D.l. man 2012-01-19 20:32:21
I just pulled the heads on my dads 350 blazer and I was wondering if the new
heads are off a 305. The bolts for the rocker arms don’t thread down as far
as the old ones. And there is allot of play for the valves. I don’t think
that it will fit. Is this the same kind of head or what?
\doc\ 2012-01-19 20:32:27
What is the casting number stamped where the rockers are located? I’ll give
ya the specs on them thar’ heads………..
D.l. man 2012-01-19 20:32:34
It is hard to read but I think that it says 8888882 and right next to it k12
on the other side it has what appears to be 21 or 12 and there is a bunch of
number further down towards the firewall that I can’t read.
Used parts suck sometimes.
Snoman 2012-01-19 20:32:41
305 and 350 heads are the same except for combustion chamber size. My
guess on the stud thread length may be the difference for head that
were on a engine with factory rolled lifters or not as chevy switch
them over to this style lifter some time ago the the lifter is
longer/taller than a flat bottomed hyd one.
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D.l. man 2012-01-19 20:32:43
I checked the lifters off the new head and they are the same size as the old
ones the push rods seem to be the same size too. And I know that they were
on the lobes when I put the intake on. they seemed to fit the old engine but
not my dads.
\doc\ 2012-01-19 20:33:04
That ain’t the cylinder head casting number dude. Doc
D.l. man 2012-01-19 20:33:06
I looked between the rocker arms and there were those numbers. Maybe I am
looking in the wrong spot. Can you tell me where I might find them.
Kenner costen 2012-01-19 20:33:43
350 and 305 and 327 and 307 heads are relatively the same head except for
combustion size and valve size. If chamber size and valve match, run them.
Does not matter unless you go into vortec or roller heads. Also on engine
notorious for lower compressions, 307 and 305 you will find larger chambers,
which does not hurt with today’s fuel.
Jeremy stec 2012-01-19 20:33:54
I bet the number is 333882. See the following:
SMALL BLOCK CHEVY HEAD CASTING NUMBERS
Casting Number CID Year Application Comments
330545 307, 350 73 Pass, Camaro, Chevelle, Nova All, Medium Perf
333882 350, 400 73-76 Pass
333882 350 74-76 Camaro, Z28 All w/o Steam Holes
333882 400 74-76 Chevelle, Monte Carlo w/ Steam Holes
333882 350 74-79 Truck Light Duty, w/o Steam Holes
333882 400 75-79 Blazer 4X4 Models, w/ Steam Holes
333882 400 76-80 Truck Light Duty, w/Steam Holes
340292 350 MID 70’s Replacement Over the counter Hi-Perf Turbo Head
354434 262 75-76 Monza, Nova Light Castings
354434 305 76-79 Truck Light Duty, Light Castings
354434 305 76-85 Pass, Camaro Light Duty, Light Castings
358741 305 76-79
367450 262 75-76 Monza, Nova
376445 350 77-85 Truck Heavy Duty
462624 350 71-79 Camaro, Corvette Hi-Perf, Extra Manifold Bolt Hole
462624 400 75-80 Truck Light Duty, Extra Manifold Bolt Hole
462624 350 75-86 Truck Light Duty, Extra Manifold Bolt Hole
462624 350 80-85 Truck Heavy Duty, Extra Manifold Bolt Hole
462624 350 80-85 Corvette All, Extra Manifold Bolt Hole
468642 350 71-79 Truck Heavy Duty, Small Plugs
468642 400 75-80 Truck Light Duty, Small Plugs
468642 350 75-85 Truck Light Duty, Small Plugs
468642 350 80-85 Covette Small Plugs
468642 350 80-85 Truck Heavy Duty
517513 267 79-82 Pass, Malibu, Monte Carlo
3703523 265 55 Corvette 195 HP
3703523 265 55 Pass 4 BC
3725306 265 56 Corvette 2 Bolt Exhaust Manifold, 210 HP
375306 265 56 Pass 4 BC
3725306 265 Early 56 Corvette 2 Bolt Exhaust Manifols, 225 HP
3731539 283 57 Pass 4 BC & Fuel Injection
3731539 383 57 Corvette 283 HP Fuel Injection
3731539 283 57 Truck
3731554 283 57 Pass 2 BC
3731762 265 56 Pass 2X4 BC
3731762 265 56 Corvette 3 Bolt Exhaust Manifold, 240 HP
3731762 265 Late 65 Corvette 3 Bolt Exhaust Manifold, 255 HP
3740997 283 57 Pass 2X4 BC, 250 HP, Fuel Injection
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D.l. man 2012-01-19 20:34:10
Thanks for typing all that out. I hope it wasn’t to much trouble?
So then going by what you wrote here for me. The 333882 is only for 350 and
up? It couldn’t go on the 305, it has to be 350. When I compared the 2
heads together while it was off I had them side by side and nothing really
stuck out like the valves being different sizes so unless they are really
similar to the naked eye they should be the same.
Mad dog 2012-01-19 20:34:41
Lifters rest in the lifter valley in the block, not the head.
Lifters are shared amongst 1st
Gen SBC’s at .842″ diameter.
1st Gen 350’s generally have 76cc open chamber heads, 305’s from the same
era used a dished piston and 58cc closed chamber heads with a very
restrictive exhaust port and smallish valves.
Pushrods are also shared at 7.8″ length,
unless the block or heads have been decked.
Locate a set of similar heads to the ones you are replacing and be done with
’79 Chevy K-10
pictures can be found here:
D.l. man 2012-01-19 20:34:45
I have found heads that are identical to the ones I’m taking off. Except the
threaded post that adjusts valve lash don’t seem to be threaded down as far
as the old ones. As it turns out I don’t know if I can set the rockers arms
tight onto the pushrods. I was wondering if it could be different heads
because of this little threaded post problem. I could just tap the post down
farther if I need to. I don’t know the pitch for those but it should be easy
enough to figure out if I just get the big tap and die set from autoplace.
Mad dog 2012-01-19 20:34:53
Oh, you’re dealing with variations on the rocker stud………it should be
fine in your case.
Unless the lifter(s) has collapsed you wont have to run the adjuster nut
down very far to achieve zero lash.
’79 Chevy K-10
pictures can be found here:
D.l. man 2012-01-19 21:10:03
Ok I have an update of what happened. I decided to see what would happen if
I tried to set the lash. I got the 1 piston to TDC and I turned the crank
over 90degrees and I started to set the lash. I got it down to the pushrod
and it got very tight. I was relieved too. I backed it off until there was a
little drag. I moved on to all of them and then I did it again to handle the
other valve on the intake stroke. I set them loose to kind tough drag. But I
didn’t over tighten them so I didn’t think that I would get any backfiring.
I then put the alternator, power steering and misc brackets back on and I
attempted to start it. I had to tighten the gas line but other then that it
was very smooth. It took some trouble to get it going and I notice it was
backfiring but I didn’t set the timing so I advanced it a little and it
seemed to stop back firing. I couldn’t get it to idle though. I think it
maybe the EGR? It sounded real smooth running although it wouldn’t idle.
I was getting allot of smoke off the exhaust too. But it could be left over
stuff that is burning off. I didn’t see the valve cover leaking and adding
anything new. I was so close to getting it back together tonight. I couldn’t
figure out a few vacuum lines so I thought we should pick it up in the
I want to thank all of you again for helping adding the technical input that
Chilton’s and Haynes don’t bother with. Thanks.
Mad dog 2012-01-19 21:10:18
The easiest way to set the lash is rotate the engine to TDC and adjust
available valves at zero lash…no drag…just zero lash, then rotate the
crank 90 degrees and do some more….another 90 and some more until after 2
complete revolutions of the crankshaft which equals 1 complete revolution of
once your sure you have set all the valves at zero lash then you can tighten
each rocker nut another 1/2 turn without having to rotate the engine over.
When it backfires it means that either the timing is retarded or the rockers
on the intake side are to tight……..this is assuming of course that you
don’t have a burnt, bent valve or stuck valve.
’79 Chevy K-10
pictures can be found here: