408 Cam on the way

Small Block Mopar Engine

  1. Idaho

    Idaho Well-Known Member

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    I have a 408 stroker in the works.
    I went with a re-ground cam.
    Saves cash at around $150 plus shipping vs $350 for new, plus I can reuse my distributor gear.
    Here are the specs from Ken at Oregon Cam Grinders

    #1357
    230/236 @ .050”, 284/290 adc, .515”/.515” lift (1.6:1 rocker), 108 sep

    As you can see it's close the Comp cams thumpr.
    I believe its typical to install the Thumpr 4 degrees advanced, bringing the torque curve into a lower RPM range. I also understand some cams have some advance built in.
    I can clarify with Ken but just thought I'd ask about this here and get comments on this cam.

    thumpr.png
     
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    • RustyRatRod

      RustyRatRod I was born on a Monday. Not last Monday. FABO Gold Member

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      Whenever I talk about camshaft timing I ignore and advance "ground in". That just opens up confusion. You need to go with static compression and then make your determination.
       
    • Idaho

      Idaho Well-Known Member

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      Static CR will be around 9.8.
      I don't get the "ground in" thing.
       
    • RustyRatRod

      RustyRatRod I was born on a Monday. Not last Monday. FABO Gold Member

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      There is typically advance ground into a camshaft. Don't try to get it, just ignore it. I would want that cam in at 4-6* advanced. But verify the static compression ratio by measuring it. Don't guess.
       
    • Idaho

      Idaho Well-Known Member

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      Everything is getting measured and checked :)
      I'm guessing it won't be quite as lumpy as the thumpr with a bit less exhaust duration?
       
    • RustyRatRod

      RustyRatRod I was born on a Monday. Not last Monday. FABO Gold Member

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      Probably wouldn't be able to tell the difference......maybe, I don't know.
       
    • Idaho

      Idaho Well-Known Member

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      Thanks Rusty.
      Comments welcome. I know there's lots of thumpr hate. Doesn't bother me.
      I'll change it out if I don't like it.
       
    • lead69

      lead69 hopeless car junkie

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      That's much closer to a comp xe274 if it was on a 108 ls (stock is 110),the thumpr has a bunch more exhaust duration and a 107 ls.
       
    • RustyRatRod

      RustyRatRod I was born on a Monday. Not last Monday. FABO Gold Member

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      I actually like the Thumpr concept. All of the data shows they run quite well.
       
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      • RustyRatRod

        RustyRatRod I was born on a Monday. Not last Monday. FABO Gold Member

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        I don't call 5* exhaust duration a "bunch" of difference. Also the Oregon grind he has chosen is on a 108, only 1* more than the Thumpr he compared it too. I think it's pretty close.
         
      • j par

        j par Well-hung Member

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        Is it a solid lifter cam or hydraulic?..
         
      • Wyrmrider

        Wyrmrider FABO Gold Member FABO Gold Member

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        Thumper hater here
        rusty where do you get 5 degrees? which would be great
        agree on the advance issue
        get 13 degrees at .050 and
        20 degrees more advertised exhaust duration for a Magnum head
        WTF
        It's real easy to roll your own thumper style cam'
        or the Hughes version- well do a quick compare I'll post one tomorrow
        comps version is like their dual power scam- a marketing gimik
        I'd take a purple power if limited lift (stockish heads) or the xe-hl grinds
        otherwise comp is a con
        anybody else think a long rod motor needs different cam timing than a short rod motor?
         
      • j par

        j par Well-hung Member

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        The thing about having a conversation with Ken is he's going to give you what you want for what you described you're looking for. It's obvious he didn't say that he wanted some kind of all out drag race cam. He wanted something that idled but sounded healthy or something like that likely. Because we all know it's hard not to make a Mopar sound healthy LOL..
         
        Last edited: Apr 21, 2020
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        • Idaho

          Idaho Well-Known Member

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          Brian at IMM who I purchased my heads from certainly got good power from the thumper in the 360 and 408.
          Folks scoff at the idea of making any compromise in performance whatsoever to gain an idle that tickles the ears.

          Well, fine, but that makes no sense to me. I absolutely love certain engine sounds. The starting cough cough sputter and rough idle of a big radial like the DC3s I used to work on is almost akin to making love. It just tickles a special part of the brain. Anyone who has been to an airshow and heard either a big radial or V12 in a warbird cruise by at close range... if it didn't make your heart pound, well there's something just missing.

          The lovely sound of a V8 cannot be matched by anything with fewer cylinders. I don't understand why. I don't need to. And when the idle has a lope to it, well, now it's reminiscent of the sound of the big birds. Will I take a small hit in performance to hear it? All day every day.

          Truth is I will likely exceed the original performance goals I had for this car. I'm kinda hoping I didn't overdo it and wind up breaking too much running gear.

          Why do we build these cars? Some like a pure repro. Mine is heavily modified. There are many things that enter the equation. Bottom line its whatever turns YOUR particular crankshaft. Right?

          You have to hear the idle before shutdown at 3:00. Turn up the sound!!


          I've been around the modern fighter jets a lot. Awesome in their own way. But the sound of the piston powered warbird is on another level.
           
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          • j par

            j par Well-hung Member

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            I sure called that one...
             
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            • 512Stroker

              512Stroker We are all here because we are not all there.

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              I love the sound of a flat crank V12 Ferrari running down the track
               
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              • nm9stheham

                nm9stheham Well-Known Member

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                Don't look at the 5 degrees difference in the .050" lift... look at the 13 degrees increase in the advertised duration. That is where the overlap is coming and excessive overlap is what causes the erratic idling.
                 
              • lead69

                lead69 hopeless car junkie

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                You need to look at the cams specs again. The thumpr has a BUNCH more exhaust duration to intake as in 14 degrees at .050 and 20 at advertised, his cam has 6 and 6 respectively add in the degree tighter ls and they are not close. The comp xe274 in most all flavors has a 230/236 at .050 duration with a bit less at advertised (depending on where it was measured between cams) than his cam but I wonder what lobes they are using since they only have .515 lift with a 1.6 and have slightly larger advertised numbers so they probably are not xe lobes.

                To the op I really like the thumprs and have built several 340s with them and have a few friends running them. They make good power and for as nasty as they sound have great streetability.
                 
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                • lead69

                  lead69 hopeless car junkie

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                  As I understand it it was a marketing gimmick that actually made power and surprised some people.


                  I was one of the first to get a thumper cam from Comp. When I ran one it was as good or better than the same duration etreme energy hyd roller. When they started testing they found the same thing. It works very well because they are all ground on 107 lobe centers.. I now use them in all the street engines I build. I do use the 235 duration in most cases, but the big mutha thumper(243) is the best I have run yet It made 571 HP in a 383 Chevy on pump gas. They are VERY GOOD.

                  JOE SHERMAN RACING ENGINES

                  I admit when I want max hp I go for a custom but I think these are great off the shelf option for a basic street/strip engine and a rough idle.
                   
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                  • Idaho

                    Idaho Well-Known Member

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                    I admit, my understanding of cam specs is limited. Can you comment on what to expect from what I ordered?
                     
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                    • j par

                      j par Well-hung Member

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                      I certainly could but let's listen to what 69 lead has to say about it.. (seeing as how my 410 stroker has damn near the same Cam and Ken has ground both of my cams for me)
                       
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                      • Idaho

                        Idaho Well-Known Member

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                        I'm very interested in your comments. Ken seems like a good guy over the phone.
                         
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                        • j par

                          j par Well-hung Member

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                          Is just as nice in person and takes the time to listen to you and your wants and expectations from your car...
                          When I first had my Stroker motor built I had Big Daddy Don garlits dreams LOL I said I wanted to be huge I wanted to barely Idol I want to set the world on fire! He said are you sure about that? I said yes! He gave me what I wanted... It couldn't do nothing till about three grand and then it damn near went off like a time-bomb!.. couldn't hold an idle barely for over 15 seconds LOL...
                          Then I went in and said I'd like it to idle LOL and I'd like to have a little bit more lower end torque and put some different gears in it so I can drive it on the freeway and the street.. And gave me my current cam... And I'm happy with it... I could see myself getting another one and it would be somewhere in between the two...
                           
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                          • Idaho

                            Idaho Well-Known Member

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                            That's a good story. Ken was likely amused :)
                            Can you tell a bit more about what you have?
                             
                          • lead69

                            lead69 hopeless car junkie

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                            Forgive me if I missed it but I don't know much about your combo and what you are hoping for.
                             
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