Guess my 273 hp

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Thanks this is 12th motor I have put in. Only the second motor ive fully gone through. I would buy a $100-200 318 and throw a cam and 4bbl at it then Rev to my hearts desire untill kaboom. I have only about $1700 into this motor. $1000 into intake setup. Weld up header kit is in the mail soon. Cant wait to feel the difference. One thing I have yet to do is some distributor work. Researching my setup it seems lots of guys like to setup dist with only 10deg of advance all in by 2000rpm. Not sure how to setup my dis to do this. I know the just of it but not how to get it to 10deg of movement.
 
If you're feeling really energetic, maybe you could read up on how to do a small amount of pocket-porting and unshrouding the valves, and smooth out any sharp edges in the combustion chamber......
 
I'm going to say 200-240. As was said the manifolds are horrid, the intake is too big.
 
I did some work to heads. Cleaned up casting. Gasket matched and smoothed edges under valve. Carbs seem well matched to setup. Plugs are good Color. Total cfm for Carbs is not 900cfm. There is not secondary squirters so its not loading up with to much fuel at higher rpm. I'm sure a dual plane intake would be nice but far less fun. Intake is one of the better ones for a street car. I'm sure its putting out more than 200-240hp. My build 318 I had was putting out more than that and this motor has a lot more go than the 318 did. Its all a guess really.
 
With a 400 HP intake and 250 HP exhaust my best guess is 50 HP less than you'd make with magnum manifolds and 75 HP less than with headers.
 
900CFM is great for a 273.

..If it spins to 11,500RPM and has 100% volumetric efficiency.
 
They are 273 heads with 1.88 int 1.5 exh. Heads have been gasket matched casting flaws smoothed bouls blended.
 
Dual carbs on a t-ram requier more cfm based on the design of the intake/plenum. A single carb of the Same cfm would be to much for Same motor because of intake design. So the two cfm totals arent all equal. Sure a single four would be enough. But if i have a small motor that needs hp because its to small to produce great torque. I would need more rpm.. A t-ram would be more optimal. I know my motor is not optimal n/a motor, but it sure is more fun opening 8barrels than the 4 it had.
 
ProStocker273 said:
I know my motor is not optimal n/a motor, but it sure is more fun opening 8barrels than the 4 it had.
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Oh, I bet! On a similar note, I've always found it interesting whenever I see car magazines compare different intakes and carb combos on a dyno. I remember, more than once, seeing a Victor intake making great power in a little lower RPM ranges it "officially" wasn't supposed to. Stranger things have happened.

Gotta get that thing on a dyno!
 
Your running 2.97's @ max hp is @ 5400rpm....If my logic is right. If you had 4.10's you would be shifting @ around 4600rpms. Like the rest have said to much intake. Maybe try a gear higher than 2.97 and bump up your max rpm to 6000rpm+. ...my .02
 
As soon as I can find a a body 8-3/4 ill have some steeper gears. They are hard to find in my area. I just switched to the 273 adjustible rockers, I think the stamp steel rockers was part of the reason power was dropping off at higher rpm. Pretty sure the manifolds are whats going to be holding it back now.
 
Shoot me your email address. I got some old 65 cyclone fender wells that I can take a bunch of pics of if your looking for a weld up design. I also have a set of Hooker race headers that I'm modifing for a 65 A too. Might be a good design start. The hard part s the #3-5 runners. They need ( at least one of them) to go out/up and back, then down as you well know.
 
ProStocker273 said:
Thanks this is 12th motor I have put in. Only the second motor ive fully gone through. I would buy a $100-200 318 and throw a cam and 4bbl at it then Rev to my hearts desire untill kaboom. I have only about $1700 into this motor. $1000 into intake setup. Weld up header kit is in the mail soon. Cant wait to feel the difference. One thing I have yet to do is some distributor work. Researching my setup it seems lots of guys like to setup dist with only 10 deg. of advance all in by 2000 rpm. Not sure how to setup my dis to do this. I know the just of it but not how to get it to 10 deg. of movement.
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Have some questions about distributor advance? You can use the search function and find quite a few very informative threads about the subject. Most small blocks idle with 12-20° initial, all in by at least 2000 rpm and total of 32-35°.
tmm
 
I'm just not sure how to lock out distributor so it has only ten degrees of mechanical advance. I know you can weld on slot to limit advance just not sure how to limit it to ten deg.
 
Exhaust manifolds are not limiting your RPM, I've never run headers and my 273 would pull past 6K anytime. Original AFB, Holley 600, and especially a TQ. I've run Duals with Turbo Mufflers and the straight thru Commando single exhaust. I'm sure it will make more power with headers but you don't need them to pull past 6K. I'd look elsewhere. Ignition, Carbs, Camshaft / Valvetrain?
 
The length of the slot determine the mechanical advance. Guessing how long 10 is is not the way. Dist machine or a good timing light and a lot of time. There is a number on the part that tells advance degrees on a om part. Rebuilds may not have the number. Limit outboard edge and run it with no vacuum advance to see where it stops. Then file some more if too little.
 
Also, a 6 pack on a 340 (1200 cfm or so) is really rated about 770 on a 340 as a 340 will never generate 1.5 in vacuum across all 6 bbl. Just too small a pump. Look it up in Vizard's caburetor book.
 
I'm not running any vacume advance. My ignition is Mopar orange box. Carbs are new and snappy. Also revved to same rpm with street master and a 1406. It doesn't sound like its floating the valves. Maybe my old tachometer is on the fritz.
 
I had the old stock SW tach in my 65 "S" and it would register up to 6K, I would bounce that needle very easily with the stock 500 CFM carb and manifolds. I dont think it was very accurate either, needle seemed heavy, slow to respond. I think it was more for looks myself positioned down by your left knee........And ditch that 6K orange box ECU. Borrow an MSD, Crane or Mallory and see if it helps.
 
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