noise from are the two early (05 and 06) 5.7's with the old FRI Sidewinder cams in them. I've been running 6.1 or PAC (stiffer than the 6.1's) springs for years and many miles and have never had any problems. So, the 6.1 springs issues running on 5.7 heads is total BS. The 6.1 pushrods are also completely adequate for a mildly modified 5.7. They're a slight bit longer and, with the 6.1 springs, will rev to 6500 RPM easily, although I have my shift points set at 6000-6200 RPM. I also have a Comp XFI series 260 in my SRT8 and it is totally quiet. I have its shift points set at 5900-6000 RPM. See signature for mods on all three.
    Last edited by magnuman; 05-02-2021 at 11:36 AM.
    06 300CSRT8, Comp cammed, 85mm TB, HP/DS Tuners, 06 Jeep GCO and 05 Magnum RT (5.7's) both modded almost the same, MDS "ON" Lt, Fumoto Drain Valves, BT Catch Cans, SRT8 CAIs, AFE Filters, Sonnax Trans Line Press Booster, SC, DS and HP Tuners, Transgo Shift Kit, ARH Long Tube Hdrs w/3 in Magnaflow/Xlerator AP Exh Sys, Bilsteins, SRT Springs/Sways, Cust Eng Cvrs, SRT8 frt/rear bumpers, advanced FRI Sidewinder Cams (Jeep 6*/Maggie 10*), 6.1 valvetrains, SLP 25% UD Pulley, BBK or Arrington 90mm T-Bodies, SOS Ign Coils,TEA ported/milled heads w/new valve seats, SRT Reps.

  10. #10
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    How bad is this "tick"?

  11. #11
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    Quote Originally Posted by cthomas157 View Post
    Thanks for the input so far. I had done some research prior to doing this swap and there are several folks that have done the same setup I'm running with a few different aftermarket cams, Comp 260 and 216 were mentioned. That being said, there also some folks saying the 6.1 springs are too stiff on the the 5.7 heads. A couple of other folks mentioned using the Manley 6.1 pushrods. Lots of different opinions... I may contact tech support at Comp and run this by them also since I'm running the newer HRT series cam.

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    Spring need is NOT determined by the head. No such thing as too much spring for a head unless it is so much it pulls the rocker stands out. So 6.1 springs on a 5.7 not an issue with the heads. The spring you need is determined by the weight of the valve, and pushrod, and the profile of the cam. Plus you need to determine what pressure you need on the seat AND what you need over the nose. When piston to valve hits happen it is the piston chasing the valve as it closes. Too little pressure. You want enough on the seat to keep the valve from bouncing, and enough over the nose to keep from lofting.
    ALL engines need to have push rod length determined. I don't care if they are identical combinations or not. There are production tolerances. May be the same heads but maybe these have the rocker stands and deck on high limit while the other set are low limit, the deck on the block etc. Every engine needs to be treated as if it were the only one in the world. Every detail attended to, nothing left to chance or assumed.

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