Head Swap

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cannucky

cannucky

The Guy With No Birthday
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I'm thinking of trashing the 360 heads the crooked mechanic put on my 318 and going back to the stock heads for more velocity and better compression , the questions are 1) will the comp cams springs for the 268h cam work on the 318 heads ? 2) will I need new retainers ? 3) whats the best way to remove them ie best tools and practices 4) will my Stealth intake work with these heads and finally is there anything I should watch out for when doing this.Thanks -Chris
 
get a spring micrometer, set them to the recommended installed height and you're good on pressure.
The thing you'll need to check for is retained/seal clearance.
You could get a rough measurement by using a fixed dial indicator with locks/retainers on the valve and the seal installed, lower the valve till max advertised lift is reached, write that down...then lower valve till retainer/seal contact and add up the diff to get your seal to retainer clearance figure.

imo just to be safe.
 
Thanks I might just pull them and take both sets in to a shop and have them do it as part of a valve job on the 318 heads , couldn't hurt they're probably pretty long in the tooth
 
Chris...If you haven't got the 318 heads yet, I'd get a pair of "302" castings. They have the small chambers and much better shaped chambers. Not sure if your stealth intake will bolt up w/o sealing problems.
 
65Val said:
Chris...If you haven't got the 318 heads yet, I'd get a pair of "302" castings. They have the small chambers and much better shaped chambers. Not sure if your stealth intake will bolt up w/o sealing problems.
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Thanks Darwin but I have the 318 heads that came off , apparently they weren't worth stealing ,I took a little layoff yesterday and am thinking of using this weekend to throw a set of rings and changing the heads back to keep it on the road while I figure out how to get a new motor into the country , onto the island , and into my backyard lol
 
cannucky said:
I'm thinking of trashing the 360 heads the crooked mechanic put on my 318 and going back to the stock heads for more velocity and better compression , the questions are 1) will the comp cams springs for the 268h cam work on the 318 heads ?
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I'm not aware of any reason why not.
cannucky said:
2) will I need new retainers ?
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They are not that expensive. Seems like cheap insurance in the event one is damaged during the removal process. Less stressful work when you know you don't have to re-use them.
cannucky said:
3) whats the best way to remove them ie best tools and practices
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I've taken a couple of grade survey stakes, stuck them in the front and rear exhaust ports and pull up steadily.
cannucky said:
4) will my Stealth intake work with these heads
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It will work, just not as good as it was designed to work. I suspect the Stealth is designed for the 340/360 intake ports. If that is the case there will be a port mismatch. It will be important to get a good intake manifold gasket seal established when you re-install.
cannucky said:
and finally is there anything I should watch out for when doing this.Thanks -Chris
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Keep the gasket debris out of the engine. Make sure ALL intake manifold bolts are out before attempting to remove intake. Make sure all items bolted to heads are removed before attempting to pull heads. Don't pry on heads to remove them.

Didn't catch the year of your heads. If they do not have the hardened valve seats, now is a good time to have them fitted. The machine shop may also be able to do a little porting and ease the transition from the Stealth to the 318 heads. If your budget can swing it, they might also be able to get the 360 valves into the 318 heads. Good luck.
 
66fs said:
What is wrong with the 360 heads?
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They drop the compression down to about 8:1 and lower the velocity dramatically , at least thats what I've been told by those in the know . This motor had new head gaskets and frost plugs done and ran like a raped ape before I took the car in for a ground up resto , it has been over cammed and started blowing oil up the top and running hot ever since this clown insisted he knows whats best for any mopar . I'm buying a stroker for the car but also plan on redoing the 318 because it's the numbers motor for the car
 
do a compression check if i were you and see were your at may be wrong push rod Letha and you are not get the valves to close all the way or you may be running the bottom of the lifter and not getting what you want . don't think its your heads at all i have done this swap before it worked great.
 
thanks guys but the bottom line is I'm going big on the replacement stroker, this is the original motor the car was built with and I am putting it back to it original configuration and then sealing it in the shipping crate the stroker comes with , ask any real engine builder about this swap and they will tell you the ports are too big and kill velocity and the displacement of the heads drop the compression down , the blow by is most likely ring related I've been driving with this issue for 2 summers and would like to think I would have heard a bad lifter or bent a xlong pushrod by now. cheers
 
cannucky said:
I'm thinking of trashing the 360 heads the crooked mechanic put on my 318 and going back to the stock heads for more velocity and better compression , the questions are 1) will the comp cams springs for the 268h cam work on the 318 heads ? 2) will I need new retainers ? 3) whats the best way to remove them ie best tools and practices 4) will my Stealth intake work with these heads and finally is there anything I should watch out for when doing this.Thanks -Chris
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I believe the chambers are basically the same, about 72cc's from the factory. So you won't gain much if any on compression with the change. I think the cam is way too much for a low compression motor. You have to get cylinder pressure up. Think about dropping back a few sizes on the cam and keeping the top end. It will be cheaper and get you time until you drop in the new motor. One more thing, the carb shouldn't be more then 6oocfm or smaller for that motor.
 
I'm going to disagree with the statement that all LA heads have about 72 cc chambers.

The smallest of the bunch are the 65-67 273 (64s are small too, but have a bolt problem.) and the 67 318 @ 57 cc

The 675 casting has 60 cc. The others are 63 cc except the 302s @ 62.6cc and the 345 casting which has a whopping 75.1. Too bad on this last one as it had the 1.88/1.60 valves.

68-71 340 heads had 63 cc chambers, the T/A heads had 66 cc, the 72 -73 heads had 65 cc chambers. Similarly the 360 heads had either 65 or 66 cc.

These are factory numbers. :downtown: You can argue the methodology of how they came up with them if you like. But, the same method was used on each casting. Therefore, the numbers are valid for comparison purposes at the very least.
 
Some people are reading between the lines too much the car is still running and the motor is going back to stock which of course means swapping back the cam eventually, I was just looking at how involved the head swap would be with a thought to keeping busy in the garage for a couple days this weekend I wasn't worried about how involved removing the heads was rather how involved the spring swap was to do , the main problem with the 360 heads is the lack of velocity due to too much port volume but the chambers are not the same for all LA heads these were measured at 68cc when they were installed and there is a drop in compression for sure ,thanks to those with constructive suggestions
ps I am running a 600cfm carb and TTi headers and a 323 gear so tho the cam is too big in my opinion I do have all the stuff crane recommends including the recommended stall
 
cannucky said:
... ask any real engine builder about this swap and they will tell you the ports are too big and kill velocity and the displacement of the heads drop the compression down...
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Any real engine builder can make any engine run. It is all about the total package and fine tuning it. I've run 360 heads on a 273, and it was killer. 318 to 340 is only .07 X bigger. Anyway, I'm glad you have a workable plan, that sounds good.
 
65TerrorCuda said:
The 302's/Stealth intake is a great combo. I had that, bowls blended and holley 390-4bbl on my 273.
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That seems to be the consensus among the people I talk to , Maybe I'll look for a pair of 302s after I do the swap and start rebuilding this motor ,who would have thought a simple question about swapping springs and heads would evoke such pissyness {not referring to you } If they think they have a better package then have at er all the power to yah guys , it's not just about making it run it's about making it run right and last and these heads have been a curse so they are going -On a side note if you think they are so great there 66fs you can buy them from me for half the $1200 I paid any time you want to buck up
 
I've got a 318 with 302s on it with .028 milled off with a stealth intake and no problem here im also running a mp .508 cam no issues there either. On the heads I gasket matched both intake and exhaust and same with the intake manifold itself now I know you cant really open up the intake side of the head that much but you can smooth it out and contour it a little better than what stock would be.
 
cannucky said:
...On a side note if you think they are so great there 66fs you can buy them from me for half the $1200 I paid any time you want to buck up
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No thanks, I do all my own work. I have plenty of untouched heads in the rack. I don't start with anything that someone else has "rebuilt". I have a set on a 340 and used to have a set on a 273. The 273 ran much better with J heads than the 273 heads. I was actually trying to save you time and money, but you're mind is made up. Put them up for sale on the forum, if you want some money back.
 
2 Darts said:
I'm going to disagree with the statement that all LA heads have about 72 cc chambers.

The smallest of the bunch are the 65-67 273 (64s are small too, but have a bolt problem.) and the 67 318 @ 57 cc

The 675 casting has 60 cc. The others are 63 cc except the 302s @ 62.6cc and the 345 casting which has a whopping 75.1. Too bad on this last one as it had the 1.88/1.60 valves.

68-71 340 heads had 63 cc chambers, the T/A heads had 66 cc, the 72 -73 heads had 65 cc chambers. Similarly the 360 heads had either 65 or 66 cc.

These are factory numbers. :downtown: You can argue the methodology of how they came up with them if you like. But, the same method was used on each casting. Therefore, the numbers are valid for comparison purposes at the very least.
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I have all those heads and have measured them all

302=64cc
68'&up 675=68cc
'67 234=62cc
915=72cc like just about all 340/360 heads +/- 2 cc
 
1wild&crazyguy said:
I have all those heads and have measured them all

302=64cc
68'&up 675=68cc
'67 234=62cc
915=72cc like just about all 340/360 heads +/- 2 cc
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I've only cc'd early 273's and 340/360's

915's = largest chamber is about 73 cc
66-67 273 = largest chamber is about 64 cc
same basic cc variation as above
Thanks for the info...
 
66fs said:
I've only cc'd early 273's and 340/360's

915's = largest chamber is about 73 cc
66-67 273 = largest chamber is about 64 cc
same basic cc variation as above
Thanks for the info...
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I was actually quite shocked to see the 302's make their advertised number 64cc, thats a 1st.LOL
 
1wild&crazyguy said:
I was actually quite shocked to see the 302's make their advertised number 64cc, thats a 1st.LOL
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From what I've read the Magnums were'nt so close to their advertised number. I used to have the heads milled to get minimum NHRA specs for Stock and Super Stock class, and it took about a .040 cut to get to minimum spec. Thanks again...
 
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