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  1. #1
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    Default 2.78 diff ratios, hi stalls and heads

    I have booked my 308 in to get rebuilt at a reputable builder here in Perth. Current plans are to build my existing original engine should it all be good once stripped down. It will be a pretty basic combo- block acid dipped, forged pistons 10.5:1 comp, balance the rotating mass, arp bolts throughout, new Holley 650 cfm and manifold and electronic ignition.

    When I spoke to the builder who is a helluva good bloke I originally said I wanted VN style heads. I am now thinking of just getting my red heads ported. I have read a lot of posts on these forums and as my Deville is to be a nice cruiser and only somewhere between 350 to 400 odd hp at the fly. Is this acheivable with the old style heads?

    Where I start running into mental trouble is diff ratio, histall cam and intake manifold choices. I have a 2.78 ratio in the ten bolt and as this is a build on a budget a nine inch is out of the equation. Trying to find a decent gear set such as a 3.08 or lower with LSD is something I am not so sure about as we are talking 30 to 40 year old parts. How can a fella be sure before he parts with the hard earned?

    Next quandery is can a hi stall be used to overcome a hi ratio diff gear? If this can be done than a lumpier cam could be a viable option and then I would opt for an Edelbrock Torker not a Performer manifold.

    Last but not least, what is a good electronic ignition set up that will offer good bang for the buck?

    I would welcome your thoughts on this fellas as I want to be certain in my head that I am spending the readies on the right sort of set up. As I said, my builder is a good bloke and approachable just interested in your thoughts.

    Sent from my SM-T715Y using Tapatalk

  2. #2
    Newbie 71QPE's Avatar
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    IMHO vn heads would make power alot easier, seeing you have to buy new cam/intake etc. although you would have to change headers as well. Not sure what emissions your vehicle has regarding egr?(no egr w/vn heads).
    With the diff im pretty sure if you want to change to 3.08 or taller from 2.78 you will need a new hemishere.


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  3. #3
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    Considering the Deville is a big cruiser, have you considered stroking it to 355?

    Yes it will cost a bit more, but if your planning on resizing the original rods and grinding the original 308 crank, maybe bite the bullet and through a stroker kit in it.

    The extra cubes will take a bigger cam and not be as grumpy as a 308 with the same size cam and have more bottom end Torque for those cruising duties.

    VN heads are easier to get more out of with little work, but if you only chasing a mild combo the red heads will do what your after (in the right hands) and you can keep the original Ď308 red motorí look.

  4. #4
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    Ignition, bang for bucks for a mild combo, Iíd use a Bosch HEI as used in Holden blue or black V8ís.

  5. #5
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    Quote Originally Posted by HXdeville View Post
    I have booked my 308 in to get rebuilt at a reputable builder here in Perth. Current plans are to build my existing original engine should it all be good once stripped down. It will be a pretty basic combo- block acid dipped, forged pistons 10.5:1 comp, balance the rotating mass, arp bolts throughout, new Holley 650 cfm and manifold and electronic ignition.

    When I spoke to the builder who is a helluva good bloke I originally said I wanted VN style heads. I am now thinking of just getting my red heads ported. I have read a lot of posts on these forums and as my Deville is to be a nice cruiser and only somewhere between 350 to 400 odd hp at the fly. Is this acheivable with the old style heads?

    Where I start running into mental trouble is diff ratio, histall cam and intake manifold choices. I have a 2.78 ratio in the ten bolt and as this is a build on a budget a nine inch is out of the equation. Trying to find a decent gear set such as a 3.08 or lower with LSD is something I am not so sure about as we are talking 30 to 40 year old parts. How can a fella be sure before he parts with the hard earned?

    Next quandery is can a hi stall be used to overcome a hi ratio diff gear? If this can be done than a lumpier cam could be a viable option and then I would opt for an Edelbrock Torker not a Performer manifold.

    Last but not least, what is a good electronic ignition set up that will offer good bang for the buck?

    I would welcome your thoughts on this fellas as I want to be certain in my head that I am spending the readies on the right sort of set up. As I said, my builder is a good bloke and approachable just interested in your thoughts.

    Sent from my SM-T715Y using Tapatalk
    308ci Heads @ B cast flow figures
    240 @ 50 hydraulic cam
    Dual plane
    650 spreadbore
    1 5/8 " try pipes
    3 speed auto
    Stall @ 3500
    2.78 diff
    Forget Hp target for a Streeter
    Enjoy

  6. #6
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    I was thinking the same as 46Crab, turn it into a Holden 350. A 350-400hp 308 is a pretty cranky engine, and won’t be a very comfortable cruiser with a TH400 and 2.78 rear end. Whereas a 350ci stroked 308 will do it far easier, less cam and will make better use of VN heads. As 46Crab says though be careful of emissions as a HX auto does have EGR and other cr@p on it that is more easily disguised with carby heads.
    You will need another LSD centre to run 3.08-3.55 gears in a Salisbury. Probably cheaper to buy a used 9” conversion.

  7. #7
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    10.5 comp cast pistons 236 242 small solid roller cam you could go hydraulic (no need to bush lifter bores) Wb heads my mate ported, torker manifold makes 300hp at the wheels . 4000 converter and 3.7.1 diff ration nice cruiser . Also had 4.11.1 and 3500 converter pain in the arse on the freeway. 4000 converter and 3.55.1 was ok but a bit of a slug. Standard ignition

    Bothe AED Bendigo and HPE do cnc porting for the early heads

  8. #8
    Do you ever leave? EH179's Avatar
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    350-400hp fwhp is certainly possible, but that highway diff is going to spoil your day!
    For a big cruiser, a stroker is a good option, especially if the 2.78 is staying.
    If you keep the red heads, they will need plenty of porting to feed the stroker.
    230 @ 050" hyd cam, either Edelbrock manifold would work... and a 3k stally.

  9. #9
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    Quote Originally Posted by tuf72 View Post
    10.5 comp cast pistons 236 242 small solid roller cam you could go hydraulic (no need to bush lifter bores) Wb heads my mate ported, torker manifold makes 300hp at the wheels . 4000 converter and 3.7.1 diff ration nice cruiser . Also had 4.11.1 and 3500 converter pain in the arse on the freeway. 4000 converter and 3.55.1 was ok but a bit of a slug. Standard ignition

    Bothe AED Bendigo and HPE do cnc porting for the early heads

    Depending on what you want I have a early head hpe top end for sale (heads, intake and a solid roller camshaft and crane roller lifters ) heads have been extensively ported and stripmaster intake has been portmatched ect... to suit the heads. Camshaft is suited to the heads , made 490fwhp with 317 cubes . Only reason I'm selling this top end is to fund a vn headed 383 that Pete at hpe is building
    No money has been spared with the heads and have receipts to match. Only thing it needs is roller rockers , I used the rockers for my vn heads. Has guide plates and 7/16" studs fitted
    Last edited by ryan350; 29-01-2018 at 11:36 PM. Reason: Info

  10. #10
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    Your getting some pretty good info here but what alot of people are leaving out is unless you want to burn your auto out you don't want your converter lock up speed greater than your cruising speed in top gear. If your doing 2500 RPM on the highway you want a converter that locks up around 2200 RPM. And no you can't go a bigger converter if you fit a massive trans cooler... If you want to launch hard choose a cam that starts making power 500 RPM before your converter locks up.. we're working backwards here but if your stuck on your diff that's it... I used to find 3.55:1 was a great ratio for my daily driver but now days I have 4.44:1 and a 0.7:1 overdrive...

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  11. #11
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    HXdeville search the thread Iíve done a screenshot of, Iím not sure on how to forward it. This may answer more questions...
    IMG_7260.jpg

  12. #12
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    Quote Originally Posted by 46Crab View Post
    HXdeville search the thread Iíve done a screenshot of, Iím not sure on how to forward it. This may answer more questions...
    IMG_7260.jpg
    You can bet TK will do an awesome job... But he's access to spare parts and what he can do with them wouldn't be considered normal...

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  13. #13
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    I had 2.78's in mine when the early head 355 went in, it wasn't that bad. If it was me and you wanted to keep the 2.78's for cruising, I'd def go 355. Won't cost that much more really. VN heads with a clean up will cost less that getting your's ported. 230@50 Hyd cam from someone like Camtech, TP or Harrop low rise dual plane, 2700-3000 stall with a good cooler. Will make 350-400 with plenty of torque with those tall gears.

  14. #14
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    Quote Originally Posted by 46Crab View Post
    HXdeville search the thread I’ve done a screenshot of, I’m not sure on how to forward it. This may answer more questions...
    IMG_7260.jpg
    TK has built two early headed 355's like that - both for a Statesman. Good budget, low maintenance 355. Works ok with 2.6 gears, better with 3.55 gears.

  15. #15
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    Quote Originally Posted by Bill355 View Post
    TK has built two early headed 355's like that - both for a Statesman. Good budget, low maintenance 355. Works ok with 2.6 gears, better with 3.55 gears.
    Bingo

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