1973 455 Stage 1: now 8.5:1 compression, how much higher possible for 2018 Premium fuel?

Man.. really?

Someone else already touched on it once, and I think it's worth mentioning again - you're pretty demanding about expecting these fine folks here to hand you lots of advice and break it down in great detail in a way you can understand. Trouble is, you aren't going to understand all this stuff without learning a LOT more about internal combustion engine theory. There are so many fine details and factors and points involved in building a great engine, and you simply aren't going to learn it from a few posts in one thread.

You've got to understand, there's guys here who have put their entire lives into learning this stuff, and I'm betting they'd all tell you that they don't know everything and still learn new things all the time. And some of them know a LOT about this stuff.

You still haven't provided a lot of specifics about your project and what your real goals are, and you just threw quite a wrench into the works with your butter smooth idle and stock exhaust manifold requirement. You can't have your cake and eat it too, there's always going to be compromise, and smooth idle/stock exhaust involves quite a bit of compromise.

When you talk about wanting to squeeze as much power as you can out of it, to the point of possibly having to run race gas because of the compression ratio, I doubt many of the folks here were thinking that stock exhaust manifolds and a smooth idle were your highest priorities. Knowing that now changes things a good bit.

I happen to agree with the fellow's advice about letting your engine builder take over and decide how to build it. Assuming they are competent of course. I wouldn't let just anybody build an engine for me, but if I found a builder that really knew their stuff, I would absolutely defer to their experience.

I have a good bit of knowledge about this stuff, and feel pretty confident around the engines I'm most familiar with, but these guys are some real experts. I would not so casually and callously dismiss their input when it sounds like you can really benefit from it.

This is some pretty complex stuff, with a lot of theories and such that come into play that require a lot of in-depth understanding, and that takes a lot of time and effort to amass. These guys giving you advice didn't just get into this yesterday. You might consider giving them a little more credit and recognizing your own limitations.

It really sounds like you need to slooooooow this project down. Take some time to talk to different folks, really start learning this stuff and trying to understand that there is no magic formula to building the perfect engine regardless of application or limitations.

The more money you're putting into a project, the more effort you need to make to ensure that money is well spent, so you end up with a product you're actually happy with. Trying to rush through this based on a few posts in one thread isn't likely to get you the result you're looking for.

 

I was going to say...10:1 TA pistons, oiling mods, current cam, correct bearing clearances, 0.020" off the block and 0.010" off the heads.

But seriously, show some respect. You asked a very complex highly variable question got all kinds of excellent advise. Just too much of it for your own taste. Some keep it simple and some like it more specific, so to speak.

 

I disagree.
I realize I am coming off somewhat abrasive, and if you'll overlook that you'll see that I am attempting to help your project. I'm not the most diplomatic fellow.
I have nothing to gain or lose here, and you seem to be hasty with decisions before knowing enough to pull the trigger.
Despite seeing the folly from the beginning, I'm kind enough to spend my valuable time to assist this because the end results would be well worth it.
(I don't even benefit from this)
From my perspective it's as if you only read every fifth word in anyone's post because we hear new revelations that seem counterproductive the further we go.

The concept of interdasting, where a lengthy subject is barely scratched at and suggestive of further dialog...the equivalent here is "Hey, I bought exactly the heads you told me to.." when it was suggested to consider, learn, and plan.

Nobody stated that those heads are designed for high rpm power, and it's been clarified that the rpm level is almost solely determined by the size of the cylinder and what exactly has been done to the heads. We simply don't know much more than "So-and-so had these done for $xx and he doesn't do anything half ass...(paraphrased)

If there were flow sheets offered, a dyno printout of the exact combo removed from... or better yet, some dimensions to work with, then the ability to use a calculator would tell us exactly what rpm range they would work with on any displacement engine.
An important step was negotiated around here, even if well intended.
I've also shown brief examples of engines with a little too much port and what methods were employed to get them to work better.
Your newly purchased heads 'could' work very nicely depending on how you plan all this out.

There's no question that I am sure of my info. I've made heads as a part of my profession, and work extensively with induction systems when it's needed. I'm keeping the posts as generic as I can and encouraging people that want to get their hands into the learning process to do so and not to ask others to do things for them.
(I did like how you came back and explained that you weren't sure of what to do. It came across differently the first time)

I think part of the issue here is different mindsets of communication.

I'm trying my best to give info that's direct to the tech aspect, with as much explanation needed to get you past what I see as misinformation on your end...and not trying to make you feel bad.
I probably overdid it a bit with the post you quoted, but there's some decent tech info in there.

From the beginning, there are parts firmly decided on without explanation as to why, how they relate to your goals, or even enough information provided for anyone else to guess.
Just like the people that have selflessly offered up how they think you'll end up happier, the fine professionals you've selected 'should' be capable of the same if they are given enough information.
I'm seeing a tendency towards micro-managing them away from their abilities with that firmness in parts selection though.
If you supply them the parts that you have selected with only brief understanding of how they work, are you going to blame them for the end result if you are unhappy?

We both believe we are doing the right thing here.
I should suggest again that any tech in here is barely beyond the surface, and would need more reading to gather a better handle on in order to effectively use.
No shame in handing over a check and letting them decide how to go about their business.
Everyone is better off.

 

I never had any impression that you were "abrasive" in any way. I listened to and valued your opinion, and decided to give you more (some of which I already stated earlier) information to make sure we are still on the same page. What surprised me was how you failed to support your previous opinions and actually apologized for maybe being wrong.

I don't see any folly in knowing exactly the result I want, but not knowing how to get there, and not having detailed specifications and measurements yet to offer. Thus I am asking general questions, and appreciating all that I can learn from everyone here. Thank you for all your advice and help, particularly IF you have the knowledge and experience to have confidence in your own advice. I am taking every word in, evaluating it, questioning further about some of it, and intend to use it all to evaluate whatever my rebuilder suggests. I feel that taking my engine to him is exactly like going to the doctor or hospital. I need to be informed about the problem, goal, solutions and options so that I can make informed decisions about what the professionals want to do.

Please believe me, I am reading every word, taking notes, and going over the information a few times. This advice from all of you is VERY important to me, and I am taking it VERY seriously. In fact, I love it... I feel highly indebted to you all, who answer and offer advice. Truly. Nobody advised me to buy the heads, I did it because I think they were a unique opportunity to get something truly trick, that I hope to benefit from using. I hope they are not too good for my application and might actually harm my goal. That is why I ask for another opinion from you all. Are they ONLY beneficial for high RPM, even though I just make this concept up in my imagination? I simply ask you all to comment about these heads, as they relate to my goal and the equipment (cam and exhaust) I have already chosen, please.

Ok, so I hope that I made a little more clear why I already decided a few things, like the mild cam, no headers, smallish exhaust system, and now these free-flowing heads. The possibly "fine" professionals I have selected are in the same position as the "fine" doctors who have done various surgeries to my body. I know that they mean well, and they know more than me, but I want to understand what they suggest when they tell me what they want to do, and I want to make sure I agree, from an educated position. So, all of your information here has been educating me to stay with MY goal instead of letting anyone decide FOR ME. I don't need to "micro-manage", but I do need to evaluate and direct (to some extent) with some understanding to support my personal concerns and goals. And YOU GUYS here have provided some REAL understanding, for which I thank you again.

I am not going to let myself get in the position of being able to blame anyone if I am not happy. By being involved and part of the decision process, I am accepting the final results as MY responsibility.

 

So, back to a couple of questions, if I haven't offended anyone with my long winded expression of what I am trying to accomplish, above.

1) Larry's first set of calculations showed me that my cam is going to give me a perfect DCR if my pistons are custom made to the right volume. And comments after that: yes, I will indeed suggest the highest surface of the piston at exactly deck level, so my squish distance will equal the thickness of the head gasket. That is all good information, don't you think?

2) The cam, my exhaust system, using exhaust manifolds, and custom pistons all seem to make an excellent combination, as far as I can tell. But what about the super-flowed heads? Are they consistent or not-so-good for my goals and for the associated parts that I want to use?

Opinions please. The engine is about to be fully measured by my rebuilder, so the actual numbers are about to be available. And, he will make suggestions, so those should be interesting.

 

[/QUOTE]
Opinions please. The engine is about to be fully measured by my rebuilder, so the actual numbers are about to be available. And, he will make suggestions, so those should be interesting.
[/QUOTE]

Assuming the builder learns more about the heads, there's a strong chance of success and plenty of ways to get there.
Nobody reading this knows enough about the heads to offer much unless they've run that set of heads personally, did the porting and flowed them (with velocity and CSA info), or has the complete build and dyno sheets of the engine they were on. Then it would be pretty easy.

I can completely understand the need to learn more and get involved, and respect the amount of proactive thought involved.
It's MUCH better to go through this rather than deal with the thread later on being filled with responses like, "Why did you let them build it like THAT!?".

Gotcha, understood...text is limiting and it's easier to understand the factual dialog than interpret the intent of the posts on a human level.

Excited to see this come together and there will be a great sense of accomplishment by having your favorite board collaborate opinions.

 

To take more advantage of good flowing heads with a smaller duration @ .050" cam, get a roller cam. With a roller cam they can grind it with more lift and keep the duration low for that rock steady idle you're looking for.

The thing about ported heads is that usually the porting will bring the max flow at a higher lift. To take advantage of heads that flow more in the higher lift range you'll need a cam that has a higher lift.

It would be a good idea to have your heads tested to see what they flow, should only cost around $50 to have a set of ports flow tested on a flow bench. Your machine shop should be able to direct you where you can have that done if they can't do it for you.

 

I couldn't have asked for a more optimistic response. Thank you, Larry. From your comment and the later comments from 8ad and 300sbb, I can see light through the trees, and future options available to me. I can use this combination for a while. Then, in the future, I can upgrade the exhaust, headers, and cam, together, to achieve whichever I want: more low/mid/high RPM power with a roller cam of short duration but much higher lift, or much more high RPM power with just a bigger (but carefully chosen) cam in EVERY direction (lift and duration).

I will get the heads tested on a flow bench, for future reference.

 

Adding that a cam's rpm range is completely tied to the head's characteristic's and the size cylinder it feeds.
The rpm range stated for any cam is dependent on several factors.
Also adding that well ported heads serve to increase flow in the low to mid lift ranges by speeding up the flow, which helps in almost all cases. Exceptions include hogging the ports to the max, obvious tactics to kill certain lift ranges as a sacrifice to others (both all out drag racing tactics), and untrained inconsistent work.

My previous suggestion that the project could be unsatisfactory was based on the very typical mismatch of major components, and was to serve as cautionary advice.
I've dealt with a lot of mismatched projects that aren't planned out very well and have components that don't work well together.

 

You have got me a little worried that my heads WERE "hogged out to the max" for drag racing. So I asked my rebuilder to have them bench tested for flow characteristics, and I will post the results here next week.

But overall, I have very high hopes. In fact today I just heard Frank Sinatra sing about the little ant that wanted to move a rubber tree plant: "I have high apple-pie-in-the-sky hopes."

 

Tom, what do you think? Is there a flow sheet available for these heads?

 

Steve was going to flow those heads this past week after cleaning and reassembly but then we worked a deal and you know the rest.
Dave B. did not supply any #'s and Steve cannot locate his orig. paperwork(it was 25+yrs ago). I do know those heads were on a
13:1 motor, no girdles, .6xx something cam, Dominator, running 10.80-11.10 IIRC in 3,800lbs 25 yrs ago. My best guess is these heads flow mid to high 200's. I really wasn't comfortable with how selling the heads went down plus not having #'s, if those heads have not been touched/modified I will refund your $$ no problem......Tom

 

Larry, thank you for these links. These are VERY educational and applicable what I want to accomplish.

 

OK, the seller is calling the heads hogged out to the max as a general term for having them ported for serious drag racing.
It doesn't mean that they are indeed enlarged to the point that they are useless. I'm sure everyone has integrity.
There are 430 heads that have really big ports though...

I've already stated that there's a minimum cross sectional area and that the airspeed through it will determine peak torque and hp rpms much more accurately than measured cfm tests or what cam is used.
The airspeed through the port is based on the size of the cylinder and the rpm, make sense?
A larger cylinder will lower the rpm where peak torque happens.

The flow charts can give some indication as to the minimum size of the ports based on knowing how much air is possible to get by a certain size hole or valve. Knowing that can also serve to determine if the flow sheets are valid.

There are some really easy ways to see what's going on as well as solve any concerns using those heads.
Look into the ports and see what the smallest areas are, be it the valve job throat or further up the port.
Simple tools can determine this, like a set of spade drill bits poked around can help with seeing size, or a caliper into the valve job.

IF...the heads are on the large side, and the area calculates out to a fairly high tq rpm, then now's the time to be considering stroker packages to make the cylinders larger.
Using a shorter connecting rod will pull on that port harder and raise the average piston speed through the cycle, fooling it.
Understanding that the cam is not controlling the power peaks as much as the ports...the use of a smallish cam will swell the tq curve below the [induction determined] peaks.

It's suggested that the heads are possibly flowing from the 250-300cfm range.
Even though that's a wide range it helps to compare other engines with similar proportions.
LS engines have heads that flow a similar range and are daily drivers being 100 cubic inches smaller.
Many still peak tq near 4k rpm and maintain low speed response with the long intake runners helping raise cylinder filling down low and fast burn chambers (similar to Buick) to offer some snap to the combustion cycle.
It isn't 'technology'....it's induction.
Buicks having wide intakes and dual planes with long runners make it harder to kill low speed response, and cubic inches cure most evils.

Hondas have comparatively huuuge ports allowing the tiny 110 inch twerp to rev up to 9k (260 cfm+)...and back the cam durations way down at lower speeds. Not exactly earth moving torque, but driveable.

I know this goes against how builds are put together, but builders that are induction strong can work from the port backwards to determine the characteristics they want the engine to have.
Determine the bore/stroke/cam after you know what you are working with.

 

I guess what I'm saying is rather than buy a hodgepodge of parts based on various descriptions and hope your builder can do the job despite supposed elusive peculiarities of it being a Buick, simply plan out what you want it to do and fit the pieces in to make it work.

 

To bench test heads, such as these, would they need to be freshened first? I suppose the valves are left in for the testing, and they are held open to the various lift positions, then tested for cfm of flow, but I am just guessing this.

Therefore the condition of the seats is not important for this testing, and they would NOT have to be freshened? My valve stems and guides are fine, it is only the seating faces that will need some work (probably just lapped), but it seems to me that this would not effect the bench testing. Am I right?