Stock to mild 318 build "Need Advice"

[MoparOrNoCar1968]

12-02-2014, 11:08 AM #1
MoparOrNoCar1968
Status Offline
Junior Member


Stock to mild 318 build
I have got a 68 coronet 440 deluxe that I am in the process of building. It came factory with a 318 2bbl/ 8 3/4 rear end /Bench seat on the column. I'm in the process of stripping the motor apart as i'm typing this . It was running fine when i pulled it but i need a little more peppy action out of it. I'm 16 years old and my dad bought this car for me last summer and we drove until 2 weeks before i got my license and we decided to strip it down to repaint. (Typical rust in quarters,trunk, deck filler,and floor pans). My Dad has had muscle cars all his life and always been a Mopar fan . He owned 2 1970 challenger rallies that he sold int 1990 to put a down payment on our house with. But anyways the build is a plan that i came up with myself by searching here and there on similar builds to mine . Any advice would be greatly appreciated .

68 model 318 La
10:1 compression on pump gas
Crank turned .10/.10
0 decked
Machined / cleaned/ and new plugs and cam bearings
Factory rods
KB167 Flat tops with valve reliefs
.030 over bore
Milodon high volume oil pump
Milodon pickup
Milodon 6 quart deep sump oil pan
Comp xe284h cam kit ( cam and lifters) 284/296 duration
1998 magnum 5.9 heads
1.92/1.62 valves
heads are 59cc
.040 head gaskets
1.6 pro comp roller rockers
Comp double roller timing chain
Home porting heads
Summit Air gap dual plane La/Magnum intake manifold
Holley 770 street avenger
Custom Pushrods
New felpro gasket set
Hooker comp headers 1 7/8'' (3 inch collectors)


Any help and advice would be greatly appreciated. i already have the heads, intake , headers, carb, cam, and roller rockers by the way. Thanks

 

[Cranky]

The cam is pretty big for a mild 318 in a fairly heavy car. How fast do you want to go? The 340 ran good because of a fairly large bore, small cam and a smallish sized cam. Also, your headers are on the large side too. With a teen, you have to think small except when it comes to gearing. That is if you want it to run good on the low end too because I'm thinking it's not going to do very well down low with your combination unless you throw a lot of gear at it.....

 

[MoparOrNoCar1968]

I'm running 3:73 gear with a 2500 stall

 

[rumblefish360]

1-3/4 tube size for the headers.
You do not have enough stall or gear.
The Magnum heads should be replaced with better flowing heads. Though I like the 1.6 rocker ratio, IMO, when time and money allow, IMO, a move to Edelbrock Magnum heads or EQ's is what you should be looking at.

 

[MoparOrNoCar1968]

My mistake the headers are 1 3/4 . I just went and looked at them for the second time since I bought them .

 

[1wild&crazyguy]

I don't like the avenger carb.
700 holley dbl pumper is my rec, and if you use those heads...i would have them ported.

 

[rumblefish360]

Hey 1wcg, how do you do with the Magnum heads?
I like the DP suggestion. Always loved a good and well dialed in DP.

 

[Cranky]

A buddy and I played with a 72 318 Demon and have a 650 DP on it. Torker intake, 360 heads with pockets ported, .480 lift cam, headers STOCK converter and lots of gear in the rear and it runs 13.50 @ 102. The combination is totally wrong and it has no low end but once it hits 3000 rpm, it's game on lol. We just threw parts at it that were laying around the shop and it really surprised us that it ran that good.

 

[IQ52]

Me, not being the sharpest tack on the board, I'm wondering about using the Magnum heads on the '68 block. The Magnum heads require pushrod oiling so I guess you are figuring on using the AMC oil through lifters with pushrods that are made to pass oil? Are you using Chevy rockers on the Magnum heads. Are they ProComp Or Pro Magnum?

It is early morning, maybe I'm just confused.

 

[Cranky]

I've heard the magnum heads are supposed to be a bit better than the LA heads but are they really worth the extra hassle to make them fit? Imo, it's not too shabby to make a teen run mid 13's with a bad combo using bolt on junk. The only things new for this was headers, MP heavy duty rockers, ignition system and lifters. Even the short block has 115k miles on it......BEFORE we started modding it.

 

[1wild&crazyguy]

Hey 1wcg, how do you do with the Magnum heads?
I like the DP suggestion. Always loved a good and well dialed in DP.[/Q


With the stock int valve 'existing valve job' and bowl and short turn work only 'nothing extreme'... 232 cfm int is what i got on the last set i did for some marine dude on base here.
A good valve job would have changed/improved that number, but i was just doing a lil bowl work to help his 360 refresh get a lil boost to the power for a 12 pack of beer.

If i had the desire to use such heads or someone wanted put some robert dinero in my hands...im sure i could do better than that.

 

[MoparOrNoCar1968]

Never mind on the magnum heads just picked up a set of 340 x heads that have had new springs , valves and a little bowl work for $300 yesterday . Good score I reckon .

 

[1wild&crazyguy]

Never mind on the magnum heads just picked up a set of 340 x heads that have had new springs , valves and a little bowl work for $300 yesterday . Good score I reckon .

Good score. Would be nice to know some flow numbers, but if they were done right in the bowl work they should flow in the 240's cfm.

 

[Cranky]

Man, that's cheap....but....iirc, the 2.02 valve is a bit too big for the teen and will touch the cylinder wall. Maybe someone else will chime in with that. I never have done much work on small blocks but the 340 head is for a large bore. The 340 engine has a larger bore than even the 360 which is 4". The 340 bore is 4.040 stock and the teen is only 3.91

 

[1wild&crazyguy]

Man, that's cheap....but....iirc, the 2.02 valve is a bit too big for the teen and will touch the cylinder wall. Maybe someone else will chime in with that. I never have done much work on small blocks but the 340 head is for a large bore. The 340 engine has a larger bore than even the 360 which is 4". The 340 bore is 4.040 stock and the teen is only 3.91

It won't hit. plenty of room.

As for the chamber size, they are usually smaller than the bore sizes of the two 340/360, so though very close ... won't be a problem.
I like to scribe them and blend them to the bore size of block used.

 

[MoparOrNoCar1968]

Now with the camshaft. Im looking for a cam that beats pretty wild at idle but has good throttle response and will operate from about 2500-6000 as this will just be a street car to put these foxbodys around to shame. Is my cam too big ? Is it streetable. (By the way i want to keep it a hydraulic cam).

 

[rumblefish360]

A 2.02 in a teen will be fine.
With that cam, you just need some gear and a good converter. Go with 3.91's.

 

[dvw]

Why not buy a junkyard Magnum 360 and slap a performer RPM and a cam in it and call it good. At worst you may have to swap some engine quest heads on it. You'll be further ahead.
Doug

 

[rumblefish360]

That's kind of what I did. I pirated a 5.9 from a 2000 Durango. Installed Hooker Super Comp headers, 2-1/2 exhaust, 650 AVS. No cam yet.

The RPM intake needs a mod if the serpentine system is retained. The bracket that holds Alt. on covers the hole for coolent. While you can make do with a dremal and clearance for the hose, IF you want to use the Magnums A/C pump, the pump bolts right over the coolent hole.

You'll need to drill and tap one of the temp sensor sending unit holes (there's 2) for a by pass hose. Plug the hole under the bracket.

Keep in mind that the engine has no provision for a mechanical fuel pump. You'll need to instal an electrical pump. I used an Edelbrock pump. Very quite, not silent, better than most other pumps.

 

[Mopar-Charger]

Why not buy a junkyard Magnum 360 and slap a performer RPM and a cam in it and call it good. At worst you may have to swap some engine quest heads on it. You'll be further ahead.
Doug

I have a charger that had an original 318. Swapped a 360 into it.

360 rebuilt with 9.5 to 1 cast pistons
original crank, rods and windage tray
202 heads with competition valve job and ported to flow 260 cfm
Edelbrock RPM intake
Holley 750 rejetted
Large tube headers (1 3/4)
Mopar Performance P4120231 cam with .484" lift, 284 duration, 108 lsa, installed at 106 intake centerline.

460Hp and 480 TQ

Not bad for only putting $1000 into a $500 engine. (found a set of ported x heads for dirt cheap)

I have 3.55, and it puts to shame almost every car on the road (killed my buddies 2010 SS camaro) poor bowties and fords