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-   -   Cylinder head/intake venting (https://www.offshoreonly.com/forums/general-q/366253-cylinder-head-intake-venting.html)

NautiB 05-09-2020 05:10 PM

Cylinder head/intake venting
 
Venting the rear intake water crossover on BBC or not?? Ive rebuilt my 502 mags. They are now 509's pushing 610hp. Ive removed the circ pumps from the system & installed crossovers with thermostats. Im running Dart air gap intakes. What are you guys doing with your builds? some other hurdles Im trying to get over are, water pressure dumps? do I need to or not? running solely off bravo style, Harden Marine SS body pumps. Oil thermostat systems. My new coolers are very efficient. I need the oil to get to temp & on a test stand I cant get over 60*. What styles & plumbing are you using? 38* & snow today, wtf?.. lol
Thanks in advance for any help!

Rookie 05-09-2020 07:11 PM

I had issues sticking valves and kissing pistons when I switch to crossovers and Merlin heads. Out of fear I do it to all of my intakes now.

NautiB 05-09-2020 08:11 PM

Rookie, got any pics of how you plumbed it?

941 05-09-2020 09:34 PM

The intake I took off my 502 mag mpi was drilled for the venting of the rear water ports and they were plumbed to the thermostat housing, I don't think it was a good way of doing it because the brass fitting were corroded closed, I feel do to low flow. The modded intake I put on was not drilled so I drilled it and ran -4 hose off each side and twined them and tied them into my exit bulkhead for my intercooler.

NautiB 05-09-2020 11:16 PM

941, did you add any type of one way valve to prevent any back flow towards the intake or do you feel there is adequate pressure & flow so its not a concern. I was wondering about teeing them into the small hose (1/4") going from exh manifold to tail on my merc/gill set up.
Curious, was there any salt water on your set up that may have contributed to your fittings clogging up, or your pretty sure it was a low flow issue?

sutphen 30 05-10-2020 08:07 AM


Originally Posted by 941 (Post 4738102)
The intake I took off my 502 mag mpi was drilled for the venting of the rear water ports and they were plumbed to the thermostat housing, I don't think it was a good way of doing it because the brass fitting were corroded closed, I feel do to low flow. The modded intake I put on was not drilled so I drilled it and ran -4 hose off each side and twined them and tied them into my exit bulkhead for my intercooler.

depending on what you used as the fitting material,,you have to open up the aluminum around the fitting so the fitting is in clean brass.I did the same as you and it clogged up.removed the aluminum away and problem solved.its all about dissimilar metals and water,corrosion big time.

941 05-10-2020 08:25 AM

Not sure, I am in salt water but I flush with salt away every time she goes in the water. The fittings in my intercooler (stainless into aluminum) came apart by just wiggling the hose. I cut them and welded new stainless 90's on them. Makes sense what sutphen 30 is saying because the other intakes I have are opened open more around the water jacket then just a drilled hole tapped.
https://cimg6.ibsrv.net/gimg/www.off...51a57b754c.jpg

https://cimg7.ibsrv.net/gimg/www.off...454c7eff64.jpg

https://cimg9.ibsrv.net/gimg/www.off...6caecd0557.jpg

941 05-10-2020 08:28 AM

This is how it was plumbed.
https://cimg3.ibsrv.net/gimg/www.off...3feeb3a1b.jpeg

F-2 Speedy 05-10-2020 08:44 AM

I did it on my Whipple motors, I drilled and tapped a pair of -4 fittings on each side and run them into a -4 to -6 Y connector and dump it out the side discharge

sutphen 30 05-10-2020 09:07 AM


Originally Posted by 941 (Post 4738157)
Not sure, I am in salt water but I flush with salt away every time she goes in the water. The fittings in my intercooler (stainless into aluminum) came apart by just wiggling the hose. I cut them and welded new stainless 90's on them. Makes sense what sutphen 30 is saying because the other intakes I have are opened open more around the water jacket then just a drilled hole tapped.
https://cimg6.ibsrv.net/gimg/www.off...51a57b754c.jpg

https://cimg7.ibsrv.net/gimg/www.off...454c7eff64.jpg

https://cimg9.ibsrv.net/gimg/www.off...6caecd0557.jpg

I did the same on my whipple intercoolers,knew those fittings would fail in saltwater over time.and ditch the salt away and use dawn dish washing detergent.flush real good and then add the dawn,,let it bubble on thu.its fun when you get to the dock and for a few minutes bubbles come out the exhaust.:D


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