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#1
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Mild 400 HP/TQ estimate
Hey all, I'm about to start assembling my 400 for my Formula. Here is my buildup:
#500557 (yes I know) 400 .030" over, decked .010" Stock (.020M .030R) 3.75" crank and reconditioned 6.625" rods TRW forged flat tops (6.70cc) 1971 96 heads- gasket match and smooth runners, no porting. They cc'd at 100cc. Right at 8:1SCR Edelbrock Performer- gasket match and separate coolant x-over 73 rebuilt 750 Q-jet tuned as per Cliff's book and advice Comp Cams XE256H 110LSA 212,218@.050 .453,.461 w/ Magnum 1.52 roller tips Melling roller timing set Performance Distributors DUI w/ custom advance curve and Livewires RARE HO/RA oversized D-port exhaust manifolds with 2.5" dual exhaust, no x- or h-pipe Any guesses on HP and torque? Granted it will be a daily driver, I'm not wanting a hot cam. My guess is about 320HP and 420lb/ft at the flywheel. Is that too optimistic or too modest? What do you guys think? Thanks
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73 Formula. 9.1:1 400 .030" over, TRW forged pistons, hand ported 6X-4s milled to 85cc, Ferrea 2.11/1.77, Crower 68404 springs, 276°/284° 228°/236° @.050 .474"/.474" 112 LSA, Performer RPM, Shaker Tuned Qjet, Hooker 1.75" headers. TH400, Hughes GM25 converter. 4.10 gear for now. 1st Drive: 12/30/16. *SOLD* 74 Trans Am 455 AT Buccaneer Red Last edited by 4mula73; 06-08-2013 at 09:29 PM. Reason: Wording |
#2
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My guess is about the same. 300 hp 390 torque
compression is a tad low, cam is small. both work OK together ,but not to the best efficiency as far as making power. Should be low octane friendly |
#3
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I think it will run similar to an 068 cammed motor
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73 Formula. 9.1:1 400 .030" over, TRW forged pistons, hand ported 6X-4s milled to 85cc, Ferrea 2.11/1.77, Crower 68404 springs, 276°/284° 228°/236° @.050 .474"/.474" 112 LSA, Performer RPM, Shaker Tuned Qjet, Hooker 1.75" headers. TH400, Hughes GM25 converter. 4.10 gear for now. 1st Drive: 12/30/16. *SOLD* 74 Trans Am 455 AT Buccaneer Red |
#4
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Desktop Dyno
Plugged your numbers into Desktop Dyno and got 331 peak HP @ 4500 and 450 peak tq. @ 3000. Nice low octane street cruiser!!! Very close to your guesstimate!!!
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#5
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About what is in the '81 TA now except I have a Summit 2801 cam-but 0.050 is close.6X-4s with some pocket work and 1.77 exhausts. Also has dual cats in the exhaust after the H pipe to clean up the idle HCs when it had to have a sniffer.
With a really tight factory convertor that bogged at the line with the 3.08s high 14s. It has a little looser 13" Continetal now but I have not taken it back to the track since I added it. I'd guess mid 14s in the 3900lber now maybe better.
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Skip Fix 1978 Trans Am original owner 10.99 @ 124 pump gas 455 E heads, NO Bird ever! 1981 Black SE Trans Am stockish 6X 400ci, turbo 301 on a stand 1965 GTO 4 barrel 3 speed project 2004 GTO Pulse Red stock motor computer tune 13.43@103.4 1964 Impala SS 409/470ci 600 HP stroker project 1979 Camaro IAII Edelbrock head 500" 695 HP 10.33@132 3595lbs |
#6
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Sounds like almost same recipe as a 1971 YS/96 400 - they rated about 300 hp via PMD.
Except you'll have better carb tune and better exhaust. If you have not already bought the cam - or can exchange it - you will never regret going to more along the #744 grind. Approx .425 lift intake / .465 exhaust ... with better LSA for low compression / pump gas. 068 range cams are just no fun at all really. With Rhoads lifters , the 744 will idle just like an 068 With optimum ignition and carb tune , will "feel" closer to 400 hp in the driver seat if you have at least a 3.23 rear. |
#7
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I am using a 3.23 to keep RPMs down because it has a TH400 and it will see highway miles. I already have the cam. I chose it because I wanted torque right off idle. Baron, I do see what you are saying however. Not a bad idea.
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73 Formula. 9.1:1 400 .030" over, TRW forged pistons, hand ported 6X-4s milled to 85cc, Ferrea 2.11/1.77, Crower 68404 springs, 276°/284° 228°/236° @.050 .474"/.474" 112 LSA, Performer RPM, Shaker Tuned Qjet, Hooker 1.75" headers. TH400, Hughes GM25 converter. 4.10 gear for now. 1st Drive: 12/30/16. *SOLD* 74 Trans Am 455 AT Buccaneer Red |
#8
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We did about a dozen 400 builds for pump gas daily drivers in the 80's and 90's .
Some i did start to finish , some just sold parts to and advised. More in the 9.0 - 9.50 CR range tho. We drove these cars daily - everywhere - everyday - in those days . The guys who went 068'ish were eating dust and debris. The difference from 068 to 744 is practically amazing ... to us simpler folks. 3.23 Auto A/C 2nd Gen Bird 400cid with that arrangement will roast tires from dead stop without power braking. Plenty of torque. Dangerous power for rookie'ish drivers . But they enjoyed the learning curve and loved their cars again . Going from 2.73-3.08 with around 200hp - to what we put in them - was a completely different car. Fun days back then . i just WANNA GO BACK Just trying to tell you ... 068 is for trailer queens / show-shine cars. No sin , just less fun . |
#9
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Quote:
73 lemans 2.93 posi th400 mild shift kit stock stall 400 stock bottom end...1970 #13 heads at 75cc..compression approx 9.6:1 stock 73 4bbl intake, qjet calibrated and points dist curved. would a 744 cam or the summit 2801 give me the low end and midrange torque to smoke some tire? or would another cam be better suited? oh and btw..are these cams run with 1.5 or 1.65 rocker arms? thanks!! Last edited by zeebo; 06-09-2013 at 06:07 PM. |
#10
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Baron, my setup will still have some of tire roasting power though, right? This is my first car so I didn't want too much power. Won't it still be fun to a novice though?
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73 Formula. 9.1:1 400 .030" over, TRW forged pistons, hand ported 6X-4s milled to 85cc, Ferrea 2.11/1.77, Crower 68404 springs, 276°/284° 228°/236° @.050 .474"/.474" 112 LSA, Performer RPM, Shaker Tuned Qjet, Hooker 1.75" headers. TH400, Hughes GM25 converter. 4.10 gear for now. 1st Drive: 12/30/16. *SOLD* 74 Trans Am 455 AT Buccaneer Red Last edited by 4mula73; 06-09-2013 at 08:06 PM. |
#11
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Quote:
Unless ... you mean its your first car ever on the road ? (like 16 ?) In that case - may take a year or so before you're chomping for mo powah it would be more power than i would want to put a 16 yo in charge of right away. 068 range is even pushing it some. |
#12
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Yes I am 16 but no it isn't my "first" car. I drive a 94 Ranger 5spd to work everyday so I'm sure there will be a huge difference from what I'm used to. I don't plan on dogging or racing the car, I just want a little more than stock.
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73 Formula. 9.1:1 400 .030" over, TRW forged pistons, hand ported 6X-4s milled to 85cc, Ferrea 2.11/1.77, Crower 68404 springs, 276°/284° 228°/236° @.050 .474"/.474" 112 LSA, Performer RPM, Shaker Tuned Qjet, Hooker 1.75" headers. TH400, Hughes GM25 converter. 4.10 gear for now. 1st Drive: 12/30/16. *SOLD* 74 Trans Am 455 AT Buccaneer Red |
#13
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Quote:
Hope it helps some. |
#14
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At 16 years old I was thrashing my current 67' GTO with a 360hp 400/4 speed and wanting more. The first car I drove was a 300hp 350 in a 70 chevelle. That thing was a turd compared to my HO GTO. Just sayin....
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-1967 GTO HO Restomod. PKMM 433ci, SilverSport T56 Magnum 6spd, Moser 9", SC&C and a bunch of other pro touring goodies - Build Thread http://forums.maxperformanceinc.com/...615847&page=23 |
#15
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thanks Baron..yeah, im looking at the summit 2802 cam as well as the crane 283801 cam--and others in that range of duration/lift..im hoping to not over cam for my application and have good low end and midrange torque too..its not a race car, but id like a cam that gives me good street manners and has a fairly lopey idle.
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#16
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For characteristics that you want and describe. Rhoads will drop lift at idle/off idle by about 4-5% .425 becomes about .405 2.93 with tight 400 THM convertor - you want about .400 - .410 intake lift at idle/off idle at the most to meet your wishes. My opinion through hands on , anyway . |
#17
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His ol man would take us out on Sundays and let us drive it while he waited to turn 16. My friend quickly became the best driver of all of us - and he still is. None of the rest of us had a dad quite like that back then. Or a car like that either . i had a Vega GT I have an almost carbon copy of his old 67, now. |
#18
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#19
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#20
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You`re close on your estimate. It will run out of power early with that 256 seat timing on 400 cubes though. Well, at least the stock rods will have a chance.
Should be fun to 4200 rpm`s or so. We`ll see what happens later after you get used to it. Gotta say, not bad for 16 yrs. old. |
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