318 stroker - Piston itch....

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Moparmal

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I was reading through the tech archive - and Id really appreciate it if BJR or Moper (or anyne else who knows exactly what I need) can help me with the following:

I have a assembled 349 stroker 318 (360 crank)

I have p-v clearance problems with the TRW forged slugs I got shaved down.


What KB Forged slug can I use with a 360 rod and crank that will keep my comp up around 10:1, but give me the P-V clearance I need to run a .540 lift cam?

Im running OPEN chamber 318 heads with the chambers run out to 63 cc
(2.02 / 1.60 valves - They flow 230/208,,,,they've been seriously welded and interfered with)

I want to use my 360 rods,

Diamond forged are NOT on the agenda because of cost.

Any advice?
 
I believe that I put a part # for pistons in the thread, but they will have to be valve relieved as they are flat tops. I think that the compression height was 1.658 but you'll have to look in the thread as I posted it there.
The part # is LC371P its a 67 - 84 piston from federal mogul. The piston is cast not forged but forged ones would be expensive and that why we used these and valve relieved them.
 
The 2.02 valves are going to hurt your performance as they are too large for the port size and this is why I used the 1.78 and didn't have to valve relieve the pistons very much. The 2.02 is going to stick out a good bit further and the piston will need to be relieved much more. This engine shouldn't need more than a 1.88 valve as the largest as the bore just can't support any larger. Once again error to the conservitive side and it will work better. The air flow #'s that the heads made with the 2.02's are also achieveable with a 1.78, and should have been used. The 2.02's are going to hurt port velocity severly, so Tq. and Hp will suffer.
 
While I dont really agree 100% with BJR on the flow aspects of valve size for you, I do agree that 2.02s on a 318 bore are not practical for you. In your case the side affect is that the valve reliefs are not easily made without going with the expensive pistons. You've run into the biggest problem with the "budget" builds. You can get a piston that's right for more cash, or you can get a Chevy piston that can be made to work, but has the reliefs in the wrong spots that you need to modify. I think if it were me, I'd go back to the post about "cheap 349 recipes" and see about taking one of those chevy numbers, and modifying it. But, that's changing the rod to chevy pin size, then re-cutting the valve releifs. Maybe a simpler way would be to have the block sonic tested first. If it can be bored to 4"(.090 over) your piston choices are tens of part numbers, not a few. And, the 2.02s will be unshrouded a bit more than on the 3.94 bore. The easy way is custom units. The harder way(s) are all compromises in one way or another. To get past each individual compromise, will take either time or money. If your time is worth money to you, or you have to pay for soem work, you may just find the custom option will costs similar money, and there will be no compromises. You get what you want, and it all fits well.
 
Had he not went with the 2.02 valve in the small port head then he wouldn't have had this problem, if he wanted the 2.02 for some reason then the better choice would have been the 360 head with the 2.02 valve and now the valve would have been farther in the chamber and not protruding above the deck of the head. This would have given him about .100-.120 more clearence, and may not have had any interference with the pistons. Also the port would have worked much better for the valve size that he used, and it wouldn't have been so restrictive.
I think that he thought that he was doing the right thing and went too far, bigger isn't always better and this is just one case of trying to improve the wheel, which in this case hurt more than it helped.
I've spent hours maxing and figuring out how to get the most HP and Tq from this combination with a given head and bore size, and tried to put it as palinly as I could so this would be a easy engine to build without any drawbacks, but I'm wrong and now theres problems. This is why I stated what valve size and head to use with what parts, and deviating from this made problems that shouldn't have been there to start with.

Also I used 360 heads not 318's with a 1.88 valve, this too is a deviation from the thread.
 
I think that he was thinking of the cylinder head 101 thread that I used the 318 heads.
 
"stuff" happens... There's stuff a lot of people have done that is hard to duplicate by others. Nevermind on the other side of the world...lol. My point was maybe the fix now is just the better slugs. and pay what they cost. Another potential down side is balancing or rebalancing that will need to be done with the forged pistons too.
 
Yep your right as the cost now would be almost equal, if the pistons are too thin for the proper valve reliefs, or maybe a head change would be cheaper with his parts. I wasnt trying to be arguemenitive (sp) just stating that he changed the head type and used too large a valve in them. Sorry if I came off wrong.
 
Thanks for the replies and sorry for the late response.

I hear you both on the head issues, however mine are not "normal" 318 heads...they have had the runners welded and the ports enlarged..the velocity has been checked and is awesome...they have over 40 hours welding work in them, and the flow figures are significantly good, especially on the exhaust side -

That said...there has to be a reason why I got P-V problems - with both Intake AND exhaust valve strike....so I think whatever the issue was...it wasnt just valve size....

We took 140th off the Speed Pro forged slugs (left around 220th) , and eventually fixed the problem, but Im restricted with cam lift.

- In summary it sounds to me like unless I shell for some Diamonds.....I should look to a 360 as a better "next option"....

FWIW I think you both summarised the "end game" of doing a 349 very well.......its probably more trouble than its worth.....

Heres my head flow figs and a pic, so BJR can rest easy ! LOL!!

( The guy that ported them , did them for an experiment - he is a very talented "head porter" - he's been doing them for twenty years)

Flow figs
int
lift..../cfm
.100/69
.200/123
.300/185
.400/220
.500/223 (Now .500/230)




 
The guy did some nice work for you on those 9973 heads. The thing that I was getting at is the height placement of the valves in the heads, chamber side,as the 360 heads would be deeper in the chamber than that of the 318 heads. This way if the 360 heads would have been used then the valves would have been about .100 deeper in the chambers and interference issues would have been minimal even with the 2.02 valves.
The cc's on this head has to be fairly small from the pics. as the valves reduce the chamber volume due to the margin thickness and area that they take up.
 
Thanks on behalf of James , BJR - (We call him the "headmaster" - you should ask Ryan from Shady about him.....)

I read you on the valve sizing...and its a valid point.

I wasnt trying to "ambush" anyone by not posting the head details earlier....I just know they work exceptionally well...but we screwed up big time with the P-V clearance.

We also had to take some meat out of the chambers , because we ended up with a static comp of 12.4:1!!

Soooooooo....

Here's another question - would you use cast slugs in a 400HP motor?

Theres a Silvolite truck slug that has the compression height I need (I think!) ....but Im worried about its "strength".....

And also - what is the normal chamber "depth" for the heads I have?

Thanks for the responses so far...and hope other folks can see the 318/60 build is not such a cheap easy deal.......
 
The cast pistons will do fine for street and mild racing, I'm making over 500 hp on cast pistons in my engine now.
But for the build the compression would have been less due to the chamber size of the 360 heads verses the 318 heads. The short block is a no brainer but the heads is what has to be watched a little more closely.
As for Ryan @ Shady Dells Speed Shop we haven't seen eye to eye, but he's young and still learning just as we all are. I guess he didn't like the fact that I was porting heads before he was born, but thats another story and I tend to leave that alone.
 
Thanks for the input BJR - and re the "Ryan J experience", it seems you are not alone.....

Anyhow - Can i beg a favour?

Would you be able to calculate static compression using the cast slugs, std factory 360 rod, 318 bore 40th over, std deck height and 62cc chambers?

If there is a calculator that does this, Id appreciate a link to it as well....:read2:
 
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