318 with 360 crank-another peeing contest

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dartjack

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I know someone has done this. Has anyone done it with stock pistons? Doing the math(sideways) it looks like it would have about 10.7 CR with open chamber heads. Does that sound even close? Someone posted recently that they were going to try it for giggles. Just wondering if any success has been had. Valve clearance would be a little close. Really not trying to start another peeing contest about not using a 360 and 4" crank here. Just got an oddball notion to do something different(oddball).

Thanks
 
Search the screen nameBJR racing or BJRacing.

It has been done. Valave reliefs are needed in the OE slug.
 
What about a thick head gasket to get some clearance (50 thou or so) and bring the C/R down to 9.5 or so. You can order anything from comitech(spelling?)
 
Why not just use the right pistons :laughing:

KB's aren't that much and offer lighter weight and valve relieves. Why put money in to a old stock piston, Think hyper are under $300 a set. Those stock pistons are been around for a long time and have to be getting worn out. This isn't the 80's anymore, lol
 
Wouldn't the piston be like .210 out of the hole if you used stock rods and pistons with a 360 crank? There's a .270" difference in the cranks, and the pistons are usually about .060 in the hole on a stock engine. I don't see how you could possibly use stock pistons.

I've been considering making a mild stroker with the 318 block, 360 crank, and 302 heads that I have in my garage for a while now, but I really don't think stock pistons would work unless the rods were shortened, but it would be way cheaper to get the right pistons than to shorten the rods.
 
was reading along and just would like to ask what is the story with thes 302 heads??
 
The stroke difference is .270 but the piston only comes up half of that. The other half is on the bottom of the travel. Figuring that most teens have a
-.060 below deck piston or so then the piston will come out of the hole about .070 or less. The first 340's came out .010 if I remember correctly and had a 10.5 CR. The more input on this post the better.

Thanks
 
damnimcooltom i do understand that i have 4 of the 302 casting heads in my garage. i just curious why this 318 head is such important ? what can i do with it
 
dartjack said:
The stroke difference is .270 but the piston only comes up half of that. The other half is on the bottom of the travel. Figuring that most teens have a
-.060 below deck piston or so then the piston will come out of the hole about .070 or less. The first 340's came out .010 if I remember correctly and had a 10.5 CR. The more input on this post the better.

Thanks
Click to expand...

Oh yeah, I forgot to cut the difference in half. But still, that's .135 out of the hole, minus .060 that they are usually in the hole...comes out to .075 out of the hole. That's a lot. You could probably knock a little off the top of the piston, but I wouldn't think you could take more than .030-.040 off, which still leaves it .035-.045 out of the hole, which is still a lot. You'd need to run a thick head gasket and not go too high on the cam lift. Most builders keep it zero to maybe .020 above deck
 
sbmopar318 said:
damnimcooltom i do understand that i have 4 of the 302 casting heads in my garage. i just curious why this 318 head is such important ? what can i do with it
Click to expand...

There the best flowing 318 head and the best when ported. There the last head to be produced until the Magnum head came out. The "302" head can be ported out to approx. 240 cfm intake. with a good balance possible on the exhaust side.

For a 318 to have this much air flow on a small port is excellent and it will make for a great street strip possibilty. The problem arises when people want to use a 360 head on a 318. There comes the catch 22 of the big ports abilty to move more air as cast vs a as cast 318 head. The problem with a 360 head is the large port window moves air slowly and ineffectivly for a smaller engine and doesn't show itself well until the RPM's are twisted up high.

This is fine for a heavy breathing street striper or light drag car, but for a heavy street car it can make for a sluggish and poor running engine down low where the street car spends it's time running.

The draw for the 360 head is "Cheap Performance" (High RPM) vs. the heavy expense of porting the 302 head, which is far superior to use over a 360 head. The problem is getting people to beileve this and/or understand this.
(Even though MoPar proved it years ago)
They just see dollor signs in there eyes and throw common sense out the window and pick up the flag of "Frugal-ness" (AKA Cheap ***) and then try and wave the flag of "I spent less, WTF is wrong with you?" Crap.

Magna flux the bear and cleaned up head, proceed from there. PM if need be.


Now, back to the topic on hand.
 
64physhy said:
Oh yeah, I forgot to cut the difference in half. But still, that's .135 out of the hole, minus .060 that they are usually in the hole...comes out to .075 out of the hole. That's a lot. You could probably knock a little off the top of the piston, but I wouldn't think you could take more than .030-.040 off, which still leaves it .035-.045 out of the hole, which is still a lot. You'd need to run a thick head gasket and not go too high on the cam lift. Most builders keep it zero to maybe .020 above deck
Click to expand...


Back when the Earth was flat, Hot Rod did one of these but used Speed Pro +.030" 318 pistons whacked .100"!!!! Bye bye valve reliefs.
An Isky 260 cam, Mopar Performance 'bracket' heads and Performer intake were used but it never saw the dyno.
 
Does anyone make a piston for this app? Maybe KB...

I did research a ton of cast pistons and none of them fit the bill as the best I could find was a 318 truck piston that had a very low compression height compared to the pass car pistons.Still would have come way out of the hole.
 
No off the self piston is available....need to find a 318 piston with a compression height around 1.46 to be a zero deck ..anything more is above the deck...
 
64physhy said:
Wouldn't the piston be like .210 out of the hole if you used stock rods and pistons with a 360 crank? There's a .270" difference in the cranks, and the pistons are usually about .060 in the hole on a stock engine. I don't see how you could possibly use stock pistons.

I've been considering making a mild stroker with the 318 block, 360 crank, and 302 heads that I have in my garage for a while now, but I really don't think stock pistons would work unless the rods were shortened, but it would be way cheaper to get the right pistons than to shorten the rods.
Click to expand...

If I got this figured right the difference is .27"/2= .135..Don't forget to halve the difference in the stroke. The full arc the bigger crank is .27" different. Thats .135 at the top of the arc and.135 at the bottom of the arc. With the piston .09 in the hole and a .058" head gasket you would have about .001 in the hole. I measured a 78 318 I have here and got the 90 thou number from that. It doesn't look like you could run much of a cam..LOL A thicker head gasket might do the trick, just bench racing...
 
You'll need to turn the main bearing journals down first, or open the block up to the 360 size. I know you weren't looking for a pissing contest or anything, but this seems to be a lot of custom work to make it happen. I'm sure Diamond can make you a piston to work.
 
dano said:
You'll need to turn the main bearing journals down first, or open the block up to the 360 size. I know you weren't looking for a pissing contest or anything, but this seems to be a lot of custom work to make it happen.
Click to expand...

Yeah, that and the piston weight difference means $$$. You would have to cut the crank mains and rebalance for the 318 pistons. It just isn't worth the money. Drop in a stroker assembly and do it right.
 
Hamburger used to make main bearing spacers for this (whoops, other way around) , maybe someone else does now. but it wouldnt be hard for a machinist and some shim stock. Offset grind the rod bearing to destroke it and youll have spent enough to buy the proper pistons.
 
Hopefully this will be a photo and commentary build. Thanks for all the input. Why do some of you think I'll be using used pistons? I'm CHEAP but not that cheap. Scat has a crank that is new and reasonable. One is on the way for $324. I have a boatload of older open chamber heads. To make them work on anything they need pistons with more compression built in. Most of us can afford a new crank. It is cost effective compared to having one turned by the time you add the travel time to the machine shop and the waiting to get it done. I've read many of your posts about having to wait on a machinest to get the job done. Same here in this area. Good machinests are far and few between. Getting the boring done is almost always a wait. Adding a crank to the mix triples the wait. Seems they can't multitask or something. If I live long enough I will own most of the machinery to do my own machining. Crank grinder is cost prohibitive though.I already have the valve grinder and I'm not afraid of using it. Been doing 3 angle valve jobs with it for 30 years or so. Have access to a Neway cutter set for real cheap. If an old boring bar comes up for cheap it will also be in the garage. Most of us can find what we need to buy within 10 miles from home. I found my Dart a mile away. Had been looking at all the local ads up to 100 miles away and this one popped up on the radar. It is out there and close to home. Most people who have stuff don't know someone is looking for it. Getting a seller and a buyer(us) together is the problem.

Crap! Now I'm being the Rambling Ranter I didn't want to attract.

Sorry guys.
 
the main bearing spacer is for sale at CP products...i read it was 300 bucks plus the block has to be aligned bore before the spacers and with the spacers...
 
pishta said:
Hamburger used to make main bearing spacers for this (whoops, other way around) , maybe someone else does now. but it wouldnt be hard for a machinist and some shim stock. Offset grind the rod bearing to destroke it and youll have spent enough to buy the proper pistons.
Click to expand...


Yeah cause people wanted to run the forged 340 crank in their 360's so they could rev the piss out of the motor.

Now today the bright idea is to run 4 inch stroke:confused:
 
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