Where do 302 heads crack?

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Ottmundr

Ottmundr

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I expect to be getting a set of 302 heads for my 68 318 since I need to replace the head gasket due to a leak.

I understand that the 302 heads can crack. WHERE do I look to check for the potential cracks when I'm at the pick and pull?

Since I'll have the heads off I was thinking I'd change the cam to something like the comp cams xe262h. I also have an edelbrock performer intake (not the RPM) and a Holley 4160 600 CFM.

Planned use is in a 68 fastback daily driver and going to the track about once a month this spring/summer/fall. Tires are 27" diameter. Current gears are 2.73. I plan on 3.23 or 3.55 at the most later this year. Trans is a904, no shift kit yet, I am planning a TF2 later as well.

I am not planning ongoing into the bottom end now. I have not checked compression and won't do it until I first swap out heads and head gasket.

Thanks for your input folks.
 
Mostly between the valve seats.......but really, anywhere they want to.
 
The cracking is typically the result of the induction hardening process used on the valve seats, and like RRR pointed out it usually shows up between the valve seats.

But the cracking problem on the 302/308 heads is a little overblown. Listening to folks on here you'd think at least every other set of heads has cracks and is junk. I run a set of 308's on the 340 in my Duster that I had rebuilt and ported, they were checked and had absolutely no issues. I even bought them on eBay based off of crappy pictures. I also have a set of 302's that were on an '86 318 I bought and briefly ran in my Duster. I actually pulled the heads last night because I sold the engine today. 85k miles and the heads look great other than the bad valve seals.

Yes, they are more prone to cracking than other heads out there. But finding a good set isn't a total crapshoot, there are more good ones than bad ones out there. I'm 2 for 2 so far.

Why the 302's though? It sounds to me like you should be looking for something with more performance. The 302's are good for a little bit of a compression boost because of the closed chambers, but they still have the same 1.78/1.50" valves as all the other 318 heads out there. The flow slightly better on the exhaust side than earlier 318 heads, but the intake side is pretty much the same as every other 318 head.

A set of Magnum heads would be a better choice IMO, larger valves, better flow, same closed chamber head. If you get them from a wrecking yard you can pull the rocker gear, which is 1.6:1. And if you're changing the cam you can just get oil through lifters with the new cam anyway. Just need oil through push rods and a new intake to complete the swap. And finding something with magnum heads at the yard is probably easier than finding something with 302's nowadays.
 
pay attention to clearances between later model heads and early model exhaust manifolds. I don't recall which early LA manifolds. Seem to recall it was a issue at left side only.
 
72bluNblu said:
The cracking is typically the result of the induction hardening process used on the valve seats, and like RRR pointed out it usually shows up between the valve seats.

But the cracking problem on the 302/308 heads is a little overblown. Listening to folks on here you'd think at least every other set of heads has cracks and is junk. I run a set of 308's on the 340 in my Duster that I had rebuilt and ported, they were checked and had absolutely no issues. I even bought them on eBay based off of crappy pictures. I also have a set of 302's that were on an '86 318 I bought and briefly ran in my Duster. I actually pulled the heads last night because I sold the engine today. 85k miles and the heads look great other than the bad valve seals.

Yes, they are more prone to cracking than other heads out there. But finding a good set isn't a total crapshoot, there are more good ones than bad ones out there. I'm 2 for 2 so far.

Why the 302's though? It sounds to me like you should be looking for something with more performance. The 302's are good for a little bit of a compression boost because of the closed chambers, but they still have the same 1.78/1.50" valves as all the other 318 heads out there. The flow slightly better on the exhaust side than earlier 318 heads, but the intake side is pretty much the same as every other 318 head.

A set of Magnum heads would be a better choice IMO, larger valves, better flow, same closed chamber head. If you get them from a wrecking yard you can pull the rocker gear, which is 1.6:1. And if you're changing the cam you can just get oil through lifters with the new cam anyway. Just need oil through push rods and a new intake to complete the swap. And finding something with magnum heads at the yard is probably easier than finding something with 302's nowadays.
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Pretty much what he said. I've had, checked, and used or sold about 12 total sets of 302s and 308s. Never found a cracked one. But - you really have to have any head checked before you pay for any real machine work anyway.
 
I seen them crack on the outside of the head on the corner head bolt holes, into the exhaust port. Friend of mine built a 360 with the 302's and didnt find out they were cracked there until it was on the run stand. sad day, two pairs ive seen do that.
 
I had a set I was going to use on a motor and one of them was cracked right between the intake and exhaust seats. So now I have one sonic checked one on the shelf! LOL!
 
dadodgekid said:
I seen them crack on the outside of the head on the corner head bolt holes, into the exhaust port. Friend of mine built a 360 with the 302's and didnt find out they were cracked there until it was on the run stand. sad day, two pairs ive seen do that.
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This also seems to be common on 920 heads (273). I had 3 of these, and all 3 of them were cracked (two were on the car). Had to source another set.
 
what you posted is basically my exact set up. 69 318, performer intake, xe262, 302 heads, holley 670 street avenger, block hugger headers, trans go2 in a 904 but i run 3.90 gears... in this
tCPPqxq.jpg

you will like this set up
 
Pentastarnut that is a sweet car. Have you ran it at the track yet>?
 
OK, Penstarnut! You have some 'splaining to do my man! Narrow body and the 5 bolt suspension? Is that the wide body suspension with inset wheels? Niice Starquest! Man, I just scrapped one of those narrow bodies this morning.

OK....Here is my wide body rally Starion in action; all images by are Jerry Winker (aka Comicozzie). We're crossing that bridge in northenr Maine AFTER slowing down to 60 or 70 MPH..... that was a 22 mile long stage and we hit 100+ a few times....
 

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thank you, track time, not yet as it's still enjoying life as a wuss trailer queen HA HA HA
... but soon we'll see what she'll do, i'm expecting 12's
the full suspension is off of a 85.5 i had a while back that was a lil rusty. it looked exactly like my current 85.5 daily driver terd
CULEEjl.jpg

nm9stheham are you on SQC ?
 
OK, well the early narrow body suspension was 4 bolt, narrower, and the front lower control arms and/or front crossmember and strut/spindle assemblies were different than the later ones. Maybe you got a later narrowbody and it had the wider stuff from the factory....Oh, I get it...that explains the 85.5! I never saw one. Looks like it had the intercooler with that... very good!

So how did the 318 fit-up go? Have any better pix of the engine bay now?
 
WTH does this^^^ have to do with 302 heads? Just sayin.....
 
Mopar Tim said:
WTH does this^^^ have to do with 302 heads? Just sayin.....
Click to expand...
Just car talk......and a threadjack that is pretty tame compared to many LOL! If you ever got into Starions or Conquests at all, you'd know they are pretty nifty RWD cars. Oh yeah, and I did ask about the 318 fit...
 
between the 2 valve seats, sometimes they leak, most of the time they dont.
 
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