1985cucv

i was wondering at what hp or rpm is the coolant bypass needed?

Spooler

550 hp or above they are needed. I have one on my truck but it is just a piece of mind deal. I probably didn't need it.

BIGDAN65

i put one on when i went to twins, prob needed it before though

1985cucv

it just keeps it a lot cooler on those back 2 correct? i dont like the price of these things there has to be an alternative!

Spooler

Yes, and keep you from popping the freeze plug out of the back of the block. It dosen't save you from the soft freeze plugs under the valve cover though. If those let go it is a not good, total rebuild time.

soulezoo

I have one and still popped the plug out the back... more than once.

It is not a for certain cure. And for what it is worth, the second time I blew it out, it had the steel plate and collar installed to hold it in. So it held it in, but blew out just enough to let it leak water when driving. I was so certain that the plug was in there for good, that I chased ghosts trying to figure out where the water was going!

The bolt in plug with the hose going out the back is best for that IMO. For the plugs in the head, tap, thread and screw in plugs to make darned sure.

1985cucv

that is a nightmare why dont they just make these things handle the power? i just dont get it. its never ending in the search for more power.

how do those plugs blow out under the head and when and at what hp do they blow out?

CD in NM

If you drive a cold truck and no warmup time, you really probably need one. If you tow a lot, the back cyls get quite a bit hotter than the others, you really probably need one. If you live in a hot climate, for the same reasons as towing, you probably need one.

I have one, I noticed that my overall driving temps stay more at where the thermostat opens rather than creeping up some on grades/hills. It is more of a faster creep up when towing, and goes a little higher by about 15-20*s.

Certainly is a good thing for peace of mind, you really never know when it is saving your butt - but you do know when your butt is wide open when you don't have one and blow the freeze plug above the tranny.

I am glad I installed the Opie, would do it again in a heartbeat.


CD

1985cucv

yeah im thinking this would be the last thing i will hopefully have to do if i do it! the thing that sucks is that it looks like you could make it for 150 bucks tops!

at what psi does opies kit open up and dump the coolant pass the bypass?

Brian Lent

EEP has the kit which replaces the rear freeze plug. I had mine blow out awhile back with stock injectors and a 62-65-12. No 550 hp. It happened with the truck up to temp and reved to 3400 rpm racing a gasser. I think that hp is irrelevant but more importantly boost, revs, and temp. EEP's kit was 160 delivered I believe but is easier to install after the plug is out cause it is a pain to get out back there. 2yrs later and no problem yet.

Ace

It's rpm dependent. The higher the engine spins the higher the water jacket pressure builds. I'd say the freeze plug kit is probably the best way to go. But you don't need to spend an arm and a leg to get some cooling benefit from tapping the back of the head. It's also a great way to install a coolant filter on that new line as well, while you're at it.

1985cucv

ace how do you suggest getting more cooling to the back i remember you had pics but i cannot find them on here

Ace

Here's the pics of my coolant bypass/filter setup:

http://stuff.is-a-geek.net/PhotoAlbu...ics/CRD_14.JPG
http://stuff.is-a-geek.net/PhotoAlbu...ics/CRD_15.JPG
http://stuff.is-a-geek.net/PhotoAlbu...ics/CRD_16.JPG

The brass valve on my head tap is for a heater bypass, you can ignore that, not necessary for running just a bypass/filter.

doug60

I was wondering ,what the out come was on your vanishing water dilemma.
I must have missed it.
Thanks for shareing
doug

1985cucv

i am going to make my own after going on another website and seeing that a homemade one works just as good!