How much power loss/gain

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TimDart

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I have a mild 360 with 9.1 comp, XE262H comp cams set, edelbrock inlet, 600 holley v/s plus FBO ignition kit. The not so good stuff is 318 iron manifolds (yes, honestly) 2" bore twin pipe standard mufflers. Smogger heads with valve seat/valve recession.

I will be fitting TTI exhaust 2.5" plus (1968-70) hi-po 340 manifolds.
Heads will be from FBO and have 3 angle valve job etc plus some porting work in the bowl area.
How much power am i losing currently and how much do you reckon the new heads/manifolds/exhaust will be worth?
I'm hoping for enough of an improvement to feel it in the 'seat of the pants'!
 
man Locomotion that article is excellent! it really sold me on the tti's. i was kinda already sold, but that cemented it! :notworth:
 
Glad to help! I did a lot of research before getting them myself.
 
Thanks Guys, a pair of really useful articles. I was suprised just how little the increase in power was between 318 and 340 manifolds given how much the latter can cost ( i found my pair pretty cheap). any thoughts on how the new heas will perform? The curent heads are not good with unequal valve heights and wera to both valves and seats.
 
That's a rough question to try to answer. A lot depends on how bad your heads are now, and how nice a job FBO can do..(didnt know he did heads...) I'd think with average street headers, and a decent set of performance heads, you should see 300hp, and 350tq..give or take. The cam is fairly mild, so it may be higher torque..hard to say.
 
Thats apretty good guess, its the figure I had in mind when I put the motor together. The heads are being done by a guy Don at FBO trusts and they should be good.
I noticed that a lot of performance orientated 360 combos in the US tend to use 750 cfm carbs. I'm only using 600 which tends to be the case with many mild engine build ups here in the UK. Any thoughts on that?
 
sure..use it. Makes sense to me..All carbs need to be set to the engine anyway. The 600 will work well on a 360 that isnt supposed to rev to 7K.
 
TimDart, I've been using an old Carter AFB 600 carb on my warmed over 360 for the past 15 or more years, and plan on using it for maybe that many more years. :) I've run the engine up to the 6000 RPM range on many occassions and haven't really noticed any fuel starvation problems. If I tried holding it there for any length of time, it might starve out, but for just running up through the gears, no problems. I run a small electric fuel pump mounted just below the gas tank and then into the regular mechanical pump. Gas line is 3/8" from the tank to the carb. (Petrol tank/line?) :angel12:
 
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