Upgrading stock 1971 318 heads

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Thanks for all the replies great info. I'm going to find out what a have currently to figure out what I would end up with. Thanks again
 
Slantsix64 said:
piston depth measurement tool?
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You don't have to have a special tool to measure the depth. If you have good eyes you can get a very close estimate with a good scale (machinist ruler). If they are stock they will either be .030", .060" or maybe .100" in the hole depending on if someone replaced the piston before you got the car. The pistons could have been replaced with anything including dome pistons. If you don't have a depth mic or some digital or vernier calipers you can use a scale (graduated machinist ruler). I used to be able to measure within .010" of an inch in my younger days using a machinist scale!! Now I need a seeing eye dog just to find my butt:rofl:

treblig
 
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Treblig said:
You don't have to have a special tool to measure the depth. If you have good eyes you can get a very close estimate with a good scale (machinist ruler). If they are stock they will either be .030", .060" or maybe .100" in the hole depending on if someone replaced the piston before you got the car. The pistons could have been replaced with anything including dome pistons. If you don't have a depth mic or some digital or vernier calipers you can use a scale (graduated machinist ruler). I used to be able to measure with .010" of an inch in my younger days using a machinist scale!! Now I need a seeing eye dog just to find my butt:rofl:

treblig
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I actually have great vision but some times I do get carb cleaner in my eyes lol
 
took the heads off piston has four notches on it 285np part number

ended up getting a really good deal on a pair of 302 heads
 
tried to clean it up a bit

20180329_162635.jpg
 
waiting on putting number one at tdc to get a measurement of piston height then i will cc the 302 heads and go from there
 
Treblig said:
Don't know if this posted correctly so I'm trying again............

The reason I asked about the year of the block and heads is that after '69 the 318 compression ratio kept dropping. It was 9.2:1 in '69 then 8.6:1 (more or less) in the 70s. I believe my pistons ('69 Barracuda) were .030 down in the hole at TDC. Your pistons (if it is stock) should be .060" or even .100" down in the hole at TDC. If your engine is a stock '71 318 you would have a hard time getting your compression any higher than 9:1 by changing the heads. It's pretty easy to check your piston depth before you do anything else. According to my Mopar Hot Rod Book the piston pin height was 1.77" in '69 then from '70 to '72 the pin height changed to 1.74". That means that your pistons (if they are stock) should be .060 down in the hole?? That's .030 (my piston depth at 1.77") plus .030 more for the change in pin height in '71. The problem is that someone might have changed the piston is the last 50 years??? So check your piston depth at TDC, this will tell you how low you can get you combustion chamber CCs before your compression gets too high. I don't think, if you have stock pistons you could cut the heads enough to get in trouble because 318 "stock" piston sit too deep in the bore??

Treblig
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i measured it up with a feeler gauge and i got 0.70 at tdc so my pistons are 0.70 in the hole correct?
 
Treblig said:
Should be either .060" or .100" down in the hole at TDC.

treblig
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Finally finshed Chamber Volume 302 heads are 64CC and my pistons are 0.100 in the hole. What would my compression be shaving 0.40 off the heads using 0.40 fel pro head gasket hoping to get at least 9:1
 
Slantsix64 said:
Finally finshed Chamber Volume 302 heads are 64CC and my pistons are 0.100 in the hole. What would my compression be shaving 0.40 off the heads using 0.40 fel pro head gasket hoping to get at least 9:1
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Not sure but I know you can also decrease the chamber CCs by going to a valve that has less dish. I know that you probably had somewhere around 8.6:1 CR with the pistons .100" down in the hole. I had 69CC heads on my '69 318 with the stock '69 pistons .030" in the hole and factory 9.6:1 CR. With the thin gasket, shaving the heads and the right valves you might be able to get 9:1 or close to it. Seems like I heard that you can also get higher compression by getting the right overlap on your cam?? Maybe someone else will chime in on the cam theory???

treblig
 
i entered my information on a CR Calculator and it says i will have 9.7:1? with out milling the head keeping it at 64cc is that right sounds high to me
 
Slantsix64 said:
i entered my information on a CR Calculator and it says i will have 9.7:1? with out milling the head keeping it at 64cc is that right sounds high to me
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Did you include the space between the deck and the piston (this is critical)??
 
All I know is I'm 0.100 in the hole the heads are 64cc how can I figure out the rest. It asks for piston dome volume also I have 285np pistons
 
just going to mill the heads 0.40 and slap them on with a fel pro 0.40 gasket and add those 340 manifolds Will be a upgrade no matter what. Thanks for the replies
 
Slantsix64 said:
just going to mill the heads 0.40 and slap them on with a fel pro 0.40 gasket and add those 340 manifolds Will be a upgrade no matter what. Thanks for the replies
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While you're at it, why not gasket match both intake and exhaust? If you have the tools, now's a great time. if
 
Ended up milling the head .45 thousandths bolted everything back up with all stock push rods etc fired right up sounds mean although i need to have the exhaust made from flange down due to changing to driver 340 manifold and passenger Jeep Grand Cherokee exhaust (moved my oil filter adapter to the front due to exit hole dumping towards the back instead of the middle.) I got to say the manifolds look huge compared to the stock ones my motor looks like it bearly fits haha I used fel pro 1008 .39 thickness but I measured it compressed and torqued and I got .30 With a feeler gauge.
 
Slantsix64 said:
Ended up milling the head .45 thousandths bolted everything back up with all stock push rods etc fired right up sounds mean although i need to have the exhaust made from flange down due to changing to driver 340 manifold and passenger Jeep Grand Cherokee exhaust (moved my oil filter adapter to the front due to exit hole dumping towards the back instead of the middle.) I got to say the manifolds look huge compared to the stock ones my motor looks like it bearly fits haha I used fel pro 1008 .39 thickness but I measured it compressed and torqued and I got .30 With a feeler gauge.
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Well let's see how it does in the streets!!!:steering:

Treblig
 
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