[walkerjay]

If I could do it over again, I'd probably add just a bit more silicone but for now, I laid a nice bead, let it tack up, then set the manifold down in one easy shot. Definitely had continuous contact between the silicone and bottom of intake and it just had a slight ooze. I figure, maybe after this cures, I can overlay a secondary bead and with the wet finger, give it a slight schmear to fill in the gaps. What do you think?

also, after setting up a while I torqued the intake in increments till i reached 30#. That's the spec I found in two manuals but they didn't mention if it was different for cast or aluminum.

thanks.

The last pic seems to show more of a gap but that's more from the overhang there....there's plenty of sealant beyond that doesn't show well in the pic. This is an example of an area I can go back and fill in. If warranted, that is.

 

[Paul Wright]

Take it off and do it again. You don't let it tack up before setting the manifold down. You set the manifold on it wet so the RTV sticks to both surfaces (manifold and China Wall). Then you let it set up. Then you torque it down.

The center part of the bead would look right if it was adhered to the manifold.

 

[walkerjay]

If you see a problem from the pics I will do it again. Much easier to redo now. But to clarify about what I said about letting it tack up, I may have misspoke. After I laid down the two beads, I let it sit for no more than 5 minutes. Yes, that was enough to give it a slight tack but when I touched it and lifted my finger, some silicone came up with it so it was not 100% tacked. I visually saw the intake compress the bead (slightly, which is why I thought a thicker bead would be better)

I want it right from the get go so I'll do it again if need be. Good part is that now I have some experience....am in the groove, so if I do it again, it should go easier next time. Shouldn't take more than a half hour to pull this off and clean it up for another go around. Worst case, i may have some silicone in the corners lift up some of my fel pro gasket, possible causing damage. Thanks.

btw, the ARP intake bolts come with 8 which have a larger integral washer flange and 4 with a smaller washer flange. All have the same head and length. Are the 4 smaller flange bolts supposed to go in a certain spot?

I'm going out to do the oil pump now, will check back regarding this subject in a bit.

 

[sgtsteve]

also, after setting up a while I torqued the intake in increments till i reached 30#. That's the spec I found in two manuals but they didn't mention if it was different for cast or aluminum.

I just went through this with my Edelbrock performer intake. The 30# torque called out in the manual was not nearly enough!!! As soon as I poured some water in the radiator it ran right out the back of the intake, until I tightened the bolts by hand and cranked them down nice and tight.

 

[walkerjay]

"The center part of the bead would look right if it was adhered to the manifold."

So in your opinion, the bead does not look right?
Bead was sticky when I set it down but not "wet".
Will a supplemental, second exterior bead do any good at this point?

Just asking a bit more info before I take it apart.

thanks.

 

[walkerjay]

I just went through this with my Edelbrock performer intake. The 30# torque called out in the manual was not nearly enough!!! As soon as I poured some water in the radiator it ran right out the back of the intake, until I tightened the bolts by hand and cranked them down nice and tight.

I'm gonna give them a shout to see what their torque specs are. I wonder if I can check water pressure in the block while its on the stand,.maybe thru the water pump holes or thermostat inlet.....something like that. I have seen mechanics use that pressure tool via radiator cap. Maybe I can pump it up and look for leaks??? I recall 16-20 pound or so of pressure but could be way off on that. will do some more research.

 

[elblako91]

If you read the back of the RTV silicone it says to apply and wait 5-10 min before sealing. So if you waited 5 min then you should be ok.

 

[Paul Wright]

Pressure checking the cooling system on the stand is a very good idea. You can make block off plates for the water pump holes and one for the thermostat. Install a fitting and put in about 20 psi of air. Check around all the junctions with a squirt bottle of soapy water.

The anecdote above about having to over tighten the manifold bolts to get it to seal is an indication of a problem. More than likely the fit angle between the manifold and head surfaces were off. Usually when you deck a block you have to machine the manifold also or it won't fit properly.
A used manifold may have been machined for a zero decked engine and if used on a non decked engine it will not fit good either.
There may be many reason why, but it's always a good idea to pre check the manifold before installing. Lot's of way to do that, they even make a measuring tool for pros but it's not something a backyard builder might invest in.

As far as re-doing the manifold, that's up to you. RTV is cheap and this is something you may have to do several times to get the right amount and a good seal.

It's like installing distributors. Once you "get it", it's easy to do it perfectly.

 

[sgtsteve]

I'm gonna give them a shout to see what their torque specs are.

Who are you calling, Edelbrock? Just curious as to what they say. My block has never been decked, intake never milled, heads were slightly decked to compensate for head gasket thickness. I just don't think 30# is enough on those bolts?

 

[The Big Al]

In reference to the angle gauge Paul shows.

The spec on the angle for a SBC // BBC is 80° when using 23° heads. (correction) The 85° is with 23° heads

You can check this with a basic protractor or even make one out of basic materials.



Mostly when this is a issue is when heads have been cut more than .060 or block decked the same or combined total. When blue printing a engine and angle milling heads this angle is checked to resurface the intake face to get correct angle for intake/head seal. In this case the use of a thicker intake gasket will be needed.



ON another note when using silicone for end seals.
I use a letter "X" punch and make several marks on the block and intake ends to give the silicone something adhere too, keeping the silicon from pushing out at HIGH RPM and crank case pressure.

The next one I do I will post pics for reference.

 

[sgtsteve]

Are stock SBC 400 heads 18 degrees? I assume your talking about the angle on the intake side of the head...hmm...Now I'm curious and will have to try to check mine if it's possible with intake mounted.

 

[The Big Al]

Are stock SBC 400 heads 18 degrees? I assume your talking about the angle on the intake side of the head...hmm...Now I'm curious and will have to try to check mine if it's possible with intake mounted.

No yours are not, they are 23° with 80° degree and I had the 85° -18° listed this is not stock.

I have corrected the posting no paying attention to my referance specs. MY BAD!

 

[71SS454]

Are stock SBC 400 heads 18 degrees? I assume your talking about the angle on the intake side of the head...hmm...Now I'm curious and will have to try to check mine if it's possible with intake mounted.

The 18 degree reference and the 23 degree reference are the valve angle inthe head. If you use the piston face as the zero, the valve is tilted 23 degrees from this. The smaller the tilt, the straighter up the valve is, which gives the air a straighter shot into the cylinder. That's why 18, and 15 degree heads make more power, the air dosen't have to slow down as much going around the curve in the bowl of the intake runner.

 

[sgtsteve]

The 18 degree reference and the 23 degree reference are the valve angle inthe head. If you use the piston face as the zero, the valve is tilted 23 degrees from this. The smaller the tilt, the straighter up the valve is, which gives the air a straighter shot into the cylinder. That's why 18, and 15 degree heads make more power, the air dosen't have to slow down as much going around the curve in the bowl of the intake runner.

Thanks for the quick lesson! All that internal stuff is foreign to me. I learned something though....

 

[walkerjay]

Pressure checking the cooling system on the stand is a very good idea. You can make block off plates for the water pump holes and one for the thermostat. Install a fitting and put in about 20 psi of air. Check around all the junctions with a squirt bottle of soapy water.

The anecdote above about having to over tighten the manifold bolts to get it to seal is an indication of a problem. More than likely the fit angle between the manifold and head surfaces were off. Usually when you deck a block you have to machine the manifold also or it won't fit properly.
A used manifold may have been machined for a zero decked engine and if used on a non decked engine it will not fit good either.
There may be many reason why, but it's always a good idea to pre check the manifold before installing. Lot's of way to do that, they even make a measuring tool for pros but it's not something a backyard builder might invest in.

As far as re-doing the manifold, that's up to you. RTV is cheap and this is something you may have to do several times to get the right amount and a good seal.

It's like installing distributors. Once you "get it", it's easy to do it perfectly.

Redoing the end seals is no biggie, if I decide i HAVE to do it. I think its going to be ok. Worst case, I pull the intake and redo it if I find a problem later. Everything is accessible and easy to work on. Redoing it now may or may not be needed. I installed some rtv around the coolant hols on the intake gasket, so pulling it up may damage/distort the gasket. I think I will hold off and see what happens once I get everything on. I can borrow my friends coolant system pressure tool so i can check that before I fire it up, and do it via the radiator fill neck.

As far as torque specs, I emailed Edelbrock. haven't heard back yet. I will leave things at about 32# and see what happens later.

 

[walkerjay]

If you read the back of the RTV silicone it says to apply and wait 5-10 min before sealing. So if you waited 5 min then you should be ok.

According to the red rtv tube I have, it says "apply an 1/8" to 1/4" bead then assemble parts while still wet. Finger tighten until silicone squeezes out, allow to dry for 1 hour then tighten" Gee, who ever thinks to read the instructions....?

 

[laser-red-nova]

I wonder what the purpose of the 1 hour wait is. It will still dry completly know matter which way you do it. I have never waited , never had a problem. I guess what I'm asking is what is the theory behind waiting 1 hour?

 

[Paul Wright]

It allows the RTV to partially cure and develop preload. That's the springiness that keeps it sealing. If you don't it, just squishes out.

 

[slickman]

I wonder what the purpose of the 1 hour wait is. It will still dry completly know matter which way you do it. I have never waited , never had a problem. I guess what I'm asking is what is the theory behind waiting 1 hour?

Humm, me too. I never wait and never had an issue.. Yet... But thinking about it, it would seal better.

 

[laser-red-nova]

It won't all squeese out there is a gap between the intake and head. So this springy thing I can't understand. My way the silicone just hardens between the gap. Your way you are just letting it pre-harden. I know thats what the directions say. I guess I'm just venting .... WHY