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.