318 Poly Suggestions

Reece Taylor

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Hello everyone,

I've got a 66 Sport Fury with a nice 318 poly under her skirt. I've been talked off the engine swap cliff and have learned to love my lil semi-hemi. I'm always dreaming of what I should do next to the car and would like some input. I've already done, edelbrock 4bbl swap, front disk breaks, some creature comforts, and a gibson exhaust. The cars mostly a cruiser but I'd like to give her some more go. I dream of going big one day and fully building the engine but for now I'm just a broke college kid. I'd like opinions on what I should do next, I'm thinkinging either a chrysler power intake (currently using a late 60s single plane), tti headers (still using stock log headers), or a semi spicy cam (no clue if anyones cracked open the engine yet). Depending on what I chose to do I might also do some light porting to the heads, mostly gasket matching as touching the bowls sounds terrifying.

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57fury440

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Back in the sixties I ran a 318 Poly. I had the factory dual quad manifold which worked nicely. One of the biggest improvements was when I added an Isky cam, solid lifters and springs. Along with that I also put a set of Hedman headers on it which were available back then. Both those modifications really made the poly come alive. They have pretty mild factory cams and the log manifolds are not the best. Your plan sounds good.
 

413

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how is college going? I‘d stick with that as your main focus, money and energy consuming activity. Plenty of yers left after than to go crazy on the car hobby.
 

CBODY67

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Find the Uncle Tony's Garage segment on the engine which Chrysler SHOULD have developed further, the A-Poly motor. Quite interesting!


For now, focus on "a torque motor that will RPM", which is kind of where you're now at. There are some additional "hot rod things" which can consume money, decrease daily driveability and mpg, and not help nearly as much as you might expect. Being that is an approx 300 cid engine, it is VERY easy to over-cam it with a cam which might work well in a 360 or even 340. AND over-carb it too. You might investigate a better electronic ignition system and add some Iridium plugs to that mix. So . . . tweak, tune, optimize the carb and ignition tuning. "Cheap entertainment", too!

I can tell you one thing I've found out over the years, it's MUCH nicer to go out, hit the key, and things start happening nicely. Than having a rumpety-rump exhaust note that does not really smooth out as the engine warms up. Might get attention at a local cruise-in, but not the best for every day in, day out, use, to me.

Headers would be advisable, if available, with about a 2.25" low restriction dual exhaust system as a complimentary pairing.

Cam, for that size of motor, probably about 210-215 degrees duration @.050", with about .450" lift, and 112-114 degree lobe separation. If Lunati has something like that, PLUS the assymetrical lobe shape, that would be good, I believe.

Just some thoughts,
CBODY67
 

65sporty

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For the future, I remember reading a story on a stroker poly build. It would be unique
 

Reece Taylor

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CBODY67

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If I'm to dive off the motor swap cliff, it will be for something better than a 440. I'll wait a few years for people to wreck some of the new dodges and pick up one of their batshit motors from a yard.
Those Gen III Hemis are already there. Just need to make sure of which version is the best as to some of the issues which some of them have tended to have. Remember to upgrade the brakes, too, with such a swap!
 

Snotty

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I've posted this picture a few times but I love it! Also from a mid-60's Plymouth, but a B Body:




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:
 

Big_John

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My advice is to not get too crazy with your build.

You are off to a good start, adding a better exhaust is good, although I'm not a huge fan of headers myself, but its all good. Mild cam might be in order too.

You haven't talked of the rear gearing. 3.23 or 3.55 would be a big improvement in acceleration and probably one of the better bang for the buck upgrades.

Just remember that gas isn't getting cheaper and a car that gets single digit MPG doesn't get driven a lot (read, no fun).
 

Snotty

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Just remember that gas isn't getting cheaper and a car that gets single digit MPG doesn't get driven a lot (read, no fun).
Ah, he's a Mopar Man, money is no issue!! Right?? That's why I like driving mine; everyone KNOWS I'm rich!!
 

Reece Taylor

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My advice is to not get too crazy with your build.

You are off to a good start, adding a better exhaust is good, although I'm not a huge fan of headers myself, but its all good. Mild cam might be in order too.

You haven't talked of the rear gearing. 3.23 or 3.55 would be a big improvement in acceleration and probably one of the better bang for the buck upgrades.

Just remember that gas isn't getting cheaper and a car that gets single digit MPG doesn't get driven a lot (read, no fun).
Thank you for the input as always John,

I've given thought to changing the rear end gearing but don't want to change the driveability too much and haven't looked into it enough to give it proper thought. If I do though I'd also like to look into doing an a518 swap. As for not driving a low mpg car, I drove mine across the state and daily drove it at college. I care more for driving and having the car seen than anything else, can't let everyone forget how good cars used to look.
 

CBODY67

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IF you do a A518 trans, you will most likely need to alter the rear axle ratio to about 3.55 or so. So that OD will be useable in normal highway speeds. Otherwise, you could well need a TBI EFI system to better meter fuel at lower rpm levels, like at 1600rpm highway cruise. Be sure to check that the A518 will work with your current crankshaft end?

One thing CAN lead to another . . . .

CBODY67
 

HotDodge

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Hey Reece, I have an overbored and hot rodded 318 in my 1960 Dodge Polara and have been around A block 318 all my life. What cfm AVS are you running? Believe it or not, you're hurting power on a stock or mild A318 using a Weiand 7503 single-plane intake, which is what I assume you are running since you said a "late 60's single-plane." Since you already have an new AVS carburetor, you will pick up performance by installing a factory 2-barrel intake and 2-to-4 barrel adapter since you can pick up 2-barrel intakes for little to nothing. Alternatively, you can install a factory iron 4-barrel intake, but they usually go for upwards of $400 which won't do for a "broke college kid." The factory 2 and 4 barrel intakes flow better than the Weiands unless the engine is built to turn high rpm.

As for the cam, a 264/.450"/110 cam wakes up a stock or mild A318 without needing to adjust the converter stall--if you're running an automatic--and rear gears. Keep in mind that LA cams and lifters don't interchange, so you'll need to get a cam from Racer Brown, Schneider, or Camcraft Cams and lifters from Melling or TRW.

Gasket matching the intake and heads will help some with a stock setup and help a lot if you put in the 264 cam. Coincidentally on another forum I was chatting with the person who built/runs www.poly318.com, and he's currently working on a technical article for porting A318 heads. He might be a good contact for you, and the website has a ton of information on our A blocks.
 

Reece Taylor

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IF you do a A518 trans, you will most likely need to alter the rear axle ratio to about 3.55 or so. So that OD will be useable in normal highway speeds. Otherwise, you could well need a TBI EFI system to better meter fuel at lower rpm levels, like at 1600rpm highway cruise. Be sure to check that the A518 will work with your current crankshaft end?

One thing CAN lead to another . . . .

CBODY67
"One thing can lead to another...."
Thats the anxiety I get thinking of how I should update/upgrade and how badly I could snowball. My car already runs in almost exclusively 3rd gear and that's good from 25mph up to spend the night in jail speeds, so I can't imagine my rear gear ratio is too high. I think I'll update to electronic ignition because I can't see that getting too out of hand... for now.
 

Reece Taylor

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Hey Reece, I have an overbored and hot rodded 318 in my 1960 Dodge Polara and have been around A block 318 all my life. What cfm AVS are you running? Believe it or not, you're hurting power on a stock or mild A318 using a Weiand 7503 single-plane intake, which is what I assume you are running since you said a "late 60's single-plane." Since you already have an new AVS carburetor, you will pick up performance by installing a factory 2-barrel intake and 2-to-4 barrel adapter since you can pick up 2-barrel intakes for little to nothing. Alternatively, you can install a factory iron 4-barrel intake, but they usually go for upwards of $400 which won't do for a "broke college kid." The factory 2 and 4 barrel intakes flow better than the Weiands unless the engine is built to turn high rpm.

As for the cam, a 264/.450"/110 cam wakes up a stock or mild A318 without needing to adjust the converter stall--if you're running an automatic--and rear gears. Keep in mind that LA cams and lifters don't interchange, so you'll need to get a cam from Racer Brown, Schneider, or Camcraft Cams and lifters from Melling or TRW.

Gasket matching the intake and heads will help some with a stock setup and help a lot if you put in the 264 cam. Coincidentally on another forum I was chatting with the person who built/runs www.poly318.com, and he's currently working on a technical article for porting A318 heads. He might be a good contact for you, and the website has a ton of information on our A blocks.
Thank you for bringing this site to my attention. I lucked out a found a factory 4barrel locally on the low which I think will drastically improve streetability. I think I'll hold off on my porting ambitious, aside from gasket matching, until poly318 does his post about it. After reading through his site I want to do a lot of the little work he's done inside all at once like the improved oil supply.
 

CBODY67

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Check the tag on the rear axle, IF it is still there, for the ratio. 2.93s were usually standard with 318s, as I recall. What size tires?

Let's presume that your tires are similar in "revs/mile" as the 7.75x14s which usually came on Furys back then and with the 2.93 rear axle ratio. That might be "in the ball park' with my '70 Monaco Brougham with 3.23 rear axle ratio and taller H78-15 tires. Let's presume about 25mph/1000rpm in 3rd, for the sake of illustration. 4000rpm will be right at 100mph in both cases . . . without any OD involved. Seems like Uncle Tony mentioned that one of the sweet spots of the Poly motors was their really good mid-range torque, which could mean that it would hold out until about 4500rpm or so? But now that I mention that, it seems that max horsepower (2bbl) happened close to that rpm? It also seems like, that when the motors were new (1955+), the rear axle ratios were more like 3.6 with the PowerFlite 2-speed automatics?

Remember, too, that the factory 3-speed w/OD setups, back then, usually had 3.70-3.90 rear axle ratios. IF you wanted performance and economy and were willing to put up with the extra activities those earlier systems needed to work as designed, it was "drag race" performance with relaxed highway cruising . . . but usually ONLY with 6-cyls and base V-8 models.

In one respect, I think it might be really interesting to see what a vintage Chrysler V-8 (A, LA, B, RB) would do with a modern 8-speed ZF-based automatic trans behind them. BUT that's a very expensive proposition, plus the cost of a new rear axle ratio so the upper OD gears can be used. Whereas upgrading to a self-learning EFI w/ignition control (on the existing engine) would be much less expensive and more cost-effective, I suspect.

Just some thoughts,
CBODY67
 
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