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  1. #1
    Join Date
    Jan 2006
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    3

    Default How do I Increase hp on 425 nailhead?

    What are some simple things that can be done to increase the output of a 425 Nailhead (465 Wildcat) for a '66 Rivi?

  2. #2
    Join Date
    Apr 2003
    Location
    Southern Province, People's Republic of Californistan
    Posts
    931

    Default

    Quote Originally Posted by rhaltunen
    What are some simple things that can be done to increase the output of a 425 Nailhead (465 Wildcat) for a '66 Rivi?
    I suggest you talk to Nailheadina67 - he seems quite happy with his Nail Head.
    Erik in Sand Dog
    "From the beginning try fixing it the hard way - because you know damn well in the end you'll be fixing it the hard way..."

    Current Boat Load:
    '67 Riviera
    '69 Riviera
    '74 LeSabre Luxus Ragtop

  3. #3
    Join Date
    Mar 2002
    Location
    Monroe,Conn.
    Posts
    3,164

    Default

    I would suggest you talk to Tom Telesco(Telriv) and Bob Quigg. Tom has some rocker arms that increase hp over the stock ones. I'm sure Tom will tell you when he is online here. Bob Quigg has the fastest 1966 Nailhead in the country (401, Dual quads, 4 speed). He has owned this car since new.


    There are a lot of things you can do to get more power from a Nailhead. These guys will tell you how.

    The Nailhead is one great Buick engine.
    Carl Rychlik N.E. GS/GN Club
    GSCA #2090 BCA #23261 BPG #1064
    BPG Car Show Co- Director
    1970 Gran Sport Stage 1 Coupe-BCA Senior Gold Award-2005 ,BCA Senior Gold Preservation Award 2011, GS Nationals/Larry Miller Best Of Show Award 2011, & HEMMINGS MUSCLE MACHINE OF THE YEAR-2006, AACA Junior and Senior 2010
    1987 Grand National (original owner)
    2006 Chevrolet Silverado 2500HD Ex.Cab w/Duramax

  4. #4
    Join Date
    Jan 2004
    Location
    Lawrenceburg, Tn.
    Posts
    7,063

    Default hp increases

    Well i will start with the least expensive;
    Clean the engine compartment and the engine. Beleive it or not a engine will run better when it is clean. Plus it is much more pleasant to work on. Dirt attracts moisture which will pull voltage off the plugwires, dist cap, and spark plugs and the battery.
    Clean all the battery terminals and check and replace any bad battery cables and dist wires.
    Recurve the advance in the distributer. There is a lot of cheap horse power here. well worth the effort and money.
    make sure that the heat risers in the intake manifold are open and that the butterfly valve is working properly. A nailhead needs heat to the intake to vaporize the fuel. liquid fuel will not burn.
    install an electric fuel pump. runs cooler ,gives a cooler denser fuel /air charge.
    port match the intake manifold and the exaust manifolds.
    Get rid of the points and condenser in the distributer, also install a multi spark ign. system and a premium dist cap and rotor with brass terminals.
    You need a cool, dense fuel/air mixture with just enough heat in the manifold to vaporize the fuel completely. the cool mixture has more oxygen to better burn the fuel charge, thus more horse power.
    install low restriction exaust system.
    install a larger carb.
    fabricate a cold air duct to the carb. easy to do and Buick says this alone is worth 8% of the total horse power that the engine will put out. 340x.08=27.2 hp increase.
    install a 180 deg thermostat.
    use a electric fan instead of the mechanical one, be carefull here, you will have to have a top notch radiator and cooling system.
    run the vehicle as light as possible, a 100lb reduction is good for 1/10th of a second. 1/10th of a second at 85 mph is a long way.
    install "shorter" tires. has the effect of installing a slightly lower diff ratio.
    These are about all the "cheap" tricks that I know, any thing more requires stuff like cams,pistons,machine work ect. BTW the ORDER that the machine work is done on a engine will greatly affect the hp out put.
    First deck the block parallel to the center line of the crank, then bore the engine and the cyl holes will be a perfect 90 deg to the crank , eliminating friction = more horse power and will live longer.
    Doc "Widely unknown"

  5. #5
    Join Date
    Feb 2002
    Location
    Da 'Nawlins Bayous.....
    Posts
    5,064

    Wink Good start

    Great info doc. One ?, how/where do you connect a c.a.i. (cold air intake) in a '66 Riv? Anyone have pics?
    [/SIGPIC]
    Jason -friends call me (J)-POP

    B.P.G. #1500
    R.O.A. # 8427


    MY (nearly) DAILY DRIVER --'71 Rivvy Black and Gold.

    '85 Regal triple gold 40k mi.
    Love your country, fear your government, drink more beer
    I pledge allegiance, not blind obedience!!!!
    You can't trust a man who never curses

  6. #6
    Join Date
    Jun 2005
    Location
    berkley, mass.
    Posts
    2,914

    Default

    if you are interested in swapping out that fan i have some very good electric units. i have an older post in the for sale section. i am looking to get 35.00 + shipping for them. they measure 24"x17"x3.5". email me and let me know. i can send you a picture.

  7. #7
    Join Date
    Feb 2002
    Posts
    2,466

    Default

    ...put the stock air cleaner away and get an aftermarket one that will flow some air along with a quality gauze filter.

    Doc I would like to hear more about your thoughts on the elec. fuel pump. Which one to use, located where on car, line size, what pressure would you run to start with? I'm just about to take this project on so would appreciate your insite

  8. #8
    Join Date
    Jan 2004
    Location
    Lawrenceburg, Tn.
    Posts
    7,063

    Default fuel pumps

    Well, here goes,
    Street or strip, or both????? That is the question. I look at things from behind a lot of years of trial and error. Some times I have used the SWAG method. [scientific wild a** guess] Personally I favor a old style Carter electric fuel pump in the neighborhood of 5 to 7 psi mounted back at the tank, on the frame, with a filter, [big] pushing the gas up to the front. It has never failed me. I know if you are running nitrus ect that you can use more. But I am talking for the money vs performance. in a naturally asperated set up. I have run these for years. They are about $60 from Summit.
    Sure, I would go with a 3/8 fuel line. I ran a 950 cfm Holley with this pump at 6500 engine rpm and it kept up. no problem. Yes you can spend more and get a pump that is fancier and prettier but your nailhead wont know the difference. If I had the money I would go with the AN fuel lines for the reliability factor.
    As for the street or strip question, strip only calls for the higher pressure pump,but any more than 4to5 psi at the carb can result in upsetting the needle and seat assembly and causing flooding. So I have in the past installed a non restricting fuel pressure regulator just before the lines go into the carb and cut it down to about 3 psi. 5 to8 psi from the pump to the carb to ensure plenty of fuel supply and then cut to 3 to not upset the needles and seats.
    Now to the cold air intake, One can go from mild to wild, On my 65 Lark, I fabbed a air cleaner that looks stock but aint, by cutting the center out[the original was too small to work with the Holley 1050 cfm 3bbl carb] Then I welded in a center piece that would fit the holley. Next I made a duct that runs from the air cleaner body to a cut out that I made just to the left of the firewall vin plate. This duct is 61/2" x31/2" x the distance from the air cleaner to the firewall. Then I cut it in two 2'' from the firewall and made a boot of rubber to wrap around it so the engine can move while it is running creating a flexible ''joint'' that wont transfer noise to the body. When I get it finished,painted up ad the new decals on it I think that it will look ''factory''.
    There are kits available, Postons sells one. The hardest thing is figuring out where to get the cold air from. The windshield wiper chamber is about the best. Once, I simply took the air cleaner that came on the car, measured about 3 in back from the end of the snorkel, cut it off, drilled 2 holes in the bell of the snorkel for screws and cut a hole in the firewall to the ww chamber. Then i screwed the snorkel end to the firewall to cover the hole and joined the two together with heater duct hose. MADE A BIG DIFFERENCE in the way the car ran at the strip. The factory knew what they were doing when they came out with the stage 1 air cleaners. well worth the effort.
    In a 66 Riv it would probably be easiest to come from the radiator core support some where with about a 3to 4 '' hose and hook to the air cleaner snorkel or possibly, come from the sides of the inner fenders. not in the wheel well though , too much dust. Possibly in the upper part above the wheel well.
    I hope that these thoughts give you some of your own, Dont just do what I said , that may not be best for you and what you expect from your car. Just consider the possibilitys and proceed from there. God bless.
    Doc "Widely unknown"

  9. #9
    Join Date
    Aug 2003
    Location
    Houston
    Posts
    1,806

    Default

    Not "simple" but don't forget about the rear-end and maybe installing a higher stall on the high end of the S/P tranny.

    I also did the valvebody transplant as suggested by Mark DeConti in this thread .

    The Wildcat should hit the road at the end of the month. I'm curious to see the results.

    Rick
    1965 Wildcat Convertible
    W.O.T. GrandPooobah

  10. #10
    Join Date
    Feb 2002
    Location
    Da 'Nawlins Bayous.....
    Posts
    5,064

    Default

    Thanx Doc
    [/SIGPIC]
    Jason -friends call me (J)-POP

    B.P.G. #1500
    R.O.A. # 8427


    MY (nearly) DAILY DRIVER --'71 Rivvy Black and Gold.

    '85 Regal triple gold 40k mi.
    Love your country, fear your government, drink more beer
    I pledge allegiance, not blind obedience!!!!
    You can't trust a man who never curses

  11. #11
    Join Date
    Jan 2006
    Posts
    3

    Default Thanks

    Thanks for all of the advice. The motor is currently being rebuilt. The moment of truth will come in the Spring when all snow has melted.

  12. #12
    Join Date
    Jul 2005
    Location
    Orange County NY
    Posts
    869

    Default Re: fuel pumps

    Quote Originally Posted by doc View Post
    This duct is 61/2" x31/2" x the distance from the air cleaner to the firewall. Then I cut it in two 2'' from the firewall and made a boot of rubber to wrap around it so the engine can move while it is running creating a flexible ''joint'' that wont transfer noise to the body. When I get it finished,painted up ad the new decals on it I think that it will look ''factory''.
    Doc, can we see this? I'd like to see this. Even if just to "ooh" and "ahh" at it. Been 2+ yrs since this post, I'm curious?
    -Pete
    --1964 Buick Wildcat (401)
    ---The Only 2-Door '64 Registered in the State of New York
    (there are four 4-door 64's reg'd in NY)


  13. #13
    Join Date
    Jun 2003
    Location
    South Windsor, CT 06074
    Posts
    894

    Default Re: How do I Increase hp on 425 nailhead?

    How about swap in a 455?


  14. #14
    Join Date
    Jan 2004
    Location
    Lawrenceburg, Tn.
    Posts
    7,063

    Default Re: How do I Increase hp on 425 nailhead?

    Dont want to take a step backward
    Doc "Widely unknown"

 

 

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