212 hemi build

G

GeroniMoe

New Member
#1
#1
Building a 212 hemi and i have 2 main questions.

1. Are ss valves necessary?
2. Are the 26lb springs with high ring keeper sufficent or should i go w/ 32lb springs.

All input & suggestions will be greatly appreciated...Will be posting pics of build

Here's a list of the parts so far

Billet Rod 3.328
Billet Flywheel w/ 32°
Black Mamba Cam .275 lift 246 duration
26 or 32 lb Springs
Aluminum retainers & keepers
Clone carb bored to .625
 
Last edited:
ole4

ole4

#2
#2
Are you using the stock rocker arms? If you are 26lb springs are fine. Why are you using the high keeper, just wondering as hemi has a shorter install height than a regular predator or clone. You will need to check for coil clearance of at least .060 at full lift. SS valves are not necessary but as the valve spring rate increases the chance of the end of the valve breaking off increases as the stock valves are thin at the top. If you are using the high groove aluminum retainers you have to use the SS valves as they are not compatible with stock valves. What was you in the hole measurement as I see you are using the .020 longer rod.
 
ole4

ole4

#8
#8
The stock hemi gasket is .043 uncompressed and would work fine. Or you could stack the non hemi metal gaskets from isky. 3 of them would be .027 so if your deck height is zero that would work just fine. When you say it is flush is it exactly flush or is is above the deck? Like Tim says you can run as tight as .025 but that assumes a good bore with little piston rock.
 
M

Moto Walt

Member
#9
#9
I have a smaller cam than you but I am milled 20 thou with the same rod as you with the thin head gasket. Only way to tell for sure is to play dough the head, turn it over. Take the play dough out. Cut it in half with a razor being mindful not to change the thickness too much. Put a digital caliper on it and account for a little bit of error.
 
trinik7597

trinik7597

Active Member
#10
#10
Don't under estimate stretch ... 30 thousands is what you need piston to head ... These motors vary greatly on spec .. just because one may sit farther in the hole with a plus 20 rod doesn't mean they all do .. when you measure something on a bench cold you always need to take into consideration you are going to be putting heat and 6000 plus rpms to it ... You can not hear piston to head contact when the motor is running and you will push the jug off if it happens repeatedly ..
 
ole4

ole4

#11
#11
Moto you are talking about valve to piston clearance, we are talking about safe piston to head deck clearance. A hemi does not have a squish area stock but once milled it does. You want .030 as tim says but with a unmilled hemi you could go .025.
 
M

Moto Walt

Member
#12
#12
Well just to be honest I didn't even do that to my engine. I helped do that with someone else engine that they took 60 thou off the head with a bigger cam than me, the thin HG and a +20 Rod.


Also if I were to do it over again. I probably would've got the +40 Rod and let that hoe pop up a touch.
 
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