Large rpm drop

yellow rose said
I'd like to see some plugs. That would be a start.

I'm sticking with my observation that your cam is wrong. I'm betting it's on at least a 110 LSA and maybe even a 112. Doing that changes the opening and closing events on a lobe package that may be correct. You don't have the induction system to run cam timing with that LSA.

Again, I'm guessing because you haven't posted all the cam numbers yet.

I'm 100% all for your 11:1 compression ratio. I hope that's what you actually have, because if you do, and you are married to that cam, I'd put the cam back to straight up, or I may even retard the cam 2 degrees past the LSA to make the intake closing a bit later. With the CR that high, you won't lose a thing down low. In fact, you may gain some if you can get to 33-34 total.

Also, 180 is as hot as I'd want it to run. Any hotter and it makes it hard to control detonation and you pull timing to help with that and you kill power.

If you have exhaust heat in the intake manifold BLOCK IT OFF. There is no need to heat the fuel like that.

Mattax has posted some incredible links in another thread (maybe he can put them in this thread because some may not see it in a different thread) about fuel vaporization and combust tendencies. It's very very good reading.

I hope your CR is that high. I'm also a bit leery of using a claimed number for valve notch volume. I've never measure them where they weren't at least 2 CC's bigger than advertised.

It was a busy day at work and didn't have time to pull the cam lobe info. But it is on a 110 lsa with 4* advance ground in it. I'll look for the cam card and see if there's anything else I missed.

I do have a 180* thermostat, engine sees close to 200* in traffic on hot summer days sometimes. Magnum heads, dual-plane air-gap, no exhaust heat anything.

I'll get to pulling plugs tomorrow when I get to work on it, hopefully it won't be raining.

Lol you're pretty set on not liking my cam, not knowing anything about the car, usage, gearing. There might be a better cam for this engine in a 2000 lb racecar set up strictly for the strip, or a better cam for a truck used to tow that racecar. Or a highway geared land yacht. To each their own though. If you know what cam I need without knowing anything else other than my compression, which you don't believe supposedly, I'll be impressed. It may not be perfect, but my cam was specced by someone who's done it thousands of times for most of his professional career, knowing most of all there is to know and actually seeing , touching the car the engine is in, backed by years of r&d research. Again not saying it's perfect, but it's probably pretty good given the situation of it all I think.

As far as my initial issue, how much of a factor would engine compression, total timing, cam choice be at idle? It's not a very radical cam.