I have a new Chevy HT502 big block crate engine that I've put in my '86 Chevy Dually. I originally bought a GM performance 19131359 manifold for the engine, and I have it currently installed and it runs like crap. I have Holley Sniper fuel injection and I have had it professionally tuned with the MSD distributor and 6AL ignition box and it still runs like crap. I believe my problem is this intake manifold. It's the manifold that comes on a HO502 engine from the factory. However, the HO502 has very large rectangle ports, its cylinder heads are part number 12562925, but my HT502 (HT stands for heavy truck) engine uses smaller round intake ports part number 12562917 cylinder heads. My best guess these are what's referred to as peanut port heads. But due to the fact this engine was never installed on a production vehicle, I have found it very hard to find what intake manifold will fit. The max RPM of the engine is 5200. I like something that idles well. Like I said earlier I have the Holley Sniper fuel injection installed so I need a square bore flange. I called and talked to Summit Racing and they suggested a Weiand 8019 intake manifold, but I wanted to check with you before I made any purchase. Thank you.
Kenny Sorrels
405 328 0881
Feel free to call text or email me anytime.