Bad Head Casting Numbers?

[CORE402]

Hey guys I have a question for you all. I have a set of 3998920 heads and I was wondering if they were worth my while to go ahead and machine these with larger valves, porting, etc? I have read in one book saying that chevy heads with the larger 76cc chambers are trash while in another they are worth while working on. This confuses me and was wondering if anyone could shine some light on this dilema. Thanks for any info you can give me.

[73'Camaro]

That may be a casting number of a head that is prone to cracking, possibly that is why people are telling you that they are junk. The older 1974 and earlier cylinder heads are worth working on because they are much stronger castings that almost never break. The newer casting bust alot eaiser and alot more often. As far as the combustion chamber is concerned, if you are running a 350 stock engine a 76cc combustion chamber will work fine. If you want some power out of the engine you will want to run 9 to 1 Compression ratio and up. This increases your engines ability to rev and get the extra top end horsepower. What size engine are you running? How much power do you want out of it?

[CORE402]

What I do know about the heads is that they made them from 72-74. They are 1.94in and 1.5ex. I have a 350 that I am going to beef up to run about 425hp and about 440ftlbs. I just heard the combustion characteristics were bad in the open style chambers. Thanks. Oh yeah I have a 73 Camaro too! Awesome choice!!!!!

[73'Camaro]

Originally Posted by CORE402

What I do know about the heads is that they made them from 72-74. They are 1.94in and 1.5ex. I have a 350 that I am going to beef up to run about 425hp and about 440ftlbs. I just heard the combustion characteristics were bad in the open style chambers. Thanks. Oh yeah I have a 73 Camaro too! Awesome choice!!!!!

Sweet, well if you want that much power you are going to have to upgrade. How much dinero $ are you willing to put in the engine, I am a engine whiz, so to speak. I have many good ideas all I need to know is how much money you have to work with and I'll let you know what will give you the most bang for your buck. Be honest, if you don't have alot of money let me know, I don't have alot of money and I don't mind blurting it out.

[CORE402]

Lol. I know what I am going to do if these are not worth while. If these are not worth my time I plan on working with a set of vortec heads. I am looking at some on ebay that have been redone with new 2.02in and 1.6ex, bronze guides, new springs, bowl hogged, etc. I may even get some camel humps, just got to deal with lack of accessory holes. I am trying to keep the rebuild under $2000. I am doing so cause I had a 402BBC that I had rebuilt for that much that would have produced similar numbers to what I want. Thanks for any more advise you can give me .

[73'Camaro]

Originally Posted by CORE402

Lol. I know what I am going to do if these are not worth while. If these are not worth my time I plan on working with a set of vortec heads. I am looking at some on ebay that have been redone with new 2.02in and 1.6ex, bronze guides, new springs, bowl hogged, etc. I may even get some camel humps, just got to deal with lack of accessory holes. I am trying to keep the rebuild under $2000. I am doing so cause I had a 402BBC that I had rebuilt for that much that would have produced similar numbers to what I want. Thanks for any more advise you can give me .

Well, you know, vortec heads don't need to be hogged out and the valve size does not need to be increased. In an article of Popular hotrodding, they had an engine and they did a bunch of things to it. When they got the most power out of it they were using a pair of stock vortec heads with screw in studs and better springs, They used a .550 lift comp roller cam and a supervictor vortec intake, and made 450 something horsepower on the engine dyno, keep in mind these are stock heads besides the studs ad springs. If I were you I would get a pair of stock heads and email me to get more info when you go to rebuild them, I am running vortec heads on my engine and if you go over .450 lift cam, there are things that need to be done. By the way I am a machinest, I worked on Cylinder heads. So you could say your are talking to a pro. Not braggin at all, just letting you know.

[73'Camaro]

Originally Posted by 73'Camaro

Well, you know, vortec heads don't need to be hogged out and the valve size does not need to be increased. In an article of Popular hotrodding, they had an engine and they did a bunch of things to it. When they got the most power out of it they were using a pair of stock vortec heads with screw in studs and better springs, They used a .550 lift comp roller cam and a supervictor vortec intake, and made 450 something horsepower on the engine dyno, keep in mind these are stock heads besides the studs ad springs. If I were you I would get a pair of stock heads and email to get more info when you go to rebuild them, I am running vortec heads on my engine and if you go over .450 lift cam, there are things that need to be done.

also, there is no way that those 920 castings will even come close to 425hp, no matter what you do to them, maybe 325hp with everything done to them (I am not jokin). Go with vortec, that head design is superb, better than camel humps also.

[mike123]

get the #062 casting!!! or dont get ne
i got a pair of #906 there just papper wieghts to me till i get some cash

[CORE402]

Yeah that is what I thought. I knew the 920 heads were not very good and that the vortecs would be superior. Pretty much everything I know of what to do with heads comes from John Ligenfelter's book on SBCs. That book was written just before vortecs were around. He too talked about how bigger valves aren't neccessarily better. What I have had in mind is a motor similar to CHPs Impersonator motor that pulled 428hp with 525fllbs with nothing more then new springs, a .480" lift 230 degrees of duration with 109 degree lobe separation. single profile cam, and some more little goodies. It was a 406SBC, so I am not expecting to get exact torque numbers out of my 350.

[73'Camaro]

Originally Posted by mike123

get the #062 casting!!! or dont get ne
i got a pair of #906 there just papper wieghts to me till i get some cash

If the 062's are the 305 vortec heads they are not as good as the 906's. The 906 heads are made for a 350ci. with the 1.94 intakes not the 1.84's. The ports are better, the chamber is much better, the kidney shape helps the quench in the cylinder with flat top pistons or dome pistons, which adds more power. Why do people diss on the 906's I would really like to know?

[CORE402]

If I were to get Vortecs what would all should I do to them before installing them? I would just assume new springs so I could go beyond .500" lift. Do they need new keepers, retainers, etc?

[mike123]

the differnce between 906 and 062 castings are teh 906 were used on work trucks they have like 15% less flow the exhause seats are hardend so you cant port them and they just dont flow nearly as good as a the 062's 062 were the proformance ones , altho the 906's are still good casting just not for all out proformance

[CORE402]

so what casting comes from GM perfromance parts for the vortec heads?

[mike123]

man just google it vortec + 062 vs 906 or somet hing i read this stuff along time ago so i dont wanna try to quote anyone , its really not hard , hotrodder.com those forums had enough info if i remmeber right

http://hotrodders.com/showthread.php...ght=vortec+062

http://hotrodders.com/search.php?act...der=descending

[Lilld]

This is @ 73'Camaro .
In this conversation you stated that if this guy needed help with a build you had some ideas and at a Budget.
I was wondering if this offer was a open door policy?
I'm building a ski boat 350 vortec motor ,
Stock bore,
906 heads
Cam/roller lifters (???)
Intake (???)
Carb (???)
Exaust fresh pickup 'Salt water"
Stock Alpha 1 out drive.
I'm thinking power range between 1500-5500 RPMS
I'd like to have a brain storming about Wich path I might consider....
Thanks Rick (lilld)