Hi all,
Just got the 427 started up and broken in last weekend, with great success but need help with a problem that I can't seem to track down.
Here are the specs on the engine before I go further
.060 427
Keith Black hypers 9 to 1 with heads i am running.
Hastings moly rings
781 heads, large valves performance springs (single with damper)
FT Solid Delta regrind to a Comp 270S 108LC.
RPM manifold
Holley 3310-1 VS just refreshed by me.
DUI HEI all in by 2800 (18+ initial 36 total) Vacuum advance 10* limiter plate
Headers, hooker
Here is my issue with the engine, it has a low speed miss that i cant seem to track down and what cyl its coming from. The miss is very pronounced, below 2000rpm after that it seems to clear up.
The engine was broken in with Lucas break in oil, 30 wt. napa gold filter. 2000 rpm for 20 or so min, no issues at that time except when i brought the engine down it had this same miss. Keep in mind i only have maybe an hour on this engine total, never even put it in gear.
I pulled both valve covers to verify the valve lash of .018 and all of them were near spot on so I moved on to compression. All cyl are within 10 lbs of eachother (150-160) I had a timing light on all plug wires and it will pulse steady on all cyl.
I put a vacuum gauge on it, full port, and here is what I found.
Engine warm or cold, idle at 850rpm i am seeing 16-17hg of vacuum but the gauge will fluctuate 1hg when the miss occurs up to 1500rpm, then it shows a rock steady 20hg but the miss is still there so something is going on. All plugs (Autolight 145) are soot black/dark brown.
Any ideas? I am this short of pulling the intake and resealing all of the ports just to eliminate a possible single under manifold leak but before that I wanted some other ideas because I can't seem to leave this alone until it's right
Just got the 427 started up and broken in last weekend, with great success but need help with a problem that I can't seem to track down.
Here are the specs on the engine before I go further
.060 427
Keith Black hypers 9 to 1 with heads i am running.
Hastings moly rings
781 heads, large valves performance springs (single with damper)
FT Solid Delta regrind to a Comp 270S 108LC.
RPM manifold
Holley 3310-1 VS just refreshed by me.
DUI HEI all in by 2800 (18+ initial 36 total) Vacuum advance 10* limiter plate
Headers, hooker
Here is my issue with the engine, it has a low speed miss that i cant seem to track down and what cyl its coming from. The miss is very pronounced, below 2000rpm after that it seems to clear up.
The engine was broken in with Lucas break in oil, 30 wt. napa gold filter. 2000 rpm for 20 or so min, no issues at that time except when i brought the engine down it had this same miss. Keep in mind i only have maybe an hour on this engine total, never even put it in gear.
I pulled both valve covers to verify the valve lash of .018 and all of them were near spot on so I moved on to compression. All cyl are within 10 lbs of eachother (150-160) I had a timing light on all plug wires and it will pulse steady on all cyl.
I put a vacuum gauge on it, full port, and here is what I found.
Engine warm or cold, idle at 850rpm i am seeing 16-17hg of vacuum but the gauge will fluctuate 1hg when the miss occurs up to 1500rpm, then it shows a rock steady 20hg but the miss is still there so something is going on. All plugs (Autolight 145) are soot black/dark brown.
Any ideas? I am this short of pulling the intake and resealing all of the ports just to eliminate a possible single under manifold leak but before that I wanted some other ideas because I can't seem to leave this alone until it's right
