These heads are crack prone? - Team Camaro Tech
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post #1 of 24 (permalink) Old Aug 6th, 09, 09:37 AM Thread Starter
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sako
 
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Location: california
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These heads are crack prone?

Jut opened up my valve covers last night to find out what heads I have.
462624
L137
NAWIAT
Thanks to Larry(larryh56) for the decode.

462624 76-87 1.94/1.50 & 2.02/1.60 valves
HP - Not listed
76 CC Chambers
These are crack prone! according to http://www.thedirtforum.com/castings.htm

What would be recomended for my supercharged sbc.
Cast Iron or Aluminum? and some numbers please. Thanks

1969 SS camaro,emerald green with white hockey stripe.383 stroker with weiand supercharger.12 bolt 373 gears. 4 speed.

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post #2 of 24 (permalink) Old Aug 6th, 09, 11:52 AM
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Patrick
 
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Re: These heads are crack prone?

I have never heard of this. This is what Mortec says about your heads:
462624.....75-86...350/400......76cc chamber, 1.72/1.5, 1.94/1.5 or 2.02/1.6 valves


I would recommend aftermarket aluminum heads for your supercharger like Dart's or AFR's.

I assume you have this engine already running with the supercharger on now right? If so just keep an eye out on everything and run them.

69RS/SS,383,10:1cr,4.10,60ft1.6sec,1/[email protected],1/[email protected],Vicjr,RPMheads,750dp, Proform main body, cam,246*-250*@.050,.510,522,1.6rr,700r4,3200stall
383 IS SOLD!
Building a 489BBC

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post #3 of 24 (permalink) Old Aug 6th, 09, 12:17 PM
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Tom
 
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Smile Re: These heads are crack prone?

Quote:
Originally Posted by sako View Post
Jut opened up my valve covers last night to find out what heads I have.
462624
L137
NAWIAT
I would be scared to death with heads that said TAIWAN backwards !

Those sound like the old smog "305" heads !
What compression ratio is recommended for your supercharger ?

http://www.racingheadservice.com/Cyl.../Aluminum.aspx

69 Camaro -originally a LM1 car. 327, Edelbrock E-streets, hooker, DUI performance distributors, ultradyne cam, stewart, TRW etc. Vintage Air, AGR steering, Corbeau GTSII seats, 700R4 transmission, 12-bolt w/Eaton 4.11:1
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post #4 of 24 (permalink) Old Aug 6th, 09, 03:18 PM
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Eric
 
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Re: These heads are crack prone?

I have a set that is cracked......

'68 Coupe 383 Small Block
4 speed Muncie (M 21)
12 bolt rear end (4.10)
Old school slappers
Old School L-60 Mickey Thompson's


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post #5 of 24 (permalink) Old Aug 6th, 09, 04:12 PM Thread Starter
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sako
 
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Re: These heads are crack prone?

here is a pic of the heads.

I have been driving the car since i got in January. No issues and runs strong.
No track time and no Dyno yet. Want to learn and test the car first before i blow anything up.
It has a GM stamping inside and TAIWAN stamped backwards on the edge. Whats up with that?
Now i want to take the engine apart to see what else is in there.
I do not know the compression or what this engine is capable of.
Smog 305 Head? what about them.
So, i should get rid of these heads.
What aluminum heads are cheap and would work with my combo?

1969 SS camaro,emerald green with white hockey stripe.383 stroker with weiand supercharger.12 bolt 373 gears. 4 speed.

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post #6 of 24 (permalink) Old Aug 6th, 09, 05:23 PM
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Tom
 
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Smile Re: These heads are crack prone?

What is your combo ? Is it the 383 in your signature ? If it is, Those are not very good heads for that. The Smog 305 heads were known for cracking. You do want some larger chamber heads with that blower and some heads that will flow good. Look at the RHS Pro Action heads that are priced reasonable and flow great.

http://www.racingheadservice.com/Cyl.../Aluminum.aspx

69 Camaro -originally a LM1 car. 327, Edelbrock E-streets, hooker, DUI performance distributors, ultradyne cam, stewart, TRW etc. Vintage Air, AGR steering, Corbeau GTSII seats, 700R4 transmission, 12-bolt w/Eaton 4.11:1
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post #7 of 24 (permalink) Old Aug 7th, 09, 10:12 AM Thread Starter
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sako
 
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Re: These heads are crack prone?

Hey Tom,
For the waiend 144 supercharger, its recommended 8.0 to 1
no more than 8.5 to 1 compression. Other than cracking, what would be the damage to the engine on the long run. I will not be racing the car till i get good headers and better exhaust. It mostly a cruiser for now.
All i know about the engine is that its a 350 sbc stroked to 383.

1969 SS camaro,emerald green with white hockey stripe.383 stroker with weiand supercharger.12 bolt 373 gears. 4 speed.

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post #8 of 24 (permalink) Old Aug 7th, 09, 10:16 AM
 
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Re: These heads are crack prone?

I ran those heads for a long time on a mild 350. They are Ok to run. They are a thinner, casting and are less forgiving if you overheat the motor. Otherwise they are fine to run. Performance wise they are not very good. Non of the factory small block heads are very good for performance.....aftermarket is the way to go if you are looking for a performance head. But if you want to run them....budget perposes becasue you already have them on the motor then they will work. Just do not overheat them.
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post #9 of 24 (permalink) Old Aug 7th, 09, 11:01 AM Thread Starter
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sako
 
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Re: These heads are crack prone?

I heard Hydraulic Roller Assemblies are better than Flat tappet for blown engines. I this true?
As far as intake runner size and combustions size, what would work better for my combo?
Thanks for the help guys.

1969 SS camaro,emerald green with white hockey stripe.383 stroker with weiand supercharger.12 bolt 373 gears. 4 speed.

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post #10 of 24 (permalink) Old Aug 7th, 09, 11:07 AM
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Tom
 
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Smile Re: These heads are crack prone?

If you want stock heads, I think the 882's would work better for you.

How about these ?

http://cgi.ebay.com/ebaymotors/PERFO...Q5fAccessories

Starting with the 1975 model (fall of 74) Chevrolet began cutting corners on the SB heads, such as the 462624 head. They were lighter, thinner castings, had an additional exhaust crossover passage (more heat) in the center of the head. Consequently, they are MUCH more prone to developing cracks, or developing them sooner, than the 1974-earlier heads. ANY 1975-later (with a date code of around Aug 74-later) PRODUCTION SB head is a lesser desireable head. I'M ONLY REFERRING TO PRODUCTION HEADS, NOT CHEVY'S OVER THE COUNTER PERFORMANCE HEADS, SUCH AS BOWTIE HEADS!
I hate to be the bearer of bad news, but you asked. If you choose to use these heads, BE SURE TO HAVE YOUR MACHINE SHOP THOROUGHLY MAGNAFLUX THEM! If they have no cracks at this time, do not be disappointed if cracks develop soon after you put them into use.

Your Date code is L137 or December 13th of 1977.

69 Camaro -originally a LM1 car. 327, Edelbrock E-streets, hooker, DUI performance distributors, ultradyne cam, stewart, TRW etc. Vintage Air, AGR steering, Corbeau GTSII seats, 700R4 transmission, 12-bolt w/Eaton 4.11:1

Last edited by TJS69; Aug 7th, 09 at 11:29 AM.
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post #11 of 24 (permalink) Old Aug 7th, 09, 11:45 AM
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Tom
 
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Talking Re: These heads are crack prone?

Here are some flow numbers comparing the 882's and fastburns and Vortec's. I have not found numbers for the 624's.

Please note That this is one time, you want big chamber heads, to keep your compression down, for a blower.




69 Camaro -originally a LM1 car. 327, Edelbrock E-streets, hooker, DUI performance distributors, ultradyne cam, stewart, TRW etc. Vintage Air, AGR steering, Corbeau GTSII seats, 700R4 transmission, 12-bolt w/Eaton 4.11:1
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post #12 of 24 (permalink) Old Aug 17th, 09, 02:29 PM Thread Starter
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sako
 
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Re: These heads are crack prone?

Thanks Tom,
Since i have no idea where Im at as far as compression ratio, and Waiend recommends 8:1 to 8.5:1 CR, what should i look for in heads. Would heads alone bring the CR that low?

1969 SS camaro,emerald green with white hockey stripe.383 stroker with weiand supercharger.12 bolt 373 gears. 4 speed.

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post #13 of 24 (permalink) Old Aug 17th, 09, 10:08 PM
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Alex
 
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Re: These heads are crack prone?

Yes

I would run something like this:
http://www.summitracing.com/parts/DR...P/?image=large

with that engine, but before making that recommendation it would help to know something about the cam and compression. Using factory 882's would also improve performance over what you have now, but the cost would be similar and you'd be leaving performance on the table using the factory castings.
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post #14 of 24 (permalink) Old Aug 18th, 09, 09:11 AM
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Tom
 
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Smile Re: These heads are crack prone?

The things that affect your compression the most, are the combustion chamber size of the heads, and the type of piston that you are using. Example : dished, flat top, or domes.

http://www.rbracing-rsr.com/compstaticcalc.html

69 Camaro -originally a LM1 car. 327, Edelbrock E-streets, hooker, DUI performance distributors, ultradyne cam, stewart, TRW etc. Vintage Air, AGR steering, Corbeau GTSII seats, 700R4 transmission, 12-bolt w/Eaton 4.11:1
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post #15 of 24 (permalink) Old Aug 18th, 09, 09:42 AM
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Royce
 
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Re: These heads are crack prone?

Until you know what pistons are in the engine it will be near impossible to know what heads you need. You can run the small blower with more than 8.5:1 compression, but I wouldn't go over 9:1.

Are you wanting the blower to make power or just for looks? If you want to make power you might want to look at The Blower Shops 194ci blower, it will ake a lot more power than the 142ci and is a better built unit.

Where are you getting your blower advice? Where did you hear a hyd roller is better than a flat tappet cam for a blown application? Ask whoever told you that , Why? For serious blown stuff a solid cam is prefered, for milder engine a hyd cam is fine either flat tappet or roller. The blower doesn't know if the cam is a roller or not. The only difference is boost creates more resistance for the valve to open against, this is why is higher boost applications a solid cam is a better choice. Hyd lifters can bleed down. As far as roller vs. flat it's no different than a naturally aspirated engine.

About cylinder heads, I would pull the heads you have off check out the pistons and go from there. Since you don't know if they are forged or not that will be another issue and will determine what boost level your engine can handle.

If I were in your shoes I would think about leaving the engine you have alone and trying to sell it complete. Build or buy an engine that is better suited for a blower. You are going to want to run more boost and make more power, it's addictive. Now if you know for sure you aren't going to want to run over 4-6psi of boost then, just slap the 142 on the engine as it sits and chances are you will be fine, read the plugs and limit the timing, should run just fine.

Royce (NO XQSSS) Bradley

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