Very mild 318 - Comp 252H vs 340 cam?

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Tylinol

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Hi everyone. I'm on that magical phase where I'm trying to pick a cam for my '69 318. Specs are as follows:

-675 heads, stock (albeit with a 3-angle valve job and some other rebuild work)
-block bored 40 over
-stock crank and rods
-KB 167 pistons yielding a calculated 8.94:1 CR
-stock manifolds with a 2.25" TTI exhaust
-Edelbrock 500cfm Performer carb
-4bbl manifold yet to be purchased (probably a Performer as well)
-manual brakes with factory AC

This car will be my daily driver, so I want good idle and vacuum but hopefully with enough cam to take advantage of some of my upgrades over the stock 2bbl setup and single exhaust. It would seem like the Comp 252H would fit the bill, and I've also heard the 340 cam referenced as a good choice for a mild 318.

Torque is priority over RPM; most of my driving is around town anyway (although I am planning on a ~350 mile road trip this November).
 
What torque converter (is it an automatic??) and what gears ?? What kind of car, Fury or Dart? Makes a big difference.
 
With no other head mods like porting and larger valves, I'd choose the 252h between those two. The 340 cam "in this instance" will be a little much, IMO.
 
Tylinol said:
Hi everyone. I'm on that magical phase where I'm trying to pick a cam for my '69 318. Specs are as follows:

-675 heads, stock (albeit with a 3-angle valve job and some other rebuild work)
-block bored 40 over
-stock crank and rods
-KB 167 pistons yielding a calculated 8.94:1 CR
-stock manifolds with a 2.25" TTI exhaust
-Edelbrock 500cfm Performer carb
-4bbl manifold yet to be purchased (probably a Performer as well)
-manual brakes with factory AC

This car will be my daily driver, so I want good idle and vacuum but hopefully with enough cam to take advantage of some of my upgrades over the stock 2bbl setup and single exhaust. It would seem like the Comp 252H would fit the bill, and I've also heard the 340 cam referenced as a good choice for a mild 318.

Torque is priority over RPM; most of my driving is around town anyway (although I am planning on a ~350 mile road trip this November).
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I ran a Comp 252 in my stock 318 1970 Duster many years ago and it had a dead stock idle and excellent low end torque with stock size tires and 2.76 gearing. The trans was a 904 with stock torque converter. Used an Edelbrock Performer manifold and Holley 600CFM carb. No head porting or distributor mods, just a fresh valve job. I swapped between the Holley and a Thermoquad 800CFM to see which got me the best mileage. The TQ had a bit better off the line response but similar mileage. Best mileage was driving 55 MPH from San Antonio TX to Joplin MO, and got 23.5 MPG. That was our family car for many years and always delivered excellent service. You won't go wrong with the 252 if you are looking for excellent throttle response and mileage in a daily driver.
 
Good questions - 904 auto with stock converter, '69 Barracuda. I'm unsure of the rear end gearing, but it's a 7.25 so I will probably be trying to find an 8.75 to swap out at some point soon anyway.
Tires are F70-14 Polyglass.
 
Tylinol said:
Good questions - 904 auto with stock converter, '69 Barracuda. I'm unsure of the rear end gearing, but it's a 7.25 so I will probably be trying to find an 8.75 to swap out at some point soon anyway.
Tires are F70-14 Polyglass.
Click to expand...
Very similar to the Duster I mentioned. I ran a 8.75 with 2.76 and the same sized tires. My tires may have been E70/14, but close!
 
Tylinol said:
Good questions - 904 auto with stock converter, '69 Barracuda. I'm unsure of the rear end gearing, but it's a 7.25 so I will probably be trying to find an 8.75 to swap out at some point soon anyway.
Tires are F70-14 Polyglass.
Click to expand...
Do you have a tach? If so, what is your RPM at 60MPH?
 
To check the rear gearing. Jack up the rear of the car and put on jack stands, put car in N and spin the drive shaft so one of the U joint caps in facing you and dot the cap with a paint pen. On one of the tires put a dot on the sidewall on the ground side. Now spin the tire and count how many times the drive shaft spins. This will give you a close guess as to the gearing..
 
I've never had the car up past 35 - the old nylon timing gear gave out before I got past the initial shakedown phase. Ultimately I'll probably have the car geared on the low side when I get an 8.75 rear end.

One last question on the 252H - it says I need different valve springs, but I can't find the needed springs listed anywhere? Were the stock valve springs really that marginal that they need an upgrade even with a mild cam?
 
Tylinol said:
I've never had the car up past 35 - the old nylon timing gear gave out before I got past the initial shakedown phase. Ultimately I'll probably have the car geared on the low side when I get an 8.75 rear end.

One last question on the 252H - it says I need different valve springs, but I can't find the needed springs listed anywhere? Were the stock valve springs really that marginal that they need an upgrade even with a mild cam?
Click to expand...
I used stock springs, just had them checked to be sure they were in good shape. Think a few of them needed some shims to bring them up to snuff though. No problems.
 
Tylinol said:
I've never had the car up past 35 - the old nylon timing gear gave out before I got past the initial shakedown phase. Ultimately I'll probably have the car geared on the low side when I get an 8.75 rear end.

One last question on the 252H - it says I need different valve springs, but I can't find the needed springs listed anywhere? Were the stock valve springs really that marginal that they need an upgrade even with a mild cam?
Click to expand...

Comp 901-16. Cheap and effective. I would not replace the camshaft without the correct springs.
 
The comp 252 is damneer a dead ringer for a stock 360-2bbl replacement cam. The 252 has 0.015" more lift/ every other spec between them, is dead nuts IDENTICAL in every way.
The last time I put a mild cam in a 318 it was a Melling 360-2 stock replacement grind. Yes it made a difference. Very noticeable gains. Dead stock smooth idle, 19" vacuum, great mileage and power was much improved. This was in an 83 D250 with untouched stock short block, untouched stock 727 and converter, 3.55s, and tall/skinny 235/8516, 10 plus. I added a performer (not rpm version) intake and carb, and hooker super comp headers at the same time as the cam, and a set of EQ 318 B heads. I am about to do the same with the 318 in my 78 Fury. No headers, and a set of machine shop fresh '302 casting closed chamber heads. This Fury isn't as heavy as the truck was,
And has a stock 904, with 2.71 gears and 5" shorter tires than the truck had (225/70-15 cooper cobras on the Fury) have either an Offy intake or another Performer to choose from on hand, as well as one of 2 fresh "Demon sizzler" TQs on hand, a 500 CFM AFB and a 600/625 comm AFB to choose between, on hand for the Fury's 318.
My fury actually don't run half bad and mileage is fantastic as is, and it even still runs it's original lean burn...
I just want *a little bit more" out of it.
 
Oh yeah. Forgot to say....
When I did the truck 318 I went with the 360 cam out of being cheap. At the time 1/2 the price of the 252, only missing the price associated with the COMP sticker. Not enough difference for the difference in price between them.
 
volaredon said:
The comp 252 is damneer a dead ringer for a stock 360-2bbl replacement cam. The 252 has 0.015" more lift/ every other spec between them, is dead nuts IDENTICAL in every way.
The last time I put a mild cam in a 318 it was a Melling 360-2 stock replacement grind. Yes it made a difference. Very noticeable gains. Dead stock smooth idle, 19" vacuum, great mileage and power was much improved. This was in an 83 D250 with untouched stock short block, untouched stock 727 and converter, 3.55s, and tall/skinny 235/8516, 10 plus. I added a performer (not rpm version) intake and carb, and hooker super comp headers at the same time as the cam, and a set of EQ 318 B heads. I am about to do the same with the 318 in my 78 Fury. No headers, and a set of machine shop fresh '302 casting closed chamber heads. This Fury isn't as heavy as the truck was,
And has a stock 904, with 2.71 gears and 5" shorter tires than the truck had (225/70-15 cooper cobras on the Fury) have either an Offy intake or another Performer to choose from on hand, as well as one of 2 fresh "Demon sizzler" TQs on hand, a 500 CFM AFB and a 600/625 comm AFB to choose between, on hand for the Fury's 318.
My fury actually don't run half bad and mileage is fantastic as is, and it even still runs it's original lean burn...
I just want *a little bit more" out of it.
Click to expand...

I've no doubt you're nearbout 100% dead on, BUT I don't believe Chrysler ground that 360-2 cam on a 110 LSA. It was very likely ground on a 114 or 115. The Comp grind being ground on a 110 helps cylinder pressure a little more and makes more power.

I could be wrong about the Chrysler LSA, but I've never known them to grind one down around 110 like the Comp.
 
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volaredon said:
Oh yeah. Forgot to say....
When I did the truck 318 I went with the 360 cam out of being cheap. At the time 1/2 the price of the 252, only missing the price associated with the COMP sticker. Not enough difference for the difference in price between them.
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And likely both were ground in the CMC factory in Michigan
 
Back a few years ago I used that comp simulation calculator and found the XE 256 did not give up any low end to the 252 but had a broader and higher peak.

It also had a WAY broader peak than the next one up- the 262, and only gave up 10 HP to that narrow 262 peak.

I'm dying for someone to try that 256 in a mostly otherwise unmodified setup with real world car and drive train specs.

I have one on the shelf but it's a way back burner project.

...although I think a well documented (as per the OP) 252 install would be a great shot in the arm for the sorely needed "one step up" 318 cam community.

I'd bet the comp HE and XE grinds are much more "modern" than the factory 40-50 year old Chrysler grinds.
 
RustyRatRod said:
I've no doubt you're nearbout 100% dead on, BUT I don't believe Chrysler ground that 360-2 cam on a 110 LSA. It was very likely ground on a 114 or 115. The Comp grind being ground on a 110 helps cylinder pressure a little more and makes more power.

I could be wrong about the Chrysler LSA, but I've never known them to grind one down around 110 like the Comp.
Click to expand...

I've been looking into the factory Chrysler cams. Specifically, at the Melling reproductions. The factory 318 is ground on a 109 degree LSA. I think the 360 2bbl cam is on 109.5 degrees.

Here's the PDF I've been pulling the numbers from: https://www.melling.com/wp-content/uploads/2017/03/engine-parts-camshaft-specifications-1.pdf
 
I'm with RRR's assessment, and
IMO
If you already have a 3602bbl cam, I would just drop that in. It's a 252. but low-lift. Tons of torque in your 8.94Scr engine.
Also, IMO, instead of spending all that coin on an 8.75, I would get me a higher stall convertor, in the range of 2600 to 2800,
I love my 2800. This is how it works in my 68 Barracuda;
the 2800 allows my 4bbl to wham open right at Zero mph. But I don't floor it yet. The rpm spools up, then at stall, it feels like a big ol' pick-up truck just snatched me out of a snowbank, and my car LEAPs off the line; I love that feeling. but sometimes it spins, and then, I do floor it! lol.
This 318 of mine is the low-compression 1973 model, all stock except a TQ/small-port iron intake; and with headers and dual 3" full length pipes.
I have run it with every gear from 2.73s to 4.30s except Not 3.73s ( I didn't have any)
I liked the 3.23s best for performance, but
liked the 2.73/2.94s the best as a DD, with the 2800TC.
 
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