How Much Can Heads Improve Compression???

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OK, I get 7.72 with the 360 heads, flat tops, the deck height, and .051 compressed gasket.... seems like math is still working the same tonight as always.
 
I would say the 318 heads might flow better with the open chambers, but since they're both ported, and numbers are unknown as of right now...I'll just shut my mouth...
 
krazykuda said:
We are going from a .065" thick gasket to .040" thick....
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Go thinner..........MP used to have gaskets that crushed in the .024/.028 range, don't remember the P/N off the top of my head at the moment, always worked good for me.
 
Well, surprising results for the head cc'ing. #-o

The old 67 273 heads are coming in at 63 cc's

The 68-72 318 head is coming in at 79 cc's.

I checked two cylinders and they both checked the same... :banghead:

200-121 = 79 cc


I can't believe that they have more volume than my 360 heads... :???:
 
txstang84 said:
273 heads it is?
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Yes, 273 heads.

According to the one book I have they are supposed to be 57 cc, but they are coming in at 63 cc.

I can't believe that the 318 heads are 79 cc.. I'll check the other one to be sure...
 
Assuming an .038"x4.15" gasket and flat tops .087" in the hole, the best I could come up with was 8.4:1 static...

I didn't see which kit gasket you mentioned--probably looked right over it...I'm pretty sure felpro blues are .054x4.15...that would drop it down to 8.1
 
The E58s also didn't have much compression. Yes, maintaining the flow and picking up compression will help but first, I'd put a cam in it. Low compression with stock cam is FAR more disappointing than low compression with a reasonable cam like the 340's. I'll take a stout cam with 7.8:1 everyday over a stock 318 cam with 10:1 with irons.

Far as I know- all that 273/318 stuff's supposed to come in right at 62 and anything else's been worked. 69cc is right around what I've seen for 587s yet that were stock. I don't think there's optimized with the parts you have on hand. The only thing that'd really be a worthwhile upgrade over the 587s is Magnums and if you're really that worried about compression, you should grab the whole long block that has the higher CR pistons than the early teens.

Krooser said:
You may want to find a pair of 302/308 heads from an 80's 318. Mill 'em down. They have smaller swirl combustion chambers.
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308s are the open chamber swirl port roller cam 360 heads '88-'92.
 
The 79 cc's is pretty amazing. Not waht I would have expected.

Measure the cc's in the valve dimples; I checked some original stock ones that were a lot shallower and they added 2 cc's; your valve dimples look like they could have 4-5 cc's of volume in them, as they are a lot larger than the stock valve dimples. That would explain the 273 heads being larger cc's than normal. Maybe find some flat valves to get rid of that volume....if you are not revving it high, you can get by with the extra weight.....
 
krazykuda said:
I'd rather build it right the first time. :D

I don't accomplish anything if I half-assed slap it together and plan to do it again later... I will then have that left on my "to-do" list. :violent1:

I want to cross it off and not feel like I'm trying to kick water up hill... :banghead:
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I would just get it running with the 273 heads.
To fix the compression right would require pistons and most likely balancing the bottom end.
Who knows what fuel will be available in 10 years?

I am lucky here in WV, with so many stock car tracks you can buy 100 octane at the local truck stop for $4.00 a gallon.
 
sireland67 said:
I would just get it running with the 273 heads.
To fix the compression right would require pistons and most likely balancing the bottom end.
Who knows what fuel will be available in 10 years?

I am lucky here in WV, with so many stock car tracks you can buy 100 octane at the local truck stop for $4.00 a gallon.
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You are so lucky , best we get is 94 octane 1.30 -1.45 a litre or 5- 6 a gallon . I can buy race fuel in 5 gallon jugs for 12 a gallon . 11.3 compression , sure would like 100 octane all the time
 
We've started rounding up camshafts so we can start checking them soon....
 
krazykuda said:
...We will be picking the cam later after we figure out which heads we are going to use. I do have some "mild" street cams that may be ok. I don't want anything too big if I don't have enough compression to back it up.... I'm thinking around 268° duration range.

Then I have to mock it up and check the piston to valve clearance....

Then assemble the engine and drop it in... :burnout:
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I had to reread this because I knew you mentioned a goal of not buying anything...what all cams do you have available? Maybe something similar to a comp high energy or are you talking about custom grinds from engines past built? Now knowing you're not likely to get your SCR goal, I agree with the above statement though.
 
txstang84 said:
I had to reread this because I knew you mentioned a goal of not buying anything...what all cams do you have available? Maybe something similar to a comp high energy? Now knowing you're not likely to get your SCR goal, I agree with the above statement though.
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What cams do I have???

Take a look, these are just what we dug out of the basement (18 of them), plus a few in the dining room (stock 360 cams) and a few in each garage, so I recon' that I have about two dozen or more to degree and compare....

A few Lunati's, some Comp, and Eddy, and some various ones that I've picked up along the way. I can't remember which one is which, so the best thing to do is degree them all and then compare them. At least that way, I can compare them apples to apples as I will degree them the same way which eliminates any differences in how each manufacturer specs their cams. They will be done my way by the dial indicator and degree wheel in a spare block with one crank and piston.

View attachment Cams A02 B.jpg
 
My pop and i restored a 79 lil red express. Working w the machine shop in my dads area we decided to put flattop pistons to make up the difference for the open chambered 360 heads and factory low compression pistons it had, we also put in a 68 340 cam. Truck ran great. Dont recall what the compression ended up at, but the ***** would ping on anything less than 92 octane, and ran like a scalded dog.

If you dont want to put decent pistons in the holes to up the compression, then you will need to go with the smallest chamber heads you have and a thin head gasket to get the compression up. Or take the big valve open chamber 360 heads and mill the crap outta them to make the chambers smaller and run em.

I am rounding up the pieces now to do a 360 build after abandoning the idea of a big valve 318. With 65cc chambers, i have to use a slight dished piston and thicker head gasket to get compression down to 10.22 to 1. Otherwise i am looking at over 11.5 to 1 with non dished flattops. Not a streetable combo at all.
 
i just updated the pictures to the newer format so they will show better in the thread....
 
Wow! Old thread.

Hey moparmat2000! Still here messing with this below?
moparmat2000 said:
My pop and i restored a 79 lil red express. Working w the machine shop in my dads area we decided to put flattop pistons to make up the difference for the open chambered 360 heads and factory low compression pistons it had, we also put in a 68 340 cam. Truck ran great. Dont recall what the compression ended up at, but the ***** would ping on anything less than 92 octane, and ran like a scalded dog.
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Flat tops, zero deck, open chambered 360 heads, .039 head gasket?
9.8-1.
A ,050 drops it do about 9.5-1.

I am rounding up the pieces now to do a 360 build after abandoning the idea of a big valve 318. With 65cc chambers, i have to use a slight dished piston and thicker head gasket to get compression down to 10.22 to 1. Otherwise i am looking at over 11.5 to 1 with non dished flattops. Not a streetable combo at all.
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Flat tops zero decked with 65cc heads and a .038 head gasket. Just shy of 11-1.
Iron headed? No pump gas unless the cam is BIG!
Aluminum head? Biggish cam will be Ok? I’ve run a Hyd. purple 292/.509 which is [email protected].
It’s doable. Tune well on all fronts.

Been there done that. Did you get away with it? I don’t know your octane availability.
 
My God this thread is old. I posted to it in 2015. I really stalled out on my build. Ended up buying a 4" stroker crank from ohio crankshaft about a month ago though. Bought some new eagle H beam rods, and a clean used set of KB forged stroker pistons off fabo these are a street engine stroker piston. With a .040" headgasket should put me right at 9.8-1 cant remember the PN of em. This will let me run the 91 octane thats in my area.

Dad sold his express, moved into a smaller house, bought a model A coupe, and is tinkering with that lately.

Problem i have lately last 5 years is dealing with a kid that has mental health issues. This **** cropped up when she turned 8 years old, My household is insane, i end up buying **** for projects and then nothing gets done, because every day there is a ******* emergency around here. Block may finally go to machine shop next week along with other stuff needed to balance the crank and bore it out. Honestly i will probably get it all back, gun brush out the oiling holes, coat it with oil and wrap it in a trash bag, and it will probably sit for another 5 years.

In 5 years she turns 18. I told my wife, at that time, this kid will find another place to live on her 18th birthday because we are no longer legally responsible. And i want her to take her nutty **** and go the **** away. Wife takes her to a head shrinker weekly, kids on meds, wife even had me go to visit w this kids head shrinker for a bit to i am guessing try to deal with this ****, i went a few visits and i finally said to the shrink, no there aint anything about me that needs fixin. Never went back.

My wife went out for a girls night out with one of her friends this last saturday night. Kid had a **** and fell in it over that. Other daughter was at a friends house overnight, my son was already asleep, so i went to bed, told my wife go out have a good time with your friends. If this kid wants to argue, she can argue with herself. Wife says things will get easier once she starts bleedin every month, i shook my head and said ummm i dont think so.

So yeah dealing with what i deal with on a daily basis, i am pretty much outta G.A.S. (Give A ****)
 
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All the 675 318 head cc to 68cc if they are bone stock 'never milled'.

Make sure the porting was tested and at least does 220cfm or you are trading power for novelty .
 
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