77 camaro 250ci inline restoration

Discussion in 'Camaro Questions' started by rezajahanshahi, Sep 19, 2010.

  1. rezajahanshahi

    rezajahanshahi Member

    82
    0
    Dec 25, 2009
    iran
    Hi
    Im going to change the 350 head with 305 head to increase compression ratio .
    The combustion chamber on 350 head is 76cc
    Which casting number and 305 head spec will be good for my application ?
    Do I need to use double spring for valves ?
    How I can modify ports ?
    Pistons are 0.030 dish .
    Following camshaft , intake and carb will be install on the engine :

    http://www.summitracing.com/parts/edl-1411
    http://www.summitracing.com/parts/edl-7101
    http://www.summitracing.com/parts/edl-7102


    Please give me advise for 305 head choice .
     
  2. ls777z

    ls777z Veteran Member

    2,075
    0
    Feb 19, 2000
    Clay,NY
    I believe 305 heads are very thin castings which means they don't take being overheated very well. Not to mention the air flow which isn't made for performance applications. Have you checked into an aftermarket steel head with a smaller combustion chamber ? They used to be fairly inexpensive, flowed better than a stock head, completely assembled and ready to bolt on.
     
  3. rezajahanshahi

    rezajahanshahi Member

    82
    0
    Dec 25, 2009
    iran
    Thanks for the reply
    Unfortunately there is not a variety of cylinder head here in iran if I want to purchase after market cylinder head its going to very expensive .
    Including shipping and I have to pay 3000$:mad:
    305 heads are available here for 300$ so I prefer to go with 305 heads .
    Combustion chamber volume of 305 is around 58 cc so the compression will be around 10:01
    Exactly what I need .
    Also by machining ports I can improve the flow.
    I have heard this swap was really common old school.
    But the casting number is important so before I go any further I can calculate the compression .
    Looking forward for your good advice .
     
  4. rezajahanshahi

    rezajahanshahi Member

    82
    0
    Dec 25, 2009
    iran
    hi
    good news :
    holley double pumper 650 cfm on the way .
    next step 4.1:1 ring and pinion .
    recently i have checked my engine compression and it was 8.5 :1 for now its okey .
    i have three choices for ring and pinion :
    motive gear
    summit
    dorman
    which product line produces reliable and noise free ring and pinion ?
    many thanks
     
  5. SupplySgt

    SupplySgt Veteran Member Lifetime Gold Member

    1,371
    2
    Jun 20, 2009
    Finally back home!!!
    Just now read through your thread. Look forward to seeing more. My dad currently lives in the ME so I'm somewhat familiar with that region of the world. I'll have to ask him if he's seen any American classics where he lives.
     
  6. Rich Schmidt

    Rich Schmidt Veteran Member

    4,097
    10
    Mar 27, 2010
    Denville NJ
    The factory 8.5:1 compression ratio is really 7.8:1. Good luck.
     
  7. rezajahanshahi

    rezajahanshahi Member

    82
    0
    Dec 25, 2009
    iran
    hi
    thanks for the tip
    since the engine is 0.030 over bored and piston rings are oversized 0.40 and compressed to fit i think my reading is correct but i need to keep in mind may be some errors are possible .
     
  8. rezajahanshahi

    rezajahanshahi Member

    82
    0
    Dec 25, 2009
    iran
    Hi
    Sorry for my absence I was really busy doing some inspection offshore :bowtie:
    Holley 650 cfm carb already in place and the result was great :smokin:
    I have changed ring and pinion from 2.56 : 1 to 3.73 : 1 and it didn’t work because of the gear box ratio so I change it to 3.07 good acceleration and good top speed
    I have used the ring and pinion from a 1974 buik century auto trany whit good gears .
    Now im going to do some modifications on the 305 cylinder head :
    Port to 1.94
    Polish
    Upgrading the cooling water ports
    Also im going to put 1.6 ratio rocker arms and I need some advice to choose the correct rocker arm brand and material .
    Cam shaft already selected and it will have Advertised Duration 285/295, Lift .470/.470 and I hope the combination works well .
    One more thing that I need your advise :
    My mechanic told me when I ran holley carb I must change the stock fuel pump and use electric fuel pump,
    is it true ????
     
  9. ls777z

    ls777z Veteran Member

    2,075
    0
    Feb 19, 2000
    Clay,NY
    I recently asked a question about putting 1.6 rockers on my 84 Z that has the original 305. I was told that there would be a clearance issue with the push rods. As far as the fuel pump try it as is. If you run into a fuel starvation problem a high volume mechanical pump would probably be sufficient. Adding a Holley doesn't mean automatically that you need an electric pump.
     
  10. aria.tabarsi

    aria.tabarsi Veteran Member

    446
    0
    Jul 4, 2010
    Persian Land
    Reza Jahanshahi
    my best friend here
     

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