302 heads and cracking

-
moparmat2000

moparmat2000

Well-Known Member
Joined
May 13, 2010
Messages
20,872
Reaction score
10,844
Location
Grand Tetons
How bad and common are the cracking issues with the 302 heads? I am interested in these for a mild 318, but hear this a lot. I'd hate like hell to spend a whole day in the junkyard pulling apart engine top ends and finding cracked cylinder heads I cant use.

Thanks in advance
Matt
 
The do crack more than most LA heads but not as easily or as often as Magnum heads. There are still tens of thousands of Magnum headed smallblocks still running with cracked heads.
 
What's the year to year range for this casting? Does it also go by another casting number besides 302? and will I find these on 318 vans and pickups?
 
I "think" there was also a 724 casting number, just three digits. Well, I know it started with a 7 and I think it had a 4 in it.... But the last set of 308 heads I cc'd measured 58 cc's with stock valves and about 64,000 miles. I think a 318 would respond well to a set with nothing more than a three angle valve grind.
 
I hear about the cracking a lot, too; with 302s and 308s, but I've never had any that were. Of course, I may just be lucky. I've only had maybe a half dozen sets between the two pass through my hands...
 
I've only seen one failed 302 head after a catastrophic overheat event. Cracked to the extent it filled number three with coolant and hydro locked the engine.
 
Note the early to mid 60's 341 castings are Poly 318 heads
upload_2020-9-30_14-14-7.png
 
Professor Fate said:
Yeah, you really don't want to use 308s on a 318 with a stock, or near stock shortblock- you lose a full point or better on your CR, and most 'teeners can't afford that.
Click to expand...
Of course, it works the other way, too- 302s on a stock 360 shortblock gives you a nice CR bump, and with a mild street cam you'll never notice the smaller valves/ports. You may even see an uptick in low-end response.
 
I had to have 3 exhaust seats put in a set of 302 heads a few years back. It was still quite a bit cheaper than a new set of heads for a stock 318, and they haven't given me any issues since.
 
First video is the #6901 cam. Second vid is the #1798 cam. Both in 318's.



 
This one here.
Along with 3.73s, 340 exhaust manifolds, weiand 8022 stealth, an Eddy 650, mopar distributor fired with a GM HEI module

Screenshot_20200930-150152_Samsung Internet.jpg
 
I was going to hit the boneyard and try to get a set. I have a few small wire brushes and can scrub between the valve seats to look em over. Are the cracks fairly visible with a magnifying glass and a flashlight after scrubbing between the valves, or do they stick out like a sore thumb as soon as I pull em off.
 
moparmat2000 said:
How bad and common are the cracking issues with the 302 heads? I am interested in these for a mild 318, but hear this a lot. I'd hate like hell to spend a whole day in the junkyard pulling apart engine top ends and finding cracked cylinder heads I cant use.

Thanks in advance
Matt
Click to expand...

Just go straight to RockAuto for their reman 302 heads (look up '88 D100 Truck) they are back in stock again. 714 heads are the same head too.

They use good cores to begin with and have magnufluxed them to make sure they are good for the reman job. They do an excellent reman job, and the machine work, resurfacing and posi seals 3 angle valve job, with valve springs installed. 1st class job.

Like 500 to your door without cores.

Then they put heat tabs on one of the head frost plugs, then if you over heat it it shows up on the heat tab and it voids the 1 year warranty. That is where the cracking comes into play when they have been overheated on a regular basis.

1020161036.jpg
 
moparmat2000 said:
What's the year to year range for this casting? Does it also go by another casting number besides 302? and will I find these on 318 vans and pickups?
Click to expand...

1986 to 1991 truck D100, D150 pickups. 318cu in 302, 646, 714 castings all the same heads.

Plug the exhaust smog hole with a 1/4" allen screw, good to go.
 
Thanks, forgot about 646. I’ll have to post some pics of the 308 heads I got to cc. We checked multiple chambers with the burette and plexiglass plate and we got 58 cc’s repeatedly. As far as we know of the history of the vehicle they are stock uncut 1991 heads. If a person had some of these there would be a 2 cc chamber reduction of chamber volume vs. the typically 60 cc fast burn head at 60 cc’s. Anyone else ever run into any 308 with such a small chamber volume? The donor was a 1991 W-250 with 360 hydraulic roller engine.
 
Professor Fate said:
Yeah, you really don't want to use 308s on a 318 with a stock, or near stock shortblock- you lose a full point or better on your CR, and most 'teeners can't afford that.
Click to expand...

But, but, but, just think of the SHITTY gas you could run! :poke:
 
I went to rock and they wanted a vin number to order these. What have you guys been using.
 
You must log in or register to reply here.
-

Back
Top