Very Mild 318 Build

-

Tylinol

Well-Known Member
Joined
Mar 10, 2012
Messages
92
Reaction score
22
Location
Nashville, TN
Hi everyone. After determining that my 69 Barracuda's 318 had more than enough wear to warrant a winter rebuild, I decided to start a new thread to get some advice on which parts to use. Coming from the Porsche world the selection is frankly pretty overwhelming...with old Porsches you have "the expensive option" and "the really REALLY expensive option - which in a way makes things easier if not less painful.

I'm intending to breathe a little extra livelihood into my 318 as I rebuild it, but probably not much. I'm married to the 14" poverty wheels and bias ply tires, so traction alone negates the point of putting out big power. It's going to be a daily driver (or weekly grocery getter since I work from home) so reliability and sturdiness is tantamount, with thriftiness being a not entirely irrelevant concern. To that end, I'd like to keep compression low enough (or timing mild enough) to not need premium gas. For durability's sake I'd also like to stick to cast iron heads.

With all this in mind, what would the recommended "recipe" be to live within these constraints but still have an engine more lively than the regular two barrel thrifter the car came with? Just port/polish the heads, bolt on a 4 barrel intake, and call it a day? OR is there more I can do without having a negative impact on the other aspects?
 
If you want to run a 4bbl, I would like to suggest a Weiand Stealth 8022 dual plane manifold. It has 318 sized runners, and ports. Appears to pick up where the old vintage edelbrock LD4B left off. These are new castings. It doesnt have a cast in provision for a coil mount, however you can probably use a 340 six pack coil mount bracket that bolts down to the intake mounting bolts. Dual exhaust , and try to hunt down a set of 68-70 vintage 340 exhaust manifolds. You can pick up repops of these if you cant find a good used set. Of course the usual internal stuff along with a mild cam, and an electronic ignition upgrade. A nice addition is an automatic timing chain tensioner from a 1990s dodge 3.9L V6. Front is the same as a 318. For some reason dodge didnt put these on the V8. Check rock auto. Use a 1992 dakota 3.9L to search. You can get one for about $30. Hope this helps.
 
Compression is not the enemy;
too much EFFECTIVE Cylinder pressure for the gas to be used is.
Wiki says you are at 600ft or so. You could stand a lil more cranking cylinder pressure (CP), no problem.
CP is the result of Static Compression Ratio (SCR), and the Intake valve Closing Angle (Ica). The best way to increase your pressure is with a high-compression piston..... but they are getting harder to find.
EFFECTIVE Cylinder Pressure (ECP), is determined by how much air the engine is ingesting. If you had a wee tiny one-barrel on your 318, you could run a lot of CP, cuz the engine would never physically be able to pull enough air in, to make a problem.
Another thing that comes into play is engine loading.
If you have a tall rear gear, like 2.76s, then 60 mph is about 3400 rpm in 2nd gear, so, the engine in second gear, is never gonna have to work hard, never get up on the cam, and never make a lotta EFFECTIVE cylinder pressure. So,again, you can run more cranking pressure.
If you build a low-powered engine, then you have to worry a lil about first gear. Again, with 2.76s, 3400 is now 35 mph, and this gear ratio will allow you to hit 4800@50mph. So now because the engine is low-powered,going from 35 to 50 is gonna take a while, so the engine will be working "hard". In your case, not to worry, because your engine would be lucky to hit 65/70% VE (Volumetric Efficiency), so it will still not be ingesting much air. My math says 440cfm@4800 @100% ,so 310cfm at 70%VE, So, again, you can run a good amount of cranking cylinder pressure.

Your engine only requires hi octane gas, when the combustion pressure in the chamber, gets to be high enough to cause a temperature rise, that causes detonation with a lower octane gas. Cylinder pressure that you measure with a gauge is only a part of this. And this detonation usually is directly related to how much air is being ingested. So if you had a cruiser that never saw WOT (Wide Open Throttle), and never sees over say 3600 rpm, for example, then you could run a lot of cranking cylinder pressure, because the EFFECTIVE pressure would always be low enough to burn cheap gas.
So then, you could run 87 all week, and then, on Friday, anticipating some romping on Saturday, you could tank up with fresh hi-test, and then let her buck.
The point is not to be afraid of SCR.
In today's engineering SCR means very little. Today, we use SCR to change DCR (Dynamic Compression Ratio), which is actually what the engine is seeing. We try to get the DCR , up into a zone that we know will be adequate for the intended useage.
DCR and SCR are cousins, the only difference being where the piston is at the start of the math. Scr uses the piston at the bottom of the stroke, and DCR uses the Intake Closing Angle. Neither of these care about how far the throttle is opened, but with Dcr , if one assumes the engine is not throttled nor exhaust choked,then one can assume a certain cylinder pressure working range for the intended fuel to be used.
Like; with open-chamber iron heads at sealevel, the upper cranking pressure limit, for WOT operation, is about;
160 for 91
155 for 89
150 for 87
The Effective cylinder pressure could be fractions of that, always less, and depends on the throttle opening, and rpm. At idle, for instance, the running cylinder pressure might be, I'm guessing, just 30 psi...... so you don't need even 87 gas for that. Running the primaries WOT (on a 150psi engine) will not even require 87 gas. The only time that engine might require 87 gas is with All 4 bbls open,and at going thru the torque-peak,and towards the power-peak a ways, where the engine is gonna be most Volumetrically Efficient, VE.
VE is simply the ratio of what volume of air the engine can ingest compared to it's volumetric displacement. For a 318, 100% VE is ~39.8 cubic inches per cylinder.
in conclusion;
Compression is not the enemy; to much EFFECTIVE Cylinder pressure for the gas to be used, is. With un-milled open-chamber heads I think it would be very hard to build too much pressure in a 318LA. and easy enough to drop some pressure with a lil cam and it's later closing intake angle.
 
Last edited:
Dual plane, performer or weiand
Small solid cam , 220@.050 .470 110
Sleepy cam that will pull hard under 5500
Figure out the chamber cc, then look at pistons. Mill if necessary to attain target ratio . Dial the cranking to around 150 psi , you can run 87 octane if ya want.
 
Dual plane, performer or weiand
Small solid cam , 220@.050 .470 110
Sleepy cam that will pull hard under 5500
Figure out the chamber cc, then look at pistons. Mill if necessary to attain target ratio . Dial the cranking to around 150 psi , you can run 87 octane if ya want.

Have you got that junk you were workin on runnin yet? I immediately thought of your build when I saw this thread title.
 
If you want to run a 4bbl, I would like to suggest a Weiand Stealth 8022 dual plane manifold. It has 318 sized runners, and ports. Appears to pick up where the old vintage edelbrock LD4B left off. These are new castings. It doesnt have a cast in provision for a coil mount, however you can probably use a 340 six pack coil mount bracket that bolts down to the intake mounting bolts. Dual exhaust , and try to hunt down a set of 68-70 vintage 340 exhaust manifolds. You can pick up repops of these if you cant find a good used set. Of course the usual internal stuff along with a mild cam, and an electronic ignition upgrade. A nice addition is an automatic timing chain tensioner from a 1990s dodge 3.9L V6. Front is the same as a 318. For some reason dodge didnt put these on the V8. Check rock auto. Use a 1992 dakota 3.9L to search. You can get one for about $30. Hope this helps.
I like your thought train but there are a few things I am not liking. 1: The Weiand MAY have bolt fitment issues. Bad core shift was present in mine and I had carbs the outside of the runners pretty good just to get the arp reduced size bolt heads into the intake to the head.
(Is use a Edelbrock Performer)

2: A 6 pack coil mount will not work. I tried this.
I made my own coil holder.
I’ll post pictures of 1 & 2 tomorrow.

3; IMO, 340 exhaust manifolds are a good but an expensive addition. (How does re-pops?) The OE exhaust manifolds will work just fine with a dual exhaust system. (TTI has a kit for your exact manifold casting numbers.)
 
Hi everyone. After determining that my 69 Barracuda's 318 had more than enough wear to warrant a winter rebuild, I decided to start a new thread to get some advice on which parts to use. Coming from the Porsche world the selection is frankly pretty overwhelming...with old Porsches you have "the expensive option" and "the really REALLY expensive option - which in a way makes things easier if not less painful.

I'm intending to breathe a little extra livelihood into my 318 as I rebuild it, but probably not much. I'm married to the 14" poverty wheels and bias ply tires, so traction alone negates the point of putting out big power. It's going to be a daily driver (or weekly grocery getter since I work from home) so reliability and sturdiness is tantamount, with thriftiness being a not entirely irrelevant concern. To that end, I'd like to keep compression low enough (or timing mild enough) to not need premium gas. For durability's sake I'd also like to stick to cast iron heads.

With all this in mind, what would the recommended "recipe" be to live within these constraints but still have an engine more lively than the regular two barrel thrifter the car came with? Just port/polish the heads, bolt on a 4 barrel intake, and call it a day? OR is there more I can do without having a negative impact on the other aspects?

What is your gear ratio, tire size and cars weight?
Is a new torque converter OK?
 
Last edited:
Ty; 1969 318's were pretty peppy. Factory specs are 230 hp @ 4400 rpm. 9.2 to 1 compression. 340 torque @ 2400 rpm. 140 lbs comp. Initial timing is TDC if it is the stock distributor. I wouldn't stray too much from this. Maybe 1 step higher on the cam, but not near a 340 cam. A rebore, if necessary. Grind any high spots from the combustion chamber to prevent hot spots. Grind any rough casting from the ports in the area under the valves. Do a gasket match for the intake and the exhaust manifolds. Heat riser valve must be free. Crossover passages must be free of carbon. Single exhaust is OK for now. Duals can be added later for more HP. New cam bearings, rods and mains, new standard oil pump. Check crank thrust before disassembly. A good valve job with seals. Throw the old timing chain on and take a compression test.

That ought to keep you busy for a while.
 
Ty; 1969 318's were pretty peppy. Factory specs are 230 hp @ 4400 rpm. 9.2 to 1 compression. 340 torque @ 2400 rpm. 140 lbs comp. Initial timing is TDC if it is the stock distributor. I wouldn't stray too much from this. Maybe 1 step higher on the cam, but not near a 340 cam. A rebore, if necessary. Grind any high spots from the combustion chamber to prevent hot spots. Grind any rough casting from the ports in the area under the valves. Do a gasket match for the intake and the exhaust manifolds. Heat riser valve must be free. Crossover passages must be free of carbon. Single exhaust is OK for now. Duals can be added later for more HP. New cam bearings, rods and mains, new standard oil pump. Check crank thrust before disassembly. A good valve job with seals. Throw the old timing chain on and take a compression test.

That ought to keep you busy for a while.

With headers, that's a 300 HP 318 recipe.
 
Oh geez, another 318 thread. :lol: There have been novels written here about cams alone. I will read along but won't comment unless someone steps in with some absolutely stupid recommendations. Then I can't help myself! :BangHead::BangHead::BangHead: :rofl: Here's a few popular threads:

2-Barrel to 4-Barrel Conversion
Cams for 318's
or look through the dozens of titles in the small block forums:
Small Block Mopar Engine
 
Last edited:
Oh geez, another 318 thread. :lol: There have been novels written here about cams alone. I will read along but won't comment unless someone steps in with some absolutely stupid recommendations. Then I can't help myself! :BangHead::BangHead::BangHead: :rofl:
LOL... is it any worse than another 408 thread???
:lol:
 
I like your thought train but there are a few things I am not liking. 1: The Weiand MAY have bolt fitment issues. Bad core shift was present in mine and I had carbs the outside of the runners pretty good just to get the arp reduced size bolt heads into the intake to the head.
(Is use a Edelbrock Performer)

2: A 6 pack coil mount will not work. I tried this.
I made my own coil holder.
I’ll post pictures of 1 & 2 tomorrow.

3; IMO, 340 exhaust manifolds are a good but an expensive addition. (How does re-pops?) The OE exhaust manifolds will work just fine with a dual exhaust system. (TTI has a kit for your exact manifold casting numbers.)

Click here for #3, the best exhaust OOTB.
Menu_ExhaustSytems

Number 2, coil bracket. The 6 pack bracket is not going to fit due to the runners being wider in the intake manifold. (The 6 pack bracket also doesn’t fit the RPM, FWIW...) The first picture below is the 6 pack bracket shown from the back showing the interference of the runners being to wide. The pictures there after are my fix to the problem after some FABO suggestions.
Thanks FABO! Your idea worked very well!
5DB1C751-41DA-4A33-9CC3-5277913D1B61.jpeg
B2615827-CD36-4715-8589-7F49F38097A1.jpeg
F617F38E-4E66-40D4-9C4F-63A11C6DFB84.jpeg
91EA3924-E69F-40D3-BD7E-5AF059AEDFEE.jpeg
 
Number 1 stated possible issue, attaching bolt issue pictured below. And the fix? A short time with a die grinder to widen the flat area for a flush mating surface for the bolt heads washed. Pictured below are both APR reduced head bolts (3/8 head) and standard hardware store bolts & washers. (9/16 head)

C5EE5DF8-70E2-483A-962F-2DCA2A9AECFA.jpeg
E9A2FF73-36C5-4248-9803-A1DC0CAD9EF9.jpeg
C045918B-3040-4891-A541-D367D44C40AA.jpeg
FF717AC8-AFF1-4364-B347-44A4B25676DF.jpeg
4B3F0213-8C8A-43F6-A148-8934ACFDC257.jpeg
D9A5A725-7BA5-4BB0-9C29-0CC7C4B228A4.jpeg
DA33ACEE-CFCA-47AA-AC4B-F0C88C100EC9.jpeg
28F69D91-1C9E-4EAC-AC06-BD74D0FE7AC3.jpeg
3FF5A0A1-B29F-4F32-83E6-095465C07599.jpeg
4C32D41C-AD1E-4744-8B2D-363F001705B0.jpeg
 
Don't waste money on exhaust manifolds up to and past 300 hp. See below. Great valve job, bore and hone with torque plate, 340 cam or less with matching valve springs, good double roller timing chain, Performer intake, Street Demon 625, 2 1/4 dual exhaust, and quick curve distributor.

https://www.hotrod.com/articles/mop...nto-300hp-crate-engine/?galleryImageId=372317


THIS ^^^^^^^^^^^

I’d like to know the info on what I asked.
Ether way, a small cam will do excellent in there. Without changing the torque converter, the biggest cam you can use is a 218@.050. I wouldn’t go that big if you have Hwy gears. 3.21’s at a min.
 
food for thought take a block to machine shop with your torque plate and tell him to hone using the torque Plate. Then go home bolt your head on flip the motor over on the stand and run a bore gauge into the bore and see how much taper and out of round you find. Then flip the motor back over take your head off put the torque plate on both of down spend the motor over and check with your bore gauge and see basically 0 taper and 0 out of round.

Torque plates do not simulate what a cylinder head is doing. They try to ,it's a good idea, but they just don't.
That doesn't even figure after the engine gets totally hot. So you probably want to get the engine block up and running temperature somehow stimulate all the stress forces and then go ahead and put the actual cylinder head you'll be using on it flip it over check with your bore gauge and map the cylinder out ...then take your torque plate and **** with the bolt torquing to where you can simulate what that bore was actually doing with the cylinder head torqued and then hone it.
 
food for thought take a block to machine shop with your torque plate and tell him to hone using the torque Plate. Then go home bolt your head on flip the motor over on the stand and run a bore gauge into the bore and see how much taper and out of round you find. Then flip the motor back over take your head off put the torque plate on both of down spend the motor over and check with your bore gauge and see basically 0 taper and 0 out of round.

Torque plates do not simulate what a cylinder head is doing. They try to ,it's a good idea, but they just don't.
That doesn't even figure after the engine gets totally hot. So you probably want to get the engine block up and running temperature somehow stimulate all the stress forces and then go ahead and put the actual cylinder head you'll be using on it flip it over check with your bore gauge and map the cylinder out ...then take your torque plate and **** with the bolt torquing to where you can simulate what that bore was actually doing with the cylinder head torqued and then hone it.
For a mild 318 build? That's pretty much unnecessary. And all that dinkin' around will get you 1 horsepower because you have perfect bores? Each to his own. Your choice on a mild 318.
 
Last edited:
For a mild 318 build? That's pretty much unnecessary. And all that dinkin' around will get you 1 horsepower because you have perfect bores? Each to his own. Your choice on a mild 318.

I was giving some real world info on @66fs post about torque plates, not to use or not use. Honestly, did you read it twice yet, because the point could be to not bother with the tq plate...
Most don't know how or when to use it anyhow.
Most of my posts are too just generally give information not to talk down on somebody's way of doing something unless of course it's destructive or useless. This is just an informative post more insight on torque plates
 
I was giving some real world info on @66fs post about torque plates, not to use or not use. Honestly, did you read it twice yet, because the point could be to not bother with the tq plate...
Most don't know how or when to use it anyhow
I read it but not twice. :BangHead::BangHead:
 
What is your gear ratio, tire size and cars weight?
Is a new torque converter OK?
Well, I've got the small rear end right now and I'm not 100% sure of the gear ratio. I imagine the diff won't last long so I guess the answer is whatever ratio I end up replacing it with. Tire size is F70-14 Polyglas on poverty wheels; I'm a big fan of the bias ply look so I'd like to keep it on these, part of my reasoning for a mild 318 vs something hotter - I'd just be spinning my tires. I think the weight is in the 2900 range? I've shaved a couple pounds of with the Borgeson power steering at least. I'd be OK with a new torque converter, especially while I'm in there.

As for exhaust, I just installed a TTI 2.5" manifold-back system before my 318 crapped out on me.
 
I was giving some real world info on @66fs post about torque plates, not to use or not use. Honestly, did you read it twice yet, because the point could be to not bother with the tq plate...
Most don't know how or when to use it anyhow.
Most of my posts are too just generally give information not to talk down on somebody's way of doing something unless of course it's destructive or useless. This is just an informative post more insight on torque plates

So... we should not use a torque plate... because it doesn’t simulate everything the running engine is doing? Your posts are confusing.
Well, I've got the small rear end right now and I'm not 100% sure of the gear ratio. I imagine the diff won't last long so I guess the answer is whatever ratio I end up replacing it with. Tire size is F70-14 Polyglas on poverty wheels; I'm a big fan of the bias ply look so I'd like to keep it on these, part of my reasoning for a mild 318 vs something hotter - I'd just be spinning my tires. I think the weight is in the 2900 range? I've shaved a couple pounds of with the Borgeson power steering at least. I'd be OK with a new torque converter, especially while I'm in there.

As for exhaust, I just installed a TTI 2.5" manifold-back system before my 318 crapped out on me.

Oh! TTI installed already, nice, OK then...
what gear ratio do you want to end up with?
Off the cuff, a cam intake duration with 210@.050, + or - 2*. No converter change needed.
 
If you want very mild then, put a performer intake 600 cfm and swap the camshaft for something in the 258-260 duration range. Get a 73 340 driver side manifold and a magnum 318 passenger.
 
-
Back
Top