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Thread: Anything new from the straight 8 hot rodders?

  1. #101
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    Ha! How very observant!! Right on!! Iy just so happens that the 74" harleys have the exact same bore as the 320 str8. The piston rings of any oversize will work and there are vastly more types and styles of rings for harleys than str8 buicks. So, then there's the piston problem. The rod could be made longer, which would force the rod ratio very high, there is such a thing as "too much of a good thing", so, thats out. I have found out that Egge Machine makes a very good piston, that can be made very much better with a little more effort, and can be made to fit harley rings. Properly preped, these pistons will handle nearly anything, and be lighter than a forging. Still the same desighn piston but we will never be able to get a short moderen piston into the 320 unless the deck is lowered. Alleycat

  2. #102
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    more power for #1950

    Thanks for your thoughts 39cent and alleycat!
    Gary (my compadre and builder of #1950) and I have been talking about your thoughts.
    The duration I gave was "advertised." The 0.050 duration is 222* Your explanation of the rod ratio effect was excellent and makes obvious why the blower makes such a difference and why the valve overlap is so critical. As our valve train is original with the exception of cadillac valves and BB valve springs, we're thinking seriously of going to a roller cam,lifters and rockers to get some more rpm. I'm concerned about finding a cam grinder that understands/ has experience with a straight 8 and the rod ratio we're talking here. Do you have a suggetion on who to use? Do you know the lifter bore? With all the racing we've done we haven't had the engine apart since 1981 ( now that I said that we're cursed!), so don't rember a lot of numbers to be looking for " off the shelf" matches.
    Yes it is street legal. Had it out last night and will again tonight. Lots of fun to merge onto the interstate heading for town, have the left lane running 80-85, ease out in front of them a bit and watch their eyes before backing off.
    The crank is original 010 under to clean it up. Balanced but not lightened so may be able to decrease some reciprocating mass there -- tho makes me a little nervous I might grind something I shouldn't and do more harm than good.
    The forged pistons are 3 ring and modern style short skirt with the wrist pin moved up for the longer rods. The deck was squared to the crank center, but not significantly shortened, but the lower end was relieved significantly for the billet rods.
    By cranking pressure do you mean a simple compression test number? The big time tuners are monitoring and data logging cylinders pressures which is the name of the game in my book. We plan on sensoring this engine with the usual (intake,exhaust,coolant temps etc) using a MegaSquirt to data log what we can. I'm not sure how they get cylinder pressures or whether that would be feasible in my price range and if anyone has info I would appreciate.
    Thanks for your input!
    Mike

  3. #103
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    320 power

    My thoughts on this. unless the factor of 'crankshaft whip' is answered the RPM,S will be limited. There isnt enough strength in most any engine to stop that.The succesful racing straight 8,s were designed to have the power taken from the center bearing area,[flywheel in the center] thus making it in affect 2 , 4cyl cranks. For pistons, 228 GMC 6 has the same piston height as the 320, they were used 'back in the day'. [by don montgomery] .090 over 228 pistons will give you around 356 cu. in.They have the same basic design as the buick, but it have larger pins. Another thought was to weld in a slight quench area in the head [fill the head]and use 1936/37 320 flattop pistons, [if available] keep the quench area tite.[030].That might give better combustion mix, and more torq below 5500 r,s. and also piston mfgs, might be more amendable about making forged flattop pistons.

  4. #104
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    320 power

    ohh I better add, the GMC pistons had much larger popup than the buick so it would,nt be good for supercharged engines. and the piston pins would havto be sleeved for buick rods.If you have the GMC pistons made, make em, 'flattop forged'.

  5. #105
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    Mike! You actually street drive it! What a gass! A Bonniville car on the freeway!! Eat a Lexus for lunch!! In light of that I think I would make the effort to retain street legality in redoing the exhaust system. Like I mentioned, you don't have to worry about tuned lenths or size to obtain a specific power range with a blower, just get it out in a reasonably non-restrictive means. I think I would do a "tri-Y" sort of thing dumping into two oval pipes at about the back of the engine, under the frame, around the corner and out right under the rear of the front fender. Have a cutout for the ''legal exhaust'' to hook to and a coupla lake pipe plug caps on it , and youre good to go. It would be a hoot!

    On the crank torsonial flex issue. The 320 crank is not exactly a lightweight crank, at 114 lbs this thing has rather a lot of meat in it. And, its good steel, it may not be 4130, since 4130 back then was rather like carbon fiber is today, but it is good stuff. Torsioial twisting comes from two actions: piston accleration and the masses restance to be acclerated, mass in motion/mass at rest physics stuff. A rod ratio of 1.9 is not bad, a 2.1 is even better. The higher the rod ratio the slower the piston accleration around tdc and bdc. A SBC 350 has a much lower ratio, the piston accleration is much higher, Ford 289 is even worse! These babys really whack into a crank! The 320 ain't even in the same boat! The main area of stress is, obviously, out on the crank arm. The solution to lowering some of this stress? Drill out the rod journals, a-la chevy! My 248 crank now weighs 62 lbs, down from the stock 80 lbs. I also ground and polished it, there's probably 2 lbs of junk hanging on it that can go ''by-by''. Even more could go if I can figure out how to drill the mains. Still worryed? Hang a fluiddamper on it.

    Compression test! Ya! Thats what I was looking for. More for my own knowledge. I'm somewhat of the notion that building as much cylinder pressure as possiable with as little dome on the piston as possiable is part of the key in making the str8 run. But I don't know where the happy zone exactly is. Sounds like you guys are going in the right direction in that reguard.

    I've been mulling around the idea of a roller cam as well. Str8's won't tollerate much duration, with the extra inches the 320 will take more but with the high rod ratio, there's a limit. A roller, with its much faster lift rates, makes a shorter cam perform like a cam that has 10-15 more degrees duration and the centerline can be advanced as well, and its not "cammie radical" to boot! There may not be enough meat on the cam to get a roller profile. There may be another way. Mopar has a .904 lifter. Comp Cams has come up with a profile that utilizes the little detail that a big lifter can take a lot more lift rate. Their MM series cam for mopars has a profile very nearly like a roller cam. Str8's have a lifter diamiter of 1''. Even better. This profile should work like a charm! There may again be not quite enough meat on the cam to get the profile and the lift. With a rocker ratio of 1.35 a bit low, get some rockers made with a ratio of 1.5 or 6 and the lift is back. All you need is about .500, the head won't hardly flow anything at greater lifts. A little more duration, about 228 at .050, will put the torque peak in at about 36-3800 with peak hp at around 5200, thing ought'a cook! Give comp a call, see what they think.Alleycat

  6. #106
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    Hey Alleycat, checkout the angle of these intake ports, this is something ive been thinking about, If only i could get my machinist son in law to bore them out. also how about changing the cam and making the exhaust ports, intakes, they sure would flow better. chuck hamann turned 132 in 10 secs with this straight 8!

    Photo Courtesy of The Chuck Hamann Collection

    oh oh the pic was removed! the site it was from deleted it.
    any how the intakes were angled up so there was better angle into the port
    (ABOVE 2 PHOTOS) Here is Chuck Hamann's flamed kandy-blue Straight-8 Buick powered altered. Chuck had to kustom-build almost everything to make this ol'Bewfurd romp. And, romp, it did. The center trophy is from the NHRA U.S. INDY National's, the Big Daddy of'em all. The end trophies are from NHRA West Central Division Points Championships.


    Photo Courtesy of The Chuck Hamann Collection



    (ABOVE) Here is Chuck and Gary Hamann's Straight-8 Buick powered RAINMAN altered roadster at Bakersfield, California in 1990. This car was running 10.00-sec @ 132 MPH times. So fine.
    Last edited by 39CENT; 02-07-2009 at 02:17 PM.

  7. #107
    39Cent:

    Do you have any more pics of the motor? Looks like injection and a very straight forward intake. A 320 or smaller?

    Thanks!

    Gary
    ------
    1950 Special Model 43 - "Yoda"
    1948 De Soto S11 - "Bobo"



  8. #108
    39Cent:

    Never mind, I think I found all there is on the web.

    Thanks!

    Gary
    ------
    1950 Special Model 43 - "Yoda"
    1948 De Soto S11 - "Bobo"



  9. #109
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    Hey 39cent! Your idea for reversing the exhaust for intake is a really good one. It never crossed my mind to do such a thing, I've heard of doing it on other engines, but it never seemed to do much in return for the effort. The str8 on the other hand looks like to me, to have exhaust ports that look to be much better intakes than exhaust with just a little reshaping and with the fairly large intake/exhaust inbalance, this is something that would maybe work very well. Sure would make a exhaust header a lot easyer to do! I think the reason Chuck kicked those injectors up at a angle , was to get a higher approch on the valve, since the higher a port can hit the valve , the better. The only problem is that the injectors have to turn the corner right at the bolt up flange which then puts the intake back to 90* approch to the valve and there is just not enough metal to raise the port, looks cool though!! alleycat

  10. #110
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    what would one have to do to swap intake valves for exhaust? would reversing rotation of the camshaft do this if the lobes are symetrical. maybe swap the existing chain drive to a gear drive to change rotation of the cam. wonder if the centerline of the crank and cam are the same as a 6cyl. chev gear drive. then you got the distributor and oil pump going backward. wonder what it would cost us to chip in and get some cams made in china or taiwan. There I go again rambling.

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