Olds Heads
#1
Olds Heads
Why does it matter if a 350 have 7a, 7, 6, or 5 heads on it. With the exception of just someone personal preference. Since motors can be rebuilt to whatever specs. For instance, my 72 cs engine will be rebuilt to the same specs as a 70 motor.
#3
It really doesn't matter too much since the heads are very close to each other performance wise. What you need to be aware of is the later heads have rotators on the valves, which means deeper spring pockets. Can't remember the specifics right off but maybe 7 was on exhausts only and 7a were on both? Again, doesn't matter that much but is a consideration when buying valves and springs.
#4
All SBO heads prior to the No 8 heads that came out with the 1973 model year are equivalent in flow and performance potential. You may find slightly different numbers on the web for chamber volume or port flow, but the reality is that these numbers are typically based on a sample size of one or two castings and don't represent a statistically valid number of samples. These heads all had chambers with a design volume of about 64cc. As-cast volumes vary by several ccs and were usually on the large side from the factory. Similarly, if the heads have ever had the valves cut or the deck milled, chamber volume will vary.
The "hardened seats" were factory issue for all Olds heads from the 1971 model year on. Understand that these are NOT press-in hardened steel seats. They are a thin layer of induction-hardening in the parent cast iron. The first time the valve seats are cut, that hardening layer is removed.
The "hardened seats" were factory issue for all Olds heads from the 1971 model year on. Understand that these are NOT press-in hardened steel seats. They are a thin layer of induction-hardening in the parent cast iron. The first time the valve seats are cut, that hardening layer is removed.
#5
The "hardened seats" were factory issue for all Olds heads from the 1971 model year on. Understand that these are NOT press-in hardened steel seats. They are a thin layer of induction-hardening in the parent cast iron. The first time the valve seats are cut, that hardening layer is removed.
#6
Not unless you tell them to and pay extra. Also, DO NOT let them install Chevy seats. The Chevy seats are too tall and if the heads are cut for them, the shop will break through into the water jacket and the heads will be junk. Be sure to use Olds-specific steel seats.
#7
Not unless you tell them to and pay extra. Also, DO NOT let them install Chevy seats. The Chevy seats are too tall and if the heads are cut for them, the shop will break through into the water jacket and the heads will be junk. Be sure to use Olds-specific steel seats.
#9
All SBO heads prior to the No 8 heads that came out with the 1973 model year are equivalent in flow and performance potential. You may find slightly different numbers on the web for chamber volume or port flow, but the reality is that these numbers are typically based on a sample size of one or two castings and don't represent a statistically valid number of samples. These heads all had chambers with a design volume of about 64cc. As-cast volumes vary by several ccs and were usually on the large side from the factory. Similarly, if the heads have ever had the valves cut or the deck milled, chamber volume will vary.
The "hardened seats" were factory issue for all Olds heads from the 1971 model year on. Understand that these are NOT press-in hardened steel seats. They are a thin layer of induction-hardening in the parent cast iron. The first time the valve seats are cut, that hardening layer is removed.
The "hardened seats" were factory issue for all Olds heads from the 1971 model year on. Understand that these are NOT press-in hardened steel seats. They are a thin layer of induction-hardening in the parent cast iron. The first time the valve seats are cut, that hardening layer is removed.
64 cc as cast? Me thinks 68-69cc as cast is a lot closer. Agree with everything else you posted.
#10
#12
SBO heads
#4 are 64cc as cast and are the best SBO head in stock form. Flow potential all the same on all the SBO heads 1967-1972. #5 are the most common and easy to find because they were used for 2 model years.
#13
I was on summit racing website looking at each olds 350 heads from 68-72 and notice all were priced the same pretty much. Are they all the same or is each year build to factory specs?
Last edited by 72cutlassdog; January 3rd, 2017 at 05:35 PM.
#14
Dave picked the #4, I assume, because the 330 heads are smaller chamber volume otherwise nearly indentical to the later 5,6,7,7A heads. One area that may be an issue is the change in cam bank angle, some claimed the 67 330 changed to the newer 39 bank angle. The earlier 330 heads all were designed for 45 degree can bank angles, #1 had unique and impossible to find replacements, rocker shafts and number 2 heads had 3/8" stud non adjustable rocker arms. Number 3 heads were like later heads except having possible pushrod interference on a later motor. Summit racing would have nothing but Edelbrock heads with big 77cc chambers.
#17
#18
Thread
Thread Starter
Forum
Replies
Last Post
2blu442
Parts For Sale
6
April 9th, 2016 11:44 AM