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

Well, that is exactly what I did with my Pontiac 455. 1969 heads were better than my 1973 heads. But they were also much higher compression, so racing fuel became necessary.

Please tell me WHAT better heads, for the 1973 Buick Stage 1. Do you mean bigger valves, higher compression, polished ports, or what else? Factory heads from a different year, of something after market, like aluminum ones?

 

I have 105 octane race gas at 3-4 locations. Easy for me to get in Western Pa. But filling my tank $120. Out of control. Lucky car does not get driven alot

 

Have you tried filling the tank with 50% 105 and 50% 91 pump gas? It is hard to imagine, for me, that you need higher than 98.5 octane. My built Pontiac 455 uses net 95 octane (about what 1969 Premium was), which is about 85% 91 pump gas plus 15% leaded race gas. But I have a 45 minute drive to acquire the race gas, pumped into my 2-gallon jugs. The race gas I use has so much lead in it, that 15% also gives me about the same lead content as 1969 Premium had.

 

I want to keep my iron heads and flow them. Are the exhaust most important to flow, or the intake equally important too?

 

I see your in Fullerton Warren, if you want a of set iron heads I've got a set being freshened up right by you at BPE in Placentia. These heads have all the work done and flow about as much as a CI head can, these were on Dave Benisek's car, Dave never did anything halfway, if your interested shoot me a PM.....Alum. as mentioned can still flow more.

Tom

 

I hope this isn't harsh or negative but I'm going to point out the flaw in thinking that 69 Pontiac heads would be in any way considered "better" flowing heads than 73 heads. There are very minor flow differences, even with the different chamber sizes and valve lengths. The stock Pontiac heads are all really restrictive in factory form, with very few exceptions.
They also respond to very well to tactics by knowledgeable builders.

Your statement about the Pontiac head swap proves exactly what my comments have been outlining (with mild technical detail).
The engine sees minimal gain with maximum hassle and risk to your engine, because you did not put (significantly) better heads on.
The difference between the early and late heads is mainly a bump in compression, requiring you to add expensive fuel and/or detune.
If the 73 Pontiac heads were mildly worked over, you could have seen an 80hp increase with a mild build, for about what you put into race fuel.
I'm using mid 70's Pontiac heads on 2 stroker builds for 600+ hp on pump gas, so rest assured they are decent castings.

I would take Staged Cat's offer seriously, so you can avoid the type of builds that require race gas and don't deliver much extra.

 

Yes Warren that’s what I do. But once I filled it with race gas because I was putting away for winter. But I am lucky I also have ethanol free gas also. Witch I know some of you guys can’t get it. If it has a carb, I don’t use regular pump gas

 

So what are the main problems with gas that has ethanol in it? I have all new gaskets and seals in my carb that are resistant to damage from ethanol. Attracts water, so causes rust? And what else?

 

Even with ethanol resistant gaskets and seals it will still break them down faster than straight gasoline. Fuel with ethanol in it slightly reduces fuel economy and goes 'stale' much faster. Not ideal for a car that isn't driven often or stored for the winter. E10 has no real benefit except to very slightly lower fuel prices, which is debatable.

E85 on the other hand is great for someone who wants to run higher compression/forced induction without relyling on race fuel. Much cheaper, available at the pump depending on where you live.

 

Ok, you guys are costing me a fortune on this daily driver Buick GS Stage 1 that I am rebuilding. I bought the cast iron heads, severely ported, previously owned by Dave Benisek. But all your advice is still sincerely appreciated.

Maybe not as good as TA's aluminum heads, but probably a lot better than my original Stage 1 heads. I still plan to use TA's 455-112 cam though, and my iron exhaust manifolds opened up to match the heads' larger exhaust ports. Also 1970 slightly dished pistons.

 

Double check your dynamic compression based on your static compression and the intake closing spec on that cam...make sure you aren't building a detonation prone engine. If so...an easy solution is to use a slightly bigger cam.
Then you won't require race gas every time you want to run it hard or risk bearing damage or worse.

 

Can someone do this for me, please, step-by-step? What information would you need, and teach me how to calculate it?

 

Here are some of the specifications:
1970 Stage 1 head, chamber volume 68cc;
TA112-455 cam, lift .455/.468, duration @ .050 210/215, adv duration 26/262, lobe center 112, overlap at .050=0;
pistons equivalent to TA1607, 4.3425 bore, 3.900 stroke, 1.997 c/height, 22.5 cc dish, 100cc gasket volume;
static compression probably about 9.5 to 9.7

 

If you google "Dynamic Compression Ratio Calculator" there are a few that come up, the one I like best is the App by Patrick Kelley. There is a discussion and link to the download somewhere on this board. Depending on the calculator, there might be additional info you need to know, such as head gasket bore and thickness, rod length, top ring land height, etc...

 

Thank you for reminding me, I see it. I did read through it, but upon one quick read, it mostly went over my head. And I did not understand the calculator in it. Now I do understand at least that.

I am a little more informed now, than I was a week ago, so I am ready for that article and calculator again.

Plus, I am just on a blisteringly fast track to rebuilding my 455, so my memory is about a day or two old for some of this stuff. I really want to drive the car soon.

 

Tough not to get sucked into the rush at this point and overlook important things.
Gotta be patient or push your deadlines off a little.
An easy thing to look at is other people's combos having a little more cam than you are thinking about now, and looking at if any have complaints about low speed performance.
Meaning, I think you can go a little bigger and end up happier in every way.