It's been a while, been super busy at work. But that means more money for new parts.

I was able to convert my ignition/distributor over to Summit Racing's HEI this week and install a brand new Edelbrock 750 cfm carb. My driveability is awesome compared to what it used to be!! My previous carb was a Holley 600. Yes, the Holley is for sale if anyone near north Alabama is interested. Throttle response with the new carb is great and the engine runs much better. I plan on taking it back out on the road this weekend and probably going to switch it back to my daily driver next week.

I have my base timing set at 10 deg. The new distributor has 20 deg mechanical advance.

Previously, I really struggled to get past 4500rpm. Now, it will go all the way to 6000rpm if I push it.

While it's been down, I also put on some extra ceramic window tint I had laying around.



Edelbrock 1407

New look. Relay added to right side of brake booster.

Rear window 2% tint

Side window 20% tint

 

Being you did the carb and distributor at the same time I wonder what one really helped the most?
I think the 600 Holley was to big for the motor. Most run a 390 and no bigger than a 450.
I can tell you a Holley 2300 v2 in the 500 CFM, they rate the CFM of the v2 & v4 carbs differently, is too large for a 258 AMC six so it has to be to large for the 300.
A 2300 in the 350 CFM is a lot better.

Good to hear it is running good again
Dave ----

 

Thanks Dave, I was wondering about the 750 too,

 

The only thing I can think of is the primary side is a lot smaller than that of the Holley and why it has better throttle / power over the Holley.
Then you look at the vacuum secondaries I am thinking the new carb dose not open as soon as the Holley carb did and that will help too.

I also know that the Eldel. carb runs leaner than Holley's and will show less HP on the dynos.
Because of the "lean" side when people switch from a overly large, poorly tuned Holley to the Edel. they run better.

But now he can say he has a 750 CFM cab on his 300 six motor
Dave ----

 

i did drive it around the area for maybe 15 minutes with the new distributor before I swapped carbs. Performance increased wit the distributor. The carb just made it better. It's very possible that my Holley was out of tune. My a/f meter read mid 14s on it at idle.

 

I ordered the 750 because I read on some forum discussing 300 sixes that the air the six cylinder sucks in is divided by 6 instead of 8, taking bigger gulps per stroke. The guy said carb calculators are made for v8 engines, not inline engines. Anyways, I figured I'd try it and if it didn't work out, I could put the carb on my 390 FE motor in my Galaxie.

Edit: found source Jalopy Journal
https://www.jalopyjournal.com/forum/threads/ford-300-inline-carb-question.701443/#post-7804977

 

Ya that seems like a lot of carb, but it you got it to work, whos to say.

 

Ok when a bunch of parts are changed at the same time it is hard to tell what fixed it or what part is now bad?
What distributor did you go from the factory TFI or a DSII? I can see it being better if going from TFI to the HEI as the TFI had the timing locked.

As for the AFR meter reading 14 @ idle that is ok but you really need to see what it is at cruise and under load.
The carb has different circuits, idle / cruise, and you need to know what the ratio is for each, mostly the cruise.
If that is too rich or lean it can hurt the motor over time, lean pinging / cylinder washing with gas.
You change the cruise ratio with jet changes or with that carb I think needle rods / jets and maybe springs? I am not into the Edle carb. and why I am not sure.

I have never heard that
A motor is a motor and size should be the same.
But we also know that straight motors, 4/6/8/12, will run lean at the ends and rich in the center where the carb is.
That is why the longer the straight motor is it is better to run 2 smaller carbs as each hole now gets the proper AFR.

Also a smaller hole manifold will keep the air / fuel mixed better than a larger aftermarket one on some motors, mostly v8's is where you see this.
This because the mixture is moving fast in the smaller hole where the larger hole manifold the mixture is moving slower and the fuel can drop out of the air and pool on the manifold floor and dribble into the cylinders.
This then acts like it is running rich / choke stuck on but the choke checks out OK.
So this all has to be kept in mind when modding a motor. It is best to ask and go with what is known to work for what you want to use the motor for, cruiser / racer / etc.
Dave ----

 

Probably it's just as important to maintain an optimum AFR as you increase throttle as the rated total WOT through put in CFM. He's rarely going to have the accelerator floored except on a trial run. 6000 RPM is getting up there for a 300 6 farm truck.

 

My old distributor was the one with the wires on it. It was an off brand. That is some good information about the fuel dropping out. I also switched to a 4 hole carb spacer. The previous spacer was an open spacer.

I want to do a drive with the A/F meter hooked up to really see what it's doing. Maybe Sunday I'll have a chance to try it.

Here is a vid of the truck at idle.

You would be surprised how high I get the RPMs when I'm driving and merging in traffic. They have to know the old truck can still get it done. Lol.

 

I always think of the 300 as a low RPM stroker torquer engine. So I looked up redline for the 300 and couldn't find that answer. My stock tach for the 6.9l diesel has an orange line and a redline. Talk about a stroker torquer. 4,000 is pushing hard. The stock tach for the 300 has no redline on it. Goes to 6,000. I would say that 4 to 5000 is like the orange range and 5 to 6000 is red territory. Merging does have its requirements though and trying to merge on a highway where everyone is doing 10 mph over or more can be a challenge for an OBS Bullnose! You probably want to run around 3,000 and limit your forays into the 5 and 6000 range to half a minute or so.

 

Not sure I would want to spend much time over 4500 in a 300. There is a lot going on in that lump, and a lot of heavy weight parts swinging around!!

 

3000 RPM is about as high as I want to push mine for 2 reasons.
It really is not pulling much up near that RPM so no need to try going higher.
I am running the factory Carter v1 carb and log intake manifold that are not known for supporting high RPM.

Are you using a factory tach and did you install it or was it from the factory?
I ask because if you installed it IIRC there is something you need to do between if used on a 6 or v8 motor.
But I would not try running it up to 6000 too many times or you may put windows in that block and that is not good.
Dave ----

 

You gotta hate when the inside parts become outside parts...

 

Well, temps dropped low and I wasn't able to mess around with the a/f gauge over the weekend. Maybe this coming weekend I can get it done.

Uploaded a short video if me driving away from my buddies house.

I don't even let it stay at high RPM that long! Not sure what the recommended redline is. According to my cam specs my powerband is from 1500 to 4000 so it may just be making noise past that. I'm running a Elgin E-1178-P.

True!

I'm using an aftermarket tach. i verified that it matches with the timing shown on my timing light. I definitely don't want any windows popping up. Even though I do have a good spare motor in the yard and a good spare block. Would be alot of labor.
yep.