best head for 318 street car

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steveh

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I'm starting to assemble parts for a future 318 build for my 69 GT convertible. Looking for ideas on head selection. Engine will never see the strip, but I do want it to have some respectable torque so it is more fun to drive on a near daily basis. Trying to compare apples to apples with this one so setting aside aftermarket heads for now.

What would be better, X, J or 302 castings? Willing to go slightly aggressive on the cam selection to make decent power, but but nothing too radical cause it is a daily driver and my wife cruises around in it occasionally.

Starting with head selection first cause I found a set of X and J castings nearby.

Not looking for a super hot rebuild, but I am tired of having to say "its just a 318". Thought about going with a 360 build, but it is a numbers matching car so why spend the extra money...maybe others have a different view which I would like to hear.

Currently running 8 3/4 with 3.55 gears and stock (old) rebuild on a 904 which will also get a refresh along with the motor.

Look forward to hearing everyones thoughts about this?
 
X or J's milled to 68cc, zero decked with KB flat tops for a 9:1CR, Air Gap, 650 and 268 cam. 302 are good if you want to build an engine 10:1 CR quench to run a lot more cam and are willing to port.
 
it's tough to spend $600 or so on a quality converter, but it will make a big difference
in you performance.
 
273 said:
X or J's milled to 68cc, zero decked with KB flat tops for a 9:1CR, Air Gap, 650 and 268 cam. 302 are good if you want to build an engine 10:1 CR quench to run a lot more cam and are willing to port.
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273,

1st option sounds more like the way to go...all else being equal roughly where would that put me in terms of torque and Hp...gonna search around for similar builds to see if I can find some justifiable numbers

Thx
 
ir3333 said:
it's tough to spend $600 or so on a quality converter, but it will make a big difference
in you performance.
Click to expand...

ir3333,

I'd like to say money is no issue, but it always is...Is the extra 600 worth it for a street build? Iknow there are alot ov variable to consider, but what is ideal for the combo outlined above
 
I'm thinking 350-375hp and similar torque
 
a good converter will make a night and day difference on the street.
...best to talk to Sean at Dynamic or any quality shop..they will want all your specs.
i know your question is heads and there are guys on here that can give you some good info but i think big ports and valves are better for hi rpm.
 
302's or Magnums. As much as I like 318/360 heads, the modern heads are just so much better off the junkyard Diplomats or Rams. The 302's will raise stock 318 compression out of the cellar..
 
A lot depends on the build and the wallet. Please describe both items.
 
rumblefish360 said:
A lot depends on the build and the wallet. Please describe both items.
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Rob,

Wallet is ok these days, but the car is a true daily driver, bout 40 miles to and from work with the occasional cruise on the week end. i dont want to sink a ton of money into it cause I also have a 67 cuda with a 340 which I will eventually build up to satisfy my need for a hot street car.

I'm thinking a set of 302s and a good set of headers is the way to go for this 318 which was freshened up about 10yrs ago. Car has a mild cam, older edelbrock intake and a 600 holley, stock 904 and 3.55 8 3/4 .

I'm trying to have the best of both worlds which is sometimes hard to do
sorry for the late response don't get on much during the week.
 
mopardude318 said:
RHS heads from brian @ IMM
Click to expand...

I agree for dollar spent besides cam these the biggest HP improvement you can do to any SB and cause they flow so well you can get away with smaller cam and make more HP than stock heads. The only real way to get CR out of a 318 is pistons, 99% of the time 302 heads are a waste of money on a straight swap no porting or milling with 318 open chamber would be lucky if you made 5hp because stock your only gonna get a .5CR bump, the only time I could see using them if you get a low mileage set for next to nothing mill and port the crap out of them to use a 268 or 274 cam on a stock short block even then a used set of magnums would be better. Fully ported 302 with big valves can't touch stock RHS.
 
273 said:
X or J's milled to 68cc, zero decked with KB flat tops for a 9:1CR, Air Gap, 650 and 268 cam.
Click to expand...

No way that makes 350hp... maybe with some good porting on the heads.

That's a 1hp/ci if it's lucky.

Heads like the RHS would be a big step up, but they cost more money. Better port, chamber, new castings. Figure how much it will cost to refurb a set of old castings and see where you land.
 
crackedback said:
No way that makes 350hp... maybe with some good porting on the heads.

That's a 1hp/ci if it's lucky.
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You could be right, my reference is those numbers is the 400hp 318 builds that a lot of you guys say no way to and what my Dynosim5 tells me. I think people get to hung up on HP number, I say build to a certain powerband that fits your needs and if that ain't enough power build bigger.
 
325 hp,in the powerband the car uses,pretty respectable. I was thinking 1.92 RHS,or EQ.230 to 240 cfm , solves the compression/hardened seat situation.RHS used to have LA valvetrain setup available,don't remember.Just a thought.
 
273 said:
You could be right, my reference is those numbers is the 400hp 318 builds that a lot of you guys say no way to and what my Dynosim5 tells me. I think people get to hung up on HP number, I say build to a certain powerband that fits your needs and if that ain't enough power build bigger.
Click to expand...

Sorry, your dynosim5 SUCKS... it's not close to real world power output. Hope you didn't pay for it.

Even the comp cams camquest can suck BIG TIME. I've seen it hit some stuff almost spot on and others be 50-100hp high and not close on peaks.

A 360 built the same as that 318 is LUCKY to make 350hp. Regardless of what some of the fantasy builds in mags tell you... 400hp 340's with stock heads and a XE268H... LMAO... NO!!!!
 
steveh said:
Rob,

Wallet is ok these days, but the car is a true daily driver, bout 40 miles to and from work with the occasional cruise on the week end. i dont want to sink a ton of money into it cause I also have a 67 cuda with a 340 which I will eventually build up to satisfy my need for a hot street car.

I'm thinking a set of 302s and a good set of headers is the way to go for this 318 which was freshened up about 10yrs ago. Car has a mild cam, older edelbrock intake and a 600 holley, stock 904 and 3.55 8 3/4 .

I'm trying to have the best of both worlds which is sometimes hard to do
sorry for the late response don't get on much during the week.
Click to expand...

Bowl port the stock heads with a 360 valves. This is a cost savings move over getting a better head (money spent) that will not really show a improvement worth the expense at the level your planning on.

The cam you select should have at least 8*'s more exhaust duration and a max of 12*'s. This offset seems to be the best in a split cam and stock to mildly ported heads.

Select the cam with the duration @ .050 in the powerband your cruising in and with as much lift as you can get without exceeding the head flows capabilities.

Use headers into mandrel bent 2-1/2 exhaust. Summit or Jegs exhaust kits are a good bang for the buck.

Whe writing this, I can not remember the Edel. intake you have. But the 600 CFM carb will do fine.
 
What is your cruising speed to work?
At what rpm are you steadily moving at?
 
Rumble, my .02. 1.88/1.60 ,in 318 heads,bowl work ,good valve job.Similar cam(210/218@ .050,112 l/c.,ran 13.20's @102 . Nice post.....
 
crackedback said:
Sorry, your dynosim5 SUCKS... it's not close to real world power output. Hope you didn't pay for it.

Even the comp cams camquest can suck BIG TIME. I've seen it hit some stuff almost spot on and others be 50-100hp high and not close on peaks.

A 360 built the same as that 318 is LUCKY to make 350hp. Regardless of what some of the fantasy builds in mags tell you... 400hp 340's with stock heads and a XE268H... LMAO... NO!!!!
Click to expand...

Ok :) well I go by a new HP standard called MAHP=Magazine Article HorsePower
So it's 350-375 MAHP
 
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