[Snake556]

Alright Mach 1/Cobra owners, I've got a question for you.

I'm looking at buying a full Mach 1 or Cobra donor car and swapping absolutely everything over to my sixxer. But before I do that, I'd most likely be rebuilding the engine to start fresh. Is there anything I need to watch for specifically? I've heard head tick can be vaguely annoying with them. Fix for that?

Any other info you guys can give me would be great!

 

[Scrun27]

Get a 2004 so the cylinder heads have the 9 thread spark plug version vs the 4 thread that can spit plugs out through the cylinder head. I've seen entire drive trains with everything you need on eBay (including the fuel tank, drive shaft and stuff).

 

[Snake556]

Yeah, I've got my eye on a few cars through auction. All accident cars, but I'm only looking at ones with minor damage, or damage not concerning the driveline/rear end/fuel/etc. There's a few '01 Cobras (and a 2003 GT with an '01 Cobra swap) on there. Looking more at the Mach 1's however.

If I end up going with the older, 4 thread version, can I have that re-tapped to a 9 thread?

 

[Scrun27]

Yeah, I've got my eye on a few cars through auction. All accident cars, but I'm only looking at ones with minor damage, or damage not concerning the driveline/rear end/fuel/etc. There's a few '01 Cobras (and a 2003 GT with an '01 Cobra swap) on there. Looking more at the Mach 1's however.

If I end up going with the older, 4 thread version, can I have that re-tapped to a 9 thread?

I don't know if you can or not.

I'm sure you already know this, but remember the Cobra engine is all forged and will hold more than 450RWHP which is what the Mach and pre 03 Cobras will handle.

If its down to Mach 1 vs 99/01 Cobra I'd go with the Mach 1 since it has "C" heads

 

[Snake556]

Yeah, that's sorta how I'm leaning. I'm not looking to run S/C or turbo'd right away, so I'm finding I'm leaning more towards a Mach 1. If I can get an '03 or '04 Cobra at a good price, I wouldn't pass it up, but even wrecked they usually sell for as much as an '03/'04 GT.

 

[Jason4.6GT]

99/01 cobras also have C heads...

 

[Scrun27]

99/01 cobras also have C heads...

You're right. They were C heads, just revised again for 03-04. 04 would be th best choice IMO.

 

[termi_GT]

You cannot retap the earlier C heads to 9 threads. The best fix for those is to do a time cert in every plug hole while the motor is out.

 

[Lariat]

As long as you aren't planning on boosting it right away, you can get away with the 4 thread plug holes. Just gotta torque em to 28 ft/lbs. Ive done some research on a 4v swap before. You do want C heads. If i remember correctly the B heads had a cooling issue? :dunno I will say, i'm eager to see that sixxer built up properly! If i lived closer id help too snake.

 

[termi_GT]

B heads can't touch the flow of a C head.

 

[Lariat]

i'm aware that they don't flow nearly as well as C heads, but i thought the B heads had a cooling issue as well.

 

[termi_GT]

i'm aware that they don't flow nearly as well as C heads, but i thought the B heads had a cooling issue as well.

Not that I know of.

 

[Lariat]

I could be wrong. Anyway, i'm no expert, i just now enough to build the 4v i wanted to build

 

[Oiljunkie]

both heads have cooling issues, that why most big power guys and anyone who doesn't want issues runs a head cooling mod of some sort.

IMO don't buy someone else's swap, do your own.

If you can find an 01 with a teksid book IMO that would be the route i would go, unless you don't want IRS then find a 04

 

[na svt]

Get a 2004 so the cylinder heads have the 9 thread spark plug version vs the 4 thread that can spit plugs out through the cylinder head.

Not all 04 heads have 9 threads

If its down to Mach 1 vs 99/01 Cobra I'd go with the Mach 1 since it has "C" heads

99/01 are also "C" heads.

B heads can't touch the flow of a C head.

Bs can outflow Cs and in stock form have a CFM that is very similar to Cs. However, their velocity is poor and therefore so is the power.

i'm aware that they don't flow nearly as well as C heads, but i thought the B heads had a cooling issue as well.

B heads do not have any cooling issues and neither do the 99/01 heads.

both heads have cooling issues, that why most big power guys and anyone who doesn't want issues runs a head cooling mod of some sort.

If you can find an 01 with a teksid book IMO that would be the route i would go, unless you don't want IRS then find a 04

There's no need for a teksid block if the power is going to be under 800rw. The need for Teksids is highly overstated.

As long as you aren't planning on boosting it right away, you can get away with the 4 thread plug holes. Just gotta torque em to 28 ft/lbs.

4v threads can hold boost contrary to popular beleif; remember guys, all 4v heads from 93-mid 04 had only 4 threads. There thousands of boosted 4vs with 4 thread plug holes. The problem isn't with the strength of the 4 threads, it's with the morons that over torque the plugs. With that, the proper torque for the plugs is 11 ft lbs, not 28 as stated above. 28ft lbs will have you installing time serts in no time.

Get a 2004 so the cylinder heads have the 9 thread spark plug version vs the 4 thread that can spit plugs out through the cylinder head.

The plugs do not get blown out through the cylinder head. They do however, come out of the hole from which they were installed.

 

[Scrun27]

Not all 04 heads have 9 threads



99/01 are also "C" heads.



Bs can outflow Cs and in stock form have a CFM that is very similar to Cs. However, their velocity is poor and therefore so is the power.



B heads do not have any cooling issues and neither do the 99/01 heads.



There's no need for a teksid block if the power is going to be under 800rw. The need for Teksids is highly overstated.



4v threads can hold boost contrary to popular beleif; remember guys, all 4v heads from 93-mid 04 had only 4 threads. There thousands of boosted 4vs with 4 thread plug holes. The problem isn't with the strength of the 4 threads, it's with the morons that over torque the plugs. With that, the proper torque for the plugs is 11 ft lbs, not 28 as stated above. 28ft lbs will have you installing time serts in no time.


The plugs do not get blown out through the cylinder head. They do however, come out of the hole from which they were installed.

Where were you earlier Todd? LOL
Thanks for setting us back on course.

Question: does the pistion ever smack the spark plug, or is that just what someone once thought happened? From what I can see its more from a loose plug getting pushed up and down until it finally comes out.

 

[na svt]

Where were you earlier Todd? LOL
Thanks for setting us back on course.

Question: does the pistion ever smack the spark plug, or is that just what someone once thought happened? From what I can see its more from a loose plug getting pushed up and down until it finally comes out.

the piston will hit the head before the plug.

 

[Scrun27]

the piston will hit the head before the plug.

My friend's Mach 1 just had the spark plug come out and the top of the spark plug was smashed against the diode. What causes that? I'm guessing that's where the myth came that the piston hits it. Maybe people are afraid and loosen the plugs

 

[na svt]

the electrode was smashed because the plug was blowing around in the hole while the engine was running

 

[Snake556]

Whoa, some seriously awesome information going on here. Thanks guys! It'll probably be a little bit until I can actually get the drivetrain etc. as I need to renew my passport so I can go get whatever car I pick up, and the two cars I was looking at getting ended up being sold. Only a flood car available now, and I'm not touching that with a 30 foot pole lol.

As soon as I find one I like though, then I'll be grabbing it up and starting my engine rebuild to begin readying to drop in!

So I should be okay with the 4 thread plugs, just make sure they're C heads (was going that way regardless, so should be fine!). She'll be getting boosted eventually, but not for the first couple years at least! Just bolt ons and whatnot.