HomeForumsTechnical – GeneralExhaust1 3/4" pacemakers on a 304?

This topic contains 13 replies, has 6 voices, and was last updated by Profile photo of doz10 doz10 4 years, 1 month ago.

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  • #17570
    Profile photo of doz10
    doz10
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    Member since: February 9, 2016
    Posts: 125

    just wondering whether or not it’s worth fitting 1 3/4″ primary pacemakers on my 304, I’m currently running a 1 5/8″ set into dual 2.5″ pipes with twin cats merged into a single 3″ system through a hooker aerochamber muffler then a lukey rear resonator, it seams to be running sweet but I’m just wondering if it’s worth swapping to the larger primary set as I have them sitting in storage anyway, engine is nothing too wild just a 284 cam, roller rockers, ported heads and high flowed banana inlet manifold, planning to use a balanced 304 bottom end with higher compression, bigger cam and a decent manifold down the track

     

     

    #17585
    Profile photo of Immortality
    Immortality
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    Member since: August 31, 2015
    Posts: 532

    I’d say they would be overkill for the current combo, might make a little more top end if you’re lucky but loose low rpm torque.  A mate recently fitted the same headers on his mild 355 with almost identical exhaust as you and noticed the above.

    #17586
    Profile photo of Slow355
    Slow355
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    Member since: March 2, 2015
    Posts: 322

    Just gives it more of a thumpy sound compared to the standard ones and obvious power advantages if running cam etc. Got a mate with a set on a standard 304 and had a very thumpy idle.

    munch munch ls1s for lunch
    Best 1/4 mile 13.1@105mph 60ft-1.8sec Reaction time .8 sec 0/100-4.8sec

    #17598
    Profile photo of doz10
    doz10
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    Member since: February 9, 2016
    Posts: 125

    I might just wait till I swap to the balanced/crankier engine then, atleast that way I’ll already have the engine out for the swap and it’ll save me going through the struggle of removing the old ones and fitting the bigger set for no real gain, as I’m sure most people on here would know how painful it can be fitting extractors on the earlier commodores, it’s no fun at all

     

     

    • This reply was modified 4 years, 2 months ago by Profile photo of doz10 doz10.
    • This reply was modified 4 years, 2 months ago by Profile photo of doz10 doz10.
    #17714
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    Anonymous Member since: January 1, 1970
    Posts: 0

    Agree with the above. No real gain to be had on a mild 304. Didn’t stop me doing it twice though lol. Had plans both times though and they work brilliantly with a 355. Also the noise is satisfying  B-)

    #17734
    Profile photo of doz10
    doz10
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    Member since: February 9, 2016
    Posts: 125

    yeah they sounded sweet on the old Calais with twin 3″ system and vortech whine, the neighbors loved it

    #17735
    Profile photo of cava454
    cava454
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    Member since: February 20, 2015
    Posts: 2 361
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    If I had them I’d just put them on.

    #17736
    Profile photo of doz10
    doz10
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    Member since: February 9, 2016
    Posts: 125

    they’ll be going on when I get the other motor built, it’s got 1 5/8 pacemakers on it already so I’ll stick with them for now, don’t want to have to pull the engine out unless I have to

    #17738
    Profile photo of vs manta 218
    vs manta 218
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    Member since: March 2, 2015
    Posts: 796
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    Personally I would take it in now and get extractors fitted and mended to exhaust so it’s drive in and drive out

     

    other wise when you change motor and do it then when the extractors have different fitting to exhaust then you will be putting on trailer and fucking around doin that to get it to a exhaust shop

     

    to me paying $200 to get extractors fitted and done now so when you change motor it’s all direct bolt up trumps doin the whole trailer shit and getting to exhaust shop like that

    #17740
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    cava454
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    Member since: February 20, 2015
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    You don’t have to pull the motor to install them. It’s not hard.

    #17753
    Profile photo of doz10
    doz10
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    Member since: February 9, 2016
    Posts: 125

    No need to take it to someone for exhaust work, I’m a fitter and turner by trade and a fairly competent welder, I built the system in it from the extractors back all mandrel bends and tig welded, it saved me a fortune and it’s better than anything I could pay to get built in my area, I’m interested to know how to fit pacemakers without pulling the engine out though coz I had a shit of a time fitting the set on it now, I don’t doubt it could be done but I would like to know how coz it was probably one of the most painful jobs I’ve had to do on a car yet lol

    #17755
    Profile photo of Immortality
    Immortality
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    Member since: August 31, 2015
    Posts: 532

    Headers go in from underneath but you need to drop the steering rack.  Easiest done with the car on a hoist so there is plenty of room.

    #17756
    Profile photo of vs manta 218
    vs manta 218
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    Member since: March 2, 2015
    Posts: 796
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    1- car on stands or much more preferably a hoist

    2- undo 2 steering rack bolts and steering arm bolt and just pull it back and down 100mm

    3- not possitive on passenger side but may need to remove starter motor or may not but that side goes in and out easily

    4- drivers side stick the factory car jack between K frame and under where engine mount bolts on to block and take the weight

    5- undo bolt holding engine mount to K frame and jack up about 40mm

    6- drivers side is then easily removed and refitted

     

     

    • This reply was modified 4 years, 1 month ago by Profile photo of vs manta 218 vs manta 218.
    #17760
    Profile photo of doz10
    doz10
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    Member since: February 9, 2016
    Posts: 125

    I wish I knew that before I fitted the set I have on the old girl now, I did it when I had the engine out to do the rear oil seal, heads n cam and it was a total pain in the ass, I’ve saved that process for the next time I have to do a set, sounds like you fellas have done it a few times before, it would probably be a lot easier to do from underneath after reading the steps you listed thanks heaps for sharing that I might be fitting the bigger set sooner rather than later

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