I seriously think between the lowish compression,...ton of overlap,...and possibly retarded cam there's just no cyl pressure ,...it doesn't even sound like much,...no pop to it
How's the fuel system ? ..I doubt the cam duration is holding it back hugger ..I ran a 270 270 610 108 cam in a 8.97 compression 464 engine and it still ran 10.16 132 ..at 3600 lbs...cam timing and fuel system would be my first 2 guesses ...try a compression test see if that eliminates the cam timing. I see you already suspect cam timing ..I really don't think those duration numbers are too crazy on a 494 .not optimal but should work better than your describing
It's not so such the duration,...I'm a bottom of the page kinda of guy myself but something is light years off,....fuel system Is bulletproof,...aeromotive in tank 340 pump,..regulated down to 8 psi via a dual stage regulator
My Erson hyd roller was ground 1 tooth off. Cam gear 1 tooth to left and crank gear at 2* retarded to get it to come in at 5 * advanced. View attachment 556974
1. Compression test 2. If the compression test shows uniform low pressure in all cylinders, look at lifter rise at TDC EXHAUST on Cyl 1 (or 6--whichever is easier.) If one lifter is well above the other, the cam is likely mis-timed. I'd expect them to be roughly equal on overlap. Depending on how fast the lifters bleed down, you may have to look at the lifter bodies directly, rather than seeing how the rocker arms are positioned.
Agree with Schurkey and BuickRat that the mechanical cam timing is probably off but need the compression data to narrow the possibilities, expecting all cylinders to be low. Unless there was a rag left in the manifold, kink bent in the fuel line, standard rotor put in the HEI or something else your helper helped you with.
Nope just an incorrectly ground and installed cam,...not doin a compression test,..it's coming out and getting parted,...time for a LS and enjoy the car
Hopefully it's a forced induction LS, or your just trading one torqueless wonder for another.. As I said last week on the phone... either weak spark, or cam timing.. I have seen guys accidentally assemble it a tooth off.. I have done it myself in the assembly room, just not paying close enough attention to what I am doing.. it's not hard to do, especially if your using the rollmaster chain set. I catch it right away when I am re-checking the cam timing, and is the reason why you never touch the timing chain, after you degree the cam during final assembly. And you always double check your work.. Sounds like a lot of work for a cam timing correction.. The 650+ HP that this thing should make is more than enough for any street car, I can't imagine being frustrated enough to want to spend thousands and thousands of dollars, and do all the work for a changeover. I thought you were looking to get it out of your garage... this plan is anything but.. Take a deep breath.. If your set on a cam change, slide in a solid roller cam, if you can't get a new one, I bet someone on the board has one sitting around... deep six the piece of crap Morel hyd roller lifters it probably has, then degree it properly, set the lash and wave it goodbye. That's a day's work for me, over the fenders... it should not take you much, if any longer. But this might be as easy as taking the timing cover off, and inspecting the marks.. If I had a nickle for every phone call I have received from someone having issues with that chain set, I would not have to go to work today. And as I said, even if you completely understand the chain set and procedure, and have done it dozens and dozens of times, it's still possible to make a mistake. Don't throw the baby out with the bathwater.. JW
Just reading Schurkey's response above.. that's the test we use on the dyno that I could not remember the other day.. Split overlap timing check.. Rotate the engine until both rockers on number one cylinder are at the same height, be aware of lifter bleed down as mentioned... The intake will be opening and the exhaust closing when your on the exhaust stroke. Stop when they are at the same height to your eye. Now look at the timing mark, it should be very near zero. One tooth on the timing chain is something like 17* off.. so if the chain is on wrong, or the cam is indexed really badly, it will be way off. 10 minute check with very minimal effort required. It would have to be off that far, to act like it does. We are not talking 4-8 degrees off, it's much farther than that I suspect. JW
It's pushed a head gasket now,...it's brother's not mine,...he wants to drive it to the beach at 80mph,...Start with one turn of the key,..and handle well,...so the car is goin a whole different direction now,.... After spending over 10k and waiting 3years for the engine,...and it do this,...he's over it,..doesn't want to look at it or drive it. Can't say I blame him and there isn't a 455 out there that will do what a LS will time after time in any weather not happening. It will get a 2.9 Whipple little later on. But just kicks I'll do the test here in a few min
Ight test complete,........it's setting 10° before 0,..used a straight edge to set on the rockers they were even within a fraction
Head gasket was from not letting the gasket set overnight and crush and retorque and or no heat cycle and retorque I'm sure,....
A new cam and its probably golden. Maybe someone may want it assembled camless instead a pile of parts. That Erson drove me crazy dialing it in.....
We gonna find out Monday,...I'm gonna pull it apart and see what's goin on,..if it gets stupid I got a few grinds here to choose from and it's goin in I gotta know what is goin on,...it's driving me crazy
Sounds like your bro needs to sell that car, and buy a camaro or mustang.. As to the last statement, I have a customer up in Alaska that has a pure street driven, pump gas, 615TQ/620HP 482, with EFI/DIS that might take issue with that. New tech is great when applied to vintage motors of substance.. and no glorified SBC will ever compete with that. JW
I hope you stick with a Buick and get it running hugger but if you decide to sell the heads let me know.
