dano
Evil Handy Man
If you are willing to go heads, cam, intake, converter, gears etc you're moving past a "mild build". If you want to go that far buy a core and build that. I like Rusty's 5.2 Mag and GM OD idea.
318 complete combo suggestions...
- Thread starter Danilo
- Start date
-
we are all presently awaiting those answers....
The 5.2 idea is great IMO only IF he has the money to get another engine and ignore the one he has in the car already. The 5.2 plus OD trans IMO is an excellent idea that can produce a good motivational experience without getting crazy. But yet provide good mileage with that acceleration.
3.55 X .69 = 2.4495 or just simply, a 2.45 final drive ratio. A VERY modest cam change IF desired would be the theme with that final drive ratio, like perhaps a mileage seeking cam (but yet still larger than stock) vs a performance cam.
3.55 X .69 = 2.4495 or just simply, a 2.45 final drive ratio. A VERY modest cam change IF desired would be the theme with that final drive ratio, like perhaps a mileage seeking cam (but yet still larger than stock) vs a performance cam.
Wyrmrider
Well-Known Member
what makes some he has a 9.2:1 motor?
Again in proper English....
Yes I am very interested in your stock bore 1969 318 Flat Top, Valve Relief, full floater pistons, as long as you are going to discard them on your rebuild.
I have a good home for them:
I have a good home for them:
I've done it more than once. It's a good combination, I don't give a rat's butt what the forum heroes say.
Man, I love that Duster!
66jim
Well-Known Member
Me too a few times.
Funny how people have done it for decades and with good results, but on a forum it's like the worst thing ever and if you do it your engine won't pull a greasy string outta a cat's butt. lol
nm9stheham
Well-Known Member
The warning about the Pistons is this:
You have the early 318 pistons, which are decently high compression. There are NO stock replacement type pistons for those anymore. The only stock type pistons sold are later low compression smog era pistons. Put those in and you will drop your low RPM torque and HP, and put a cam in and the low RPM gets lower.
That low RPM torque is important for a cruiser car.
So replace the pistons with some decently high compression, non-stock ones. That will require a re-balance of the crank, rods, and pistons as you can't find stock weight pistons anymore except the low compression, smog era ones.
nm9stheham
Well-Known Member
Yes the guy who sold his 'cuda to my son did that.... He exchanged the stock 273 for a 408 stroker and said it ruined the car for uses like the family going out for ice cream and such.
Wyrmrider
Well-Known Member
That block looks nice
did you mick the bores
maybe a hone and re ring with those pistons
how far down are they
did you mick the bores
maybe a hone and re ring with those pistons
how far down are they
All Done ^^^^
1969 318
9.2:1 Stock Pistons
Runs like the wind.
1969 318
9.2:1 Stock Pistons
Runs like the wind.
AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
- Joined
- Jan 19, 2014
- Messages
- 25,870
- Reaction score
- 13,175
For hours and hours of Part Throttle cruising; you can't beat cylinder pressure. You can get it in several ways.
If you want a strong low-rpm take off, you will need a combination of ; cylinder pressure, stall, and gears.
If you want a strong top end you ill need some rpm, and that spells cam. Or a set of worked heads and then a matching cam.
If you want to keep the factory stall, hiway gears, and a take-off at least as strong as the factory; you only have two choices;1) leave it factory stock, or 2) keep the cylinder pressure the same as it currently is.
But since you are changing the pistons, anyway;
1) you can increase the pressure, keep the cam stock, and reap the torque benefits, while maintaining the shape of the current power curve.
2) you can maintain the pressure with a bigger cam and matching increase in compression ratio, or
3) you can maintain the current pressure with a different type of cam, or one that makes more power at the same pressure., or
4) you can sacrifice some low-rpm torque, to get some higher rpm power, and then bandaid the situation with a higher stall TC.
To that end; it is almost hard, with a 318, to make too much pressure for a small performance cam; the swept volume is just 652 cc on a stockbore engine.
The KB 167s are advertised at 1.810 Cd so that totals 9.59 from crank cl to top of piston. If your deck was 9.600, this would get you a deck clearance of .0095 or 1.9cc. Adding 6.2 for an .028 gasket, and estimating 5cc for eyebrows and 60cc for the closed chamber heads, gets you a total chamber volume (with .038Q), of 73.1cc, and therefore a compression ratio of 10.0
This will nicely support a 268 cam with a 63*or greater Ica.
But that is waaay more cam than you need. So what do you do? The Q is .038 under a closed chamber head,which is real nice. Going to the .039FelPro will jack that up to .049 which some guys have trouble with detonation. You shouldn't, but some do.
So the .039 adds 2.4cc and the Scr becomes 9.7, which works with a 60* or later Ica, and you can install a 262 at that . A 262 could be a [email protected], which IMO, is a real nice 318 street cam, when matched to a decent compression ratio; not 7.8!
But what I would do, is try to run the .028 gasket at 10.0Scr with the .038Q. But, if it does detonate; I'm not averse to taking it all back apart, and custom machining the pistons, leaving the Q-pads alone.
Why?
Because at PartThrottle it will pay handsome dividends. And cruising for 6 to 8 hours is PT. Driving around town is mostly PT. Normal acceleration is PT. Ima guessing 98% of your driving hours are gonna be PT.
When will you be at WOT, with the secondaries open?
I'm guessing at KD when passing.
With 2.94s, 60 would be 3400 in second. This is a good number if you have delayed your all-in timing to it.
With 3.23s it would be 3740. This is a better number, and it is hardly likely to detonate, this late in the rpm band.
What about taking off from zero mph?
Well firstly; it is hardly likely that your secondaries are gonna open below about 2800rpm. And they may not be fully open until a lil later; YOU get to set that.
And secondly; contrary to popular opinion, you don't have to run your timing on the ragged edge of detonation. At WOT you are only ever gonna be below 3000 rpm but one time, in first gear, below 28 mph with 3.23s. So give the engine only as much timing as it asks for.
And thirdly; if the tires spin, the load goes away, the rpm flashes past 3000, and you are in the clear.
And fourthly; you can put a smaller carb on it, or just not floor the one you got.
And fifthly; you can reduce the load with gearing.
Detonation is caused by too much heat in the chamber for the octane (detonation-suppressant) in the gas you are using. So the solution is simple, keep the heat in check. Your solutions are; fresh cold air, proper AFRs,a properly sized exhaust system, proper ignition advance, engine loading, and finally coolant temperature. And I use some oil cooling under the valve covers.
The most likely time for detonation to occur is from stall to about 3600 rpm. And that is the reason for the sub .040 quench, which is actually squish. That tight space squishes whatever is in there, out across the chamber like a shotgun blast, stirring everything up; so every molecule of gas gets blasted to smithereens,and they have the best chance at finding oxygen to react with. This is not a detonation suppressant, but the complete mixing promotes an even chamber temperature, which prevents or reduces the primary source of detonation, namely hot-spots.
So yeah, I'd try 10/1 with a 262; even a fast-ramp 262. Check out Wrmriders posts. But like I said; I'm willing to take it all back apart; I'm 66,semi-retired, and got lots of time.
Besides; if you don't try it, you'll never know what coulddabin. And if you have to redo it, you got stories to tell your grandkids.
Oh yeah, be careful, each bigger cam (7*), with no other changes, raises your rpm of peak power about 200 rpm..... but reduces your bottom-end torque. Which usually calls for more stall rpm, also about 200 rpm. Before you know it, your stall rpm is higher than your cruse rpm, and the TC is slipping all the time, and your gas-money ends up heating the atmosphere.... instead of propelling your vehicle.
If you want a strong low-rpm take off, you will need a combination of ; cylinder pressure, stall, and gears.
If you want a strong top end you ill need some rpm, and that spells cam. Or a set of worked heads and then a matching cam.
If you want to keep the factory stall, hiway gears, and a take-off at least as strong as the factory; you only have two choices;1) leave it factory stock, or 2) keep the cylinder pressure the same as it currently is.
But since you are changing the pistons, anyway;
1) you can increase the pressure, keep the cam stock, and reap the torque benefits, while maintaining the shape of the current power curve.
2) you can maintain the pressure with a bigger cam and matching increase in compression ratio, or
3) you can maintain the current pressure with a different type of cam, or one that makes more power at the same pressure., or
4) you can sacrifice some low-rpm torque, to get some higher rpm power, and then bandaid the situation with a higher stall TC.
To that end; it is almost hard, with a 318, to make too much pressure for a small performance cam; the swept volume is just 652 cc on a stockbore engine.
The KB 167s are advertised at 1.810 Cd so that totals 9.59 from crank cl to top of piston. If your deck was 9.600, this would get you a deck clearance of .0095 or 1.9cc. Adding 6.2 for an .028 gasket, and estimating 5cc for eyebrows and 60cc for the closed chamber heads, gets you a total chamber volume (with .038Q), of 73.1cc, and therefore a compression ratio of 10.0
This will nicely support a 268 cam with a 63*or greater Ica.
But that is waaay more cam than you need. So what do you do? The Q is .038 under a closed chamber head,which is real nice. Going to the .039FelPro will jack that up to .049 which some guys have trouble with detonation. You shouldn't, but some do.
So the .039 adds 2.4cc and the Scr becomes 9.7, which works with a 60* or later Ica, and you can install a 262 at that . A 262 could be a [email protected], which IMO, is a real nice 318 street cam, when matched to a decent compression ratio; not 7.8!
But what I would do, is try to run the .028 gasket at 10.0Scr with the .038Q. But, if it does detonate; I'm not averse to taking it all back apart, and custom machining the pistons, leaving the Q-pads alone.
Why?
Because at PartThrottle it will pay handsome dividends. And cruising for 6 to 8 hours is PT. Driving around town is mostly PT. Normal acceleration is PT. Ima guessing 98% of your driving hours are gonna be PT.
When will you be at WOT, with the secondaries open?
I'm guessing at KD when passing.
With 2.94s, 60 would be 3400 in second. This is a good number if you have delayed your all-in timing to it.
With 3.23s it would be 3740. This is a better number, and it is hardly likely to detonate, this late in the rpm band.
What about taking off from zero mph?
Well firstly; it is hardly likely that your secondaries are gonna open below about 2800rpm. And they may not be fully open until a lil later; YOU get to set that.
And secondly; contrary to popular opinion, you don't have to run your timing on the ragged edge of detonation. At WOT you are only ever gonna be below 3000 rpm but one time, in first gear, below 28 mph with 3.23s. So give the engine only as much timing as it asks for.
And thirdly; if the tires spin, the load goes away, the rpm flashes past 3000, and you are in the clear.
And fourthly; you can put a smaller carb on it, or just not floor the one you got.
And fifthly; you can reduce the load with gearing.
Detonation is caused by too much heat in the chamber for the octane (detonation-suppressant) in the gas you are using. So the solution is simple, keep the heat in check. Your solutions are; fresh cold air, proper AFRs,a properly sized exhaust system, proper ignition advance, engine loading, and finally coolant temperature. And I use some oil cooling under the valve covers.
The most likely time for detonation to occur is from stall to about 3600 rpm. And that is the reason for the sub .040 quench, which is actually squish. That tight space squishes whatever is in there, out across the chamber like a shotgun blast, stirring everything up; so every molecule of gas gets blasted to smithereens,and they have the best chance at finding oxygen to react with. This is not a detonation suppressant, but the complete mixing promotes an even chamber temperature, which prevents or reduces the primary source of detonation, namely hot-spots.
So yeah, I'd try 10/1 with a 262; even a fast-ramp 262. Check out Wrmriders posts. But like I said; I'm willing to take it all back apart; I'm 66,semi-retired, and got lots of time.
Besides; if you don't try it, you'll never know what coulddabin. And if you have to redo it, you got stories to tell your grandkids.
Oh yeah, be careful, each bigger cam (7*), with no other changes, raises your rpm of peak power about 200 rpm..... but reduces your bottom-end torque. Which usually calls for more stall rpm, also about 200 rpm. Before you know it, your stall rpm is higher than your cruse rpm, and the TC is slipping all the time, and your gas-money ends up heating the atmosphere.... instead of propelling your vehicle.
Last edited:
Thanks! There is a lot to wade through here - and lots to learn. I am going through this slowly to be sure I have it all. I am not against using the stock pistons if they are in good shape - especially as it seems that is a good way to go (from what I am reading here).
If you are doing a full rebuild anyway, get the blocked decked to zero.
It’s a matter of expense to fix a problem that’s not really a problem or running what ya got and making due with it and enhancing what you have via of camshaft to help and minor mods to what you already have.
Enhance what you have at a relatively inexpensive cost or re build and modify everything at a much higher cost.
There is a larger return in rebuilding and modifying everything. But it is MUCH more expensive!
Your doing a total rebuild with aluminum heads? I’d skip the flat top KB slugs and go right to the dome slugs for more cylinder pressure and a nice cam.
Enhance what you have at a relatively inexpensive cost or re build and modify everything at a much higher cost.
There is a larger return in rebuilding and modifying everything. But it is MUCH more expensive!
Your doing a total rebuild with aluminum heads? I’d skip the flat top KB slugs and go right to the dome slugs for more cylinder pressure and a nice cam.
You can get good quench with the KB pistons without decking the block. BTDT.
nm9stheham
Well-Known Member
But would he not go past 10:1 static CR and then get in the regime where he could not readily run pump fuel? The AL head chambers are in the 62-65 cc range. Seems like the cam to run pump fuel with the significantly higher CR of domed pistons would be getting pretty big, so might not suit the 'cruiser' use, and get into fuel mileage issues too. (Of course, that's 'big' relative to a typical 268 cam.)
nm9stheham
Well-Known Member
It has its advantages.... But that ought to be judged from a teardown and bore/piston measurements. If the bores are worn, out-of-round and tapered, and worn pistons, then you'll end up with an engine with a lot of blow-by and more limited life. Good piston-bore fit is one of the fundamentals of a good running engine.
PRH
Well-Known Member
I haven’t built a 318 in quite a few years.
KB/Icon lists the deck height for the 318 as 9.578 instead on the 9.599 listed for 340/360 blocks(and 9.585 for Magnum motors).
I don’t know if that’s accurate or not, but my recollection is that the deck heights are different between them, but I wouldn’t swear to it.
So..... 318 decks shorter than 340/360...... fact or fiction?
I don’t have a 318 block here, otherwise I’d just measure it myself.
KB/Icon lists the deck height for the 318 as 9.578 instead on the 9.599 listed for 340/360 blocks(and 9.585 for Magnum motors).
I don’t know if that’s accurate or not, but my recollection is that the deck heights are different between them, but I wouldn’t swear to it.
So..... 318 decks shorter than 340/360...... fact or fiction?
I don’t have a 318 block here, otherwise I’d just measure it myself.
I run a 11-1 w/ cam @ a 224@050 on 93 pump.
2500 stall, 3.55’s in a 67 Cuda. I will work on the tune for less octane. I know I can do this. I just need time to heal (back) & good weather.
AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
- Joined
- Jan 19, 2014
- Messages
- 25,870
- Reaction score
- 13,175
I ran a tic under 11/1, w/cam @[email protected], on 87E10, @367 cubes
aluminum heads, fresh-air, clutch, 3.55s, and in a 68Barracuda at 3650 pounds. The bottom end was, by all opinions, BB strong.
If yur doin' it with iron; kudus to you.
-
