Stock Cylinder Head Flow Numbers Needed

[Mikes5thAve]

They show the same tank straight through the 80s and the biggest issue was always some people having to extend the fuel filler pipe. So I wonder if something changed after a certain year to cause the problem. I don't have a car that new the tank has been moved in.

 

[Fresh Air Inspector]

Hello All,

I double checked the cylinder head casting number on the car to make sure my notes were correct. It is in fact a '302' head (casting number 4323302). Also, I corrected a typo in my response about my horsepower and torque targets. I had torque at 275 lb. ft. when it should have been 375 ib. ft. or better.

Hello Duke5A,

The second set of numbers you sent are very revealing and interesting. It also highlights that the stepped headers from TTI show the best results as well as fitting best.

Thanks for the exhaust routing and size feedback. I need to check the drivers side clearance for the 'over the axle / out behind the tire' exit. The rear anti roll bar maybe a conflict. Truth be known I would prefer dual exhaust as opposed to a single big pipe.

Thanks for the trans swap info - some of the info I've collected shows floor pan modifications (enlarge the tunnel for the transmission tail section), in addition to fabricating the rear mount crossmember. That said, the swap doesn't appear to be that difficult. Need to find a tidy floor shifter when the time comes to install it.

Hello Mikes 5thAve,

As Duke5A pointed out the latter cars have a dimple in the trunk floor to allow a 'bubble' for the fuel tank vent and hose to sit inside. The RockAuto link below shows pictures of a replacement tank - this one happens to be the same one I have in my car. To move the fuel tank over would, as Duke5A indicates, require beating the s... out of the trunk floor. If RockAuto is any indicator, a fuel tank without the vent is NLA.

More Information for SPECTRA PREMIUM CR1B

 

[AHBguru]

Point of order:

If this car is a factory 4bbl car (VIN code S), you already have the 345 heads, which are J heads. If everything else on the engine is untouched, the best/easiest/cheapest thing to do to wake it up is to convert it to Mopar electronic ignition. The timing curve in the 4bbl squads was very conservative, especially compared to the 2bbl cars (which was excellent). Swap it over, find a reman non-feedback Mopar Quadrajet (17085408 or 17085411), set the base timing around 9* BTDC, shoot for 32-35* total, and at least 50-55* with the vacuum at 4000 RPM. If you run the EGR, you can sharpen the curve up a little bit more without it getting sent to detention. Oop, detonation.

Or, for almost the exact same money, buy the Magnum 360.

 

[AMC Diplomat]

Point of order:

If this car is a factory 4bbl car (VIN code S), you already have the 345 heads, which are J heads. If everything else on the engine is untouched, the best/easiest/cheapest thing to do to wake it up is to convert it to Mopar electronic ignition. The timing curve in the 4bbl squads was very conservative, especially compared to the 2bbl cars (which was excellent). Swap it over, find a reman non-feedback Mopar Quadrajet (17085408 or 17085411), set the base timing around 9* BTDC, shoot for 32-35* total, and at least 50-55* with the vacuum at 4000 RPM. If you run the EGR, you can sharpen the curve up a little bit more without it getting sent to detention. Oop, detonation.

Or, for almost the exact same money, buy the Magnum 360.

Many AHBs came with 2bbl carbs and smaller heads. It really depended on how it was ordered/emission laws where it was in service

 

[Duke5A]

Yeah, no floor pan modification is necessary. The front half of the 518 is the exact same shape and size of a 727.

With 340/360 in a factory 318 short block you're looking at a static compression ratio in the low 8's. This is going to hurt if you're looking for close to 400 ft/lbs of torque. Converter and gears also come into play and have to matched to the cam. If everything isn't matched you'll end up having a three legged dog.

Since your car is an '88 the block will have provisions for a roller cam if it doesn't already have one in it. I would highly recommend talking to someone who regrinds cams and a custom roller ground for your application. If you provide the core cam grinding used to be pretty damn cheap.

 

[AHBguru]

Many AHBs came with 2bbl carbs and smaller heads. It really depended on how it was ordered/emission laws where it was in service

If the VIN was "S", as I noted, that meant 318 4bbl (ELE) police. That would have the 345 (J) heads.

If the VIN were 4 or R, from '85-89, then it would have 302 heads. It's that simple. The OP has since stated he has 302 heads, so he's got either a P, 4, or R in his VIN.

From '84 - '86, they had 3 emissions packages: Federal, California, and Export. From '87 -'89, just one: Everything was Federal, as the cars met CARB requirements, and Canada went to catalyst emissions.

 

[Duke5A]

Here are those photos of the exhaust routing behind the tires. Board doesn't allow for sending photos in PM.

 

[volaredon]

Ugh
I don't make it over here much, spend most of time on FABO and FTO of this series of sites, though I do also have an F body.
And have had it longer than my fury or my trucks.
I'm tired of the "dump the 318 you absolutely have to get a 360 magnum" mentality.
Almost as bad as most of the hot rod world's "stick a shivvy motor in there" which has become "just stab an LS in anything " I hate THAT more than anything.
There are reasons I've been a die hard Mopar guy since before I could drive...
But for daily driver or weekend cruiser there is nothing wrong with the 318. Nothing.
And the thought on "302 heads are junk" same thing. Only in this case it's relative. What are you replacing with the 302s? Wire out something else? Edelbrocks? Just what? Junk compared to what? I've retrofitted 302s in a couple of engines that originally had '163 open chamber heads on them and in each case there was a noticeable improvement in how they ran.
Nobody pays for the work I do on my cars but me. If I had a magazine or TV show backing o may well do things differently. But until then..

I've had 2 diplomats. Both 318s and 85 and an 89. Both fleet cars, I believe both AHB. Long gone now, I know the 89 was an AHB. The 85 was a fire chief car before I got it the 89 was a university of Illinois campus security car. I never had the heads off of either (I did do a crank kit on the 89 but never had to pull the heads to do so) the 85 was a 2bbl and the 89 was a 4bbl motor and the 89's heads did say "360" on the top sides.
Both 2.93 gears, I had both cars for many years each. That 89 was a slug from Day one, and really drank the fuel as compared to my 85 on which I'm 98% sure had the 302s stock. I know my 87 can w/318 had '302s in it. And that thing ran absolutely fantastic. That 89 was one of the worst for not being able to get out of its own way that I've owned. And I did literally everything to that one to be able to wake it up short of a rebuild or can swap. Though I didn't touch any of that on my van or my 85. Coincidentally all 3 of those vehicles had 2.94 in the rears.
In my experience the 302s were worthwhile in "bang for the buck"

Not everyone here (I'd bet less than 30%) here actually drag race their cars where the last 1/10 second really matters.
I have a set of fresh 302s here that I may pull apart and clean up the casting goobers (which I have never done to a set of "those" heads before) before I put them on my 56k original miles 78 sport fury. And I don't care that everyone else thinks those heads are "junk" they're what I have

 

[AMC Diplomat]

I'm tired of the "dump the 318 you absolutely have to get a 360 magnum" mentality.

OP is in a far away place and that makes getting parts difficult. The magnum suggestion has more to do with affordability and availability.

Even where I'm at, it took me a year to find a 360 LA that was usable and at a realistic price. I can find magnums every day here though. There's not a strong mopar following around here. There are a couple amazing hoarders and that's about it.

 

[volaredon]

You could make excuses for each case but it's becoming a general overall mentality that 318s are universally "useless garbage" and that is actually far from truth.

 

[Mikes5thAve]

It's not that 318s are garbage it's more that people come up with some plan to spend a bunch of time and money getting more power out of a 318 and while it's doable sometimes they'd be better off starting with a 360 for what they are trying to accomplish.

Noting overly wrong with 302 heads other then you have to check for cracks which isn't super common but they were known for. That was a common swap for older 318s and at one point people were putting them on their 360s for a while too and opening up the ports to match the bigger runner size.

 

[Mikes5thAve]

Hello Mikes 5thAve,

As Duke5A pointed out the latter cars have a dimple in the trunk floor to allow a 'bubble' for the fuel tank vent and hose to sit inside. The RockAuto link below shows pictures of a replacement tank - this one happens to be the same one I have in my car. To move the fuel tank over would, as Duke5A indicates, require beating the s... out of the trunk floor. If RockAuto is any indicator, a fuel tank without the vent is NLA.

More Information for SPECTRA PREMIUM CR1B

For this like I said it was very common for people to slide their tank over despite the year to add dual exhaust. If or how they cleared the vent I don't know but the main issue they ran into was sometimes having to extend the filler pipe.
The latest M body I bought has dual exhaust with the tank moved and at some point I need to drop the tank because the fuel guage has problems so I'll get a chance to see what they did.

 

[Ele115]

318's are not useless garbage. For the sake of context, what people on this site have are low compression smog engines. You COULD make them kinda quick. It takes parts and possibly some machining, and you're getting into spending money. That's where people opt out. Last one or two I did was using late 60's heads and pistons, and that makes a huge difference. Those parts are really not easy to come by. You'll run into sunk valves and high price tags. Or you go the magnum route. Machine shop pricing and availabilty becomes an issue too. With enough money, anything is possible. I often go with Trick flow heads and Aftermarket cranks. That's the way to go. But that would not work for other people. It's different for other people. For the longest time RB engines were cheap enough that it was the way to go. Now people do Magnum 5.9's, newer "Hemis", LS engines Etc. What you have available and what you can afford to do down the road will dictate how you plan it. You may save $1500 on an engine and use $1500 on the rear end or something, That is why no two cars are the same.

 

[Duke5A]

It all starts with a plan and realistic expectations. Knowing how all the parts affect one another with the pros and cons of everything in the sum of the final package.

 

[Fresh Air Inspector]

Hello All,

Like most things in life, lots of theories and opinions. As the OP, they are appreciated. When it comes to modifying cars always remember, everyone has a passion for a particular manufacturer or model of vehicle as well the drivetrain. For some of us, me included, opting to follow the path least travelled is standard operating procedure.

In fact my youngest son and I are considering modifying the Slant 6 in his '83 Dodge pickup. Before this kicks off another series of responses; yes, it will be more expensive than doing a V8 and yes, a V8 will have more HP and torque! But, as the saying goes, the joy is in the journey and not the destination.

Thanks again for all the thoughts and feedback.

 

[Mikes5thAve]

I also have an 83 pickemup with a slant 6. Right now it's a parts truck but I'm hoping someday to find a good cab for it and I don't know if it'll stay a slant 6 or if something else might end up in there.

 

[Ele115]

I just scrapped a Cummins service truck with that same rusty old square cab. The roof was pretty much rusted off. A shame. You could put a cheap turbo kit on that for giggles. The Chinese sell them really cheap.

 

[Duke5A]

In fact my youngest son and I are considering modifying the Slant 6 in his '83 Dodge pickup. Before this kicks off another series of responses; yes, it will be more expensive than doing a V8 and yes, a V8 will have more HP and torque! But, as the saying goes, the joy is in the journey and not the destination.

You know what to expect then. I just decided on building a Ford 300 I6 for my OBS project rather than a 351 V8. It's going to cost twice as much and I'm going to get less out of it - way less. On pump premium I'd be looking at 250HP and will most likely build it for pump regular, so even less still. Truck was my grandfather's, so I'm trying not change everything on it.

 

[Ele115]

And the truth is, there is nothing wrong with that. Just enjoy it.

 

[Fresh Air Inspector]

Hello Duke5A,

Sounds like a great project. The Ford 300 I6 is a fantastic engine and incredibly reliable, so much potential. If memory serves, some engine builders were taking 351 heads (can't recall if they were Windsor or Cleveland), cutting one cylinder off each and welding the two '3 cylinder' heads together. I'm always amazed at type of out of box thinking.

Enjoy the journey!