Performance cam for 318 Poly??

[Jay Gibbs]

Looking for someone who has experience with 318 poly cams...I purchased a "performance" cam to drop in my 318 poly to complement my 4 bbl upgrade. The company I purchased it from (very familiar with the poly engine) says it is ground for a good overall performance and power increase while not losing too much power down low or vacuum- (what I wanted it to do) I was ready to install until I posted the specs on this forum and was told it is NOT going to do what I want and may in fact be less of a cam than the factory installed one.

I know nothing about cam grind numbers and am hoping someone with more experience than me can tell me if I bought/was sold the right cam or not! Attached is the specs sheet. Any help would be greatly appreciated.

J.G.

 

[C Body Bob]

Looking for someone who has experience with 318 poly cams...I purchased a "performance" cam to drop in my 318 poly to complement my 4 bbl upgrade. The company I purchased it from (very familiar with the poly engine) says it is ground for a good overall performance and power increase while not losing too much power down low or vacuum- (what I wanted it to do) I was ready to install until I posted the specs on this forum and was told it is NOT going to do what I want and may in fact be less of a cam than the factory installed one.

I know nothing about cam grind numbers and am hoping someone with more experience than me can tell me if I bought/was sold the right cam or not! Attached is the specs sheet. Any help would be greatly appreciated.

J.G.

View attachment 195178

That’s real close specs to the MOPAR Purple Shaft cam I ran in this 318 powered drag car & it ran mid 13’s in the quarter with 1.90 60 ft. You’ll be fine. If not enough put a 3:55 gear in the rear.

 

[C Body Bob]

Another thing. Valve lash is important. When I set it it ran way better.

 

[Jay Gibbs]

Another thing. Valve lash is important. When I set it it ran way better.

That's awesome...thanks so much.

I've run into another potential issue...I just pulled the intake and (aside from the current cam looking pretty worn, I see what looks like a big crack in the lifter valley just forward of the distributor??!! Pic attached...is that supposed to be there???...

Thanks,

J.G.

 

[C Body Bob]

Nope. That’s not good. Go find another engine.

 

[Jay Gibbs]

Well that just sucks more than I can find words to describe...Wow....just wow.

So now the big question...since I will no longer have a numbers matching car, do I go out and find another 318 Poly or do I just go ahead and drop in that 400 horse 440 I've thought about for some time now? I suppose from a resale standpoint, I'll get more money back out with a 440 when the time comes if/when I ever sell the car??...

 

[C Body Bob]

You have a date code correct Car. Vin numbers on the block didn’t start till mid 68. So you can find a date close to the date on yours. Switching to a big block is a bit of work.

 

[Joesportfury]

I may have a 65 poly engine core if you decide to build one

 

[max1196]

If you're referring to the poor quality of the molding of the block, where there is a lack of a bridge between the left and right bank of the lifter bores, that's just Chrysler for you. Here's some examples, nothing wrong.

 

[moper]

There's nothing wrong with your block. It's been running fine with that since it was born.

 

[Jay Gibbs]

There's nothing wrong with your block. It's been running fine with that since it was born.

Wow man...that's shocking. Is there any way I can tell that this is the case with my engine too?...the edges on my "space" in the valley seems quite jagged which led me and others to believe that a lifter must have stuck at some point and caused the crack. Some of the pictures you posted made the gap look more smoothed on the edges like the molten metal just didn't meet in the mold upon casting. If it is remotely possible this is a normal situation, I'll continue pulling it apart to complete my original project...many thanks to all who have assisted me with this from afar!

J.G.

 

[Slantsix]

Chrysler was cheap bastard, so missing peace of block etc.... its ok

 

[moper]

Whomever thinks a lifter sticking did that doesn't know how cast iron behaves. If a lifter had stuck (and by "stuck" I mean stopped dead during a running event where some inertial energy could be present) the lifter bore would have fractured. Not a little connector piece well outside the bore. That's an area that probably was cast solid but during original machining fractured and broke out. If you're that nervous look in the oil pan. If it's in there it broke while you were running it and it's been in there for decades. If it's not, it broke prior to assembly. Either way no harm no foul.
These cars were designed to last the payment book. The work was production line which means some were great, most were average, and others were horrible...

 

[Jay Gibbs]

Alright, it's balls to the wall on my project!...decided since the heads were a little gunked up I'm pulling them, stripping them down and cleaning them. Going to lap the valves too since I'm in this deep already. Going with new stem seals, springs and lifters. Next, the perf cam and new timing chain goes in. Hopefully at some point I'll actually get to installing the part that started this whole project- the 4 bbl intake and carb!...

 

[Jay Gibbs]

Slightly off subject but how the heck do you CORRECTLY remove the brass rocker shaft lock plug???...I've tried several of suggestions I've found on various websites dealing with poly engines and have found no suggestions other than things like "vise grips and angle cutting pliers" which don't lend themselves to damage free removal. I've moved the plug out maybe a couple mm's and have chewed it pretty good. Its not corroded, just a tight interference fit. Its soft and easily marred and will need to be reused!...I have found no source for replacement. I'm sure back in the day it may have been procedure to just "yank/pry it out" and buy a replacement which is now not an option. It would seem that some kind of slide hammer would be the way to go, but I'm open to any non-barbaric means and suggestions!...

Thanks,

J.G.

 

[stubs300]

Are you talkin about the freeze lookin plug at the end of the rocker shaft? There's no need to remove that, why do you want to remove it? There will be nothing for you to do to the shaft once you remove it, except go buy a new one. But it's your gig, so Good Luck!

 

[moper]

I've not taken a 318 Poly apart before - but yeah - if it's the rocker shafts - just run some solvent through them. You don't need to do any more than make sure there's no big chunks of metal up there, and there's not really any way for them to get up inside there...

 

[Jay Gibbs]

Are you talkin about the freeze lookin plug at the end of the rocker shaft? There's no need to remove that, why do you want to remove it? There will be nothing for you to do to the shaft once you remove it, except go buy a new one. But it's your gig, so Good Luck!

Nope...it's the small pressed in button looking plug atop just one rocker tower on each head. It holds the rocker shaft in place. I was looking to remove each head's rocker shaft and arms and completely disassemble the heads for cleaning. I figured it out...just required patience and a little more muscle... before and after shots...

 

[Jay Gibbs]

Stripped bare head after cleaning and repaint...

 

[t57f100]

That's awesome...thanks so much.

I've run into another potential issue...I just pulled the intake and (aside from the current cam looking pretty worn, I see what looks like a big crack in the lifter valley just forward of the distributor??!! Pic attached...is that supposed to be there???...

Thanks,

J.G.View attachment 195293

did you put it back toghter and run the engine i to have this same issue