More Small Block Questions

[64 SRT8 Dart]

When mounting pistons (flat tops) is it worth putting them on "backwards," so to speak, like you hear about the bigblocks?

I have fed mog/sterling 285NP's and they have the notch in the piston that lets you know which way to put the piston in.

Also, I have a hydraulic cam. What pushrods do I need to run 273 adjustable rockers with it?

Okay, one more. The deck height on a factory 318 is supposed to be 9.6".
How can I get the piston to deck height without assembling the rotating assembly? Stroke is 3.31", Rod is 6.123", and piston comp height is 1.72".

Any help is very appreciated!!

 

[70aarcuda]

When mounting pistons (flat tops) is it worth putting them on "backwards," so to speak, like you hear about the bigblocks?

I have fed mog/sterling 285NP's and they have the notch in the piston that lets you know which way to put the piston in.

Also, I have a hydraulic cam. What pushrods do I need to run 273 adjustable rockers with it?

Okay, one more. The deck height on a factory 318 is supposed to be 9.6".
How can I get the piston to deck height without assembling the rotating assembly? Stroke is 3.31", Rod is 6.123", and piston comp height is 1.72".

Any help is very appreciated!!

on the deck height ...if you dont assemble the engine...you can only guess at where the pistons will be in relation to the deck since the deck height on a factory engine will be all over the place...now if you take the block to the machine shop and have them square the block...then by doing the math on your crank...rods and compression height on the piston you will be in the ball park...then again....unless your rods have been blueprinted..and the crank has been index and stroke equalized....there will be some variations...

 

[64 SRT8 Dart]

on the deck height ...if you dont assemble the engine...you can only guess at where the pistons will be in relation to the deck since the deck height on a factory engine will be all over the place...now if you take the block to the machine shop and have them square the block...then by doing the math on your crank...rods and compression height on the piston you will be in the ball park...then again....unless your rods have been blueprinted..and the crank has been index and stroke equalized....there will be some variations...

I wonder what the equation would be? I would've thought that you would take the stroke + rod length + comp height then subtract from the deck height. However, that doesn't work out.

 

[70aarcuda]

http://www.summitracing.com/parts/cca-7821-16

pushrods...

 

[71beater]

1/2 stroke + rod length + comp height

 

[67Dart273]

So far as I know, the only foolproof way to get deck height it to take ONE complete piston/ rod/ bearing assy. and install it in all 4 corners and measure it.

 

[64 SRT8 Dart]

Thanks 70aarcuda! So the pushrods for the solid cam ARE different than the hydraulic ones?

 

[rumblefish360]

Great answer. To zero deck the blo k to the pistons max height, have the manchinist do it. Don't guess and tell him you want *** wacked off the top.

Go to Hughes engines and rent there pushrod measureing tool and the. Order pushrods from them. Tell them your running a Hyd. Cam and mechanical 273 rockers. They'll set you up.

Swapping pistons around cam be done on any engine. (Swapping the banks there in.) Not just big blocks. Regardless, it isn't something I would do for a street engine. They are designed a certain way for a reason. While power can be found in doing such things, I'll play it straight myself so I can rest assured it'll be and stay good for a long time.

 

[OldmanRick]

"aar" is exactly right about mock up and proper measurements to know what you really have. I'll just throw in, that on average the comp height usually ends up in the 1.80/1.82 range to get to zero deck.

 

[70aarcuda]

take 1/2 the stroke...3.31/2=1.655
plus rod length 6.123

plus the compression height of the piston...1.72 as noted in 1st post...

1.655 + 6.123 + 1.72 = 9.498.....

so if the block is at 9.60....your pistons will be down .102 in the hole

 

[rumblefish360]

A d yes, the pushrods are different.

 

[64 SRT8 Dart]

So far as I know, the only foolproof way to get deck height it to take ONE complete piston/ rod/ bearing assy. and install it in all 4 corners and measure it.

Never thought about it that way. Cool beans, thanks sir for the info. Will definitely be interesting to see what it looks like when I assemble it, I'll make sure to put those four in first!

 

[70aarcuda]

Thanks 70aarcuda! So the pushrods for the solid cam ARE different than the hydraulic ones?

yes...the pushrods for solid lifter is usually longer ...

 

[64 SRT8 Dart]

take 1/2 the stroke...3.31/2=1.655
plus rod length 6.123

plus the compression height of the piston...1.72 as noted in 1st post...

1.655 + 6.123 + 1.72 = 9.498.....

so if the block is at 9.60....your pistons will be down .102 in the hole

Okay, so lets say my machinist zero decks the block to those pistons. Isn't .102" a lot to take off the deck???

 

[OldmanRick]

http://www.summitracing.com/parts/cca-7821-16

pushrods...

Also, notice these are cup & ball for the 273's instead of ball & ball like the stamped rockers.

 

[OldmanRick]

Okay, so lets say my machinist zero decks the block to those pistons. Isn't .102" a lot to take off the deck???

^^^^^^^^^^ Meaning new pistons. Most likely KB's..http://www.summitracing.com/parts/uem-kb167-030/overview/make/plymouth

 

[64 SRT8 Dart]

Hmmmm, well let's say that the block is already machined like that :sad4:

 

[70aarcuda]

Hmmmm, well let's say that the block is already machined like that :sad4:

need piston with different compression height....

like said..about a 1.82 will get ya near zero deck

 

[70aarcuda]

http://www.kb-silvolite.com/kb_car/...=search&mfg=Chrysler&EngSize=318&RodLen=6.123

either one of those KB have a compression height of 1.81...

 

[pishta]

Hell yes, .100 off a stock piston is huge. Get taller pistons. decking that much will ruin the fitment of the intake. Put a std crank in there, TDC to each corner and measure to deck off journal, subtract 1.79 (1/2 of stroke), then subtract 1.062 (1/2 of rod journal). this should get you pretty close to deck height. Measure your piston crown to part line of connecting rod cap and rod. The difference is your piston relief, either positive (out of the hole) or negative (in the hole). Eg. 360 with H116CP pistons with a compression height of 1.670 yields a .017 quench. I suppose you could use 1.687 as the pin height to deck with these figures.....but do the math or drop an assembly in and measure.

http://www.moparmusclemagazine.com/...3_how_do_i_figure_my_compression/viewall.html

 

[OldmanRick]

Hmmmm, well let's say that the block is already machined like that :sad4:

All i can say is if you've taken .100 of the deck, good luck getting a intake manifold to fit.

 

[64 SRT8 Dart]

All i can say is if you've taken .100 of the deck, good luck getting a intake manifold to fit.

Yep, that's exactly what's happened.rotest:

Haven't put anything together yet but had the thought runnin through my head lately about it.

I took everything up to the machinist and he said that he would take care of everything, including zero decking to the pistons. The part number is on the pistons, and knowing the machinist, I figured he would look them up for the comp height before cutting into anything. However, on my receipt it shows "zero deck V8." Doesn't show the amount he took off.

This is also gonna affect the pushrod length as well. Not to forget about the head bolt depth.

 

[rumblefish360]

You'll need to mill the heads and or the intake to fit if the milling is so.

 

[273]

http://m.summitracing.com/parts/uem-1266-std These are stock replacements so they shouldn't need balancing and are 0.021" taller then your pistons which puts you 0.081" in the hole, I'd still go with Hyper KB's zero decked the only way to build a 318 instead of milling the **** out of everything.

 

[64 SRT8 Dart]

You'll need to mill the heads and or the intake to fit if the milling is so.

Yeah, guess I'll find out when the assembly is in. :happy1: