I need some help. I have a 72 skylark with a 455 and Stage 2 street eliminator heads. I'm having problems with the car pinging under load. total timing is only at 24 degrees. It pings no matter what gas I'm running regular unleaded, supereme, with octane boost and race gas. Here is my combination. 1976 455 block. bored .30 over, 10.2-1 pistons TA 1611B and all oiling mods. 850 holley HP carburetor. 84 jets front and rear, (I also have a 1050 dominator I can try ) SP1 intake, TA Stage 2 Street eliminator heads, TA 1.6 roller rockers, TA 210S-HL solid camshaft .567/.565 - .248/.244, Double roller timing chain w/multiple keyways. set up per camshaft instructions. MSD distributor and box. the box is set for 24 degrees total timing at 2500 rpm. turbo 400 with coan 9" 4000 stall converter. 4.10 gears with a 285/60-15 tire. the other problem I have is the car seems to be down on power. It ran a 12.33 at 107 with a 1.43 60ft time. it pulls ok in first gear then falls off in 2nd and 3rd. any help would be greatly appreciated.
Well being only 24 degrees of timing it will be down on power. But too me this sounds like your running out of fuel. On my 11.0 combo I ran a 1000cfm 4150 when I tried to run below 82/90jets it fell over on top end. Do you have a power valve up front and not in the rear.......if so you need to have a 6 or 8 jet size spread to the rear. In fact I would try goin 88 up front and 94 in the rear if you have a power valve in the front and not in the rear. With more fuel you can put more timing in it
aeromotive 1000 pump and filter, -10 fuel line, -8 return, also have the aeromotive pump controller. fuel pressure set at 6.5 lbs.
That should be enough pump and line. I would like a little more pressure. 7.5ish or 8 personally. I assume the float level is up to proper level too. Unless your running your linkage 1:1, I wouldnt run s PV both front and rear. Did the carb come from holley this way??? What is your carb part number
1.43 short time is pretty stout,..it will be faster with the Dominator more than likely ..but like Ben said you need more jet I'd leave the 84 in front with a 6.5 PV then put a 94 in the back with a pv plug and see what happens,...the pv flows roughly 10#s so that would put you at 94 square at wot,..you have a sump or a baffled tank? All the pump and line in the world wont help if it cant get to and stay at the pickup,...I would also get the timing to 32° to start,...no reason why that combo should ping,...hot lash is in spec I assume? You have to set it a little tighter with aluminum heads cold
My car last fall went 6 72 in the 1/8 which is a upper 10.50/low 10.60 1/4, and I only had a 1.48 60 ft. We were s little over 100 mph in the 1/8 1.43 should get you low 6.50/upper 6.40s at some where near 105 in the 660 and lows 10.30/ upper 10.40 near 129mph in the 1320, if everything works right and pulls through I had a setup early on that 60ft 1.62ush time but the motor only ran went 12.0s at 111ish. Never could figure out why it had short times that should had been 11.60s. The motor never made that much power. Sure was fun running a car with a very similar et cause I would always be out in front right away. It really shouldnt of had those 60fts.
I'd like more information on exactly what MSD box and distributor are being used. It can't be pinging at 24* total timing, especially with aluminum heads and lower compression (definitely not 10.2:1)
I'd hope for a slipped balancer and then check the cam timing. Maybe you calculated the compression ratio incorrectly and its much higher than 11:1..
As Ben stated that is plenty of line and pump. Interested on the fuel tank info. Was the cam degreed to ensure accuracy? I'm interested what your actual SCR is? Assuming 4.342 bore, 3.9 stroke, 0 deck, 20cc piston top, 68cc heads, & .040 FelPros it would be 10.69:1. Do you know what rods and gaskets your using? What about deck height?
With 0 deck, compression could be as high as 11.1:1. And DCR approaching 8.5 with that cam at 106 ICL.
Very true, that DCR would be very high even for an aluminum headed 455. Hopefully we get some info on those unknowns, including the requested MSD info .
Something is clearly not adding up. 1.43 is indeed stout, but no way that is happening with 24 degrees of timing. I use the same cam, intake TA Stage 1 SE heads with a Qjet and full exhaust, 3.73’s, a Coan 258mm I think, and run 10.90’s in a heavy convertible. It would seem like you are running out of fuel, but who knows? Start with the timing. Maybe the balancer did indeed slip.
12.33 and 107 mathematically speaking are in line with each other,...a more typical 60ft for low 12's is a 1.63. Its certainly possible it jumped out there with a 1.4x and then laid over and never could recover but it would have been audibly struggling
