360 Advice Needed - Autocross / Street Engine Build

Kicker92 said
Thanks to all you guys for jumping in to help, this is exactly why I'm asking the questions at this stage.
It's seems that I have some mis-matches in this setup, if I understand correctly:

1.) DCR is generally too high for 91 pump gas: Baseline @ 8.8:1 , goal would be to reach under 8.2:1
Possible solutions with current bottom end:
- Increase cc's of cylinder heads (I think some CNC prepped edelbrock heads are 68cc's, drops DCR to 8.3:1)
- Increase head gasket thickness (0.054" gasket would drop it to 8.4:1, but quench height would become 0.049")
- Increase cam duration from 275 to 284 (only lowers to 8.7:1)
or a combination of the above???

2.) Gear ratio / high stall converter:
- Seems like 3.55 gears with a 2500 stall would be an ideal compromise here.
- Alternative might be to keep the 3.91's, but put in the stock 11" converter.
A bit slower off the line, but the gearing puts me at about 5600rpm at 110 mph, and backroad cruise of 2000rpm at 40mph

3.) Manifolds:
- I'd like to look of it being mostly factory, and the lack of headaches that seem to come with headers.
- That said, if this thing is going to die off after 4500-5000 rpm, or have heat issues from choking that off, I may need to change.
- Headers would need to be shorty style, any suggestions who makes a good pair for the a-bodies?

4.) Oiling issues?
- I have a windage tray, and a high volume pump.
- Other than that, the oiling system is stock and I haven't considered it much.
What did you end up doing to keep it picking up oil at the track?

Thanks,

Ryan

nm9stheham said
If the OP if gonna pull some cornering G's, THIS is good advice. IMHO, the OP should spend some time reading up on pan baffles, one way doors, etc.

Nice comprehensive post, blu. FWIW, the lower 500 RPM performance on this cam's advertised RPM range is not too surprising.... I find that most cam mfr's including Lunati and Comp, push the lower RPM limits down too far, so they look better on paper. Crane's RPM range numbers to be more conservative and more reliable.

That 91 octane sure is more of a problem than I expected. OP, what is the source of 94 octane out there?

And that may point to a milder ramp cam. Or the solid lifters; they will avoid the pump-up problem but then there may be increased lifter weight added to the valvetrain weight.

Yeah I was a little surprised about the 91 octane too. I have iron heads so that’s part of it, plus the open chambers, over the deck pistons etc don’t help with my quench. And the 3.55 gears don’t help either, recommended gears are 3.73 for that cam but I think even that may be optimistic, I think 3.91’s are more realistic. Heck even the manual transmission, I had to go to a double pumper with mechanical secondaries because everything is instant, I couldn’t bring in enough fuel fast enough with vacuum secondaries. And I run an A/F gauge for tuning, so I’m not guessing based on plugs.

The fast ramps on the Lunati I think are a little deceiving. I’m no engine guru though, seems like the DCR still only gives you a snapshot and the window is really small because of the fast ramps. Cranking pressure on my 340 is 175-180 psi.

For oiling I agree with autoxcuda, the milodon road race pan probably the best pan you’ll get off the shelf anyway. I run it, it has all the tricks with baffles and trap doors. I use it with a stock windage tray and a hv oil pump.

I have mixed feelings about the TTI shorties. I may have had expectations that were too high, but I switched back to my Doug’s D453’s a little more than half way through the install off the TTI’s. Ground clearance improvement was less than I expected, clearance issues were worse (no better than the Doug’s, just different). I have a write up in my build thread My "new" '74 Duster- or why I need a project like a hole in the head