Looking to get into a bit of racing at the local strip in a street car class with my son looking for input and info on stock 318 upgrades... what we have is a 1988 dodge diplomat with a roller 318 and 302 swirl port heads all stock with 2bbl... now I've had a few guys tell me the roller 318s will run hard and they talk about seeing them run 15s with only 4bbl,gears and exhaust... that so far is our plan to go for.. really not wanting to do head work or anything at the moment just thinking basics... Any other things to do to help improve?? Anybody with any real times of running stock 318s?? What would a good intake and carb be?? We are thinking a 8 3/4 with 4:10ish gears?.. if we hit 15s we will be happy most cars in the class are stock mustangs and camaros running similar times...

I had a detective diplomat it was one of my favorite cars. I took it to the track a couple times and it was the slowest thing ever, but yeah 4 brl headers and dual exhaust would help. What about the ignition does it still have that lean burn stuff? I would check out the explorer 8.8, see if the width is close.

My Dart.. running on a 318 + ported J-heads. 12:1 CR on E100. 4.88 gears. Manual tranny. Best so far NA 9.2 1/8 1.90 60". Should be ~14.3 in the 1/4.

Regrind the stock cam, valve springs, timing chain and a Performer RPM. 4.10 will work. We ran a old 318 with stock 360 smog castings, stock short block, 484 purple cam (too big so no tire spin with street tires), stock conveter, stock 360, T quad. 14.0-14.1@100
Doug

Budget build would be to X the catalytic converter and have the carb rebuilt by a good shop and have them rich'n up the carb. Use premium gas. Could prevent you from cracking those 302 heads. You'll get more consistent and dial in a better number. Its always better to build with consistent car.

1972 Plymouth Satellite Sebring Plus:
318 two-barrel (motor rebuilt a long time ago), auto left in "drive", 2.71 open rear end, 215/70R14 tires, factory stock except for dual exhaust:
18.36 @ 75.37 MPH. (1/8 mile was 11.80)

DO NOT put 340 or 360 heads on your engine, the compression drop will kill power. Get an LD4B intake, 750 Holley vacuum secondary carb, small tube headers and most important get at least a 3500 stall convertor and 4.56 or 4.88 gears. You'll need the convertor and gears to get the car to jump off the line.

Had often thought of using a stock 360 2 bbl. intake and carb (maybe a 383-400 2 bbl.) for stealth mode. 360 cam is a bit larger. Aren't those cars kinda tough to put true duals exhaust on, due to gas tank location? Maybe 2 1/4" head pipes to a 3" single with a discrete tip, again to be sneaky. 'Trash that lean burn' as per Mopar Action article from years ago, simple to do. Leave the LB computer in place to fool people. Factory high stall converter. Used to see guys with all sorts of go fast parts, headers, intake, huge carb etc. and quite often my 66 Barracuda with a stockish 273 would dust them. Its all in the tuning.

No it doesn't have "that lean burn stuff" on it. It's worse. It has a feedback carburetor and the car is partly run by computer.

The first thing to do has nothing to do with engine. The car may be equipped with a 7 1/4 rear end with as numerically low gears as 2.27, something like that. While the 318 is not a high revving screamer as installed, it would benefit from gears in the 3.23 to 3.55 range. There is a possibility that it's equipped with a more desirable rear such as 8 1/4 or even 9 1/4.

The second thing is to find a mid '70s 360 intake manifold. It will be spreadbore and may or may not contain EGR. No worries. The EGR is easily blocked off with an EGR valve, not hooked up to vacuum. If you are a carb guy, a Thermoquad will work, as will a Quadrajet. If you are bucks-up, a 625 Street Demon will bolt on. This intake is a true high rise and surprisingly good. If the port mismatch bothers you the heads can be opened up to match on three sides, IMHO the inner side of the runner curve doesn't matter as much. If you don't care to use a die grinder the intake will work as is. It's a heck of a lot better than the stock 2-barrel.

Don't let talk of heads cracking bother you. Mine weren't cracked. The cracked ones don't leak and came out of running engines. "Richen up" the carb? How on a feedback carb? Ditch the carb entirely. See above.

The stock cam isn't horrible, 0.390 lift, 191 degrees at 50, 110LSA. I replaced mine with the camshaft from a TBI 360. You can have your stock cam reground by Bullet for used to be $120. The 259/316 Bullet hydraulic roller grind is what has been suggested as the largest and this one is flirting with disaster IMHO as there isn't much valvespring installed height to work with. I ended up cutting down my valve guides (easy job) and using springs like the Comp 901s. If you don't want to go that route I'd suggest keeping lift below 0.430. There may be another stock cam that the cam gurus know about that will work better. They'll have to tell you that. I'd keep the hydraulic rollers.

Dual exhaust is a must, use an H or X pipe if you can. It isn't the converter that's the plug, it's the whole exhaust system. The stock manifolds aren't bad and you have them and they fit.

Transmission is an A-998 and it's a 3-speed with a 2.74 First gear. Nothing to do at this point.

Ignition will be adequate with a stock type electronic distributor, recurved, with stock type coil and ignition box. Seems from my online reference that your engine may indeed have a real distributor with advance and everything. I was surprised at that.

Good Luck with your efforts!

R.

I like Dogdays approach. If your willing to add the 4:10 gears, it will help get you off the line a bit faster, as long as your not over reeving at the top end. Watch your shift points, high RPM shift points is not going to be the fastest 1/4 mile time. Gene

Thanks for replies.. I already on the parts shelf have a cast intake off a 80s ramcharger and a holley 600 I was thinking of putting to use.. i also have a torker 340 but from my reading don't seem like a good choice
. I have a set of A body headers that from my reading fit the car also.. my buddy has hoards of mopar parts and has several surgrips with different ratios.. he has 3:91s and even one with 4:56s which I think might be a but much unless I had real tall tires.. what's the shift point of a stock 318? My buddy today told me he had a dead stock 75 duster with 318 2bbl the only thing he did was put in 4:10s and a set of slicks and it ran 14.90s shifting at 5000.
. Is that about right? Guys keep telling me 318s like to rev even in stock form?

1975 Fury wagon (b body that year), original 160k long block(heads never removed), factory 904 rebuilt with a shift kit, original high stall converter, 2.76's or 2.94's iirc, stock 2bbl carb and intake.
Removed/blocked egr, recurved distributor, remove cat, single turbo muffler, fresh valve seals.

17.80's in the 1/4..... I can't recall the speed exactly..... Seems like it was close to 80.
Kick down linkage adjusted so it would shift just before the motor really started feeling flat...... probably about 4800rpm or so.

It was way way more responsive to drive than my friends 79 Magnum with its stock 318 2bbl.

The "if it were me" answer is, I'd lose the roller cam.
Extra weight for the lifters that the wimpy springs have to control.
I'd use the smallest Howard's street force cam and new stock type hyd flat lifters.
Another good choice would be a Comp 260h, or the smaller Summit cam.
Install some stock replacement 340 springs and new stock style seals.
Someone would probably give you some stock 318 flat tappet pushrods.
New timing set.

Then the other stuff that has been mentioned...... Duals, 4bbl, gears, etc.



I don't have the OE specs, but a Clevite stock replacement roller cam for the 318 2bbl(part number 229-2153) shows the specs as :
.390/.390 lift, 270/270 advertised duration, 191/191@.050, 115lsa, installed at 115.5.

Possible that it's a 115.5 LSA, that 110LSA number came from a source I cannot now find.

As the ports on the 302 head are not very large, on the worst ones it seems you can get your thumb stuck in there, IMHO it does not pay to use very deep gears. 3.91s would be the absolutely highest numerical ratio I'd go and I bet it would ET the same with 3.55s.

I respectfully disagree with Fast68 on lifter choice. If the engine has a realistic redline of 5000rpm because of cylinder head, worrying about lifter weight becomes secondary. I'd suggest the low cost 340 springs Sealed Power VS678 or Enginetech ERV901. 91lb seat load and 326lb/inch spring rate. Why risk a lifter break-in failure when a higher possible rpm has little value? The Bullet grind mentioned above has .474 calculated lift and 209 degrees at 50. The 1.625 installed height really begins to cramp at that lift.

Anyway, different strokes for different folks.
R.

Use the lean burn dist with a MSD 6530 Digital programable box.
https://www.msdperformance.com/products/ignitions/street_and_strip/parts/6530

Then headers with dual exhaust, and 4-bbl intake and carb.

More than one way to skin a cat for sure.
i think my main reason for the flat tappet cam preference is the low cost and wider selection.

That Summit cam kit is probably under $110.

I'm pretty sure the factory 318 flat tappet cam is a 110lsa.

In 1990-ish I built a low buck 318.
Rebuilder cast pistons, mild port work on some open chamber 318 heads(flowed around 180), std performer intake, 600vs Holley, 1-5/8" headers, 340 cam and springs.
I don't remember the tq but it was about 275hp on the dyno..... And I seem to recall it peaked solidly over 5000rpm(like 5500-5700).

I'll have to see if I still have the dyno sheets.

Stock 318 with garbage valve guides and mileage Stock best it ran 17.8

Changed to stock TQ intake and headers and 2.71 gear as 16.8

Changed to 3.55s and curved dist 15.8

This was in a 3950 car Plymouth Sat

Yes Pigs can fly that car proved it The one head were so warped that it could rock but thick head gaskets took care of that problem

Advise stick to what you in tend to do a high stall is recommended but I stayed away See if you can finc a factory 2200 stall they worked well on my other car . No headers then get a a exhaust cutout cheap good power

With LA heads I push my timing as high as I can often in the 43-46 degree range but every car is different. My advise here is a accell dual point dist and or pertronix conversion cheap power with out vac advance

Have fun!

I like 451's idea with the locked out distributor and programmable Msd. I think you got the right idea. It would really like intake carb, headers and dual exhaust. Maybe just put a summit x pipe and mufflers with just dumps. Then gears. 8 3/4 would be cool especially if you can borrow some chunks to see what it likes, but I'd just do a 3.73 or 4.10 exploder 8.8.

I messed around with my duster for a while when it had the slant in it. I put a super six 2 brl. setup and opened up the outlet on the stock manifold. It didn't make much of a difference until I made a 2 1/2" exhaust for it. Big difference With those 2 upgrades. Then I recurved the distributor, again a nice improvement. Tried a bigger 2 brl, it liked that. Then I put an explorer 8.8 with 3.73s from that point compared to bone stock it was a huge difference. It wasn't bad at all to drive. I never liked slants, but it was growing on me. A guy at work raced a grand national and we were talking about putting a gn turbo on it but it cracked the head or something. I really bought the car to do a bb swap which eventually happened, but it was fun to start from scratch with it.

Watch E-bag for an old Edelbrock with the 318 sized ports. They pop up frequently for $100 or less.

Cam, 360 heads, headers and a decent 4bbl, my 318 ran 13.68 in my 3400# 'Cuda. Had a good converter and gears in it as well..

Okay, so my memory wasn’t 100%.
It was a Carter 625 carb, and I also ran a Holley 650DP on it.
My notes say 8:1cr........ and it liked a bunch of timing.
It also didn’t peak as high as I remembered.

Best run was with a 1” open spacer under the 650DP and the timing at 42deg.

Back in 1990 the dyno software was giving the results for every 250rpm.


RPM ——TQ/HP
2500——284/135
2750——294/154
3000——299/170
3250——313/194
3500——314/210
3750——325/232
4000——328/250
4250——327/265
4500——326/279
4750——318/288
5000——309/293
5250——290/290
5500——272/285
5750——250/274