Are You Happy With Your 318

[whitedawg]

I recently acquired a 73 Road Runner with the original 318 and 3 sp floor shifter. Currently leaning towards keeping the 318 or possibly stroking it to 390.
What have you done to your 318 to maximize the potential?
Thanx

 

[rumblefish360]

You mean in the as delievered state? Or rebuilding it?

I took a stock '79 318 and added some bolt on parts and a small cam. The compression was low in those years, so it made sense to keep it small. 216/228 split from crane, .454/.480 lift.

I never got a chance to really dial it in and test it at the track, but largely untuned, it ran a 15.14 @ 89 mph at Atco on a cold Nov. day. Not bad for that cam, LD4B,625 Carter, headers with a suregrip equiped rear and 3.21's on a stock tire.

Heads were bone stock minus correct valve springs... of course.

The big issue with your teen and car combo is low compresion and car weight.

What gears do you have?
Whats the goal?
Just "Pepping it up?"

 

[72 Charger SE]

Here's what I did to my 318 many years ago: .030 overbore, shaved heads .030 to bump compression, small split profile MP cam (don't remember specs, but not radical), Edelbrock Performer intake with Holley 600, headers and dual exhaust.

With those mods and a bit less weight, my car was at least the equal and maybe just a tad quicker than my other 72 Charger that was running a stock 383 (from 69 Charger.)

Still wasn't enough engine for me and I finally switched to a 440 for the extra torque to get things moving.

 

[whitedawg]

Thanx Not looking to tear up the strip, just to liven it up some at the stop light. Currently running a 440 in my 60 Dodge, so I dont have the need for a BB at this time maybe sometime in the future.

 

[rumblefish360]

What gear ratio do you have now and is a change OK?

For a basic hot rodder package and your post in mind from above.

Milling the heads alittle for a increase (and larger valves would be nice as well. 1.88-1.60), a 340 replacement cam (110 centerline for a choppy idle) Performer intake and carb of your choice not exceeding 650 cfm unless it is a T-Q and use the small primary one at that. Headers a plus, but I hate the one size fits all. They really suck.

 

[whitedawg]

No sure about the gears. Change is always possible;
what do you recommend. After what the previous owner refered to as the "tombstone" incident the car was parked for several years with damage left front fender

 

[wookie77]

Well, just my $ .02 ...

In my 3200lb-3500lb ( depending on which book you reference ) '69 Coronet, My little 318 used to hold it's own against 5.0 mustangs at stoplights... That was before I parked it for over haul... I had a Holley 750cfm vacuum secondary ( by the way, that carb is NOT too large to run on that engine since it is a Vac. sec. it operates much like an AVS, TQ, or even QuadraJet since the engine only opens the secondaries when it needs to. But because of the slightly larger primaries you may lack a very small amount of throttle response) I also was using an Edelbrock Performer intake, Hooker headers and flowmaster 50 series 3 chamber mufflers on 2.5" dumped pipes. That was also with a 904 auto and 2.76 rear end. From what I understand, SUUUURVEY SAYSSS.... Use a 340/360 HP cam with a dual plane manifold 600-700 cfm ( NON DOUBLE PUMPER carb) and a decent set of headers and mufflers and it will wake up the 318. I went to see Bob Mazzolini and we talked for a while about this very subject. He pretty much agrees except he was swearing by 360 heads as well.

 

[rumblefish360]

360 heads work very well with the small valve IF the RPM range is to be higher and a decent compresion can be met. The problem between a 318 vs a 360 head is the port size of the 360 head. There large. While they will flow alot, they are no subjected to the same amount of draw a 318 produces at any rpm in a apple to apple compare.

For use of this head on a 318, the 318 needs to turn more RPM's. IMO, a cam shaft of greater than a 280* cam is where the port and engine RPM start to meet. The flip side is cost. A rebuilt 360 head can run you between $400 and $600 with new valves and comp valve job.

Porting a 318 head to meet the 360 heads performance is more expensive. Even though the head will be more responsive. Which is better for the street, milder cam and gears.

 

[rumblefish360]

No sure about the gears. Change is always possible;
what do you recommend.

Preety much what I described above except actual components. Like a Performer over a LD4B. replacement 340 cam over the Crane I used. Let me give you a example or two since I'm not exactly sure where you wanna go with this and you do have a 440 car to boot.

600/650 cfm carb
Performer intake
Comp XE262
http://www.compcams.com/Cam_Specs/CamDetails.aspx?csid=626&sb=2
Stock exhaust manifold cam - http://www.compcams.com/Cam_Specs/CamDetails.aspx?csid=635&sb=2
preped 318 heads with 360 valves, lite milling to 8.5-1 or better.
headers or exhaust manifolds with dual exhaust
This should be a high to mid 14 second car. Mileage should be good, I got 17 on the hwy with my similar 3.21 geared combo, and No MSD, which would have help some.

650/750 cfm carb
RPM intake
replacement 340 cam or this Comp cam Comp XE268
http://www.compcams.com/Cam_Specs/CamDetails.aspx?csid=627&sb=2
360 heads milled down 9.0-1 or better would be nice. (Compresion an issue, though not the end of the world here)
Headers into a 2-1/2 exhaust
Increase stall converter and 3.55's on a stock tire, 3.73/3.90 on a 26-26-1/2 inch tire.
Low 14 to high 13 seconds are doable here. Mileage should still be good. Greater than 15 mpgs on the Hwy.

Notice theres no converter changes here, though they would help, but there not a mandotory thing. (Humm SP?)

Any build more powerful than this I'd recomend a rebuilt 318 with KB slugs @ zero deck and cams starting at 230+ @ 050 which in general, for that engine size, will have power starting at around 2200 rpm and go to 6000.

A FYI, the Hooker "Super Comp" headers, (NOT the regular comp 1 size fits all style header that normaly scraped 3 yubes on the floor on the drivers side,) fits excellent though the 2 draw backs are price and a larger tube @ 1-3/4 will lack some intial low end torque.

I'm at the point that I no longer care because these not only fit great and fit in easy, they don't scrape the ground at all I think there the 5115's. They also fit Cuda's and Challengers.

 

[S.I. Coronet]

I have a 318 in my 70 Coronet.
Its got a 750 Holley, performer intake,72 "J" heads shaved down, .030 over flattop pistons, Comp Cams 280 magnum cam, Electric ignition, Summit headers ,Flowmasters.
Its a nice cruising engine for the car.

 

[q-ship]

A stock 318 has a ridiculously low compression ratio of just over 7.4:1, at least the two I have measured did.

It's hard to get the compression up to 9.2:1 (or thereabouts) cheaply, but is a tremendous boost in performance and millage. Probably a 50+ HP gain (but you will need Premium fuel).

The 302 heads are excellent for a cheap improvement for a 318, but a 360 would be a better choice overall, for either stock or stroked use, as you would need to get heads, manifold, etc. for a 390/318, and you could use the stock 360 stuff for satisfactory (not ideal, but satisfactory) performance.

Just my 2 cents.

 

[69 Runner]

With a compression ratio of 7.4:1 it would be a good candidate for a BLOWER