The problem with smogger teeners is the low compression. They were designed/engineered/built to do a specific job, and they do it pretty well. The problem comes when we expect results from it that comes from hi-compression 340 thinking.
With a stock 318 with its 240/248/112 cam and approximate 7.8 real Scr,and at 600ft elevation; the Wallace gives us a picture that looks like this
Static compression ratio of 7.8:1.
Effective stroke is 2.89 inches.
Your dynamic compression ratio is 6.93:1 .
Your dynamic cranking pressure is 132.22 PSI.
V/P (Volume to Pressure Index) is 110.............................................. 110
Read about VP here; V/P Index Calculation
VP paints a picture of the engines performance at the rpms we typically see in streeters., namely stall to 3000 or a bit more. 3000rpm with 3.55s comes to 25mph in first, and 43 in second. So when an engine has as little as 110VP, you know what that stock smogger feels like. And you certainly don't want any less low-rpm performance than that. Your first cheapest line against this is the rear gear, which you already took care of, to the tune of 3.55/2.76=
plus 28.6% increase.This increase can be directly applied to your available engine torque at stall to see the performance improvement.
Your next go-to should be the TC. Comparing the 2500 to the 1800 we see the engine spool up the power curve an additional 700 rpm. Now stock teeners make peak torque just after 2500 maybe as late as 2800, and there is a pretty good amount of torque there, in fact rivaling or even exceeding a stock 340.
You can directly compare the performance increase with a little math.
Say at 1800 your teener makes 160 ftlbs and at 2500 it makes 200. This would represent a 200/160=
plus 25% more torque. That's a really big deal.
Your total is now 28.6 plus 25=51.6%. Your combo will feel 51.6% more powerful at the start line.That makes a nice blast off.
Now lets go back to just the 3.55s and up cam it to 252*. Here's what your new VP looks like
Static compression ratio of 7.8:1.
Effective stroke is 2.82 inches.
Your dynamic compression ratio is 6.78:1 .
Your dynamic cranking pressure is 128.35 PSI.
V/P (Volume to Pressure Index) is 104.................................................. 104
Notice the loss of; 1 less 110/104 =5.77% performance through-out the range of stall (1800) to about 3000 rpm or a little higher now. Almost 6% loss of VP in the rpm range most of your driving is gonna be, namely up to 25mph in first and from 25 to 41 in second. The only cure for this is to bring the cylinder pressure up.
Here is your smogger at 9.2Scr (about the max you can run it at, with the factory heads) and the 252 cam;
Static compression ratio of 9.2:1.
Effective stroke is 2.82 inches.
Your dynamic compression ratio is 7.98:1 .
Your dynamic cranking pressure is 159.81 PSI.
V/P (Volume to Pressure Index) is 130 ..................................... 130
Wow! 130 is a really really big deal, being 130/110=plus 18% stronger through-out the rpm range from stall to maybe 3500. But the pressure will make the difference from there all the way to shift-rpm.This is how you cure the low rpm performance blues. In fact, you could probably leave the 1800TC in there, and not notice any softness, as compared to the oem cam with the 2500TC.
Ok but I get that not everybody wants to slam pistons in it and machine decks etc. to get to 9.2cr.
Another option since the intake is coming off, might be to pull the heads and cut the deck surfaces
Another option might be a fast-ramp solid flat-tappet cam to maintain the early intake closing spec but faster everywhere else and with more lift. Either or both of these will bring some pressure to the table..... but not to the level of pistons.
And finally, if you do opt for a typical 252*HFT cam and experience the softening of the take-off performance....... you can still band-aid it with a higher stall TC, so you don't notice it. The only downside to this is you don't get the fuel-efficiency that high-compression/low-stall brings to the table, that the 3.55s took away.
And I guess I should add that the 252 cam might not show as big an improvement as one might expect, cuz in your combo I did not read that she was getting headers ...... so I assume she will be wearing the teener logs.
If you go the modest FTH route I highly recommend to establish a performance barometer with the 4bbl and well-tuned teener, the factory cam, and the factory TC, perhaps a collection of timed zero to 50 runs. Then you can repeat the tests with the 252 cam; and again with the TC of your choice. This will leave no doubt in your mind s to whether or not the time and trouble was worth it. I use the G-tech Pro-SS, but a stopwatch works not bad in the hands of a helper, sitting in the backseat, watching the speedO over your shoulder. The G-tech can data-log and create horsepower graphs.
Ok but not to leave you hanging, here is the stock smogger with the stock cam and just a compression boost to 9.0
Static compression ratio of 9.0:1.
Effective stroke is 2.89 inches.
Your dynamic compression ratio is 7.97:1 .
Your dynamic cranking pressure is 159.55 PSI.
V/P (Volume to Pressure Index) is 133 ............................................................ 133VP
Wait! Where have we seen that before lol. Sometimes less is more.
This would give you more torque,more power at the rpms you normally drive at, and more fuel efficiency so more gas-money in your pocket. The downside is a slight LOSS of ET from say 4000 to 5000(the shiftrpm of the 252 cam); which with 3.55s will be from 57.5 to 72 mph in second gear (so in town,no big deal there); and from 34 to 42mph in first gear (still no big deal IF she's still spinning there,lol, and if not then,really it's) just 8 mph. The rest of the time that 9.0 is working hard for you, and saving you cash at the pump.
And if you have never had an SBM that makes 160psi, man you are in for a treat.
Look out!!,if you decide to up the compression you need to match it to the cam, cuz otherwise your results will vary, and it may get ugly if you get the pressure too high. The calculator is your friend; click the link below
Wallace Racing: Dynamic Compression Ratio Calculator
Happy HotRodding
For those that might want to know; I used 48*Ica for the factory 240/112 cam, and 52*Ica for the 252/110 cam, and 600ft for location elevation.
