just air.... i've only done a pressure test with air, no coolant is in it, and the oil is sitting in the pan since it hasnt been fired up yet. it's leaking on the bottom side of the intake and the top side near the 4 corner bolts. 1st time it was with the cork end gaskets and the felpro intake gaskets with thin film of rtv around water ports and what not.. waited 24 hours and still leaking air. 2nd time was with the actual edelbrock gasket and gasgacinch and rtv run around the end pieces with no cork gaskets which yielded no results. 3rd time was with mr gasket type gaskets which were a little thicker and rtv end gaskets which did nothing. i ran a silicone hose in the distributor hole and you can hear the leak going with the pressure tester on....it drops fast....
the way I am reading it, you are using air pressure on the intake manifold, and hearing air rushing through the crankcase. Am I right in this assumption? If that is the case, is the valvetrain all installed and adjusted? If yes...read on. You will always hear some air rushing through the crankcase if you are putting pressure on one or more cylinders. The rings don't fully seal and air will always rush by, no matter what. Even zero gap and gapless rings will leak a little--that is a given. The air goes right into the crankcase. Now that said, are you seeing leaks at the top of the intake using air pressure and like soapy water? That is a little different issue. My suggestion, if you haven't already, drop the intake on to the heads/block with no gaskets at all. Watch the angle at which the the intake meets up with the heads. You will visibly be able to see a major mismatch between the angles, if there is a mismatch. With the intake still on the block/heads, there should be about 1/32 to 1/16" gap between the BLOCK and the intake on the ends. It will be very close, or should be. If there is a large gap, then maybe the heads/block have been milled. Milling makes the heads closer together, which makes the intake sit higher. One of the downsides to having all of the bolts being vertical is that if you don't tighten them EVENLY from side to side, inside out, that it will sometimes "cock" the intake and cause it to leak. But if they're tightened evenly and properly, it will work great. For intance, if you tightened 2 bolts on one side, it can pull that side of the intake down onto the head at an angle. Then tighten the other side, the intake will be "cocked" and sometimes cause a leak at the bottom of the "loose" side. As for end gaskets, I always throw the cork crap away. Half the time they do nothing but cause problems, such as being too stiff and causing the intake to not fully tighten down against the heads. I have never used anythign other than RTV orange. Just make damn sure the block is CLEAN and the intake as well. I usually rough sand them with a sanding pad on a die grinder. Gives the RTV something to "grab". Then clean both surfaces with acetone or something similar. I use methanol because that's whats available--and it does a good job if you let it dry. Even with boosted engines I've never had one leak unless the bead of RTV was too thin. Don't be afraid to put a big bead on there! Just let it dry FULLY. Meaning 48 hours before you crank it up. The only gaskets I've ever used on windsors were 1250's, 1262's (FelPro), and 90103-1 Mr Gasket. A small mismatch is no big deal. Won't affect power much if any (speaking from experience). The FelPros are thinner and let the intake sit down in the heads further, plus they are soft and will conform to the surfaces better. Once the motor has heat cycled a couple times (like up to 200 deg, then back to room temp), I like to re-tighten the intake. They're usually loose. Also, what kind of fasteners do you use? The Edelbrock intakes have larger bolt holes...like nearly 3/8" inch and the 5/16" bolts need a washer under them to keep them from pulling down into the intake. I use studs on mine--with grade 8 washers and flange nuts. Don't use regular old washers because they'll just deform and affect the preload on the parts that are assembled. I never used the stock bolts because most of the time they're stretched after being off and on a few times. I've had more than one that came out looking like an hourglass...almost ready to pull apart in the middle. And Several times I've seen them loose after a few heat cycles. Heat makes things move around especially if you have aluminum heads. Also makes the gaskets (especially the felpros) soft and pliable and helps them seal. Hope that helps a little...
How much air pressure have you built it up to before the air leak was detected ? More than about a pound or two is probably more than any gaskets (the end gaskets in this case) will stand before being forced out of place. The crankcase isn't intended to be run with more pressure than a road draft tube or PCV system can handle. Pressure will force oil out the crank seals as well. I think you're making a mistake testing for leaks like this.
I would never take a die grinder to the port surface side of an intake if that's what you mean. What I meant was the edges. It just needed a slight edge taken off to clear the tops of the heads, just a little clearance problem. Didn't seem so strange or unusual at the time.
i have 351 cleveland heads on one of mine (took some welding and drilling, water ports are different), never say never, some hillbilly can always prove you wrong with a little machine work.......................
No matter which heads you have on a 302 block, you still cannot bolt a 351W intake to the heads. Nor even a 351C intake. I've bolted 351C heads on a 302 block and aside from the fact that the 302 "Windsor" head ports and bolt holes are wrong for the Cleveland heads, the intake itself fits perfectly between the heads. The only way you'd possibly fit a 351 intake on a 302 block would be to mill the crap out of the intake head faces. And when you were done milling them, there would be no bolt holes left to use.
Well, i believe i found the problem. But first, thanks for the postings. I knew there would be air going through the crankcase in that instance, however, the soapy water effect was what was worrying me. After looking at it more closely, with new gaskets on and off, and on and off, etc etc...... i took the feeler guage and starting measuring gaps between the heads and intake and concluded i needed to take the heads back off.... it seems that when i got the block machined at the local shop, they apparently took the dowel pin out and drilled the hole out, i'm guessing slightly off, after talking with them, they vauguely remembered doing something like that... of course they dont admit they might have cost me a lot of time. so the right head (left looking at the front of the engine) isnt sitting perfectly parallel. To the naked eye, it didn't register, and even the gaps i was getting at .036 and .040 should have been taken care of with the .060 thick gaskets i was using. Thats why it was a conundrum. It's back on without the dowel pin in the back, that was the only way i could get the head to move even slightly. The gaps looked a ton better with marginal space. Now i am waiting for the rtv to setup and i'll do another test, looks like it will work this time.... I never had any trouble with intakes untill this one. whew....
Can't understand why they would have to drill the dowel hole after milling. Maybe deburr the top of it only. I wonder if the head dowel hole is off from the factory a bit. As stated, never run without the dowel in the head, may run for a bit but can wreak expensive havoc if the head moves. Had a similiar problem with the first RPM manifold. Put it on Todd's 302 with RPM heads and it ran like crap. Figured it was fuel or ignition, replaced all wiring and distributor etc. Ended up taking the manifold off and using a straight edge, found the end pieces were machined incorrectly and had a .060 difference front to back. Called Edelbrock and they replaced it "no charge". Only problem I have ever had with any of Edelbrock products.
after running a straight edge on mine, that was another contributing factor, i already got another manifold, and fixed the dowel pin....it's coming back together now...
