Tslayer66

Finally getting started on my mild CAM Swap on my 82. Swapping CAM, Heads and and adding a Renegade Intake at the same time. Big job for me as i am a novice, however doing with my sons, so its a nice bonding opportunity So far we have pulled the hood, radiator shroud (what a super pain!), radiator, water pump etc...
Before i go further i need to ask about the timing.

So right now the timing is set advanced (i believe). Currently my timing mark is exactly at 12:00 on the harmonic balancer when the distributor is pointing at the number one spark plug. So before we do the CAM swap and start the engine break in should i set the timing to 0 degrees TDC or is it ok to leave it advanced?

Appreciate the help!

derekderek

The distributor has to come out in order for the Cam to come out you have to redo all the timeing after the Cam is installed.

HeadsU.P.

No need to worry about the IGN timing / harmonic balancer right now. You will set all that later.
Before you pull your timing chain / cam, turn the crank by hand until both dots on the sprockets are across from and near each other:
crank at noon and
cam at 6 o' clock.

That way, you will not make a mistake when you install cam, sprockets, chain. Its an easy visual to spot the dots and have it right on the money.
(Later you will move the crank to # 1 firing position)

jackson

OP
Yes, distributor comes out first & goes in last.

Go ahead & set motor at true TDC with rotor pointing at #1. That's best reference point as most but not all will get disturbed by your cam & intake swap.

BTW ... which cam & heads are going in?

FYI: Changing heads & cam (are you also changing rockers?) likely to change rocker arm/valvetrain geometry ... and Especially If you use either roller rockers or roller-tips, you'll need to check that geometry as you assemble. Possible different pushrods with different length may be needed. Plenty of online and print tutorials on RA geometry-setup you should familiarize yourselves with ASAP.

Fast81

Another thing to consider, the ECM can only handle so much cam duration and CR before custom chip burning are in your future.

Which ones you using ?

derekderek

Don't worry about timing now. You are gonna be turning it over by hand as you install and check timing chain. And drop the oil pan.

Tslayer66

Thanks for reply, I do realize I will need to pull the distributor. I was only concerned if I should keep a point of reference as you described. Probably over thinking it, just trying to prevent future problems if I can.

As far as the parts I’m using. I did my research with my ECM and cross fire setup. For the CAM I’m using Comp Cam 12-388-4 https://www.summitracing.com/parts/cca-12-388-4. It should be ECM friendly. Also using the Com Cam high energy lifters.

For the heads right now I’m looking at the Brodix IK 180 https://www.summitracing.com/parts/bro-1021005 however I have not ordered these yet.

Rocker Arms I have not researched yet. So any input is appreciated

thanks!

Fast81

Cam will be fine, heads however........................have too small of chambers for your motor. The 82 L83 motor re-used the 6cc dished pistons from the L82 to get the L83 to factory 9.0:1 CR -- and this was using the same '624' heads with 76cc chambers from all the previous C3 L48 years. These Brodix 180s you're considering with the 64CC chambers will push the static CR close to 10.5:1.

so it will create a cam/CR mismatch in that your cam is a 9.0:1 CR stick while your heads will make the motor 10.5:1. Most recommendations are that you can safely go up/down .5 from the cams designed CR .
This would mean you should only push up to 9.5 CR using your 9.0 CR chosen cam. A head in the 70-72cc range would do this.
Now is you wanted these Brodix 180s with 64cc on an L48 starting with 8.5:! CR, i'd say great choice as the 64cc would bring it up to 9.5:1

Good luck

jackson

fwiw
data at GM Heritage center dot com reads (MY 1980) L82 has flat head forged piston ... and (MY 1982) L83 has sump head cast piston.

resdoggie

You haven't stated your budget but I would go with the aluminium heads, 64 or 76 cc's, calculate a workable dcr for use with a bigger cam in the 0.500+ range and longer duration. Otherwise, save your money for the heads and stick with the cam you selected. Depending on the cam and dcr, you can go 10.5 cr and higher on pump gas.

68post

Hold on, conventional wisdom is that you can use one point higher compression using AL heads vs iron heads. That said, an iron head vortec style chamber runs on regular unleaded @ 9.3 compression with very short cam timing, pulling a much heavier vehicle and sometimes under severe load conditions.
If there were a problem on regular unleaded - I'm sure an upgrade to a higher octane pump fuel would be worth the extra power and efficiency.
It likely won't reach exactly 10.5-1 w/o decking the block or shim gaskets, but I'd make sure to have fast-burn chambers in any new cyl head purchase.

Dart Pro-1 Platinum heads and Profiler would be heads to consider also, in my opinion - before Brodix. Or AFR if the budget gets stretched. $.02

7T1vette

Tip for a novice on this 'first time' work:

Before you remove the distributor, do two things:
1. place a reference mark on the distributor housing base facing directly forward. Normally you would also put a matching mark on the intake manifold so you could line up the distributor the same at assembly. But, you are swapping the intake manifold, so you need to put the mark 'straight ahead' and then install it so that the mark is 'straight ahead' when assembled.

2. remove the dist. cap and put a big piece of duct tape from one side of the dist housing, up and over the rotor, and down to the other side of the dist. housing. Make sure the tape is adhering well to the housing and rotor. This will keep the parts of the distributor reasonably well aligned when you remove it AND when you re-install it. There is a helical drive gear at the bottom of the distributor (driven off the cam). As you remove the dist., the gear will turn and you will lose orientation of the rotor and housing if it is not kept together as a set. With it taped, the distributor will 'rotate' out of its location; and it will need to be rotated back in to position at assembly time.

If you regularly do this kind of work, you really don't need to do this. But, it really helps and simplifies this work, if you are new to it.

jackson

I've had two MY 1971 L48 ... both CJK ... both had OE 487 heads ... not 882, not 624. I've never owned an L83.

also, same source reads L83 piston 0.025" below deck and head gasket is 0.021" thick with 4.60cc volume. Same source reads chamber volume 73.27cc.

JMO ... I do not KNOW, but with all else same, I doubt 64 chamber on L83 will even make it to 10:1 ... JMO

JMO ... L83, renegade induction, good 64cc chamber, that cam & optimized ECM ... I doubt it'll make 350 hp at crank ... probably no more than 325 ... JMO

With such a small cam as OP proposes ... JMO ... No need or real benefit from roller rockers or roller tips. OE type slider shoe rockers are Very forgiving on geometry.

Perhaps the folks at Renegade (who developed their own xfire intake) have a good handle on what size chamber & CR & cam works well for L83? Ask 'em?

Brodix Iron Killer series DO have the more modern fast-burn type chamber; Nothing like chevy humps or fuelies.

Fast81

Same dish design, different material. 82 were not forged, but cast

Fast81

You are talking CR vs. head material and in that aspect you are right -- given the cam matches the CR
The point i was making is that his chosen 64cc chamber in the Brodix would push his CR way beyond the 9.5 CR upper limit of his 9.0 CR cam.

1982 ECM is limited in the duration it can handle and since CR and duration are linked, the highest CR the ECM can handle is around 9.6-9.75 and 64CC chambers yield over 10.3-10.5

Fast81

GM used the 462624 76cc chamber iron heads on all Vette motors (except L82) from 1978 even into the C4s of the mid-80s.