318 Upgrade

[Spacegrass]

Is that the one that was for sale South Jersey? looks like a nice car

Thank you! This was in Amish country. 27k original miles on it, barn kept for most of its life and then maintained by a collector for the past 5-6.

 

[aaronk785]

It's free so try it and buy the headers.

 

[toolmanmike]

My 120,000 mile '71 Dart GT with the original 318 has an Edelbrock LD4B with a 1406 600 cfm carburetor. My exhaust consists of factory manifolds, FlowMaster 40s and 2 1/4" pipes.

Sounds like you might have a little cam in there. Sounds great though.

 

[aaronk785]

If i had the intake of I sure would consider a cam and lifter kit and new chain. Something like summits k-6900 cam kit only 122.99$.

 

[Spacegrass]

If i had the intake of I sure would consider a cam and lifter kit and new chain. Something like summits k-6900 cam kit only 122.99$.

I would consider a cam swap if it were easier to do! From what I understand it would require me to lift out my engine (I could be misinformed), and I don’t have the means for that yet.

 

[aaronk785]

No need to pull the engine. Should just have to pull the radiator. If you don't want to attemp this I fully understand. The other upgrades should be fine. The rear is probably a 2.76 so upgrades won't make as big of a difference.

 

[Spacegrass]

No need to pull the engine. Should just have to pull the radiator. If you don't want to attemp this I fully understand. The other upgrades should be fine. The rear is probably a 2.76 so upgrades won't make as big of a difference.

That’s really good to know about the radiator pull! In that case, it seems like a fun summer project - and more justification behind throwing that higher CFM carb in there

 

[318willrun]

That’s really good to know about the radiator pull! In that case, it seems like a fun summer project - and more justification behind throwing that higher CFM carb in there

I've swapped cams without pulling the motor no problem. Never tried it in a early A, but in your body style no problem.

 

[aaronk785]

If you go with cheap headers I would go with Hookers. They have thicker flanges and thicker tubing than the Hedman's and mine fit perfect with power steering in my 68 dart. They do hang low like all cheap headers.

 

[Mattax]

Everything is stock besides that K&N and the exhaust! My buddy has an Edelbrock 1411 that he’s trying to get me to stick on there, and he’s basically giving it to me so I’m considering it even though 750CFM is way too big.

Mpg isn’t a massive issue for me. Personally I could do for a lot more response on the highway, and that’s my primary issue. I’ll be doing a lot of long drives from Philadelphia to South Florida and it would be great to have something that can get me there fast and reliably.

I asked about the K&N because it looked like a 14" diameter and I wouldnt have thought an aftermarket air filter base plate would fit on a factory 2 bbl carb.
(The top filter can be hinderence because it can create turbulence.)

One thing to check before all that is whether your car has the OSAC. That really killed part throttle response and is easy to bypass.

Speed is not really an issue with a 2 bbl. Passing power will be better better with a 4 bbl. So if you want to try one, sure.
I agree, the larger the throttle bores, the more difficult it is to tune and respond well. I'm all for used carbs, but that one will be more difficult than a smaller one. Also the 750 is known for coming with a short booster which can result in wacky response.

One thing to be aware of is if the car is equiped with a idle stop solenoid. Take a look at the factory carb and/or shop manual.
This was part of the emissions package too. If it was there, it was there because the timing and fuel mix at idle put a lot of additional heat into the cylinders. The solenoid is the stop for the throttle position while running at idle. When the key off, the solenoid retracts further closing the throttle to prevent dieseling.
Deleting the solenoid (if its there) may then require a little modification of the distributor advance. Tuck that away for when the time comes.

 

[Mattax]

They do hang low like all cheap headers.

They will never survive around here.
We have some good roads and many more really rough ones.
Beat the hell out of the Headers by ed I had on the car - even when running 225-70 r14s
Ground clearance and lots of tire sidewall are vital for survival in what one friend dubbed Baja North. LOL

 

[Spacegrass]

I asked about the K&N because it looked like a 14" diameter and I wouldnt have thought an aftermarket air filter base plate would fit on a factory 2 bbl carb.
(The top filter can be hinderence because it can create turbulence.)

One thing to check before all that is whether your car has the OSAC. That really killed part throttle response and is easy to bypass.

Speed is not really an issue with a 2 bbl. Passing power will be better better with a 4 bbl. So if you want to try one, sure.
I agree, the larger the throttle bores, the more difficult it is to tune and respond well. I'm all for used carbs, but that one will be more difficult than a smaller one. Also the 750 is known for coming with a short booster which can result in wacky response.

One thing to be aware of is if the car is equiped with a idle stop solenoid. Take a look at the factory carb and/or shop manual.
This was part of the emissions package too. If it was there, it was there because the timing and fuel mix at idle put a lot of additional heat into the cylinders. The solenoid is the stop for the throttle position while running at idle. When the key off, the solenoid retracts further closing the throttle to prevent dieseling.
Deleting the solenoid (if its there) may then require a little modification of the distributor advance. Tuck that away for when the time comes.

Air cleaner fit just fine for me! Sat on nice and snug and screwed on tight. What do you mean by turbulence?

I’ll definitely check for OSAC and that idle stop solenoid. A few quick google searches haven’t pulled up anything about the car having either, but I don’t know for sure until I check for myself.

 

[aaronk785]

Yes I must admit I try to be very careful but it never fails I end up hitting them. Mine have the usual smashed tubes. Not to bad yet but over time I will have to replace them. This time going with dougs. Sick of dealing with it.

 

[Mattax]

Air cleaner fit just fine for me! Sat on nice and snug and screwed on tight. What do you mean by turbulence?

I’ll definitely check for OSAC and that idle stop solenoid. A few quick google searches haven’t pulled up anything about the car having either, but I don’t know for sure until I check for myself.

G**gle will never show you that stuff. At one time it might have. Those days are over.
duckduckgo is better.
A forum search is better.
IMO the best starting point for research is from Ma Mopar herself.
Engine compartment may have a vacuum diagram and the original tune up information sticker.
Owners manual will (usually) have some very basic info and some diagrams.
Most of the good info is in the factory service manual (FSM), Technical Service Bulletins (TSB), and Master Technicians Service Conference(MTSC). If you want explanations, that's the focus of the MTSC.

Owner's manual if not with the car AFAIK you will have to find an original.
Shop manuals are reproduced both in paper and digitally. A fair number have been scanned and uploaded to MYmopar.com and are (or were) available for free download as pdf.
Many MTSC books and films are at that site as well. (or were, I didn't see them the other day)
They are also at the Imperial Club's website as page scans in jpg.
Master Technician Service Conference - Chrysler's Training for Mechanics
The Imperialclub is posting them as information and education only, no ads, so doubt they would be asked to take them down.
Digitized Technical Service Bulletins along with a lot Dealership info can be found in the The 1970 Hamtramck Registry Library Page (1970 - 1974)

Here's a '73 OSAC valve that was posted by another member.

And here's the carb that was on his 318.

Chrysler sometimes called the vacuum port 'timed' becaue it goes to the distributor.
Except with an OSAC it goes to the OSAC valve first. Bypassing the OSAC valve bypass the delay. I normally discourage bypassing emissions stuff as it usually doesnt effect performance on a stock engine. This one is an exception. See MTSC #308 to see how Chrysler tried to head off complaints about it at the time it was implemented.
How it works is explained on page 11 of the 1973 Chrysler Clean Air System Reference, MTSC Service Repair Book (Session 302)

What the guy is pointing to in the photo above is a vent to the vapor capture system. Except his is capped. Since you're using an open air filter I don't think it matters. In fact if the filters in the charcoal cannister have deteriorated, capping will keep charcoal from migrating into the fuel bowl. You still will need the cannister for the fuel tank venting.

I don't see a solenoid stop on the opposite side.
I do see a electric assisted well type choke with external vacuum qualifier. Those work well.

 

[Mattax]

Air cleaner fit just fine for me! Sat on nice and snug and screwed on tight. What do you mean by turbulence?

Air flow can be smooth or turbulent.
If the air is moving fast enough, roughness along the surfaces can easily make the flow turbulent.

Consistant carburetor performance depends on consistant pressure at the vent and the air bleeds.
It also depends on veleocity through the booster for creating the low pressure point.

If the air is turbulent at the vent, air bleeds, or try to get through the booster, all bets are off.
With the filter top, many times its been found to create turbulance.
Take a look at a factory filter housing to see how the top and bottom were shaped to encourage smooth flow into the top of the carb.

 

[DartGTDan]

Sounds like you might have a little cam in there. Sounds great though.

No sir, completely stock internals with the exception of Cloyes double roller timing chain & gears.

 

[Spacegrass]

You have power steering, so headers get interesting. TTI and Doug's are said to clear. Doug's didn't clear my power steering coupler.

I traded in those SBC headers, got some Patriot headers and am having them put on at the shop. Passenger side was fine, but sure enough - that power steering coupler is an issue.

Will it just be a matter of removing it for installation? Or do you think I’m going to have to get a set of TTIs?

P.S. 750CFM carb works great, but buddy totally screwed up the throttle body assembly. Luckily the Dart Facebook group steered me towards the right parts and how to put it all together right.

 

[dano]

I traded in those SBC headers, got some Patriot headers and am having them put on at the shop. Passenger side was fine, but sure enough - that power steering coupler is an issue.

Will it just be a matter of removing it for installation? Or do you think I’m going to have to get a set of TTIs?

P.S. 750CFM carb works great, but buddy totally screwed up the throttle body assembly. Luckily the Dart Facebook group steered me towards the right parts and how to put it all together right.

Pulling the steering column is not uncommon for the install. In my case with Doug's headers, the stock coupler would no clear the rear tube. There are several ways to deal with that if it is an issue.

 

[lemondana]

Did the Dart Facebook group show you how to modify your kickdown linkage and throttle bracket, since no one else has mentioned it. It is the most important thing that must be done right now!

 

[mygasser]

re the header ground clearance issue, i folded up a 12"x3" skid plate and welded it to the k member going under the driver's header. of course it reduced clearance even more but was a sacrificial part that could be periodically replaced and saved the headers from damage. it worked for me.
neil.

 

[Spacegrass]

Did the Dart Facebook group show you how to modify your kickdown linkage and throttle bracket, since no one else has mentioned it. It is the most important thing that must be done right now!

Yes! I have the right adapter, springs and bolt, and have looked at the pictures enough to assemble it correctly in my sleep!