Installing aftermarket heads safety

Lwiss · Dec 13, 2009

Would it be safe to install aftermarket H/C/I on a stock bottom end that has 140 000 km on it? aprox 90 000 miles.
With what I want to install the engine would be able to run 7000rpms.

Thanks

Win · Dec 13, 2009

Do you have any leaks or any blow by?? Good compression in the cyl??? Running 7000rpm on a stock 302 bottom end isn't going to happen. If you have a healthy motor right now you can throw on a set of Heads, a new cam and intake and you'll be just fine.

NXcoupe · Dec 14, 2009

Yeah, even if it was a brand new 302 with 0 miles, the stock bottom end is not going to live at that high of rpms. the rods will fail. The crank can take the r's but not the cast pistons and stock rods. It'll do it for a little while, but not forever. And when it fails, it's not pretty, usually takes the block and everything inside with it. Had one come apart on the dyno once. It was the aftermarket cheap upgrade from stock rods. 6800 spewed it's guts all over my floor. Guy knew he was pressing his luck, just wanted to have some fun with it.

GREG@SN95 · Dec 14, 2009

No... Fresh top end on a worn bottom end is never a good thing...

Rebuild the bottom end...

What H/C/I are you thinking about installing that will let the motor rev out to 7 grand?

Lwiss · Dec 14, 2009

Ok, thanks for clearing that up for me, and for the HCI combo i dont remember, all i know is it was an e303 cam, edelbrock heads and intake.
It was the owner of the performance shop that suggested me to do this.

dutch · Dec 14, 2009

should be fine as long as the stock bottom end is healthy, just do a compression test.

birel21y · Dec 14, 2009

Hmm.. here is my stock cobra bottom end after 6,200 rpms

GREG@SN95 · Dec 14, 2009

Lwiss said:
Ok, thanks for clearing that up for me, and for the HCI combo i dont remember, all i know is it was an e303 cam, edelbrock heads and intake.
It was the owner of the performance shop that suggested me to do this.

lol, he's full of shit... no way it'll make power or be able to rev out that high...

Paul · Dec 14, 2009

+1

If the guy running the shop told you to spin that combo to 7,000 rpm, he's a moron. It takes quite a bit of work and somewhat expensive hardware to live safely at that kind of RPM for any length of time.

GREG@SN95 · Dec 15, 2009

Paul said:
+1

If the guy running the shop told you to spin that combo to 7,000 rpm, he's a moron. It takes quite a bit of work and somewhat expensive hardware to live safely at that kind of RPM for any length of time.

yup... don't go back to that guy ever again... He's an idiot and can be very dangerous to the well being of your car...

sn95gtvert · Dec 15, 2009

omg to that cobra block, only 6,200 rpms did all that damage? how much stress was being put on that motor? are you sure it wasnt more like 7200 rmps?

modo · Dec 16, 2009

factory dampeners love 6000+ rpm :headbang:

kidding

birel21y · Dec 17, 2009

sn95gtvert said:
omg to that cobra block, only 6,200 rpms did all that damage? how much stress was being put on that motor? are you sure it wasnt more like 7200 rmps?

Thats road racing for you... 4500-6200 constantly for 20-30 min. at a time. Autozone harmonic dampener cracked, and rotated 180* LOL!!!

modo · Dec 17, 2009

birel21y said:
sn95gtvert said:

omg to that cobra block, only 6,200 rpms did all that damage? how much stress was being put on that motor? are you sure it wasnt more like 7200 rmps?

Click to expand...

with a good dampener (sfi) the motor would have still been alive.
Thats road racing for you... 4500-6200 constantly for 20-30 min. at a time. Autozone harmonic dampener cracked, and rotated 180* LOL!!!