Rpm 340 Cyl heads on a 318 !

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SS Lancer

SS Lancer

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Good morning gents - could u tell me if the 340 Rpm heads will fit on a 318 block without modifications?
I know they should bolt on etc but with the bore being smaller I was concerned thanks - Chris .
 
Dome pistons in a 318? Your best bet is call someone like racetec and have them custom made to your specifications
 
I would use metric rings also, and get the pins in the smaller chevy diameter, then you can use chevy rods, in a 6.125 or 6.250, or whatever length you decide
 
sounds like you are thinking over your head
what exactly is your goal
what is an RPM head?
340-360 heads will lower your cr as the factory did with the late 318 4bbl cars
you can mill your 360 heads or buy pistons to raise the compression back up
but what are you trying to do
what gas?
you will have to balance with new pistons
cc those heads and figure out what compression height and dome cc you need to get you where you want to be
post up the rest of your project weight, gears ,trans usage, usage, usage
 
Wyrmrider said:
sounds like you are thinking over your head
what exactly is your goal
what is an RPM head?
340-360 heads will lower your cr as the factory did with the late 318 4bbl cars
you can mill your 360 heads or buy pistons to raise the compression back up
but what are you trying to do
what gas?
you will have to balance with new pistons
cc those heads and figure out what compression height and dome cc you need to get you where you want to be
post up the rest of your project weight, gears ,trans usage, usage, usage
Click to expand...
Ten 4
 
Keep in mind also, that head, or any head really, will flow less air on that 3.910 cylinder than it will on a 4.040.... more food for thought
 
1Badcolt said:
Thank you
Click to expand...


You may get by without notching the bore with a 2.02 valve. Maybe. I always notched the bore, even with a 1.88 valve. It's one of those things you can actually learn with a flow bench. So I'd plan on notching the bore for a 2.02 valve and any bigger than that and you definitely need to notch the bore.
 
yellow rose said:
You may get by without notching the bore with a 2.02 valve. Maybe. I always notched the bore, even with a 1.88 valve. It's one of those things you can actually learn with a flow bench. So I'd plan on notching the bore for a 2.02 valve and any bigger than that and you definitely need to notch the bore.
Click to expand...

Thank you
 
By notching the bore- I assume you mean "fly cutting the pistons?" or actually notching the edge of the cylinder wall to accommodate large dia valves?

If you notch the pistons get them notched for the valves you are running not oversize. Different diameter valve heads will strike the pistons at diffrent spots and depths.
Easy thing to do is spin cut a valve shaft to a take the valve head off and then bring it to a point.
Assemble the bare heads on the block and with the piston a TDC use the new valve to make a prick punch in the top of the new piston.
This will let the machine shop know the true center of the valve so they can fly cut the radius.
There are plenty of kits out there with all this work done for you. Just running a diffrent cam profile can change stuff.
Good luck,
Joe
 
Syleng1 said:
By notching the bore- I assume you mean "fly cutting the pistons?" or actually notching the edge of the cylinder wall to accommodate large dia valves?

If you notch the pistons get them notched for the valves you are running not oversize. Different diameter valve heads will strike the pistons at diffrent spots and depths.
Easy thing to do is spin cut a valve shaft to a take the valve head off and then bring it to a point.
Assemble the bare heads on the block and with the piston a TDC use the new valve to make a prick punch in the top of the new piston.
This will let the machine shop know the true center of the valve so they can fly cut the radius.
There are plenty of kits out there with all this work done for you. Just running a diffrent cam profile can change stuff.
Good luck,
Joe
Click to expand...
Thank you
Cambell Enterprises in VA sales alot of stroker kits for the 318 pushing it up to 390 & 392 CI
I will check with those guys and see if they ran into this small issue .
 
Dear bad
by notching you are looking at a half moon out to the combustion chamber - not the gasket pretend your are flying through the intake and what do you see when you come through the valve- iron walls are not good for flow
are these Iron heads? post up the casting number- I have no idea what an RPM is?
here is a good place to start for a piston search click on the picture of the piston to pop up compression ratios with different head cc's
Chrysler : United Engine & Machine Co. Incorporated, Performance Pistons
but you have to know your head cc's and not just the advertised/ published data- measured cc's
once we know your casting number or head mfg members can give you a ballpark for what they really are till you get them cc'd (that's a DIY task)

yep if it turns out that you need crank work and a balance job then you are close to a stroker kut
 
Alum Edelbrock
Rpm 340 heads .

Screenshot_2018-08-02-17-24-33.png
 
Syleng1 said:
By notching the bore- I assume you mean "fly cutting the pistons?" or actually notching the edge of the cylinder wall to accommodate large dia valves?

If you notch the pistons get them notched for the valves you are running not oversize. Different diameter valve heads will strike the pistons at diffrent spots and depths.
Easy thing to do is spin cut a valve shaft to a take the valve head off and then bring it to a point.
Assemble the bare heads on the block and with the piston a TDC use the new valve to make a prick punch in the top of the new piston.
This will let the machine shop know the true center of the valve so they can fly cut the radius.
There are plenty of kits out there with all this work done for you. Just running a diffrent cam profile can change stuff.
Good luck,
Joe
Click to expand...


Notch the cylinder wall. The bore is small enough that it becomes an issue with the 1.88 valve as far as flow goes but IIRC the 2.02 will hit the cylinder wall or be even closer than the 1.88 valve.
 
202 valves like careful cam selection, gears, 340 type converter or to go with cam and the rest of the package
really easy to overcam SBM especially 273- 318
not something I would do with stock converter and 2.74-3.31 gears
which trans 904-727 or stick?
sorry about the RPM
they are usually bigger than the cc's claimed-
are these new? get them checked out for guide tight and valve/ seat concentricity, check the springs,
anyone with recent RPM experience speak up
if you have a choice the ones without the .060 cut are easier to work with
if you do have to use the fly cut ones figure on a couple of extra trial assemblies with pop up pistons
if these rpm's are swap meet check for flat and surface finish cc anyway
 
It will work, no modifications. Get the closed chamber versions if you're ordering the custom pistons. I agree with the metric ring package if you are staying factory stroke. If you are stroking it, keep the thicker rings. No need to notch the bores. BTW all that does is help flow, aside from adding a small amount to the combustion volume.
 
1Badcolt said:
Thank you
Cambell Enterprises in VA sales alot of stroker kits for the 318 pushing it up to 390 & 392 CI
I will check with those guys and see if they ran into this small issue .
Click to expand...
What are you doing with this engine? The usual questions of SCR, DCR, cam size, fuel type and all that jazz apply. The pN 60779 version of these heads that you are looking at have 63 cc chambers, and that + a stroker kit will push the SCR/DCR well above the stock 318 levels. You gotta do the same homework each time.
 
Dear bad
by notching you are looking at a half moon out to the combustion chamber - not the gasket pretend your are flying through the intake and what do you see when you come through the valve- iron walls are not good for flow
are these Iron heads? post up the casting number- I have no idea what an RPM is?
here is a good place to start for a piston search click on the picture of the piston to pop up compression ratios with different head cc's
Chrysler : United Engine & Machine Co. Incorporated, Performance Pistons
but you have to know your head cc's and not just the advertised/ published data- measured cc's
once we know your casting number or head mfg members can give you a ballpark for what they really are till you get them cc'd (that's a DIY task)
 
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