302 casting on a set of 318 heads

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Here is cam and lifter set I am considering for the 74 teener I have for sonny's car. Looking hard at the 302s. If I pull trigger on em it will be after first frost. Thinking LD4B on it with a 650 eddy. Also have a set of 68 340 hi po exhaust mannys, and a mopar electronic distributor I plan on firing w an HEI module.

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moparmat2000 said:
Here is cam and lifter set I am considering for the 74 teener I have for sonny's car. Looking hard the 302s. If I pull trigger on em it will be after first frost. Thinking LD4B on it with a 650 eddy. Also have a set of 68 340 hi power exhaust mannys, and a mopar electronic distributor I plan on firing w an HEI module.

View attachment 1715387187
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Nice cam, would like to see how it all around runs when it's done.

Yes, Nice Build selection of parts.
We Tried the Eddy 650 AVS on one, it was too much, Went back to a new 1406 600 just right.
Your cam may handle the 650 though. Tweek and Tune, Tweek and Tune.
 
Thanks. I still got to pull the teener out of my 67 notch shell. I put it in there as a mockup for modding the wiring harness, as well as mocking up the FEAD and making custom alternator brackets for a denso mini alternator, and custom making a fiberglass fan shroud setup for the aluminum radiator.

When it cools off a bit out there, I i will get it out of the car and on the stand. Car this engine was from was an 88k mile 1974 granny moredoor dart. Am hoping the bores are decent enough to ball hone it, rering it, put new bearings and oil pump in it. Then add the cam, a Cloyes true roller timing chain. Got a new magnum 3.9 chain tensioner for it. Mildly ported 302s and an LD4B. Hoping for about 300HP w some low end grunt. Should be plenty with 3.73 gears to make it a fun street car.

Was looking at a thread Rainy has on a 74-75 teener she pulled the heads off of. Flat top pistons, and zero deck height. If the 74 teener I have is the same, those 302s could put it at a 9.5-1 ratio. I am thinking the 1.75" and 1.50" valve sizes are prob fine for a stock bore teener. Too big of a valve and too much hogged out of the runners and port velocity suffers with such a small bore.

The plus with the teener though is a 4.00" stroker crank will make it into a 390. And it fits easily.
 
With 302's you'd be right around 9.6 IF the pistons are very near zero deck. But near-zero-deck 318 pistons went away after about '70 or so due to emissions... and they had 4 small valve notches. Let us know what you find in there; take pix!
 
Heres a copy of pic in Rainys thread. Its at TDC where the piston sits as you can see from the timing tab in the pic. Now that I look at it again, it looks to be slightly below zero deck height. Would love to CC that and see what it actually is. No valve cuts in the pistons. I think it was the stock original long block in a 75 dart. The 74 I have has never been apart either. I am assuming it will be about the same.

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moparmat2000 said:
Heres a copy of pic in Rainys thread. Its at TDC where the piston sits as you can see from the timing tab in the pic. Now that I look at it again, it looks to be slightly below zero deck height. Would love to CC that and see what it actually is. No valve cuts in the pistons. I think it was the stock original long block in a 75 dart. The 74 I have has never been apart either. I am assuming it will be about the same.
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Thinking those are about .140ths down in the hole.

Have been dying to get a set of these from rock auto to see if they are same as the factory mopar 69 9.2:1 318 valve relief pistons.

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318 3.jpg
 
Dang I was drilling into this about a year ago. The big ticket here is getting the right compression height to match up with the 69 318 valve relief pistons. Think that number should be 1.741 CH but I am not sure.

I should just order one in from Rock and match it up to the factory 9.2:1 set I have here.
Proof will be in the Pudding . . .
 
That's what wakes up the 318s with the 302 heads, to get that compression up: 9.5:1 with the Factory 69 318 thinner smaller bore diameter head gasket.
 
The 340 does not have a double spring
it has a dampner
That Summit cam is an old Cam dynamics chevy grind- way obsolete
LOTS of better choices out there
good moves on the pistons
 
Looking like the Rock single 69 pistons are 1.72 CH equaling 8.5:1 compression.
The 69 pistons with the premium rings have the compression height of 1.741, thinking these are the pistons to get bumping compression to 9:1.
 
Boy here is a nice looking set of valve relief Sealed Power Pistons too, if that is the correct picture for the parts. They are standing up nice.
Sealed Power # 285AP

SP285AP.jpg


Shoot Summit is showing only 1.72 CH on this part number set . . only 8.5:1 cr

Wrong Pictures can be deceiving. Going Back to RockAuto they got the right stuff.
 
George Jets said:
Looking like the Rock single 69 pistons are 1.72 CH equaling 8.5:1 compression.
The 69 pistons with the premium rings have the compression height of 1.741, thinking these are the pistons to get bumping compression to 9:1.
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Mmmmmm.... not quite. The CH you are looking for is around 1.810-1.820" for the pre-70-ish taller pistons. 1.822" CH is zero deck with standard LA block's deck height. The best stock type piston you can find today is gonna be around .070" in the hole. You have to go to something like the KB's the find near zero deck pistons, or EGGE 318 poly cast replacements (with the notches in the wrong place), or some NOS off of eBay if they show up.
 
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moparmat2000 said:
Why not buy the 69 318 pistons then. They are a different part number, but are available on the rock.

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Unfortunately that's not gonna do what you think. Those are just REPLACEMENT PISTONS for a '69 318, not actual '69 pistons. The CH of 1.741" will give you a static CR of about 8.2 with 302 heads and a .039" thick head gasket and standard deck height. They'll be about .080" in the hole.
 
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nm9stheham said:
Unfortunately that's not gonna do what you think. Those are just REPLACEMENT PISTONS for a '69 318, not actual '69 pistons. The CH of .1741" will give you a static CR of about 8.2 with 302 heads and a .039" thick head gasket and standard deck height. They'll be about .080" in the hole.
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Needed to know this, thank you

Glad I was able to score a factory set of the valve relieve std bore 318 9.1 pistons off Craigslist here for my next build. So I am good for one build, wish someone made new duplicate pistons to match them.


Just kind of guessing here, you are saying that the 1.741s sit .080ths in the hole. Minus the .030 CH here brings the Factory 69 Mopar Pistons sitting .050 in the hole. I know they are not zero deck but close.

69 9:1.jpg
 
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George Jets said:
Boy here is a nice looking set of valve relief Sealed Power Pistons too, if that is the correct picture for the parts. They are standing up nice.
Sealed Power # 285AP

View attachment 1715387272

Shoot Summit is showing only 1.72 CH on this part number set . . only 8.5:1 cr

Wrong Pictures can be deceiving. Going Back to RockAuto they got the right stuff.
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Yep, I checked the FME catalog and it say 1.720" CH. And SCR is 7.9.... with standard LA deck, 302's (62 cc chambers), and .039" head gasket. These would really suck for SCR with 675 heads!
 
George Jets said:
Needed to know this, thank you

Glad I was able to score a factory set of the valve relieve std bore 318 9.1 pistons off Craigslist here for my next build. So I am good for one build, wish someone made new duplicate pistons to match them.
Click to expand...
Get out out a caliper and check the piston height from top of the pin bore to the top of the piston crown. Add 0.492", or post the measurement here, to see what you actually have for sure for CH.
 
What about KB 318 pistons. Zero deck height? I am still just bench racing a parts combo here, but what about those, and just use my 74 318 heads I already have, deck em, port em, and hog out the intake side for 1.88"s. Use a comp cams 268 XE cam. Shows piston head volume at 0.00. Does that mean they are at zero deck height?

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nm9stheham said:
Get out out a caliper and check the piston height from top of the pin bore to the top of the piston crown. Add 0.492", or post the measurement here, to see what you actually have for sure for CH.
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OK we have 1.280 CH from the top of the wrist pin to the top of the piston + the .492 ths you recommend,
gives a total compresion height of 1.772 CH

Way better than the 1.741 CH ones.

 
moparmat2000 said:
What about KB 318 pistons. Zero deck height? I am still just bench racing a parts combo here, but what about those, and just use my 74 318 heads I already have, deck em, port em, and hog out the intake side for 1.88"s. Use a comp cams 268 XE cam. Shows piston head volume at 0.00. Does that mean they are at zero deck height?

View attachment 1715387286

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Nice piston, but Dang still only 1.741 CH (compression height)

Think the Piston Head volume of Zero means no Valve Reliefs . . . ?
 
moparmat2000 said:
What about KB 318 pistons. Zero deck height? I am still just bench racing a parts combo here, but what about those, and just use my 74 318 heads I already have, deck em, port em, and hog out the intake side for 1.88"s. Use a comp cams 268 XE cam. Shows piston head volume at 0.00. Does that mean they are at zero deck height?
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Understood on the bench racing the parts LOL. You're hitting the usual wall with the 318.... no cheap high compression ready-to-drop-in pistons for getting the SCR up out of the low 8's. True NOS early pistons is all I know of.

That piston head volume of 0 for those particular Silvolites means no valve reliefs.

The KB167's will get the deck height up to about -.012" below the standard LA deck. Static CR is now around 9.2 with the 302's and .039" thick head gasket, or 9.5 with a .028" thick head gasket. Or mill the stock 675 types by about .040" to get to the same spot. But the 302's closed chamber is my preference as you can get a
good quench gap with the KB167's and that .028" thick head gasket.

Here is the rub with the KB167's.... the crank balance goes off, by 60-80 grams lower bobweight. (That assumes your '74 LA318 has the heavier, later 318 rods, which supposedly started in '74.) You can use stock pins to get partway back or find some good 273 pins to get it really close, or just get the crank alone balanced to the new bobweight. Being lighter on the bobweight means you just drill some weight of the front and back crank counter weights so is reletively easy, and not too expensive if you have a local shop that will balance the crank to your spec'd bobweight. (Which is what I do.)
 
George Jets said:
OK we have 1.280 CH from the top of the wrist pin to the top of the piston + the .492 ths you recommend,
gives a total compresion height of 1.772 CH

Way better than the 1.741 CH ones.
Click to expand...
And some have reported finding some 318 pistons about .050" below deck, so this must be that piston. Just avoid the Silvolite 1278's like the plague.... CH = 1.682".... 0.164" in the hole! App notes say for trucks.
 
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