confused about engines

Thegiecks · Mar 20, 2008

Well, I have an offer to buy a 1979 Mustang Cobra. 4 spd, built 302 bottom end w/ 289 roller heads and intake, and a Holley carb. 373 gears, and some other mods.
My question is, w/ the 302 bottom end, and the 289 heads (which are roller heads) can the engine rev to 9K rpm's? he is saying he has had it that high before. Now the reason the car is so cheap is beucase, he says he flattened the cam ( non roller) on one cylinder. The back right cylinder is dead, no compression. He said he drove it home from the track, no noises, no problems besides lack of power. And it has sit for 2 years.

Is this thing worth it? And is this possible to rev so high?

Mustang5L5 · Mar 20, 2008

If he's revving it to 9000RPM, i wouldn't buy it.

9000RPM 302's are rare...and they usually involve blueprinting and balancing pretty much everything to get it. Does the car look like it's had a high-end rebuild done to it?

Sounds to me like it needs a rebuild again.

redneck15431 · Mar 20, 2008

Also I would think that if a cam lobe was flattened there would be problems on two cylinders instead of one. There is a problem specifically with that cylinder; whether he blew a hole in the piston, valves not closing, or the rings are totally shot. And yeah, I agree if he was running it to 9k rpm I wouldn't buy it either. It's hard on stuff when you start revving that high.

LiquidGT · Mar 20, 2008

9000rpm is it a Mustang or a S2000, like 5L5 said everything would have to be balanced and blueprinted. Unless you plan on building a different engine and trans and the body/chassis is good then buy it.

Fast63 · Mar 21, 2008

a flattened cam does not cause the cylinder to have no compression, something else is wrong. Expect that the engine needs a complete rebuild, and some parts need to be replaced. I don't think that engine could even get anywhere near 9000rpm, except in nuetral. Those engines were rated at like 170hp from the factory with a redline of like 5000rpm. And those "roller heads" are dumb because there is no such thing as a "roller head", especially on a 289 which never had roller anything. 289 heads are not even any better than 302 heads for flow, although they will increase compression a little bit.

If you really want the car, low ball him. Otherwise, I would pass because it sounds like he has no idea what he was doing and abused the car.

NKau · Mar 21, 2008

From the sounds of it, the seller doesn't know his ass from a hole in the ground. What does this 'built motor' consist of? Don't buy the car unless the car itself is really nice and the price is cheap. Should be able to swap a nice later 5.0 roller motor right in place of the crappy old flat tappet 302.

irish · Mar 21, 2008

It was raced, thats one strike

He said roller heads, he does not know much about engines, strike two

He says the cam lobe has been wiped (see strike two) strike three

Some people love those style of mustangs, if the body/interior are not trashed and you can buy it cheap(needs a motor job cheap) then go for it, otherwise keep searching. Here are a few random thoughts in no particular order:

If he does not know much about motors, I wonder how he accurately measured the "9000 rpm" <--which I doubt very much, you CAN make a 302 rev really high, but is is super expensive to do. Rev power is the most costly way to go fast. Thats one reason strokers are so successful.

I would suspect some sort of catastrophic failure in the motor beyond a wiped lobe, buy it cheap, prepared to throw a motor in it.

good luck!

Matt

Venom351R · Mar 22, 2008

If it was even possible to run that motor to 9,000 RPM I dont see anyway he could drive it home from the track w/ no noise or no issues. I would expect that motor to blow up long before 9,000 RPM's. Just to give you an Idea Nascar builds motors that run at 8,000-9,000 RPM's. I doubt he put that kind of work, money into this motor. As stated unless the car is really nice on the inside and out then stay away from this disaster. There are many 5.0 Mustangs out there for sale that run great and were not blown up at the track.

Ike83 · Mar 22, 2008

Ummmm......like.....I was always under the impression that the first Cobra wasn't available until 1993.

Venom351R · Mar 22, 2008

http://www.allfordmustangs.com/photopost/showphoto.php/photo/19777

http://musclecars.howstuffworks.com/classic-muscle-cars/1968-ford-mustang-428-cobra-jet.htm

1993 was just the start of the SVT Cobra, not the cobra name brand.

NIKwoaC · Mar 22, 2008

Ike83 said:
Ummmm......like.....I was always under the impression that the first Cobra wasn't available until 1993.

No, you could get a Cobra back in the day (79,80,81 IIRC), but it was really just a body mod thing, it didn't actually have any performance mods over the "normal" V-8 or turbo-4 cars. It had a big cobra hood sticker and other treatments on the body and interior. Pretty cool looking cars, I think.

289 heads that flow well enough to rev to 9K? Is this guy nuts? Even if the valvetrain and bottom end held together long enough, I think you'd need some serious port work to be able to flow enough air to rev anywhere near that high.

Mustang5L5 · Mar 22, 2008

Ike83 said:
Ummmm......like.....I was always under the impression that the first Cobra wasn't available until 1993.

The first SVT Cobra was in 1993

But ford had Cobras in the 2nd gen and early 3rd gen Mustangs. 1978-1981 i beleive.

They were just decal and appearance packages. No performance mods really

confused about engines

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