IS it possible to get 450 hp and over 500lbs of torque out of a motor that is equipped with 1975 block bored .038 over 10 to 1 JE Pistons 1975 heads converted to stage 1 (no port work) crower cam .507 intake .525 exhaust performer intake holley 750 roller rockers headers and all the goods MSD 6al box, MSD coil, MSD Distributor If this did make that power what is some guesses that it would run at the track in a 65 skylark with 3.55 gears and slicks. thanks
Although you're not too specific about your cam, it sounds like a reasonable goal, although I'd definitely go for some porting on those heads! Make sure you get the 10:1 compression. Check your chamber volume and deck height. Milling the deck is the preferred way to increase compression, because it improves the "quench" area. (Smaller quench area [given safe piston clearence, of course!] increases combustion speed, reducing detonation.) If you get 450 at the crank, run an automatic, and get good traction, you should make mid 12's with no problem, unless the car is unusually heavy, or runs into other troubles... Just a rough guess from a guy running a heavy car on drag radials, without nearly your level of mods!
Hi Guys, Bryan....it may be possible but DO NOT use those '75 heads, they are 78cc open chamber heads and you will have NO quench what-so-ever!! You will require the best gas (more than just 93 pump) to keep it out of detonation with any kind of real throttle mashing.:grin: I would advise NOT putting ANY money into those '75 or '76 heads for that reason. Look for '74 or earlier. Go here...http://www.atlantabuick.com/CastingNumbers.htm and read this info concerning head numbers to look for and towards the bottom of the page you will find the "Best to the Worst" list of BBB heads. You will notice that if you plan on doing no porting then you will want to find a pair of the 400/430 "Big Port" heads. Those casting numbers are in bold and came from '67 and '68 400's and 430's not 455's. After that the '70 and '71 455 heads are next best desirable and so on till you get to the "bottom-of-the-barrel..'75&'76's! Also.....if you are serious about the performance you want then BBB's want....NEED a carb bigger than a 750...an 805cfm Q-Jet or a 850DP should be a starting point for you!:TU: There are MANY better choices for a BBB cam than that "cookie-cutter" Crower piece too. :Smarty: Take a look at what http://taperformance.com/camshaft.htm has to offer. Also take a look at Charlie Evans' list of camshafts from the various companies. http://chicagolandbuick.org/partners/Charlie Evans cam tables.htm . This is a VERY good compilation of Buick BB cams. BUT.....there are still more available that has not been added to that list yet!:Smarty: If you spend a little time here and do some research in past posts you will find LOTS of valuable info pertaining to the build-up to get you where you want to be no matter the HP....er....TQ:laugh: you require to get your car to whatever goals you have! You will literally have hours and hours of GOOD KNOWLEDGABLE reading contained on this board!:TU: Hope this helps....
well this motor has been together for nearly 9 months. I used all of the 75 parts. i did no work to the heads except polishing the bowls. We did take some off the block but only about .006 thousands. now the quench, why is a 78cc head require 93 octane or better gas. i don't understand the whole quench theory. also by the way, if i can make my 750 holly flow like a 850 it will be better than an 850. The reason why is the velocity is much greater and that is what you are shooting for. now if you can make an 850 flow over 900 than you have something, but then it would be too much carb for the motor. thanks for the help though
Hi Guys, Bryan....first of all I would like to say that my response was not meant to be "abrasive" if you took it that way, I'm sorry if you did. I'm not saying your '75 heads will not power your 455 but that they are by no means anywhere near the best choice, same for the camshaft and carb too. I'm just saying with a couple of simple changes in those regards it'll be like you have a different animal altogether! For an excellent description of the defenition of quench go to this thread... http://www.v8buick.com/showthread.php?s=&threadid=23088 "Erik from The Netherlands" did a fine job in his description of the "what and why" of it all. BBB's have comparably smaller volume intake ports that just about any other BB which causes them to have MUCH higher port velocities and for that reason they like BIG carbs! I've ran a 1050 Dominator daily, on the street before without a hitch other than noticably poor mileage, never a stubble, hestitation or anything that points to the carb being too big. :grin: Not true for a Buick Big Block and quite to the contrary if you re-read the above answer. Buick 455's love 950HP Holleys and 1000, yes 1000cfm, Thermoquads!! These will have every bit just as much throttle response as your 750 will as long as the carb is tuned correctly. Think of it this way....a 750 on a 455, especially one that is built for the 450+HP and above that you want, is like you going out for a jog but only allowed to breath thru a straw while doing so! This has been proven time and time again for many years among the Buick community. Just look around or ask to more knowledgable than I that frequent this board. I'm sure they will concur in like manner. NEVER take advice about carb'n a BBB from anyone who does not have first hand knowledge about what makes 'em work. A BBC 454 for instance has MUCH larger intake ports so the velocity that a BBB has is just not there. They NEED a smaller carb or they will fall flat on their face unless they add numerically higher gears to make the engine rev faster and get into an RPM band that will support the additional cfm. If you look at BBB low-lift flow numbers they are higher than a comparable BBC due to higher port velocities not to mention a BBC has little-to-no quench either with their HUGE 119cc chambers!:TU: Again...I'm not trying to be abrasive or anything just stating the facts about the engine I love!!!:Brow: Have a good one.....
i understand and i don't take it that way. as far as the carb goes i did hear that from a chevy guy, so maybe i should up the annie to a 850. Also as far as that cam goes, cams are usually ground by one or two companies, and the companies like ta, crower, crane and comp, buy a cam that they want ground. my cam is .507 intake at 234@.050 and .525 on exhaust with a 244@.050. all on a 108 lobe center. This is much like one of the TA cams. I know this cam is working well with the motor. the heads i know arn't the best and never clamied them to be! I used them because my car is mostly a street car. Now if i were to buy an 850 dp, would i expect to pick up, even with unported heads? Is it worth doing it if it is not a race car? Is the 750 Vacuum seconday holding me back? I need to know and i would like your advise! I do not take any offense to this if anything i find it quite informative and i appreciate your help termendously.:beer thanks
The short answer, yes. I run an 850 double pumper in my 72 with 73 stage 1 motor that is essentially stock except cam, headers, carb and intake. The engine will take all the 850 can suck in and probably more. A simple way to find out if you are under carbed is to put a vacuum gauge on the motor that you can read while driving. Do a WOT run and check to see if the engine is pulling any vacuum. At WOT it shouldn't pull any. If you are drawing vacuum you are under carbed. :Smarty:
