Need cam ideas for my 318 Duster

[HP2]

I want a cam for my 318 and need some advice.
I want my Duster to be an easy mannered street toy for day trips and once a while to the strip. My goal is to run a high 7 on 1/8 mile with a car that works good as a daily driver.

Swedish krona is way down and I’m on a budget so I have to build on what I already have as long as possible.

Car is a 71 Duster, body all stock except for fiberglass hood and bumpers. Full interior. Don’t know actual weight.

Engine is a 318 fresh short block rebuild I got from a friend just before he passed away. He had it as a reserve for his 340 he raced.
KB 167 pistons, .030 over
Manley H-beam rods
Balanced 340 crank
Zero decked block
An expensive adjustable timing gear (I forgot the brand)
SFI approved balancer
Milodon low profile 7qt oil pan
Edelbrock 60779 heads. Will do some blending and mild porting.
273” rockers
Have both dual- and single plane intakes to choose from (need to check exactly what I have), and a bunch of Holley and Edelbrock carbs. Well, I also have a very nice TQ "Muscle Car" gem.
Old long tube headers (1 5/8”) and full 2.5” exhaust with free flowing mufflers.
MSD 6AL and original old Mopar distributor (recurved but will of course need to be redone again)
No power brakes.
I have a small converter, have to check and see exactly what it is but I will remember it stalls at around 2,500-3,000.
727 auto.
3,91 SG. Have a 4.88 3:rd member with spool but I don’t think I wanna go that route since it will be a driver. And it’s unnecessarily fun on a rainy day lol.
28” high street slicks

I plan to clean up the runners and polish and do a little un-shrouding to the the combustion chambers.
I have access to machinery to shave them off a little if necessary to tailor compression ratio.

I will be very careful when doing rocker geometry and set them to “1/2” by the B3 Engines method.
Roller rockers is on my wish list, but it will have to wait.

We can get 93 octane from pump here.

Long post so I hope I got it all covered!

Here are my questions:

1. First maybe a stupid one: Would a little chamfering in the cylinders where the flow from the intake valve comes, where the intake valve is closest to the cylinder wall, in do any good?
2. What cam do you suggest? Can’t afford a roller. Afraid of today's flat tappet hydraulic cams and lifters. Have had my share... Not afraid of (and used to) mechanical cams. Like the clatter. Hopefully better quality than today's hydraulics too.
3. We have pretty good gas here in Sweden as said earlier. I’d say that 190psi cylinder pressure is safe with alu heads with our gas. What CR should I aim for with your choice of cam?
4. What's an economical (but still good) choice of pushrods?

Thanks in advance!

 

[toolmanmike]

There have been so many threads about 318 cams. All are different depending on the rest of the combination. Just remember, there is no "Magic cam grind"

 

[rumblefish360]

I want a cam for my 318 and need some advice.

Well. You have come to the right place.

I want my Duster to be an easy mannered street toy for day trips and once a while to the strip. My goal is to run a high 7 on 1/8 mile with a car that works good as a daily driver.

That would be a minimum of 12:40’s in the 1/4. That makes a nice hot rod without to much camshaft.

Swedish krona is way down and I’m on a budget so I have to build on what I already have as long as possible.

I hear ya there. Let’s do this!

Car is a 71 Duster, body all stock except for fiberglass hood and bumpers. Full interior. Don’t know actual weight.

P/S or A/C?
I’d guess if it was a loaded car with all the power goodies, it’ll be close to 3500 lbs. if it’s all manual, like mine, it’s 2990 lbs all steel original /6 converted to a 340, aluminum top end and headers. That 340 is lighter than the /6.

Engine is a 318 fresh short block rebuild I got from a friend just before he passed away. He had it as a reserve for his 340 he raced.
KB 167 pistons, .030 over
Manley H-beam rods
Balanced 340 crank
Zero decked block
An expensive adjustable timing gear (I forgot the brand)
SFI approved balancer
Milodon low profile 7qt oil pan
Edelbrock 60779 heads. Will do some blending and mild porting.
273” rockers
Have both dual- and single plane intakes to choose from (need to check exactly what I have), and a bunch of Holley and Edelbrock carbs. Well, I also have a very nice TQ "Muscle Car" gem.

Let us know what intakes you have and what carb you would like to finally run with.

Old long tube headers (1 5/8”) and full 2.5” exhaust with free flowing mufflers.
MSD 6AL and original old Mopar distributor (recurved but will of course need to be redone again)
No power brakes.

Good, very good. No worries about low vacuum for P/B.

I have a small converter, have to check and see exactly what it is but I will remember it stalls at around 2,500-3,000.
727 auto.
3,91 SG. Have a 4.88 3:rd member with spool but I don’t think I wanna go that route since it will be a driver. And it’s unnecessarily fun on a rainy day lol.
28” high street slicks

Your kind of split on the gear ratios for the goal. The 3.91 will do for sure. Those 4.88’s will be handy for the track.

I plan to clean up the runners and polish and do a little un-shrouding to the the combustion chambers.

Don’t polish the runners.
Polish the chambers

I have access to machinery to shave them off a little if necessary to tailor compression ratio.

9.0 - 9.5 - 1 will be good. That’s about what the combo hands out.

I will be very careful when doing rocker geometry and set them to “1/2” by the B3 Engines method.
Roller rockers is on my wish list, but it will have to wait.

Excellent

Here are my questions:

1. First maybe a stupid one: Would a little chamfering in the cylinders where the flow from the intake valve comes, where the intake valve is closest to the cylinder wall, in do any good?

Yes and no. The saying goes, “The juice is t worth the squeeze.”
In other words, the amount of work you do in the cylinders will be a positive move not worth the effort to barely make again worth the effort. If at all. This type of work should be reserved for an all out effort. Not a mild street car. It can also produce negative effects with the piston rings and longevity depending on what is done and how far you go.

1. What can do you suggest? Can’t afford a roller. Afraid of today's flat tappet hydraulic cams and lifters. Have had my share... Not afraid of (and used to) mechanical cams. Like the clatter. Hopefully better quality than today's hydraulics too.

A minimum for a solid camshaft I’d consider would be 234@050 on a 110 LSA (perfect for a 2.02 headed 318) with as much lift as I can reasonably get or as much as the head flows well in.

If the flow slows down after .500, let’s say by a few cfm, then a slightly over a .500 lift cam is what I’d look for. If you find a cam that works but the lift is .490, don’t worry about it.

1. We have pretty good gas here in Sweden as said earlier. I’d say that 190psi cylinder pressure is safe with alu heads with our gas. What CR should I aim for with your choice of cam?

Cam and compression work together to keep the package balanced. My recommendation above will work well.
I run a Hyd. roller @224@050 with a 11.5-1 compression on our top grade of 93 just fine.

1. What's an economical (but still good) choice of pushrods?

Thanks in advance!

You’ll have to shop around. Being the engine is still mild, you can use a stock size 5/16 and as thick of a wall as possible and you’ll be good. Thicker is better though.

Try Smith Brothers. But their are many places.

Personally, I think the 3.91 gear will be great for around town.
However, the 318 will need to turn some good rpm’s at the track and need at least 4.56 gears with your 28” tires to run the time.

The problem is the engine is torque challenged and can use the gears to help release the power quickly to run that time.

I suggest trying the 4.88’s even around town. If you have to go far and must use the high speed roads, these are NOT your friend. Even the 3.91’s will be a bit rough at minimum highway speeds.

 

[RustyRatRod]

That engine has enough balls for the Crane magic cam. If you can find one.

 

[JoePole1]

That engine has enough balls for the Crane magic cam. If you can find one.

Or git one re-ground to that spec.

 

[RustyRatRod]

Or git one re-ground to that spec.

Oregon Cam Grinders has one surprisingly close, too.

 

[rumblefish360]

I just thought about a possible use of an OD trans. I forget the exact ratio of the OD gear. I think it’s.69. But with;

3.91 X .69 = 2.69
4.88 X .69 =3.36

You’ll have to find a place to custom stall the lock up converter.

 

[AJ/FormS]

You said

I want my Duster to be an easy mannered street toy for day trips and once a while to the strip. My goal is to run a high 7 on 1/8 mile with a car that works good as a daily driver.

Yur gonna need ~350 hp with a Superstock chassis.
With a street chassis, that will be about a second slower.
Thus you will need the equivalent of a 100shot of Nitrous on top of the 350.

My street chassis barely got into the 7s, at 93mph. By the Trapspeed and car-weight, this was about 430 hp, for 7.92 seconds and spinning all the way. That was fast enough for me, one good run and I went home.
But, I have an HO367 with alloy heads and that run was done at about 180psi. AND I used FOUR gears to get there!
But, I have 3.55s and a GVoverdrive so for me, 65=2240 rpm. This makes a fun car to drive, but that 230/237/110 cam of mine she sucks gas pretty hard. So, I retired her from DD.

As for you
Good luck getting enough cylinder pressure for that size of cam. and if you don't have the pressure, she'll be a lousy DD
I did a quick study, and and for that 235* cam, say with an Ica of just 66*, to get to 190psi will require, an Scr of 11.7
In a 318@20 over, that comes to a total chamber volume of 61.6cc With a zero deck and 5cc eyebrows and a Fell-pro 039@ 8.6cc, that means your head chambers have to be down at 48cc or less. IIRC the Edelbrocks come to you at 63cc. You see the problem?
And that is a two edged sword. If you cut the heads down, you may have to cut the eyebrows for more clearance, and the intake will have to be cut, and maybe the chinawalls.
You said;

I want my Duster to be an easy mannered street toy for day trips and once a while to the strip. My goal is to run a high 7 on 1/8 mile with a car that works good as a daily driver.

and you said

I want a cam for my 318 and need some advice.

IMO my advice is to lower your expectations.
Those 4.88s are lousy for a DD.
Those 3.91s with 28s, are 65= 3100 at zero-slip, say
3150@ 3% slip , but, how many DD miles can you get out of 28" street slicks?

IMO, with your stated goals, yur gonna have to give something up, especially being in Sweden; unless it's like 10 minutes to work.

 

[harrisonm]

Roller rockers is on my wish list, but it will have to wait.

I would SERIOUSLY consider doing the roller rockers now and go with a roller cam. I have heard of so many people having problems with flat tappet cam lifters that I don't think I would go that route. You understand that too. Lots of performance-oriented machine shops will not even build an engine with a flat tappet hydraulic cam. Evidently almost all hydraulic lifters nowadays come from China. All I know is what I have read and heard. BTW a well-known machine shop here will only build a complete engine if you go with a roller cam.

 

[HP2]

I would SERIOUSLY consider doing the roller rockers now and go with a roller cam. I have heard of so many people having problems with flat tappet cam lifters that I don't think I would go that route. You understand that too. Lots of performance-oriented machine shops will not even build an engine with a flat tappet hydraulic cam. Evidently almost all hydraulic lifters nowadays come from China. All I know is what I have read and heard. BTW a well-known machine shop here will only build a complete engine if you go with a roller cam.

I'm well aware of the hydraulic lifter pandemic and that's why I want a flat tappet mechanical setup. I assume their not the same since they are just a fraction of all lifters and are hopefully not made in China.
Roller cam is not an option since I don't have the funds. On top of that it seems like the bad manufacturing/ quality control pandemic is spreading to rollers too. Lots of reports of failing roller lifters on the net.
Having an engine built on the other side is not really on my budget. There are good engine builders here in Sweden too but, again, it's out of my budget.

 

[HP2]

Well. You have come to the right place.

Thanks!

That would be a minimum of 12:40’s in the 1/4. That makes a nice hot rod without to much camshaft.


I hear ya there. Let’s do this!


P/S or A/C?
I’d guess if it was a loaded car with all the power goodies, it’ll be close to 3500 lbs. if it’s all manual, like mine, it’s 2990 lbs all steel original /6 converted to a 340, aluminum top end and headers. That 340 is lighter than the /6.

No PS or AC. No heater either but I'll have to add one for it to be usable here.
This is also a slant six car from factory. Probably just under 3k with the fiberglass pieces.

Let us know what intakes you have and what carb you would like to finally run with.

Will have to dig out the stash and get back with the details!

Good, very good. No worries about low vacuum for P/B.

Your kind of split on the gear ratios for the goal. The 3.91 will do for sure. Those 4.88’s will be handy for the track.

Don’t polish the runners.
Polish the chambers

No, I will polish the chambers and the exhaust runners. Intake will be made "rough".

9.0 - 9.5 - 1 will be good. That’s about what the combo hands out.

I really want to get a higher CR than 9.5 or I will need a custom grind to get good cylinder pressure. Or advance it.
I have run 190 psi with iron heads with no problem before on 93 pump gas.

Excellent


Yes and no. The saying goes, “The juice is t worth the squeeze.”
In other words, the amount of work you do in the cylinders will be a positive move not worth the effort to barely make again worth the effort. If at all. This type of work should be reserved for an all out effort. Not a mild street car. It can also produce negative effects with the piston rings and longevity depending on what is done and how far you go.

I has been thinking a lot about this and I just wanted to hear if it's been done and the results of it. Wont do it anyway on this engine since it's together and fresh.

A minimum for a solid camshaft I’d consider would be 234@050 on a 110 LSA (perfect for a 2.02 headed 318) with as much lift as I can reasonably get or as much as the head flows well in.

If the flow slows down after .500, let’s say by a few cfm, then a slightly over a .500 lift cam is what I’d look for. If you find a cam that works but the lift is .490, don’t worry about it.

Cam and compression work together to keep the package balanced. My recommendation above will work well.
I run a Hyd. roller @224@050 with a 11.5-1 compression on our top grade of 93 just fine.

I'm thinking the same. Not much more than 230 deg and around 109 LSA.
Do you know your CP?

You’ll have to shop around. Being the engine is still mild, you can use a stock size 5/16 and as thick of a wall as possible and you’ll be good. Thicker is better though.

Try Smith Brothers. But their are many places.

I will look around!

Personally, I think the 3.91 gear will be great for around town.
However, the 318 will need to turn some good rpm’s at the track and need at least 4.56 gears with your 28” tires to run the time.

The problem is the engine is torque challenged and can use the gears to help release the power quickly to run that time.

I suggest trying the 4.88’s even around town. If you have to go far and must use the high speed roads, these are NOT your friend. Even the 3.91’s will be a bit rough at minimum highway speeds.

If time hasn't been another factor I have a A518 46RH sitting. But it needs rebuilt and then some fabbing and fitting. Then a 4.88 would be just fine. But then I also need an expensive custom OD converter. Not this year.
Thanks for your input!

 

[HP2]

That engine has enough balls for the Crane magic cam. If you can find one.

Do you have the specs?

 

[HP2]

I just thought about a possible use of an OD trans. I forget the exact ratio of the OD gear. I think it’s.69. But with;

3.91 X .69 = 2.69
4.88 X .69 =3.36

You’ll have to find a place to custom stall the lock up converter.

Exactly, would be great! And an Eaton Truetrac

 

[HP2]

You said

Yur gonna need ~350 hp with a Superstock chassis.
With a street chassis, that will be about a second slower.
Thus you will need the equivalent of a 100shot of Nitrous on top of the 350.

Hmm, not what I wanted to hear lol. Well, I do actually have a complete used nitrous system that I've never used...

As for you
Good luck getting enough cylinder pressure for that size of cam. and if you don't have the pressure, she'll be a lousy DD
I did a quick study, and and for that 235* cam, say with an Ica of just 66*, to get to 190psi will require, an Scr of 11.7
In a 318@20 over, that comes to a total chamber volume of 61.6cc With a zero deck and 5cc eyebrows and a Fell-pro 039@ 8.6cc, that means your head chambers have to be down at 48cc or less. IIRC the Edelbrocks come to you at 63cc. You see the problem?
And that is a two edged sword. If you cut the heads down, you may have to cut the eyebrows for more clearance, and the intake will have to be cut, and maybe the chinawalls.
You said;

Getting enough CP is the challenge. I know. 63cc is what they say, but I haven't measured them so can't say for sure.
Wallace calculator doesn't fully agree with yours, or do I miss something? With this:

HUG STL3842AS-8​

Hughes cam I get 186.8 PSI with 9.6:1. Or I'm I lost in the math?
Hughes Engines

and you said

IMO my advice is to lower your expectations.
Those 4.88s are lousy for a DD.
Those 3.91s with 28s, are 65= 3100 at zero-slip, say
3150@ 3% slip , but, how many DD miles can you get out of 28" street slicks?

IMO, with your stated goals, yur gonna have to give something up, especially being in Sweden; unless it's like 10 minutes to work.

I have started to lower them already. And thinking of adding that nitrous system LOL.

 

[rumblefish360]

As mentioned earlier by AJ, the cylinder pressure is low and that makes the low rpm band sponge soft. While I don’t think it’ll be that bad, more compression is better.

Your current engine specs pose a problem in your goal. I kept the cam small and within the stall of the converter. Moving the cam around can help a little but so so try it as it should be installed first.

IMO, a call to Schneider cams here in the states could very well yield you a better choice than an off the shelf cam.

Also, if you’re OK with making your own exhaust pressure wave cancellation boxes for your car, this would be a very good improvement on low end torque. I seriously suggest a look into David Vizards exhaust suggestions. The idea is to mimic the dyno engine room where the exhaust goes to open air after the header and collector.


I don’t know the cylinder pressure of my wife’s engine.

It is a .030 - 360, zero deck Federal Mougal hyper slugs, nearly identical to the KB-107. Trick flow heads. The head gasket is in the brain fade area. IIRC, it’s a Cometic at .035 X 4.04.
Cam card below. If anyone does the math, please post it up.

 

[RustyRatRod]

Do you have the specs?

Yeah. .467/.494 222 and 230@ .050 on a 114.

 

[aaronk785]

Crower has one that is very close. It’s a beast series cam. 222 234 at .050 .480 .494 lift on a 112 Lsa.

 

[HP2]

As mentioned earlier by AJ, the cylinder pressure is low and that makes the low rpm band sponge soft. While I don’t think it’ll be that bad, more compression is better.

Absolutely

Your current engine specs pose a problem in your goal. I kept the cam small and within the stall of the converter. Moving the cam around can help a little but so so try it as it should be installed first.

IMO, a call to Schneider cams here in the states could very well yield you a better choice than an off the shelf cam.

Also, if you’re OK with making your own exhaust pressure wave cancellation boxes for your car, this would be a very good improvement on low end torque. I seriously suggest a look into David Vizards exhaust suggestions. The idea is to mimic the dyno engine room where the exhaust goes to open air after the header and collector.

I have completely forgot about the pressure wave termination box! I better find his books, that's really interesting.

I don’t know the cylinder pressure of my wife’s engine.

It is a .030 - 360, zero deck Federal Mougal hyper slugs, nearly identical to the KB-107. Trick flow heads. The head gasket is in the brain fade area. IIRC, it’s a Cometic at .035 X 4.04.
Cam card below. If anyone does the math, please post it up.

View attachment 1716353319

 

[AJ/FormS]

Wallace calculator doesn't fully agree with yours, or do I miss something?

You cannot use the 050 numbers.
You have to use the advertised numbers.
It says so right on the top line;
"seat to seat or advertised".

(Use seat to seat or advertised specs for Intake spec for best results)

Dynamic Compression Ratio Calculator
Number of Cylinders :​
Bore in Inches :​
Stroke in Inches :​
Rod Length in Inches :​
Static Compression Ratio :​	1)
Inlet Valve Closes ABDC :​	°
Boost Pressure in PSI :​
Target Altitude :​	(Feet)
​

As for this cam; Hughes fails to publish those numbers, so you have to guess, by looking at other older obsolete grinds.

History shows that Hughes cams are "hi-intensity." or at least higher than some others.
Here's my attempt at converting this to advertised?
238/242/108 ....... This might be;
284/292 gross advertised; it might be a lil less, and lashing might take a few degrees but there is no way for me to guess what it would be, so at this stage, I'm not looking for super-accuracy. I just want to estimate the point when the Intake valve actually closes.
From those numbers, I can guess the overlap to be ~72 degrees. Giving 36* to the intake side I get
180 less {(360+36) less 284} = Ica of ~68* This would be at about Split overlap.
To get 190psi with an Ica of 68*, in a 318+020 @500 ft elevation will require an Scr of 11.9,
If you advance that to in at 66*, as in the example I previously explored, then the Scr becomes 11.7
the swept of this engine is ~665.7cc
To get 11.7;
665.7 ( CD-1)= Combustion chamber so;
665.7/10.7=62.2cc; TOTAL chamber size.
Therefore, to get the head volume;
62.2 less (deck, eyebrows, and gasket)=
62.2- (zero +5 +8.6)= 48.6cc maximum
and yur hoping the 039 FelPro is gonna hold.

Now remember, I guessed at ALL the advertised numbers, so I might be out a bit. This does not change the fact, that it's a very long way from the delivered 63 to the required 48, equals a required loss of 15cc, and then you still have to machine the intake to fit, then portmatch.
>And that was the point I wanted to make.
>And, normally not a problem, is, that dropping the heads drops the headers; which sometimes requires some header "adjustments".
>Also, I guessed at your operating elevation. 500ft either way will change the numbers a little bit. I was not striving for accuracy, Rather, shooting for "awakening". and that has not changed.
Happy HotRodding
------------------------------

Btw, I have a similar-sized cam, but a hydraulic flat tappet
230/237/110. The advertised is
276/286/110.
Mine has overlap of 61*
Giving 30 to the intake I get an Ica of 66*
My chambers are 63 +8.6 +5 -2.5pop-up= 74.1 Very close to what you will get. BUT, my swept is 752cc, and therefore my Scr is (752+74.1)/74.1= 11.15
If you have; 63 +5 +8.6 +zero deck= 76.6, then your Scr will be (665.7+76.6)/76.7= 9.69
At 9.69 Scr, your CCP might come in at 150psi,
and your bottom end performance is predicted to be less than the stock LA318
Whereas my bottom end is so strong, I have in the past, run it with a starter-gear (manual trans) as low as 8.59, and she would easily have run geared at 65=1600. But as I was sorting this out, I ended at
10.97 Starter and 65=2240, which gave a reasonable hiway economy with a killer take off. This car is a killer-fun street car.

 

[rumblefish360]

Absolutely


I have completely forgot about the pressure wave termination box! I better find his books, that's really interesting.

Yea! The How to build horse book. Very good information and practical knowledge proven factual through dyno testing. Further more, on various car shows with dynos, IE; Engine masters, Horse Power TV, etc…. They show the use of the extended collector pipe and EM tested lengths on different tube size headers.

I have the metal to build my own now. But now I have to replace my welder. 20 years of service and more than a couple of bad falls, I had to retire it.

I’m sure it’ll be a bit of a PIA to build because of the ability of limited real estate area.

Golden rule to the box, 1 cubic inch of box per cubic inch of engine for each box. 360 CID engine? Two boxes at 360 CID.

 

[rumblefish360]

You cannot use the 050 numbers.
You have to use the advertised numbers.
It says so right on the top line;
"seat to seat or advertised".

(Use seat to seat or advertised specs for Intake spec for best results)

Dynamic Compression Ratio Calculator
Number of Cylinders :​
Bore in Inches :​
Stroke in Inches :​
Rod Length in Inches :​
Static Compression Ratio :​	1)
Inlet Valve Closes ABDC :​	°
Boost Pressure in PSI :​
Target Altitude :​	(Feet)
​

As for this cam; Hughes fails to publish those numbers, so you have to guess, by looking at other older obsolete grinds.

History shows that Hughes cams are "hi-intensity." or at least higher than some others.
Here's my attempt at converting this to advertised?
238/242/108 ....... This might be;
284/292 gross advertised; it might be a lil less, and lashing might take a few degrees but there is no way for me to guess what it would be, so at this stage, I'm not looking for super-accuracy. I just want to estimate the point when the Intake valve actually closes.
From those numbers, I can guess the overlap to be ~72 degrees. Giving 36* to the intake side I get
180 less {(360+36) less 284} = Ica of ~68* This would be at about Split overlap.
To get 190psi with an Ica of 68*, in a 318+020 @500 ft elevation will require an Scr of 11.9,
If you advance that to in at 66*, as in the example I previously explored, then the Scr becomes 11.7
the swept of this engine is ~665.7cc
To get 11.7;
665.7 ( CD-1)= Combustion chamber so;
665.7/10.7=62.2cc; TOTAL chamber size.
Therefore, to get the head volume;
62.2 less (deck, eyebrows, and gasket)=
62.2- (zero +5 +8.6)= 48.6cc maximum
and yur hoping the 039 FelPro is gonna hold.

Now remember, I guessed at ALL the advertised numbers, so I might be out a bit. This does not change the fact, that it's a very long way from the delivered 63 to the required 48, equals a required loss of 15cc, and then you still have to machine the intake to fit, then portmatch.
>And that was the point I wanted to make.
>And, normally not a problem, is, that dropping the heads drops the headers; which sometimes requires some header "adjustments".
>Also, I guessed at your operating elevation. 500ft either way will change the numbers a little bit. I was not striving for accuracy, Rather, shooting for "awakening". and that has not changed.
Happy HotRodding
------------------------------

Btw, I have a similar-sized cam, but a hydraulic flat tappet
230/237/110. The advertised is
276/286/110.
Mine has overlap of 61*
Giving 30 to the intake I get an Ica of 66*
My chambers are 63 +8.6 +5 -2.5pop-up= 74.1 Very close to what you will get. BUT, my swept is 752cc, and therefore my Scr is (752+74.1)/74.1= 11.15
If you have; 63 +5 +8.6 +zero deck= 76.6, then your Scr will be (665.7+76.6)/76.7= 9.69
At 9.69 Scr, your CCP might come in at 150psi,
and your bottom end performance is predicted to be less than the stock LA318
Whereas my bottom end is so strong, I have in the past, run it with a starter-gear (manual trans) as low as 8.59, and she would easily have run geared at 65=1600. But as I was sorting this out, I ended at
10.97 Starter and 65=2240, which gave a reasonable hiway economy with a killer take off. This car is a killer-fun street car.

I like your guesstimate on the cam numbers. Makes sense. Probably pretty accurate IMO. With RPM, the ramming effect, though low through a dual plane will help the dynamic ratio and I’d bet still use low octane.

Excellent mention on first gear / rear gear ratio for a good take off from a stop number mention.

 

[1MeanA]

A 12 second 'easy mannered street toy' 318 Duster is a tall order. More cubes or lower expectations would be the answer. As has already been said just get a proper cam selected for the combo and that is all you can do. Over camming is going to ruin the street experience which is where this car will spend most of its time. I expect something in the 220-230 degree duration range will be max. The Comp Cams High Energy high rate of lift cams might fit the bill...something like the XE262 or XE268 which seems to be popular with the 340 crowd. People say they can be noisy.

 

[Bewy]

You are going to have a 3 digit problem getting a 12.4 quarter time, 'easy mannered', daily driver.
Those 3 digits are 3-1-8. I can suggest cams etc like the others have posted, but I think you should re-think your goals with that small engine.
And don't waste your time with the DCR calculator, like others do. The quoted 'seat' timing varies between manufacturers because they use different tappet lifts, anywhere between 0.004" & 0.008". So that is one variable that affects the final number....that is NOT taken into account. The real problem with the DCR calc is that it uses the IVC number as a guide to how much air is drawn into the cyl. That takes no account of how well the intake port flows & in your case with E heads, you would expect more air to flow into the cyl compared to a stock head.....but both would compute the same number for the DCR!!!

 

[rumblefish360]

Hence why I didn’t make anfuss with it in the first (and always) place. Head flow is never part of the thinking process. Also hence why I mentioned RPM & the ramming effect as a helper.

 

[rumblefish360]

@HP2 what is the local speed limits you will often drive?