Re: {Chrysler 300} Fuel injection on old cars

A number of Club members have asked about the jetting changes I made to my 300F (same carburetion as a 300G). I will attempt to answer this in the following, but keep in mind this is what worked for MY car, and not all cars are the same, ignition tuning, general engine health, etc.

Stock 300F/G jetting is:

Idle Jet: .035”

Primary Main Jet: .089”

Secondary Main Jet: .0595”

I ended up with:

Idle Jet: .0395

Primary Main Jet: .095”

Secondary Main Jet: .068”

First, this compensates for today’s fuel that requires 14% more volume to produce the same energy as the fuels of the 1950-60s. Second, my engine has been bored to 430 cu. in, 10.0-10.3 to 1 compression, and a camshaft with 218/224° duration and .462/.470” lift compared to stock camshaft with 210/210° duration and .430/.430” lift.

Based upon my experience and calculations, if you have a totally stock 300F/G, I would start with the following jetting:

Idle Jet: .038”

Primary Main Jet: .095”

Secondary Main Jet: .064”

These settings richen the Idle Jet by 15%, the Primary Main Jet by 15% and the Secondary Main Jet by 16%. My additional jet enlargements compensated for the engine internal improvements.

The change to the Idle Jets (this requires you to drill out the factory jets which are the small brass tubes underneath the primary venturi clusters) made by far the largest improvement in normal drivability. The car idles better with less open Idle Mixture Screws (1 ½ turn now down to ¾ turn). Off idle and pull away is amazing for the throttle response and smoothness. The larger Primary Main Jet is also apparent in how smooth the car now cruises at normal speeds. Also cold starts are smoother when the choke is operating.

I would also advise actually “synchronizing” the carburetors using an air flow meter (Uni-Syn). I made an adapter with a plastic soft drink cup that had an upper OD that matched the AFB air horn diameter, and then cut out the bottom of the cup to be able to fit the synchrometer into it. Then you can perfectly dial in the air balance of both carburetors.

Dyke Ridgley

On Friday, May 17, 2024 at 9:42:45 PM UTC-5 Henry Schleimer wrote:

I’m also curious about determining jetting. My first rebuild about 35 years ago was a warmed up 318 with a 600 Holley. After running it in I took it to a chassis dyno place for a tune up. (My copy of Petersen’s Complete Book of Plymouth Dodge Chrysler recommended chassis tuning!) It showed the Holley ran rich out of the box. Seems they all did back then as they were “Performance” carbs. The guy did a simple re-jet and took if from 12.5 AF ratio to 14 from memory. Car ran great for the next 10 years I owned it so well worth the time to test the car under load with actual instrumentation rather than guesswork or iteration. Doesn’t have to be like the scary YouTube videos you see today where they push an engine to 6000 rpm. >From memory he only took it to 4000 rpm to see what the carb was doing. I did get worried when smoke started pouring out the back though! The guy had a laugh! It was residual oil in the exhaust from my previously worn out engine being cooked off by the pipes turning red hot. With the car not actually moving but the engine at full throttle at 140 km/hr tyre speed there was no wind to keep the exhaust cool! After he showed me the rust flakes piled up in the ends of the pipes I decided it was time for a new exhaust system as well, ha!

Henry

From: chrysler-300-cl...@xxxxxxxxxxxxxxxx [mailto:chrysler-300-cl...@xxxxxxxxxxxxxxxx] On Behalf Of Jean-Yves Chouinard
Sent: Saturday, 18 May 2024 11:45 AM
To: Dyke Ridgley; Chrysler 300 Club International
Subject: Re: {Chrysler 300} Fuel injection on old cars

Hi.

Could you share some details about the rejetting you did on your 300F?

Was the car running too lean? How is it now? Runs richer?? What size jets did you use?

Thank you!

Jean-Yves Chouinard.

From: chrysler-300-cl...@xxxxxxxxxxxxxxxx <chrysler-300-cl...@xxxxxxxxxxxxxxxx> on behalf of Dyke Ridgley <ridgley...@xxxxxxxxx>
Sent: May 17, 2024 11:38 PM
To: Chrysler 300 Club International <chrysler-300-cl...@xxxxxxxxxxxxxxxx>
Subject: Re: {Chrysler 300} Fuel injection on old cars

I don't want to be a contrarian, as I think the modern fuel injection systems are amazing in self-learning capabilities, etc. However, Carter Jets are $5.25 each from Mike's and a good set of Jet Drills is not expensive. I can buy a lot of jets for the cost of a modern electronic injection system, fuel pump, etc. Also, when the electronics in an injection system or fuel pump fail on the road, you are not going to fix it there. You are getting a tow truck. I can't recall a carburetor problem that totally stranded me on the road. The timing of this thread is perfect, as just this afternoon I completed rejetting my 300F to compensate for modern fuel and a different camshaft. I am totally amazed at the result, what a rocket! Idles and starts perfectly hot or cold, and cruises so smoothly.

Dyke Ridgley

On Friday, May 17, 2024 at 5:55:04 PM UTC-5 jsnowosacki wrote:

I think that Edelbrock system is the one Herb was talking about.

Herb and his son Mike are both members and in the club roster

Herb is herbMcC...@xxxxxxxxxxxxx and Mike is my65...@xxxxxxx

Between them they have a bunch of letter cars and at least one Imperial.

On Fri, May 17, 2024 at 4:41 PM apozdol <apo...@xxxxxxxxxxx> wrote:

Edelbrock sells a underhood pump. Just route a return. No personal experience with this.

Sent from my T-Mobile 4G LTE Device

-------- Original message --------

From: John Nowosacki <jsnow...@xxxxxxxxx>

Date: 5/17/24 4:18 PM (GMT-06:00)

To: John Grady <j...@xxxxxxxxxxxxxxxxx>

Cc: James Douglas <j...@xxxxxxxxxx>, chrysler 300 club <chrysler-300-cl...@xxxxxxxxxxxxxxxx>

Subject: Re: {Chrysler 300} Fuel injection on old cars

The last two years at Carlisle Chrysler I spoke with Herb McCandless as he was touting what he considered to be an 'easy' and 'effective' EFI system that he and Mike put on a couple different early 60's Chrysler products. I think one was Herb's Imperial that he has put quite a few trouble-free miles on since the conversion.

He's a great guy, and I'm sure he'd happily supply the details of how it was done and what products were used.

On Fri, May 17, 2024 at 4:10 PM John Grady <j...@xxxxxxxxxxxxxxxxx> wrote:

Hi James ,

a few words ; i tried to do all that 5 years ago— I did actually . First you cannot “ weld” the tank as it is too thin you blow holes in the thin metal instantly , and it warps instantly . it is galvanized ,burns off in and out plus it is rippled with lines embossed in ( 60 F anyway) so you cannot add a flat plate etc etc . Trying to do that cost me two tanks destroyed , one new . And a month.

I wanted pickup and return in a little box at bottom as is common in race cars . I Over thought all this . Box prevents starvation of pump , the overspeed that results can hurt it

I did finally do it by rethinking it, using teflon washers and so called “ bulkhead fittings “ . I soldered the brass washers to the fitting on the one outside the tank . Nut inside

I bought a FiTech system , hot stuff at the time , Porsche pump outside , filters etc Two lines . RPM pickup , bung for O2 ( those punt too ,and very location sensitive)

Used the old suction pipe as a vent . Did not want return spraying around inside making gas vapor .

All along had late night misgivings about complexity , safety and failure modes . Any of this punts on road you are done for .

No one can help you . Tow . To where?

Then I started reading about fires with high pressure fuel , etc etc and a guy killed by fire at drag race when clutch explosion severed FI fuel line . Bad way to go .

I had mine inside frame at times most of way but still . Thought about steel pipe sleeves.I had run up firewall

like they show you to do. Don’t want to be toasted critter .

Time passed , years. —- maybe a month or two of effort had gone into all this and its details back then . Wiring complicated to slow pump depending on need otherwise screaming at full output . Poor info on all that , regulator or not etc etc After a while I felt just not ready for prime time on my car in general . OK on oem , And Holley is in this business now .

But i read one day in Hot Rod of a low dollar Ford 460 build ( offset grind con rod journals Chevy journals / rods etc .Got up over 500 cubic inch . ( I always liked that motor) .Aluminum heads. Point is 600 ho 600 ft lb . maybe 5k$ . That’s 225 hp more than ram car , with one simple carb that costs less than a rebuild of carbs.

But critical :— for $ reasons They used a Brawler carb ( low end holley) and remarked they were amazed with AF senders on each cylinder it was perfect A/F ratio across ALL operating ranges . (!!!) Out of box,they touched nothing ) .Did not have to . Air flow is air flow …. any motor , was my thought

They further remarked that carbs are extremely accurate now , order of magnitude better accuracy than our AFB , due to computer modeling of flows etc arising out of pollution control efforts . Add in it is calibrated for ethanol gas , which our 300 are not , so ours will run a bit lean . You may get there , ” Tuning” I doubt it . And I have a life to live , not stressed by fighting with old inaccurate carbs. —- That seem to end up rich to run at all .

So I did a 180 , removing all the FI stuff , who needs all these hassles and failure modes especially . And unfixable even by a holley engineer for weeks if it acts up . plus fire . Plus computer BS . And related intermittents.

No thanks . Good in a toyota as an engineered system .

Good thing to talk about , hard to decide . Ignore hype , think for yourself ….

Hope this helps ; your tank stays as it is . Engine too .

nice thought , right?

Spare carb in trunk if worried. Save 2-3 k and months of time …

jg

Sent from my iPhone

On May 16, 2024, at 6:43 PM, 'James Douglas' via Chrysler 300 Club International <chrysler-300-cl...@xxxxxxxxxxxxxxxx> wrote:

I was wondering the same thing about where is the fuel p[pick up…

I am going to buy a new tank for the ’64. I plan on drilling and welding a return bug into it. New Tank---no boom.

I also want to see if I can adapt a Walbro in tank pump and maintain the stock sender unit.

I can tell folks that I purchased a new repro sender for my ’47 DeSoto and the thing was junk. I wept through the plate as they just put a minimum of sealant and then riveted the two plates. I needed to drill it out and then make a gasket with sealant and then rivet it and then hammer the rivets flat. A PITA for a “new” sender.

James

From: chrysler-300-cl...@xxxxxxxxxxxxxxxx <chrysler-300-cl...@xxxxxxxxxxxxxxxx> On Behalf Of John Grady
Sent: Thursday, May 16, 2024 12:13
To: chrysler 300 club <chrysler-300-cl...@xxxxxxxxxxxxxxxx>
Subject: {Chrysler 300} Amazon.com MOTOR METER RACING Swing Arm Type Universal Fuel Level Sender Float 0-90 ohms Suitable for Depth 5-27 Adjustable

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<image001.jpg>

Hey, guys .. found this , it is a great thing ; it comes 0-90 ohms but you can flip it over to get 90-0 ( does not say that anywhere but i did it ) we are 90 ohms empty close to zero full ( 10 ohms I think ) we don’t care too much about F but sure care about E .
So I made a mistake started copying bends etc on stock unit . Not too swift of me; then realized that cannot work . So when all else fails , read the directions .
The way this works the arm always moves 90 degrees , so pivot has to be in middle of tank depth . so that is 1/2 full it moves up and down equally from there . Many oem have pivot up high and bent arm but then travel cannot be 90 degrees as At E float might then hang straight down ( !) which i did in error by putting pivot where oem was and tried bending arm . All wrong . read directions ( lookin at myself)

so pivot half way in tank easy , after flip over , then arm is just straight you cut it for total travel of arc up and down . They give you a nice chart for those lengths , just measure depth of tank where float will be
Really well made variable resistor, much better quality than stock , real springs pushing contact , not bent sheetmetal —and only 25$ . plus you can slide arm in and out get E perfect if you want to fuss around .
huge problem solved ! ( does not fix poorly calibrated gauges , but this end can be right) Will have to remount to mopar disc , that’s easy .
awwwright !
john g
Sent from my iPhone

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