Need help, advice with my 318 build

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Pompis

Pompis

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I'm going to rebuild my 318 with desire to have much torque from idle and up. I want the engine to be strong and have relative good mpg, after that I want it to be "fast". So in that order I have choosed my parts to suit my needs.

I have bought:
KB167 30 over pistons
Scat I beam rods
302 heads
Comp Cams XE250H
Home made "Hedman Tight tubes"
Street Demon 625 cfm carb

When I bought the cam I was thinking of putting it on a stock 318. But that never happened so know I think the cam is on the tipping point on not to run it. Going to zero deck the block so I can utilize good quench. Haven't cc the heads but since I probably need to resurfacing the heads I haven't done it yet. And when I play around with diffrent quench distance and different chamber size I'm getting somewhere between 9.5:1 - 10:1 in static compression. And when I use those numbers in a dynamic compression calculator and set the cam as the specs I'm getting numbers between 8.27:1 - 8.72:1 DCR. I think those number are on the high side after reading on the subject. What do you think?

For know I'm going to run 2.76 in the rear and I have bought a lower first and second gear for my 904 to have lower cruise rpm but stil help take of. I know a bigger cam would need lower gear in the rear and therefor bad for MPG in the theory. I know I need to compromise since I cant have all my goals to the extreme at once, but I hope I can maybe make it work or do I need to change to the XE262H cam? But then I will give up some mpg and down low torque? Can I maybe retard the cam timing to help bleed of some cylinder pressure to lower my DCR?

I have start to do some minor "porting", cleaning and matching on my 302 heads. In the after math I maybe started to soon before knowing all that I wanted to have answer to before start grinding. Didn't know that the swirl was in the bowl and I have already remove some material in the bowls on one head. I think I want the swirl effect for my build and I hope I haven't ruin the advantage of running the 302 heads with how I have grinded the bowl. My horsepower goal just to put it there for some reference how I think and want it, I hope it will do somewhere between 275-300 hp at crank. But the torque, good mpg together with the engine and it's parts working together very optimised is my main goal. Don't know if it's doable with my part choices and if I'm dreaming to much.

Here some picture of my heads so far:

The untouched head exhaust port.
DSC_0672_zpsnh0jko1z.jpg


The grinded exhaust port.
DSC_0671_zpsu06epou5.jpg


The untouched head intake port.
DSC_0673_zpsx7zlshvh.jpg


The grinded intake port.
DSC_0674_zpsndqsdl8c.jpg


I'm not done completely with the head I started on since I'm taking it slow to only clean up and make it smoother and wider in some spots like in the thread 1wild&crazyguy started. What do you guys think and do someone have any good tips or opinions for me to do?

Thanks FABO
 
The 302 castings are known to crack, make sure that you have them checked before putting any time/money in them...
 
Looks almost identical to our build we did in our truck with the XE 256 H cam which made it into a super little engine. Great low end and a top end pull that suprised me.

I would suggest getting the valve stem/seat cutter 4726 and add positive locks. This gave me a clear .500" of available lift. Most 318 heads can get tight with lift close to .450" and the stem height can vary a great deal.

Hearing what your goal is and your rear gear ratio I would use the 250 if you stay with stock valve size.

[ame]http://www.compcams.com/catalog/COMP2011/pdf/COMP_Catalog_2011_362.pdf[/ame]
 
I like more cam here. Those are good heads for a 318 and cleaning up the ports will help a lot. Take a look at the Comp 265DEH.
 
I have done a very similar build on a Ford small block with even less cam duration, but with a lot of lift. I would suggest going to 1.6 rocker ratios; you can keep duration low but get more breathing with that to make up for it. The more you can open up the ports, then better you will like the top end RPM performance. You can use a thicker head gasket to make the SCR and DCR lower, but I have run 10:1 SCR with quench and low duration, and it was perfectly OK with premium gasoline.

For your use, I would stay with the duration in the 250's range but I would prefer a wider LSA for the mileage and torque, at least 112 degrees. I would be looking at the Lunati Voodoo 10200700. The Crane 'hydraulic economy' cams in the 70's made for good torque and mileage had a 114 degree LSA.

I like what you are doing there and the fact that you have your priorities clearly defined.
 
Awesome build. Very similar to my build except I am going for a bit more performance 2000-6000 RPM.

Ok on the cam, it has a built in 4 degree advance to make up for low compression engines, so installing it 4 degrees retarded(from factory) or what would be center will help. It may help to go a tad bit further maybe 2 degrees. Torque won't suffer much and with all that compression may help you run without detonation. Look into that if you keep that cam for sure.

As for a cam change, I would look at the 700, 701, 702 Voodoo cams from Lunati. They all play into your plan to a certain extent but all(even the smallest) will have more cylinder pressure bleed off than the Comp you currently have. They also have 4 degree advance so the same rule applies on your new build(Good Compression/quench) with them as well.

Next your heads, I am no expert head porter or anything but from the one picture your work so far looks good to me. To keep the good port for torque, just don't mess with the floor too much. Pushrod pinch can be reduced a bit but for your goals you don't need much. I think the heads stock, with what you have done and a valve job should get you to your goal no problem.

I believe your plan is solid, don't get discouraged.
 
You could have a small dish machined in the non quench side of the piston to get CR down
 
RustyRatRod said:
I like more cam here. Those are good heads for a 318 and cleaning up the ports will help a lot. Take a look at the Comp 265DEH.
Click to expand...
Without more cam I don't see it hitting 275 even with 2.02/1.60s in the 302s and a strong deal of port work.
 
BTW, I would not ever retard a cam just to lower DCR. It effects other performance aspects. Change the head gasket or open up the non-quench areas of the cylinder head since you are working on the heads anyway.
 
Thanks for all the opinions and guidance it really helps. I want to make the engine, trans, gearing and suspension work together well. My goal isn't really to make that 275 - 300 hp my goal is more to make we say that I'm going to have 250 hp at the crank. That those 250 hp is utilized and dialed in so I have a very efficient power band for my driving style.

If I play with the numbers and say that my 250 hp is reached at 4500 rpm. Then building the same engine with but with some more porting and higher lift and duration cam and we got 300 hp at 5500-6000 rpm. That 300 hp engine maybe have ~250 hp at 4500 rpm also but missing a whole lot from idle to 1500 rpm. I will probably seldom rev as high as 4500 + rpm so that 300 hp at 5500-6000 rpm will probably never be utilized for my driving style and if I doesn't change rear gearing It will probably be a slower from the line compared to the 250 hp engine with same gearing. So that's how I think and why I want to stay around that cam duration so I dont need to sacrifice to much low end power and mpg. But I will say that Lunati Voodoo 10200700 cam sounds very interesting. But since I live in Sweden and already have the cam I'm going to run it to see how it turns out but in the future a cam change feels possible. Those other cam also sounds good. I feel I need to test and see how my way of thinking and building this engine turns out before I decide to change cam.

I have a header flange that I'm going to build my own "Hedman tight tubes" on. They are laser cut from 0.472 inch steel (12mm) so they are thick and sturdy which I think is good? They got the "connected strips of steel" on the "wrong" upper side they need to be at the bottom so I can change spark plugs. But going to build the headers first then weld in new strips of steel at the bottom and then cut the upper ones.

But back to porting my exhaust side, if you look in the picture I have done very minor work at this side of port since I didn't have any gaskets to guide me to grind away any material. But now I got this header flange from a friend so now I have something to grind away to match against. Is it worth and good for the flow to take away all the material so I match the header flange?

DSC_0682_zps8ooxnlav.jpg


DSC_0681_zpsnbk0wdui.jpg


DSC_0680_zpsyxdpoaik.jpg
 
Are the header tubes going to be inside the holes in the flange? If so, then the hole area will be smaller.

I was taught that it was most important to avoid large increases in the exhaust port size from the valve to the end of the port, more important than a perfect match to the manifold, and that a modest step up in size to the manifold was not a problem. But, I am an amateur with porting, so perhaps some one more experienced will give the best advice.
 
1wild&crazyguy said:
OK...so here are the ex numbers, keep in mind i used a 1.65 flow pipe...i worked the snot out of the exhaust 'roof especially'...so that means back to work on the intake port so that these heads have a better N/A flow ratio...


the exh flow on my bench stock 'as cast' with 1.65 flow pipe peaks at about 132 cfm
here are the ported numbers from the port shown in my previous post.
-----cfm@lift----28'' w/ 1.65 flow pipe
.100--n/a
.200--96
.300--132
.400--148
.500--159
.600--179
w/o flow pipe, peak is 156cfm....

the exhaust ports on a 318 head basically kick *** for such a tiny port, the floor is sweet...and even with NO port window enlarging they flow fat.
Click to expand...

Do not open them up IMO. They already flow decent and will require more intake work if you go crazy on them. I know it is easy to focus on "port matching" but that is not what is important.
 
nm9stheham said:
BTW, I would not ever retard a cam just to lower DCR. It effects other performance aspects. Change the head gasket or open up the non-quench areas of the cylinder head since you are working on the heads anyway.
Click to expand...

Interesting, I believe the reason that there is a 4 degree advance designed into the "centerline" of most cams is to increase DCR on most older engines. So would you agree that at least taking that out and installing them "straight up" on a fresh 10:1 may help things? But yes you are correct when retarding it affects performance by moving the power band up.

Opening up the non quench would help but you don't want to risk any thin areas. Head gasket will effect quench.
 
The age of the engine has nothing to do with why camshafts are ground on an advance. The reason is very simple People always tend to overcam an engine. So, to compensate for that, grinders through the years have learned to grind 4* advanced in the hopes of picking up some of that bottom end torque lost to an otherwise poor camshaft choice.

Also, there is no set in stone amount of advance. Some grind 4*, some 3*, some 6* and some none at all. That's why it's always best to put the wheel on it.
 
Well by older I meant lower compression, as in most people like to over cam there low compression stock motor, so built in advance would help DCR. So if you are building a higher compression engine you can remove that advance, and that should help.
 
For example if the OP chose to run the lunati voodoo 10200700 then wouldn't it be better to remove the 4 degree advance on his engine combo?
 
Dartboy52 said:
Well by older I meant lower compression, as in most people like to over cam there low compression stock motor, so built in advance would help DCR. So if you are building a higher compression engine you can remove that advance, and that should help.
Click to expand...

I completely disagree. I would never in a million years purposely retard a camshaft.......unless it needed retarding to reach where the cam card said it is supposed to be installed. That's the stupidest thing I ever heard.

Just pick another camshaft.
 
RustyRatRod said:
I completely disagree. I would never in a million years purposely retard a camshaft.......unless it needed retarding to reach where the cam card said it is supposed to be installed. That's the stupidest thing I ever heard.

Just pick another camshaft.
Click to expand...

Wow, ok. Bit harsh there, I never thought installing a 4 degree advanced cam in a straight up position would get a "never in a million years" or "That's the stupidest thing I ever heard" response. I have read you can usually go 4 degree off the cam card either way for tuning. And that 4 degrees advanced is usually the sweet spot, so it is usually best to degree to the card.

I agree that the OP should pick another cam preferably something with a wider LSA, but they posted that they wanted to keep that cam, trying to give suggestions. If I was way out of line I apologize.
 
Dartboy52 said:
Interesting, I believe the reason that there is a 4 degree advance designed into the "centerline" of most cams is to increase DCR on most older engines. So would you agree that at least taking that out and installing them "straight up" on a fresh 10:1 may help things? But yes you are correct when retarding it affects performance by moving the power band up.

Opening up the non quench would help but you don't want to risk any thin areas. Head gasket will effect quench.
Click to expand...
My thought is that the cam retarding also effects other things, like the overlap; more retarding will likely result in more intake charge dilution. So the retard-the-cam approach will have other effects.

Also realize that I am heavily into getting a wide torque band so tend to favor cam advance in general. I can see some specific racing uses and hi-rev only setups where a more retarded cam makes sense. But that is not where the OP needs to go to reach his #1 and #2 goals.

Removing material from the non-quench areas is typically very shallow so si not that risky IMHO; it does not take much depth of grinding over that whole area to remove 2 or 3 cc's of wall material. Heck, I removed 7 or 8 cc's from some SB Ford heads once in that area, no problemo. And the OP can also look at the valve head shape to add combustion chamber volume; using valves with a V-shaped dish on the valve head easily can add 2-3 cc's of chamber volume.
 
RustyRatRod said:
The age of the engine has nothing to do with why camshafts are ground on an advance. The reason is very simple People always tend to overcam an engine. So, to compensate for that, grinders through the years have learned to grind 4* advanced in the hopes of picking up some of that bottom end torque lost to an otherwise poor camshaft choice.
Click to expand...
100 % agreed.... don't let poor customer choices ruin your cams' reputations! It's the only reason that makes sense to me why this is done so commonly nowadays, but was not done 'back in the day'.
 
Thanks for all response in the subject. I feel fine not going crazy at port matching as my starting idea was just to make the ports more even and a little better flowing. As I understand that smaller intake ports helps keep the port velocity up which in that case helps the lower rpm torque? Also I read somewhere that the 302 have a flow restriction to only support around 300 hp and that's why I want to do some minor work to help the flow and maybe in the future I want to choose a little bigger cam. So I'm trying find that sweet spot just in between stock and ported.

I'm probably going to put the tubes inside the flange so your right nm9stheham the area are going to shrink. I'm just building the headers to help the restriction in the exhaust to make the whole engine combo more efficient. So I hope that it's somewhat right to do since I already have them and like to build and fabricate my own stuff as much as I can.

Windage tray is something that might be thinking of also to make it more efficient?

Have some more grind questions about the combustion chamber. You don't want to have any sharp edges in the combustion chamber as those gets hotter? Is it alright to just smooth this edges? Going to buy a plexi glass and CC my heads soon and then I will find out where I'm going to be more exact where my compression will be. So if the chambers are to small the smoothing of the edges will lower my compression. Not going to touch the quench area I rather take material in the chamber. My second question about the chambers is it ok to grind it a little further than smoothing the edges and shape the non quench are to the cylinder shape or does that edge doesn't effect the combustion process?

DSC_0691_zpscmyschqe.jpg
 
You are overthinking things.
Your Dcr will be fine with quench equal to headgasket thickness.Just put it all together as you said in post one. Since you have the 250 cam,plug it in. Put enough spring in it so it revs decently.If you have room for 1.6 arms do it.Put the cam in so it's exactly on split overlap or a couple of degrees advanced to exact split overlap. Forget about retard.
With that size cam, almost anything you do to the heads will help when the cam starts choking things up..If you are financially able, I'd agree on a bigger cam being ok, so long as it has a fast rate of lift. In fact, I think your combo would be a very good candidate for a custom cam.
The 2.76s, even with a 2.74 first may be a real downer, but you can deal with that later.If your TC is a little loose, it may be fine. For sure you are gonna need a SureGrip or two big tall fat tires.
You don't say where you are in Sweden, and since the elevation in your country varies to nearly 7000 ft, there may be plenty of headroom in the Dcr. I would slam it together with .039ers at Zero deck and tune the snot out of it.Keep in mind that; higher-number gears, less loading, higher elevations, looser TC, reduced combustion chamber temps, and later or lower full power-timing, are all tools to be exploited with engines running on the edge of detonation.There is no command that the engine must receive full timing at any particular rpm. Nor is there a command that it must have a particular amount of power-timing. Let your combo tell you what it likes, and tune it from there, using the tools.
For your stated use sacrificing compression in the hopes of side-stepping a possible WOT problem, when none yet exists, is to sacrifice some part throttle driving pleasure' and possible economy.Yeah I know nobody likes to build their stuff twice, but with your stated goals and with your chosen combo, I personally, would be prepared to.Besides, when it's all done and behaving like a terror, and doing all the things you wanted it to, then you can report back with your personal success story.
And if you do have to mess with Dcr after it's built, for goodness sake don't retard the cam. Get a cam with a later closing intake, or machine the pistons as already mentioned.Just don't mess with the quench/squish pads.
BTW the new tranny ratios are a wide ratio set, with bigger cams,they work best with a wider LDA. At 250, this won't be an issue. As others have recommended bigger cams, this is something to keep in mind . However I can't see it being an issue for you, with your stated goals
Ok so that's my 2cents.
 
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