RE: [Chrysler300] 300H performance

I would go back to stock.. ”good ideas” from any one “expert” individual about cams are seldom that. Chrysler knows more. Knew more…by far. It is already optimized, unless you want 4 mpg and no idle, to gain 1 second in quarter? Your point about carbs running fuel curves someplace other than designed is right on..also due to alcohol.

Increasing overlap of cam impacts ram tuning alignment RPM range with cam some, (If you have rams? I am mainly F guy, ex J guy) but then might you end up with two tunings, or RPM ranges?? ? The ram RPM is set / fixed by geometric length, the cam RPM by overlap and dwell. Not to be messed with, unless in tandem? But it works ok, long ram with a hotter cam, particularly higher lift comp cam, just not optimal. Unknown? See how J and K rams changed, to short rams, with hotter cam? Non ram quads are a lot easier, it would seem; mostly cam is in control then… Borrow wide range O2 sensor, check mixture is right. ‘top pro” carb builders can screw up—was there a discussion about alcohol? ..Is MPG about right? 11-12 or so ? Rebuilt with alcohol in mind?

There are hundreds , literally, of 300F and G running around with “high Compression” ; no need to back off over pinging if distributor curve and particularly amount of light throttle vacuum advance is set up/ limited -- right? Adjustable canister? Pinging while driving at high vacuum..? ==fix that, easily! Pull vacuum line for a start, so what , for now a little less MPG. . Pinging while accelerating I can no longer hear, but that means back off mechanical timing, vacuum disconnected for that test , but not much back off.. .Have to be sure what is causing pinging. Two entirely unrelated things in a way…or can be. Mechanical compression ratio on some new cars is approaching 12 ;1 , running on today’s high test, Not advocating that, but 10.5 ought to be ok , although given a choice maybe 9.75 good for street car? Those are small changes, hard to even measure right.

Check vacuum at idle, too. Various things can ruin that..

But following is root of problems, I think……

In Mass we have to deal with oxygenated fuel , and alcohol. In high test gas… Alcohol generates far less power, in a gas calibrated carb, ------it just likes / needs richer mixtures than gas.(physical fact) , across the whole RPM range--- If that alcohol fuel mix is in a gas calibrated carburetor, it will ping easier, run fussy, as lean is where you are, for sure, and lower total power.. But fixing it by rejetting carb stuff might get you 7 mpg. I have found empirically, if I keep my foot out of it, regular gas gives me 2-3 more MPG, as it generally is all gas, not power robbing , but compression liking alcohol.

On 300’s .., the carbs, are not designed for WOT fuel glow on alcohol, IMHO. = pings, unless richer, or you have real gasoline .

Alcohol thus is a VERY sad joke. You are getting less real gas, less distance traveled , for same price, Might as well be water , ---FI adjust for all this, tank by tank, via o2 sensor, carbs do not.

I had a lot of trouble, but also experience to share, on 67 dart slant six convert I drive everywhere ..after going nuts with 1 bbl carbs, 3 of them, due to popping back if you get on it , even with full accell pump shot, and low power, generally running poorly, this line of thought about alcohol led me to change main jet two numbers toward rich. (Holly system) ; 4 bbl Holley jets fit that, from Holley 4bbl kit.

??? what good is great (20) MPG, if car is a disaster to drive, was motivational thought—I’ll take 18 mpg, good running. . Dart set up was lean from Mopar in 67 looking for MPG, ----ON GAS!!! Unbelievable difference now, in daily use; MPG went up--21! Runs well right after start, instead of balking; . Runs perfectly on alcohol gas . BS over. Best thing I ever did. But have not gotten into 300 this way, few of us have, carter not so easy..I also found out there are two stages in some Holley 1bbl on power valve enrichment , three stages in other 1 bbl, they all fit onto this car ; vacuum diaphragm on holly puts a little blocker finger into main jet, makes jet smaller with high vacuum (raise cruise MPG) . Found poor tolerances on that , nylon thing, sticking, had worn loose on its shaft, trimmed it so it ran true inside the last carb, about 5 years ago, at time of jet change.. No more problems .

Analogous part on Carter is metering rod. Seems a bear to change calibration, (replace with different is only way? ) . Or, maybe not ..keep rod and open main jet rod is running in ; I think Holley numbers equate to .001, was an .002 change on dart Holley, if feeling playful . Hard to do that. Machinist with numbered drills? I have found that Edelbrock (carter) comes “rich”, performance AFB already opened up by Edelbrock, probably due to drivability problems with old calibration on today’s gas. I know that, from new Edelbrock/carter AFB on 273 swap into 78 Dodge truck. 9 MPG, but no popping back or drivability issues,--- I was hoping for 14 MPG after 11 mpg from gas hog 4bbl 360. No way. Alcohol again? Maybe areal good guy at Edelbrock knows all this, can get us new AFB metering rods (only) for alcohol gas? Or copy numbers off a new Edelbrock?

= Change your main carb to Edelbrock ,same size bores, but has alcohol high test calibration ? Cheap to try, relative to engine work? I bought “remanufactured” one, from them, cheaper. Looked new, think it is.

Hope that info helps you, Mike; yes go all stock, set up right. All this is information only; not advocating.

Love 300H, ---from HRM wins at 62 nationals with 400Hp one .They got into high 12’s!! 3 seconds at 110 MPH (over other , ~ 16 sec 300’’s”) is a mile! No need for 440,although that 413 car had one hell of a cam at end …over 290 / .450 as I recall.

Another fact is that our 300’s are slower today than many Toyotas. Evolution. May be perception to owner it is not fast, compared to daily 400 HP SUV! . But that is Ok. My stock 012 ram truck hemi shortbed amazes me. Far faster than any 300 I own, to 100 anyway.. I have to be careful not to burn out , even with the huge tires on it .

But makes me want to do something to uphold the 300F honor. 300F with 450” 392 is lurking in mind. With 10.0 , hemi tolerates more , and FAST EFI …. Have enough ,er, gas pains from Carter, rams, alcohol. Pinging etc. But my F runs pretty good. .

Could go with small Fast system, or even dual quad one they make, on your H, end carb issues for good. Make it look stock? I am surprised no one in club has tried that yet? Have they?

Best regards,

John Grady, PE

From: Chrysler300@xxxxxxxxxxxxxxx [mailto:Chrysler300@xxxxxxxxxxxxxxx] On Behalf Of Michael Moore mmoore8425@xxxxxxx [Chrysler300]
Sent: Monday, January 12, 2015 1:59 PM
To: Mike Moore
Cc: Listsaver 300 Club
Subject: [Chrysler300] 300H performance

I have not been happy with my 300H performance for along time, probably coinciding with the departure of good hi test gasoline.

To date, I have had both AFBs restored by a top shop, I have had the original distributor restored, I have checked the valve settings and I have timed the engine correctly after I installed a new damper. The engine is stock (except camshaft) with a .020 overbore and the compression is excellent although I did not record it. The engine was rebuilt around 50,000 miles ago by a top midwestern shop.

I have assumed my problems relate to the Barnes camshaft which the builder had custom ground to reduce the cr so the car could run on regular gasoline. It reduces cr by adding overlap. I have acquired a stock 300H camshaft which I have yet to install. I am doubtful that will resolve it, but the engine would then be back to stock 300H ex-factory configuration.

I was talking to some friends yesterday about the engine and my unhappiness, and their view was that my real problem was the compression ratio is so high. I have to run it somewhat retarded to keep it from pinging, and by the time I get the idle speed up nothing (carnbs, timing etc) is set where one would think it should be.

I have puzzled about how people can buy a crate 440 and get great performance without fuel injection. I have considered buying a crate engine and swapping it but retaining the original engine for posterity.

t was suggested I buy just new heads only to lower the cr, and that I buy a set of Edelbrock AFB clones matched to the heads and use my intake manifold along with an appropriate camshaft.

Has anyone done anything like this to a 300H"

Thanks, Mike Moore