318 cam suggestions

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Looking for cam suggestions for my 318. It’s bored .030 with flat top pistons and I’m getting ready to put on speedmaster aluminum cylinder heads on with an air gap intake and a 600 Holley carb. 727 with 2000 stall. posted from mobile
 
Gears and Compression ratio ?

Intended use ?

2000 rpm stall probably gonna be your limiting factor.
 
Compression ratio is the big question here. Throughly delve into this before you buy any new parts.

Compression and intake charge trapping efficiency are key to making a strong running combination.
 
Can’t recall gears off the top of my head. 2.73 maybe? Possibly 3.23. Not sure It’s an 8.25 from a roadrunner that the previous owner put in.
Compression is a best guess as well. 10:1 presumably once I get these aluminum heads on.
 
Can’t recall gears off the top of my head. 2.73 maybe? Possibly 3.23. Not sure It’s an 8.25 from a roadrunner that the previous owner put in.
Compression is a best guess as well. 10:1 presumably once I get these aluminum heads on.
You got gears and stall for mild cam and cr for a larger cam, your gonna need a cam least big enough to run 10:1 and pump gas, probably gonna need more stall and possibly gears down the road.


* if you have 10:1
 
Looking for cam suggestions for my 318. It’s bored .030 with flat top pistons and I’m getting ready to put on speedmaster aluminum cylinder heads on with an air gap intake and a 600 Holley carb. 727 with 2000 stall. posted from mobile
THat should be a decent combination with a old 340 grind.
 
Choose anything from 210-240 @.050 up to .510 lift and ground on a 110 or narrower LSA. Choose bigger numbers the hotter you want it.
 
The alloy heads when combined with a tight quench,
will support very high cylinder pressure on pumpgas .
Good luck getting there with flat-tops and a 340 cam.
It will never happen. See Note-1


If you ignore the pressure possibility, the guy in the next lane with an identical set up but pushing 200psi, is gonna teach you the high-pressure lesson.
Making Power is all about the power of expanding gas pressure. All the cams in any catalog cannot make power without compression.
Each bigger cam will just extend the operating range about 200 rpm higher. So all of a sudden, 5 cams later, your power is peaking some 1000 rpm higher, say 5400rpm, but your pressures is some 40/50 psi down from where it should be with alloy heads, and so, your hiway gears are keeping you in that oh-so-modestly-powered zone to say 4000 rpm/40 mph. Don't even imagine this combo can spin two tires bigger than the 205s that may be on it; 205s if yur lucky.
But
Match your cam to your Static Compression Ratio, so as to get a Dynamic Compression Ratio in the window of 8.8 to 9.1, WITH a tight quench, with the alloy heads and you are guaranteed to have a fun car
Do it right, and it will spin tires, make tremendous torque and great fuel mileage, and it will do it all on 87E10 gas.
Do it wrong, and you'll be burning best gas, having a dog off the line, and fighting detonation.
But with the 2.73 gears; you'll have a great passing gear at 40/45 mph.
Ask me how I know.
I'll tell ya; cuz I did it twice with same results. My loss is your gain.

Note-1
That 340cam, in already 4 degrees advanced, has an ICA of 64*..
To make a 9.0 Dcr will require an Scr of 11.3. and an SCR of 11.3 requires a maximum total chamber size of about 64.3 cc.
If the pistons are down at the usual .057, that is already 11.4cc.
The .028 gaskets will not survive this pressure without special prep, so yur gonna have to use the .039 Fellpros, making your Q already .096, which is more that double of where it needs to be. But, that FellPro gasket is 8.6cc IIRC.
So far then, we are up to 20cc, so the heads are gonna need to be 44.3cc. It doesn't really matter tho, cuz there ain't no Q with is combo, so there is no sense running it.

To get the Q you need, the pistons have to be up at the tops of the bores for an .039 gasket. for a deck clearance of zero, and a Q of .039, which is already baggy. But these pistons will need some eyebrows so lets call them 5cc, and the 8.6 gasket totals 13.6cc so now, the heads can be up to 50.7cc, to run the 64*Ica.

The next smaller Ica might be 61*Ica, and it will run at 11.1 Scr, for a total of 65.6cc, and now the heads can be 52cc

Once the pistons are up at the decks with a tight Q, there is a dozen ways to skin this cat, but the 340 cam should not be one of them. I guarantee you that after the tune is in, you will not be sorry about the money you spent in zero-decking.

And like has already been said, the 2.76s gotta go sooner or later. Whereas;
IMO, if you get the pressure up to a minimum 180psi(alloy heads), the 2000 stall can stay.
But if the convertor has not yet been ordered, I would wait until you know exactly how much cylinder pressure your 318 is making. For a streeter; the more pressure it makes, the less stall she'll need .

Oh and BTW, Yes, I have run a Scr of 11.3/ Dcr of 9.2 with alloy heads, and at .028Q......... on 87E10!,
for at least 1 year and many miles.
But when that smaller cam dropped lobes in it's fourth year. I dropped some pressure on purpose and installed the next bigger cam. Down to 11.0/ Dcr of 8.8, and pressure down to 180/185..
But-um, I have a 367, and a starter gear equivalent to 4.12s, so I didn't really need all that pressure, lol. Truthfully, I really miss having 195psi, but 185 on a 367 is still too much off the line. But it pulls pretty hard at the top.

If I was building a 318,
I'd still target a zero-deck, and use the .028 gaskets, but I would use closed chamber iron heads, setting the pressure to 165>170psi. Then; if the pressure is too high, I have several detonation-fighting tools in the tool-kit, namely;
Installing a spreadbore/vacuum-secondary carb, and staging the secondaries a lil later.
and/or slowing the timing down,
and/or retarding the cam,up to 4 degrees
and/or gaskets up to .012 thicker,
and/or the next bigger cam will delay the Ica another 3 or 4 degrees.

It's way easier to engineer 165 psi for iron, than 195 for alloys.
 
Last edited:
The alloy heads when combined with a tight quench,
will support very high cylinder pressure on pumpgas .
Good luck getting there with flat-tops and a 340 cam.
It will never happen. See Note-1


If you ignore the pressure possibility, the guy in the next lane with an identical set up but pushing 200psi, is gonna teach you the high-pressure lesson.
Making Power is all about the power of expanding gas pressure. All the cams in any catalog cannot make power without compression.
Each bigger cam will just extend the operating range about 200 rpm higher. So all of a sudden, 5 cams later, your power is peaking some 1000 rpm higher, say 5400rpm, but your pressures is some 40/50 psi down from where it should be, and so, your hiway gears are keeping you in that oh-so-modestly-powered zone to say 4000 rpm/40 plus mph. Don't even imagine this combo can spin two tires bigger than the 205s that may be on it; 205s if yur lucky.
But
Match your cam to your Static Compression Ratio, so as to get a Dynamic Compression Ratio a tic over 9/1, WITH a tight quench, with the alloy heads and you are guaranteed to have a fun car
Do it right, and it will spin tires, make tremendous torque and great fuel mileage, and it it will do it on 87E10 gas.
Do it wrong, and you'll be burning best gas, having a dog off the line, but with the 2.73s; you'll have a great passing gear at 40/45 mph.
Ask me how I know.
I'll tell ya; cuz I did it twice with same results. My loss is your gain.

Note-1
That 340cam, in already 4 degrees advanced, has an ICA of 64*..
To make a 9.0 Dcr will require an Scr of 11.3. and an SCR of 11.3 requires a maximum total chamber size of about 64.3 cc.
If the pistons are down at the usual .057, that is already 11.4cc.
The 038 gaskets will not survive this pressure without special prep, so yur gonna have to use the .039 Fellpros, making your Q already .096, which is more that double of where it needs to be. But, that gasket is 8.6cc IIRC.
So far then, we are up to 20cc, so the heads are gonna need to be 44.3cc. It doesn't really matter tho, cuz there ain't no Q with is combo.

To get the Q you need, the pistons have to be up at the tops of the bores for an .039 gasket. for a deck clearance of zero, and a Q of .039, which is already baggy. But these pistons will need some eyebrows so lets call them 5cc, and the 8.6 gasket totals 13.6cc so now, the heads can be up to 50.7cc, to run the 64*Ica.

The next smaller Ica might be 61*Ica, and it will run at 11.1 Scr, for a total of 65.6cc, and now the heads can be 52cc

There is a dozen ways to skin this cat, once the pistons are up at the decks with a tight Q, but the 340 cam should not be one of them. I guarantee you will not be sorry, after the tune is in.

And like has already been said, the 2.76s gotta go sooner or later. Whereas;
IMO, if you get the pressure up to a minimum 180psi , the 2000 stall can stay.
But if the convertor has not yet been ordered, I would wait until you know exactly how much cylinder pressure your 318 is making. The more it makes, the less stall she'll need, for a streeter.
I’m not going to lie this might be too much detailed information for me to comprehend. Time to figure out what all of that means.
 
I’m not going to lie this might be too much detailed information for me to comprehend. Time to figure out what all of that means.
Start with figure out compression then someone can figure out the dynamic compression ratio you need to run pump gas that will tell what size of cam you'll need. But might be on the large side so you probably will need at least a stall up grade and possibly gears. Or run thicker gaskets to run a smaller cam. We won't know until you calculate possible compression ratio.
 
It means he's trying to make himself sound smart.
Rusty, by now you should know better. By your knocking me down every chance you get, it shows one of three, maybe four things;
1) you ain't no Christian brother to me, and
2) maybe your sliderule is a lil rusty, or yur just too lazy, or too disinterested in helping a fella spend his money in all the most effective places.
3) yur just jealous cuz you didn't get to the table faster. Look I waited until post #13 to give you plenty of time to post something constructive; but all you came up with was a vague and cruel post #12 , and an even more cruel, post #16.
4) just maybe, yur not quite as smart as you think you are; here's a tip, trade in your sliderule for a laptop.
Please notice, I didn't question your smarts, I only compared yourself to yourself.
I have zero interest in proving any smarts, and no matter how often I tell you this, you don't seem to grasp it; kindof like you and Christianity; you just don't get it.
Look Rusty, I know you're a smart man; your history follows you around. But for some reason, yur like a crusty old man, liking to throw out insults to anyone not worshipping the ground you walk on. It just so happens that I seem to get the brunt of it. I dunno why you don't like me and I don't care anymore. But if you keep it up, you will be recognized on FABO not as TripleR anymore, but as TripleC; namely, the crusty old codger of crabbiness.

And finally, I'll tell you one more time,
if I have offended you in the past, speak now, so I can apologize, and release you from the misery that unforgiveness is causing you. Listen, if you know anything about the GoodBook you know that Unforgiveness will kill you; so speak! Let's get it over with, before the catching-away makes it impossible; tic-toc.
 
Rusty, by now you should know better. By your knocking me down every chance you get, it shows one of three, maybe four things;
1) you ain't no Christian brother to me, and
2) maybe your sliderule is a lil rusty, or yur just too lazy, or too disinterested in helping a fella spend his money in all the most effective places.
3) yur just jealous cuz you didn't get to the table faster. Look I waited until post #13 to give you plenty of time to post something constructive; but all you came up with was a vague and cruel post #12 , and an even more cruel, post #16.
4) just maybe, yur not quite as smart as you think you are; here's a tip, trade in your sliderule for a laptop.
Please notice, I didn't question your smarts, I only compared yourself to yourself.
I have zero interest in proving any smarts, and no matter how often I tell you this, you don't seem to grasp it; kindof like you and Christianity; you just don't get it.
Look Rusty, I know you're a smart man; your history follows you around. But for some reason, yur like a crusty old man, liking to throw out insults to anyone not worshipping the ground you walk on. It just so happens that I seem to get the brunt of it. I dunno why you don't like me and I don't care anymore. But if you keep it up, you will be recognized on FABO not as TripleR anymore, but as TripleC; namely, the crusty old codger of crabbiness.

And finally, I'll tell you one more time,
if I have offended you in the past, speak now, so I can apologize, and release you from the misery that unforgiveness is causing you. Listen, if you know anything about the GoodBook you know that Unforgiveness will kill you; so speak! Let's get it over with, before the catching-away makes it impossible; tic-toc.
lol
 
Back to the original post. What is the purpose of your build?
cruising, quarter mile or fun street? It makes a big difference.
 
I'll save some time for a few of the usual suspects-

Choice A- stock 318 cam

Choice B- .650 lift (mild) cam with 4000 stall converter and 5.13 gears
(...and zero torque until 3000 RPM)

That's it.

Pick one.
 
Now we're getting somewhere. You need low end torque that will pull hard from idle and rev nicely to about 5200.
without machining for much higher compression, like Toolmanmike, i'd look towards stock 340 cam but with a little less duration (204 / 214?) and 3.23 geared rear.
 
I’m almost positive the rear end already has 3.23. I’m learning that going with a 2000 stall when having the transmission rebuilt was possibly a mistake.
 
Now we're getting somewhere. You need low end torque that will pull hard from idle and rev nicely to about 5200.
without machining for much higher compression, like Toolmanmike, i'd look towards stock 340 cam but with a little less duration (204 / 214?) and 3.23 geared rear.
With 10:1 cr ?
If that is what he's got.
 
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