Mercury Cougar Owners banner

1 - 7 of 7 Posts

·
Registered
Joined
·
38 Posts
Discussion Starter #1
I know that this has probably been covered before, but I want you folks suggestions here:

While the body of my cat is being re-done, I am wrapping up my engine build plans. I was originally going to go with a 6" rod, flat top piston, Aussie headed engine. Well, I got a deal on a set of CJ rods w/flat tops so the 6" rod idea is out the window. So I am now looking at sticking w/std rod length & .030 over bore flat tops. Will the Aussie heads give me too much compression? I have 2v heads now that I can have rebuilt, but for the $$$$$ that will take, I am thinking of getting a set of Powerheads Aussie heads. They seem like a pretty good deal for the $$$ (anyone running these? - what are your thoughts on them).

I have a set of 2v full length headers, an Edelbrock 2v - 4V intake, and edelbrock carb to start with. I have not decided on a cam or convertor yet, but will wait to match with the heads I get. I currently have an FMX trans, but am thinking of swapping in a C4 for clearance/less HP loss.

I also have a 3.50 trac loc gears for the rear.

Let me know what you think.
 

·
Registered
Joined
·
5,883 Posts
First off, sounds like you have some neat ideas, so good luck and keep us posted on your success.
Next, all aussie heads aren't created equal. So, decide what heads you are going with and post that here. A lot depends on chamber volume. And volumes differ with different heads.
As for the rods, did you think of swapping the rods you got a deal on for a set of long rods and pistons?
You never know.
Personally, I like the long rod engines.
 

·
Registered
Joined
·
38 Posts
Discussion Starter #3
Thanks for the info on the Aussie heads. I don't know too much about them other than the obvious of the combo of the small chambers and runners. If I was to get the Aussie heads, I would probably get a built set from Powerheads. If I remember correctly, they were around $1100 completely rebuilt w/studs and CNC porting. With the cost of cores that I have seen, then add the cost of a complete rebuild/machining, I don't see how a person could pass on the Powerheads.

I had not thought of swapping my rods/pistons. I would like to go with the long rod setup. I thought I read that with the longer rod and quench chamber setup, it can handle more compression without pinging. I want to maximize my setup to run on premium for the street (with setting back the timing a bit) and perhaps a little mix of race gas and more timing of the track. The car won't see a ton of miles, but I want to be able to drive it to work or a cruize on occasion.

I may just through the flat tops in a short block and put my 2v heads on top. But then again, I would still end up having to fork out some cash to freshen them up.

Too many decisions to make and not enough money.
 

·
Contributing Sr Motorhead
Joined
·
5,470 Posts
well, if the Aussie 2V heads are anything like the quench 4V (M-code) heads in volume, you'll have 11:1 compression. That's not totally unreasonable for the street, but you'd better have a couple gallons of racing fuel mixed in to get the required octane for spirited driving.

My wife's 70 Mach 1 is an all-original 21k mile M-code (11:1) car, and I really don't want to mess with trying to lower the compression, so we just drive it as is. 3/4 tank of super unleaded, then two gallons of unleaded racing fuel. Be careful with that stuff, though. It has a tendancy to eat rubber seals and hoses. It also soaked right in to the carb float, making the float heavy and sinking to the bottom of the bowl, then flooding out with all of the extra gas getting past the needle and seat. The proper fix is to change to a brass float. Just something to watch out for.

Another option would be to use the dished pistons that the Q-code 4V used. That would lower your compression with the aussie heads to around 10.3:1.

The 2V heads you already have will give around 9.5:1 compression as is with your flattops. Why mess with a good thing?

Your call on what you want to do.

The stock 2V cam is pretty wimpy, only a .407 lift on both intake and exhaust. You can get a 'new' CJ-spec cam from Crane. The CJ cam was .480/.490 lift. Bear in mind that the CJ camshaft was retarded for emission reasons, so you'd probably want to advance it by 4* or so to increase bottom end torque. I wouldn't suggest going too radical with the cam. Waaaay too many people overcam their motors, and are disappointed with the results.
 

·
Registered
Joined
·
38 Posts
Discussion Starter #5
Thanks for the info on the compression ratio's. I hear ya on sticking with the 2v heads. I guess I just want to get as much power as I can out of the engine and 2v parts that I have. I really can't afford to swap out to 4v parts right now. If I was to swap over to other heads, I would probable just take the big leap and get into the Yates aluminum heads. But that motor would be destined for the dream of having a Daytona Cobra kit car.
 

·
Registered
Joined
·
89 Posts
hey Steve,

Stock rods with good bolts will suffice to over 7000. I would recomend a set of Keith Black KB148 pistons which have a 13cc reverse dome to lower compression. I tend to preffer the use of the phrase "reverse dome" over "dish" since a dish can mean just any depression of haphazzard location in the piston top, while "reverse dome" means a depression with a perimeter mirrored to that of the combustion chamber to maximise the availbe surface area for maximum quench effect. Quench distance is very important when you are trying to exceed compression limits for availible octane. The KB 148 set up with a .040" quench distance should develop about 9.9:1 compression. I'd preffer to tighten the quench down to about .035".
Unless you own a cylinder head chop, then only Aussie heads to buy are the CNC Aussies from Power Heads. They are ready to go with screw in studs, hardened exhaust seats and all.
There was quite a discussion about cams recently just for a 2v cleveland, you may want to look into that message thread. Just don't go with that Edelbrock cam that matches the rest of your componants, I think that cam sucks. The ramps are way slow and the dual pattern is not nessasary when used with headers and an efficiant exhaust.
 

·
Premium Member
Joined
·
2,142 Posts
Compression Ratio

Actually with stock specs the 4V (63cc) heads produce only a miserable 10.24:1 with a FelPro gasket. 11.0:1 is only with a zero deck and true flat top (no reliefs).

10.24:1 is just fine assuming you have lowered the dynamic compression ratio to the 8.0:1 level by selecting the correct camshaft. Dynamic is all the engine sees anyway. Check out some searches on the web for this topic.
 
1 - 7 of 7 Posts
Top