Eddies Vs 915 J's

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frosty_the_punk

frosty_the_punk

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Ok, so I have a nice mild little 318 in my valiant. it's dyno'd at about 350hp @ 5700RPM

10.2:1 comp
Hydraulic cam 227/242 @ .050. 107lsa. about .480 lift
Performer RPM. 650AVS
Stock 915 J heads with ferrea 2.02/1.6 valves and a 3 angle job
1-3/4" headers

I have a set of bare Edelbrock heads on the shelf. Also a complete six pack setup with new carbs and all the promax tuning stuff

I was looking at setting the heads up with milodon 2.08"/1.6" valves
Maybe get someone to clean up the guides and do a minor amount of port work.

I am also looking at a set of 1.6 roller rockers to bring lift up to the 500 mark.

If I put these on the 318, how much horsepower could I realistically expect to gain..if any?
 
A few thoughts - the Js with a decent valve job should flow around 220 at .550, but you're not anywhere near that lift. The numbers at .300 lift would be more important and the Js should be around 175. The numbers I've seen (in testing my stuff and what I've read) give the RPMs about 10 more cfm from .200 or so up throughout the lift range and having about 20cfm more at .500.
In terms of the getting "the heads" done - I'm assuming you mean the Js? I think 2.08s is a little much. I prefer 2.05/1.65 for my factory heads when porting at least to a Level II (meaning working the entire port but not maxxing out). At that level they would be making similar mid-lift numbers to the RPMs, possibly a little more. But the camshaft will still limit how much of that better port you take advantage of.
IMO - the 1.6s might add some lift but you really need a new cam to match whatever head choice you make.
The 6bbl is a horsepower robber. Unless eye candy is what you want, stick with the RPM/4bbl combo.
With the right cam and valve springs - I'm sure you can get another 30-50hp but you will need to raise the rpm range you have now to reach that.
 
I don't think you would gain much switching heads on a 318 like yours, maybe 20HP tops. If it was a strong 360 or stroked you would see a bigger gain. I wouldn't bother with a 2.08 valve even on a stroked sb. The 6 pack would work better on any setup properly tuned until you get up over 5,500 rpm then it starts to fall off but it looks way better than any 4bbl set up!!!
 
In my case - it's dyno proven. After tuning with both, the RPM/4bbl was over 13% higher horsepower and torque on the same long block over the factory 6bbl. The big block 6bbl is another matter.
 
That's a ton of head with 2.08 valves on a 318. I made the mistake of overheading a 318 and I saw 0 gains whatsoever. In your case I think the otb eddys with a little port match and cleanup will be perfect and don't overcarb it, it will be a waste. That engine can only use so much cfm and the rest is just a waste. Yea they look cool and may help at 6000 rpm a little but I would stick with single 4
 
Cheers guys, This is what I was hoping not to hear but feeling i probably would.

I think it makes sense to get much gain out of the edelbrock heads a cam change is definitely in order.

As for the six pack manifold, I am keen to run it for the "wow" factor and am tossing up ideas in my head as to the best way to improve it's performance to make it equal or even surpass a modern dual plane 4bbl.

If I go ahead with these modifications I plan to take photos along the way and start a thread detailing my mods. However I'm not a professional by any means and have limited knowledge of air flow characteristics.

But that will be another thread lol.
 
Hi Frosty, I have seen a 340 out her in Australia make no more power when swapping from ported j heads to ported edelbrocks.

From what I have seen a j/915 head flows around 200 to 210cfm with a 2.02 valve and no porting. A friend had a set of std 2.02 valve edelbrocks flowed recently and they were 240cfm just with seats tidied up no porting at all.

The closed chamber head should give you a little bit more comp, assuming that your 915 heads are still around 68 to 70cc and haven't been decked a lot but then you will want more cam to take advantage of it all.

The 20kg saved over the front end of that little VC would help out as well.

Go the VC!
 
Cheers Evil66

The J heads aren't ported at all and if i swapped to the edelbrock heads they would be ported substantially.

regarding compression, I run dome tops in my 318 so I would have to have the chambers worked on the eddies to avoid piston/head problems.
 
How much power are you looking at gaining? If you want to good kick in the butt, I would just swap the cam out for something better, Solid flat tappet will do wonders! Something in the high 230's intake, low-mid 240's exhaust and .500-.525 net lift will work very well.
 
Don't over build a 318. Without more compresion the difference will be little. I put a bigger cam in a 9:1 motor and gained .1 at the strip. It would work OK on the street but bog at the sript with the extra bite.
 
maybe find a 340 or 360 and build that with the eddy heads...

that way you can drive it now until you are ready to drop in the new engine :D
 
moparlover said:
maybe find a 340 or 360 and build that with the eddy heads...

that way you can drive it now until you are ready to drop in the new engine :D
Click to expand...

:banghead::roll: Edit: I understand your point however "just build another engine" isn't a very economical solution for me, dollar wise.

Especially living in australia where 340 engines basically don't exist at all, and a bare 360 block is worth $800

plus the fact that I've spent about $5000 on this 318's bottom end, which should now be good for 7000RPM all day.
 
MRL Performance said:
How much power are you looking at gaining? If you want to good kick in the butt, I would just swap the cam out for something better, Solid flat tappet will do wonders! Something in the high 230's intake, low-mid 240's exhaust and .500-.525 net lift will work very well.
Click to expand...


Cheers Mike, I've been looking at the COMP cams FL solids actually.

I was considering 239/243 cut on a LSA of 110 or 112 if I can get away with it and a couple of degrees installed advance.

Lift at the lobe would be .350"/.361"

With this cam, I'd use 1.6 rockers and the Edelbrock heads would be ported to max effort, so around 290CFM at .550"

I don't know what sort of power is possible but ideally I'd like about 430-450hp with an RPM limiter set at 7000 tops. or maybe I'm dreaming?
 
Ted Carlson said:
Don't over build a 318. Without more compresion the difference will be little. I put a bigger cam in a 9:1 motor and gained .1 at the strip. It would work OK on the street but bog at the sript with the extra bite.
Click to expand...

This thread is about swapping cylinder heads. If I need more compression, i'll get it during the head swap.

please keep in mind this 318 isn't a junkyard special, it's fully balanced with a steel crank, H beams and forged pistons with dome tops and a zero deck.

Like I said, current compression ratio is 10.2:1 with the J heads.

I could easily get 12:1 with the eddies, but I don't think that will be necessary.
 
I think this will turn into a "how to match parts" thread...lol.
If you are "max porting" the RPMs you will need a cam with more lift and duration than the FL lobes you mention and compression to make it work. Take away lash and geometry & you have valve lift around .515. With the FL duration you note and the relatively low valve lift the ports will be way too large for that combo unless you up the compression above that 12:1. If you have them and they are "as cast", I'd leave them at gasket match and hand blend the bowls. You will be losing too much by going "full boogie" if you indeed wnat a cmashaft that small. I'd suggest looking into the Bullet FF277/373 or something similar if you do "go big". You have a short stroke, small bore engine. You have two choices: give it compression, cam, and port volume and rev it high (like peak power in the 7K range and shifting at 8) or keep the port volume down to keep everything else midler to make more torque where you can use it.
 
450hp. Eddys will get you that without any porting. Dont fully port the heads, just a good valve job and some minor clean-up. Spend your money wisely, put a good solid cam in it, with the right springs, good rocker arms and let er rip.
 
frosty_the_punk said:
This thread is about swapping cylinder heads. If I need more compression, i'll get it during the head swap.

please keep in mind this 318 isn't a junkyard special, it's fully balanced with a steel crank, H beams and forged pistons with dome tops and a zero deck.

Like I said, current compression ratio is 10.2:1 with the J heads.

I could easily get 12:1 with the eddies, but I don't think that will be necessary.
Click to expand...
How do you have zero deck with a dome piston? In your orig post you said you dynoed at 350 HP at 5700 rpm.... Then you said you want to get to get 430 to 450 HP.. I don't know how your gonna gain almost a 100 HP over a already decent set of heads, unless you turn more RPM. Its a small displacement engine, its gonna be a high rever to get anywhere near 450 HP.. I think a custom grind solid cam is the best bang for the buck in this situation....
 
moper said:
I think this will turn into a "how to match parts" thread...lol.
If you are "max porting" the RPMs you will need a cam with more lift and duration than the FL lobes you mention and compression to make it work. Take away lash and geometry & you have valve lift around .515. With the FL duration you note and the relatively low valve lift the ports will be way too large for that combo unless you up the compression above that 12:1. If you have them and they are "as cast", I'd leave them at gasket match and hand blend the bowls. You will be losing too much by going "full boogie" if you indeed wnat a cmashaft that small. I'd suggest looking into the Bullet FF277/373 or something similar if you do "go big". You have a short stroke, small bore engine. You have two choices: give it compression, cam, and port volume and rev it high (like peak power in the 7K range and shifting at 8) or keep the port volume down to keep everything else midler to make more torque where you can use it.
Click to expand...

Cheers, I will have a look at the bullet cam lobes. but I think as I want to keep it streetable 248 @ 50 might be a tad much duration?

When I say a rev limit of 7k I mean that's where i'll shift, so peak power would be in the mid-high sixes.
 
MRL Performance said:
450hp. Eddys will get you that without any porting. Dont fully port the heads, just a good valve job and some minor clean-up. Spend your money wisely, put a good solid cam in it, with the right springs, good rocker arms and let er rip.
Click to expand...

Thanks, I guess I haven't had a lot of faith in edelbrock's "out of the box" performance after reading so many "no gains" after swapping from iron heads.

I guess that's why i need the cam change to go with it!

would high 230's low 240's in duration @ .050 and .500"-.525" like you suggested earlier be potentially sufficient to reach the 450hp mark?

Also would 110-112 be too wide for the lobe separation? I'm trying to keep as much idle vacuum as i possibly can (would actually like to gain some over the current cam)

That's exactly the range of solid camshaft I've been looking into.

Would a 2.02" valve be sufficient or would a 2.08" be better?
 
replicaracer43 said:
How do you have zero deck with a dome piston? In your orig post you said you dynoed at 350 HP at 5700 rpm.... Then you said you want to get to get 430 to 450 HP.. I don't know how your gonna gain almost a 100 HP over a already decent set of heads, unless you turn more RPM. Its a small displacement engine, its gonna be a high rever to get anywhere near 450 HP.. I think a custom grind solid cam is the best bang for the buck in this situation....
Click to expand...

Dome top pistons have a compression height just like any other piston. They are essentially a flat top piston with a wedge shaped dome, only the dome part sticks out above the deck. the rest is 0.000" below the deck. hence it's a zero deck engine with a dome top.

It dynod 350hp at 5700 with stock heads.
With better flowing cylinder heads an engine makes more torque higher in the RPM range, often moving peak horsepower up several hundred RPM.

I was never expecting 430-450hp with the current camshaft and a head swap alone, but wanted opinions as to whether the gains (beyond 350hp) were worth it while leaving the cam and only changing the heads.

This engine is 323ci, it's only 5.2% less displacement than a std bore 340. With the right cam and heads it could make serious horsepower.
 
With what you mention as cam size, and a rough idea of the RPM's mid-lift abilities - I feel confident saying you can eclipse the 400hp mark with a maxrpm of 7K. Peak power will be lower than 7, but so will your total output be lower than it could be with a larger cam. I don't think 450 will come with the lower end you have. Especially given the need to customize the pistons to work with them. If you had a clean slate, could run a flat top, high static ratio, a tight chamber, etc etc etc, then yes. I think it's doable with enough cam and compression. But not with what you have as a shortblock. I also think the compromise with adding the heads will be loss of some lower end torque. You will make more power at peak torque - but it will be a more peaky power curve, and pushed up in the rpm band from where it is now. The car will still feel faster - the heads take a bunch of weight right off the tallest point over the front wheels.
 
What the car weigh and what MPH has it put down at the track?

You could get tons of power out of that 318 on the right dyno. Whether it proves it at the track????? That's the $64,000 question.

Increasing the Ede valve size on a 318 is a waste of funds IMO. Run them with a 2.02 and a good valve job.
 
crackedback said:
What the car weigh and what MPH has it put down at the track?

You could get tons of power out of that 318 on the right dyno. Whether it proves it at the track????? That's the $64,000 question.

Increasing the Ede valve size on a 318 is a waste of funds IMO. Run them with a 2.02 and a good valve job.
Click to expand...

Exactly ^^^^^^^^ dyno numbers are pretty much worthless since there are dynos out there that are happy as a lark. Not to mention I've never seen a dyno lay down any numbers at the drag strip. The drag strip oughtta be the end all be all in terms of figuring power. Anything else is just a bunch of bullshit.
 
All very good points, slam a custom grind solid in that baby and be done with it already! Swaping to the ed heads is not gonna be a huge improvement...They are lighter, but what you got is already there and making decent power
 
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