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Tech / General EngineIs your car making a strange sound or won't start? Thinking of adding power with a new combination? Need other technical information or engine specific advice? Don't see another board for your problem? Post it here!
Couldn't even ring out 1hp per cube on an engine dyno. Times certainly have changed. Interesting that Vizard was the dyno man. Fun vintage read. Thanks for posting.
"Yet the big disappointment was that the engine only picked up 11 HP from the headers."
Not shocking to anyone who has tweaked stock exhaust manifolds. An LT1 with matched/ported iron exhaust is a match for most headers. Oval track crews have been aware of that for decades, since many classes require(d) stock exhausts. Of course, there are significant variations in "stock" exhaust manifolds. Mopar had some very nice cast iron "headers" for some years for that very reason.
"Yet the big disappointment was that the engine only picked up 11 HP from the headers."
Not shocking to anyone who has tweaked stock exhaust manifolds. An LT1 with matched/ported iron exhaust is a match for most headers. Oval track crews have been aware of that for decades, since many classes require(d) stock exhausts. Of course, there are significant variations in "stock" exhaust manifolds. Mopar had some very nice cast iron "headers" for some years for that very reason.
Very interesting. I'm not overly enjoying my header experience on my LG4, there's a set of L69 manifolds and y pipe in the junk yard. It'll cost me $100, but would return a stockish appearance and hopefully reduce engine bay temp. Gasket match and send?
Thank you sir. I have a lot of respect for David Vizard, and when the end of page 2 leaves me with the cliff hanger "What 305s do seem sen-sitive to...., well, I just had to see page 3!
It's an interesting article. David was his usual methodical self.
To me, the low C/R, and the smallish 256 cam are limiting factors. I don't know all of the 305 head casting #s, but I don't recall 185s offering any special advantage. His trick back cutting the valves is good, though not revolutionary. So good results from a mild effort.
It's an interesting article. David was his usual methodical self.
To me, the low C/R, and the smallish 256 cam are limiting factors. I don't know all of the 305 head casting #s, but I don't recall 185s offering any special advantage. His trick back cutting the valves is good, though not revolutionary. So good results from a mild effort.
Agreed. It holds water to the later Hot Rod LG4 build and the Super Chevy LG4 build as well. Both of those builds got higher flowing heads in the end and made 300+ HP. I'm keeping the 9.5:1 LG4 with the 416 heads (1.84/1.50) and adding an Edelbrock 2101 intake + RV cam (420/443 110 lsa). I would guess 225ish, but that's not the goal, the 700R4 will hold it, the Borg Warner 3.27:1 will deliver it and (hopefully) nothing will break including the bank.
I put a Summit K1103 cam, shorty headers, Edelbrock Performer intake and 650 DP on a stock flat tappet LG4 engine back in the 90s and it was a disappointment. Only pulled 14.8s and my stock auto LB9 91 Z28 pulled 14.7s They were both 2.73 geared Im sure and would have improved with steeper gears and a lil more stall but almost the same in power. Looking back Maybe the 214int 224 Dur cam was a lil much for that engine? Id say a set of 059 Vortecs or Trickflows built for 305s would really pep a 5.0 up though from what ive read.
09-15-2021, 07:53 PM
