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500, 472, 425, 368 Discussion, 6.0 368 pros and cons in Cadillac Engine Technical Discussion; So a bigger motor is a direct fit in? How about the 4100's? Could you drop a differnt motor in ...
  1. #16
    1990CaddyBrougham's Avatar
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    Re: 6.0 368 pros and cons

    So a bigger motor is a direct fit in?

    How about the 4100's? Could you drop a differnt motor in one of them witho no problem?

  2. #17
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    Re: 6.0 368 pros and cons

    Quote Originally Posted by Benzilla
    How much will draining the cat do for power? also, how did the modified '68 472 intake manifold help?

    sorry for the dumb questions, but I'm just getting into engine modding.
    Draining the cat did ALOT. My exhuast had a rotten egg smell.... I pryed the plug off and drained all the beads... drove it around for a long time like that (she was loud) finally got a new plug in there... no more smelly exhaust, and you could feel more power.

    the modified '68 472 intake manifold REALLY helped too.... it really flowed alot better and the power increase was abundent..... At the time of the accident, my 425 was still mostly stock, and I had alot more plans for it... but, for where it was, the thing hauled.... any speed it would put you in the seat... including 70mph.... downshift to 2nd at 70 and open the secondaires, and you could just feel the car accelerate fastly.... I gotta say she was a quick car for remaining mostly stock despite a few bolt on tricks.

  3. #18
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    Re: 6.0 368 pros and cons

    Quote Originally Posted by 1990CaddyBrougham
    So a bigger motor is a direct fit in?

    How about the 4100's? Could you drop a differnt motor in one of them witho no problem?
    the 368/425/472/500 are all the same family, (mostly) everything bolts right up.... a 500 would have been nearly a direct swap in my '79... swap the 425 pullies, oil pain and oil pump over and we were good to go.

    the HT4100.... dosn't share much with any other engine at the time... so there is no direct swap for that.... its one of the more difficult engines to swap with for a few reasons too. But on the whole, it isn't all that bad and a 500, 425 or even a 350 is you wanted a SBC could be swapped in realitively easy.

    Realitive is a loose term.... the space is there, and most the parts to get it to fit can be had for cheap.... then its just a matter of making it all work.

  4. #19
    The Ape Man's Avatar
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    Re: 6.0 368 pros and cons

    The 425 isn't going to be much cheaper to operate than a 500 if used in the same chassis. A good 500 driven conservatively will get pretty much the same fuel economy as a 425. If you pound it the story changes. The bottom line is vehicle weight, gearing and aerodynamics. You cannot obtain highway mileage with a '77-79 RWD Cadillac in excess of about 21 MPG without changing one or more of these. I've owned several cars over the years that started with 425s and landed up with 500s. Each rides better due to the additional weight of the 500. It's more than 40 Lbs difference. I have not weighed any but I'd guess it to be more like 100-125 Lbs difference. GM put their engines on a diet during the 425 years. An interesting swap would be a drivetrain from a 96 or so FWB into a 10% lighter HT-4100 powered RWD Fleetwood. That would probably reach the limits for fuel economy.
    500 C.I. equipped RWD vehicles used a Cadillac rear axle that was different than corporate axles. The gear ratios were something like 2.93:1 or optional 3.15:1 .

  5. #20
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    Re: 6.0 368 pros and cons

    For the largest pre-war engines, check here: http://en.wikipedia.org/wiki/List_of...e_superlatives
    Go to the very bottom of the page. Largest is a 21.5L 4-cylinder!

    Sadly, even the 500 has been surpassed recently. By 1%... 2003 Viper with 505ci.

    anyways, back to the thread...

    A 500ci motor will make more power and torque than a 425 given equal emissions equipment and exhaust. 75ci of extra fuel and air being pulled in each intake stroke will make a difference. It's the same reason that people stroke their motors to go faster. Just because the factory only had 180hp out of a hugely de-tuned 500ci motor does not show the motors potential. By the same token, you could swap in any number of V6's made in the last 20 years that also make 180hp and then build that up, but it wouldn't get you the goal you are after.

    I might just have to snag a 425 out of the junkyard and weigh it... I actually re-checked my data and found that the 472/500 motors are more than 60# heavier than a 350 SBC, but if a 425 comes in light enough. hmmmm...

    I guess the direction of this thread shows the fate of the 368. Red-headed stepchild of the bunch I suppose. Only a product of the fuel economy requirements that started in the late '70's and probably never would have existed otherwise. Cadillac probably could have kept the 425 motor up with emissions regs for longer with better EFI systems, but that combined with fuel economy requirements forced Cadillac to make do with shrinking down their big block untill a new engine family could be designed.

    Logically, I suppose one would put in a 400ci Chevy smallblock before a 368. The 400 motor weighs less, costs less, has tremendous aftermarket support, etc... But, that wouldn't be a Caddy motor then, and that's the whole point here. I'm pretty sure you already have a bellybutton haha.
    I suppose if you just can't find anything larger than a 368 to replace the 4100, then go for it. Coming from the 4100, it will probably feel like a sports car anyways. 1.9L more - it's like you've got an extra engine under the hood! Of course, be prepared to long for even more power and the urge to swap in a larger Big Cad when you find one

  6. #21
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    Re: 6.0 368 pros and cons

    For the largest pre-war engines, check here: http://en.wikipedia.org/wiki/List_of...e_superlatives
    Go to the very bottom of the page. Largest is a 21.5L 4-cylinder!

    Sadly, even the 500 has been surpassed recently. By 1%... 2003 Viper with 505ci.
    Nope!

    I said "largest production V8 used in a car" and the 500 still holds that fame. None of those pre-war engines mentioned were production, they were all low-quantity hand built jobbers.... same witht he Viper... that is not a production car, or engine.... the 500 was.

    Shes still got the claim to fame .

  7. #22
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    Re: 6.0 368 pros and cons

    The internet can be a dicey place to get correct information. The 472/500 can be found in several different places weighing anywhere from 625# to 720#. Same charts show the sBC at 575#.
    Here's one:

    Scroll down when you get there.

    http://en.wikipedia.org/wiki/Cadillac_V8_engine#425

    The thing that worries me is they say that the 472 was heavier than the late 429. Anyone weigh a late 429???

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    Re: 6.0 368 pros and cons

    429 was more heavy then the 472.... thats one of the many "advancements" they didhad with the "modern" engine at the time..... dunno why it would say that...

  9. #24
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    Re: 6.0 368 pros and cons

    The 500 is the largest **V8** ever used in a regular production car. Lets not get into double digit cylinders and industrial or crate engines. The 500 was the largest V8 ever put into a passenger car that roled down an assembly line.

    As for direct swaps with the HT4100 look to Oldsmobile. The Olds 350 and 403 are pretty direct swaps. An Olds 455 can be made to fit, but it has a higher deck height than the 350 and 403 so you'll need to do some modifications. You just need the motor mounts, brackets, etc. from a Diesel Caddy (The GM Diesel of the early 80s was based on the Olds 350).

  10. #25
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    Re: 6.0 368 pros and cons

    this might be a little off topic but wouldn't a high compression 472 get better fuel mileage than a low comp 425? Just wondering because I recently replaced the 425 in my 77SDV for a 1969 472 with 950 heads and a 6500 block.

  11. #26
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    Re: 6.0 368 pros and cons

    Wow this thread grew a TON in the last 30 hours since I was last on here!

    Anyways, will a '77-'79 Sedan deVille run a quicker 1/4 mile than a '75-'76 deVille? I think so. I think it's like 17.5 or so for the 425 and like 18.1 for the 500.

  12. #27
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    Re: 6.0 368 pros and cons

    Quote Originally Posted by I~LUV~Caddys8792
    Wow this thread grew a TON in the last 30 hours since I was last on here!

    Anyways, will a '77-'79 Sedan deVille run a quicker 1/4 mile than a '75-'76 deVille? I think so. I think it's like 17.5 or so for the 425 and like 18.1 for the 500.
    yes.

  13. #28
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    Re: 6.0 368 pros and cons

    Having had a 78 Fleetwood Brougham and 75 Deville, both stock, they're both equally slow. I'd dropped the beads out of the cat on the 78 and after that it was noticibly faster.

  14. #29
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    Re: 6.0 368 pros and cons

    The '76 will win. It has a much better gear ratio for 1/4 mile times.

  15. #30
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    Re: 6.0 368 pros and cons

    Quote Originally Posted by I~LUV~Caddys8792
    Anyways, will a '77-'79 Sedan deVille run a quicker 1/4 mile than a '75-'76 deVille? I think so. I think it's like 17.5 or so for the 425 and like 18.1 for the 500.
    From: http://www.100megsfree4.com/cadillac/cad1970/cad77.htm (hope they don't screw up this link like cadillacowners.com did...) <- edit: yeah, they censored me. WTF? #$%^ pinkos...

    (1977 Cadillacs were) "an average of 950 pounds lighter than their massive predecessors"...

    The rule of thumb in drag racing is that for every 100# you drop, you should go 0.1 second faster. So, they drop 950# but at the same time lose 75ci and only go 0.6 seconds faster through the quarter, not 0.95 sec.

    Still too many variables to compare the two and draw many useful conclusions - you can't compare different engines in different chassis and draw any conclusions except that a stock '77 Caddy was faster than a stock '76 Caddy.

    Let's run a stock '77 against another '77 with a stock '76 500ci motor swapped in before drawing any conclusions. I know where I'm putting my money... But, hey, maybe we're wrong about this whole displacement thing and all the stroker kits and big engine swaps and etc out there are just a scam...

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