Is there a cost effective way to make these dome pistons have less compression to use on a 60% track 50% street cruising fun car.
I have a new set that I picked up cheap and would like to put them to use, I was saving them to build a race car but another car now may be a while. I have a couple sets of Closed Chamber heads so I would not want to buy open heads now.
I have one set of cc heads that were running in my car before and one chamber has some scars from a previous owners valve failure. They are not bad and I was thinking if I grind out the chambers to open them up a little, like perhaps smoothing out the sharp edge around the chamber it may lower it enough to run on 93 premium pump gas.
Of course I am not an experienced porter so I will have to learn as I go and buy the tools for cc'ing the heads.
Or would using thick copper head gaskets bring it down. Also not decking the block so they stay somewhat in the hole, since I have a virgin 2V low mileage block I can use.
I only drive casually on the street and will not be doing hardly any full throttle runs on the street except when I go to the track and then I wouldnt mind adding some race gas mix and advancing the timing on those occasions.
Anone tried this before?
Also what crank is better a 1972 from a 2V or a 1970 from a 4V they are both standard size, the 4V looks to have a small ground off area with a deep dot punched in, I think I read this was for hardness testing. Or are they the same for a street strip motor that will go about 6500 rpm

Kostecki Engine Center did some work like that, they've long since deleted the pics from the server though. they stat with Aussie CC chambers and open them up considerably. they're almost an OC chamber when they're done.

something i've not seen mentioned here or anywhere else,

Singh Grooves

http://www.rexresearch.com/singh/singh.htm

there's a guy that did an experiment with an sbc online with limited success if any, but i don't think he incorporated the grooves, only a single channel. i've been wondering if Singh grooves could be added to CC chambers. i'm surprised they haven't turned up at Engine Masters yet. those ProComp heads with too much material in the chambers(sunken seats) might be a good start?





"Enlightened statesmen will not always be at the helm" ~ James Madison

http://www.kec.com.au/articles_detail.asp?i=17

"...and the combustion chambers are opened up to decompress the engine to the required 9.5:1 ratio."

"...Clevelands running unleaded fuel like a hemi-style head best, with no quench area at all. They found that even a small quench area led to secondary detonation, which is why the entire quench area is removed on the CNC mill. These are not all-out power heads. They have been designed to maximise port air speed to aid cylinder filling and boost torque using standard 2V valve sizes."

production cranks are pretty much the same, the lack of a test mark doesn't mean it's a lesser crank, it just wasn't tested. i don't believe we've ever run down exactly what the differences between the 4M, 4MA and 4MAB cranks are though, could be the oil drilling angles or who knows what?

"Enlightened statesmen will not always be at the helm" ~ James Madison

They may be advertized as 12.5 : 1 pistons, but they aren't.
I cc'd everything when I put my engine together. I have 4V iron closed chamber heads. It came out to 11.3 : 1. I run 93 octane pump gas with no problem. I have about 36-38 degrees total timing. When at the strip I advance it 2 or 3 more degrees and run some race gas. It runs 11.70's.
If you leave your slugs down in the hole and run the CC heads you will be OK (my opinion based on my actual engine). The cam you run could have some bearing on this also. I have a solid flat tappet 242/248, .579/.609, 108 LSA. Runs great !
I ran the same cam and pistons with 4V open chamber heads too. No problem there either. It ran low 12's if my memory is correct (gettin old).
I like the closed chamber heads better

Danford1

like with that cam?
I think I may start to build one with the TRW's, but it will be later on this year.
I guess if the compression turns out too high I can always switch to a E-85 carb

it's not the static compression ratio but the dynamic CR that really matters, that's why Dan specified what cam he's using. the closing point of the intake valve plays a major role in how much static CR you can successfully run on a particular fuel.

http://kb-silvolite.com/calc.php?action=comp

it's pretty hard to get anyone to nail down a specific guide as to how much octane is required for a given DCR, i think some of the desktop dynos will give an octane requirement, but to get the right answer you need to use accurate inputs.

"Enlightened statesmen will not always be at the helm" ~ James Madison

here's a thread that gives some DCR/octane recommendations. at first i thought these were on the cautious side, but that's the idea i think, not to have a detonation problem.

http://www.ford-trucks.com/forums/663107-dcr-opinions-please.html

"Enlightened statesmen will not always be at the helm" ~ James Madison

I put L2348F in my CC 4V rebuild. When I turned the engine around with the head just siting on the block it lifted the head .030. That's with the piston .025 in the hole with a used gasket on it! Don't know how much my heads are milled?
Mark

My vacuum at idle in gear is about 7 inches. Not very much. If you have power brakes, I think you need more than that. I have manual brakes ...

You know................. with all the friggin measuring I did when I put the engine together, I never got around to measuring the piston to valve clearance! I shift at 7200 rpm. This spring I advanced the cam 2 degrees and still didn't check it. I haven't been to the strip yet this year, but it has seen 7200 a few times since the cam advance and it is still running strong. My guess is I'm at the ragged edge. When/if it blows up, I'll find out for sure >

Cheers.
Danford1

PS If the weather is nice this Wednesday, I may go run the snot out of it at test and tune night. See if I can improve on my best of 7.47 in the 1/8 which is a 11.66 in the quarter. The 2 degree cam advance feels good according to my seat of pants-0-meter.

What brand cam is that, or is it custom?
I have 7-8 vaccum now and the brakes still work, although putzing around in a parking lot the sometimes stiffen up.
I am going to look into a reservoir, or vaccum pump anyways.

It is a custom ground solid flat tappet from Scott the Mad Porter from this forum.
His name is Scott Johnson, here is the websitehttp://www.reincarnation-automotive.com/.
I bought a package that had the cam, lifters, valve springs, retainers and locks. I have been very happy with the purchase. (Sorry, I can't find my receipt and don't remember how much I paid). I know it was reasonable though.

Another Great guy to deal with is Mark McKeown from this forum. His site is mmeracing.com .

A custom ground cam doesn't cost much more than an off the shelf cam. Custom ground is the better way to go.

I've dealt with both people and would happily deal with both of them again >

Cheers.
Danford1

Just cranked over engine to set timing on new rebuilt engine. 190 psi on number 3 pump. Cam .540 240@.050 110 lca.

What car are you using that engine on?

you can always tune the car to run on E85 it's 105 octane. and that may be the easiest route. It's also the same price as 87 octane unleaded. If it's available in your area.

running E85 is gonna require either buying an E85 carb, or an experienced carb guy to go through and recalibrate every circuit. the changes are not necessarily linear, you can't just 'jet up' from my research. Bobby at Competition Carburetion has been recommended but i'm on hold ATM as far as running straight corn from the pump. it may turn out to be my only reasonable option though.

on top of that, a wide spec window and varying seasonal blends could have a guy chasing his a$$

"Enlightened statesmen will not always be at the helm" ~ James Madison

thanks Tinman, for all your responses. I was looking at this kit and pondering the E85 idea.
As far as seasons go, here in Miami, Fl. There are no seasons its one long summer with a couple of cold weekends in the winter so I think the blends are pretty regular and its abundant at the pumps now.
http://www.summitracing.com/parts/QFT-34-106/?image=large

I am sure there is more to it than this kit, they also sell a $600 carburator that is set up for E85. The fuel pump and the lines will have to be upgraded as well.

i had not seen that QF was offering a metering block kit, last time i looked at their site they only offered complete carbs, definately more economical to go with the kit.

but it just occured to me that the boosters may be challenged to flow the increased volume? if needed, i wonder if they can be opened up while still installed with the metering blocks off?

then there's the air bleeds, would probably need to install replaceable threaded style air bleeds or the mods are irreversible/untunable.

here's a press release on the QF E85 complete carb,

"Bowling Green, KY Racing and performance enthusiasts all over America are taking notice of E85 as a viable fuel thanks to its terrific 105 octane rating, but the special requirements of E85 might limit its use in high performance cars. The fuel system specialists at Quick Fuel Technology have solved that problem with their new 750cfm E85 performance carburetor.

E85 requires more fuel flow then conventional gasoline, so Quick Fuel calibrates the dedicated billet metering blocks (also available as a separate kit, part no. 34-106) and adjusts air bleed sizes and power valve settings at the factory for easy tuning. Special bullet type Stainless Steel needle and seat assemblies prevent sticking caused by contaminants in the fuel. Since ethanol can deteriorate rubber components, special E85 resistant GFLT accelerator pump diaphragms are used in the carb. The QFT® aluminum fuel bowls are specially coated for corrosion protection, specialty composition floats are alcohol resistant and have a longer stainless steel hinge for improved leverage to close the larger needle and seat.

These high performance carbs feature a billet throttle body with a multi-link tunable mechanical secondary activation. Teflon coated throttle shafts feature low profile button head screws, and stainless steel throttle plates. Quick Fuel equips their E85 carbs with dual inlets for superior fuel flow and clear sight windows for easy float level adjustment."
http://news.hspn.com/articles/1000/1/New-E85-Performance-Carburetor-From-Quick-Fuel-Technology/Page1.html
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so yeah, the kit's far from complete, still need the SS needle/seats, powervalves, air bleed work, no mention of flowing the boosters anywhere, they may be within limits as-is. the QF website doen't mention any SS needle/seats, i wonder if they're the 'off-road' type? the QF website could be a lot more complete, a lot of the E85 carb components don't show up in the parts searches.


"Enlightened statesmen will not always be at the helm" ~ James Madison

I sent in a new quick fuel dp gas carb for rework to set up for E-85. All parts can be purchased but they did change boosters to annular type. This takes special tool to spin booster into body. They were easy to work with and took all info down to set up for my cars specific's. I can't tell you exact cost as I bought some conversion parts from summit then wound up sending everything to QF to set up after finding out new boosters were part of the deal. I think I'm in about $400 though.

Would love to tell you how it works but have not used it yet.

As far as seasonal tuning goes, as a drag only car I will only be into summer blend. Not sure I would mess with e-85 in a 4 seasons carburated car.

Shane