Hello all, i'm looking for some help with getting my freshly built 400 running well.
Engine: '72 400 block, bored to 413, mild cam but more aggressive than stock. '69 GTO heads, Edelbrock 750, plugs gapped to .045, total timing set around 32 advance
It idles very well and revs in neutral just fine, but has very little power on the road, and falls on its face around 3k under load, backfires and makes a "chooching" sound (backfire out the carb?). I'm learning as I go with this project so I have very little experience with the fine tuning aspect. It almost feels as if the choke is not opening, but I'm sure that's not the issue.
I adjusted valve lash with the engine running, which helped a lot, but didn't completely resolve my issues ( one or two are still clacking on the driver side so Ill need to revisit that again). Before I did this, the spark plugs had some carbon build up (enough that they needed replacement for the engine to start, but didn't look terrible). When I pulled the plugs they were dripping with gas. I'm inclined to think I resolved this issue with the valve lash adjustment, but wanted to include it in case it's a symptom of something else.
Does anyone have any advice on what my issue might be? It FEELS like its leaning out, but it could also be running too rich, I don't have a good enough ear to tell the difference between timing and fuel issues. The engine has maybe an hour and a half of run time on it (cam break in, some idle while making adjustments, and a few trips up and down the road in an effort to begin seating the rings before my cylinder walls run out of abrasion).
I'll hopefully be getting the car to my engine builder this week to help me diagnose it, but I thought I'd make a post here to see if anyone thinks these sound like symptoms of a specific issue.
I've heard the edelbrocks can be fussy with too much fuel pressure, so i've installed an inline fuel regulator and set it to 4 psi, but have not fired it up since to see if any difference was made.
Thank you in advance for any help!