I finally got my car together and have been able to drive it some. My problem is that the motor revs very slowly above 4,000 rpms. Last year it would spin out to 6k very easily. The only thing i've changed are cylinder heads.

My first guess was valves. I have a flat tappet hydrolic cam. I had the valves set very conservative at first (had them out quite a ways) but have now turned the nuts down 1/2 turn. Valve noise has increased with this. When I originally set the valves I turned them to zero lash plus another 1/2 turn.

I also replaced the fuel filter just in case. Didn't seem to help.

Plugs look very rich, which is odd, because i didn't change any carb settings since last year. I'm running 2.02 1.60 valves this year vs. 1.84 1.50 valves last year.

 

my first guess is you have TPI

 

No, i'm carb.

Did some more testing today and checked the plugs, they were bone white. I guess the dark rich color came from having them set at .035 vs .045 and from just tooling around in the car, not getting on it much.

An extremely lean condition would make for slower high rpm revs, correct?

So, it looks like the 600 cfm carb isn't going to cut it as it is. I'm not sure if i'll try and jet it richer, or step up to a 750.

 

Running leaner, from what I've noticed when it happened to me, makes the engine feel lazier... less responsive and less punchy than one running right or slightly rich.

What heads did you have before? What do you have now?

 

If you were running lean, I would expect it to spin up a bit faster than if it were fat, the down side being it would burn the crap out of your engine.

I suspect a timing advance issue.

 

I'm pretty positive the timing is good to go.

I was running a set of bone stock 416 heads, (stock valves and everything) I've changed over to a set of 882's with some mild port work and resized for 2.02 1.60 valves. Running undercut swirl polished valves.

 

i'd say your poor head choice led to it. 882 heads are horrible. you probably had more flow with the 416 305 heads i would think.

 

Ditto. Those heads suck. You have a lot less compression now too, which would mean you need more timing. Going from 58cc chambers to 76cc chambers and changing the compression that much will affect a few things. Timing being one of the things that should be compensated.

Honestly, you're better off slapping the old heads back on but putting 1.94 valves in them and cleaning them up a bit.

 

ooook gone over this before.

So please explain to me why my plugs are as white as can be? and these heads are not so crappy that they will rev like this. Enough circle track guys around here spin them to 7k+

I'm sorry, but there is no way in hell a bone stock, carbon filled 416 head with stock 198* whatever valves is going to flow that much worse than a decently worked 882 with new 2.02 1.60 valves.

Sorry i'm coming off so pissed here, but i just get tired of the "416 heads are ***" syndrome on this site.

Just had to get that out, i'm better now.

If I could I'd just delete this post now and be done with it.

 

Dont let them get you down like that man. But seriously, they are right. The 416 heads do flow more. The runners are a much better design, and with the bigger valves installed they will flow better than an 882. Plus you keep your compression ratio. The reason you see a lot of guys on the circle track running them is because of restrictions and rules.