Experts and Know-it-alls welcome..
I'd like to put in a MILD cam.. To be honest, I'm not really going for hp, just want something a little lumpy..love the sound..! Recommendations on cam that I wouldn't have to change anything else to get the lumpyness... 318, 3spd manual w/ 3.23
Before you do anything
to your 1973 318 shortblock,
I highly recommend that you figure out what the final assembled compression ratio will be.
And figure out exactly which transmission you have and the ratios.
To run an A230 (ratios of 3.08-1.70-1.00), with a 3.23 rear gear, your engine will need a good amount of low-rpm and midrange torque. A lumpy cam will destroy the bottom end of an 8/1 engine.
Even the whiplash will start out very soft from idle, picking up as the Rs rise, and finally at about 2000 to 2200 when it starts acting normal.
Yes that Whiplash cam will work in an 8/1 engine; but it needs an automatic transmission with a 2000 or better stall. Which means that in that combo, the engine will never have to pull below 2000, and the Rs will spool up fast enough to cover the what little hole might be left.
But the manual trans does not have that option.
As a lo-po streeter, you will be spending a lot of time below 2000rpm. With 3.23s, and 26" tires, 2000 comes at 16 mph in first. but not until 28 in second/48 in third.
So on a typical drive around town, you might take First gear to 2800/ 22mph then shift into Second. The Rs will fall to 1550 and there you are stuck in la-la land until over 2000/28mph .
When merging onto a hiway, you soldier on, hitting 2800@40 mph, then shift into Third. The Rs fall to 1660 and there you are again in soft-zone. From there,it's a long way to 2000=48mph. Then the power will pick up on the way to 65=2700
Because of the hole caused by the lumpy Whiplash cam, you will tend to avoid that hole by reving the engine higher. To drop into Second at 2200, you would need to rev First out to 4000/31mph.
Think about it.
To run with that combo of Whiplash/3.23s/wide-ratio manual trans, your 318 needs a lotta cylinder pressure, and the only way to get it with that cam, is to pump up the static compression ratio. And then you may run into problems with too much pressure after say 2600/3000.
FABO has seen several guys complain about exactly this, even with automatics; and one automatic guy finally pulled it out.
If you have to run that cam, install an automatic, and run a 2600TC, at least. Hughes makes several stipulations; the first of which says;
WARNING: Our Whiplash cam is designed for basically stock, low compression engines. This cam will run on pump gas in a 318 with 8.6:1 or less compression and iron heads. If your compression is higher than this you may need to use a higher octane race fuel. Your vacuum should be in the 9"-11" range using this cam.
(Figures calculated using stock stroke & compression at 750' altitude.)
Note-1; WIKI says you are closer to 480ft elevation.
Note-2; pay very careful attention to how Hughes has worded this warning. They go straight to race gas after 8.6
click on the link;
Hughes Engines
