I'm suspecting a vacuum leak on my intake gaskets and will replace tonight. Was wondering if anyone had any tips & tricks to get the suckers to seal properly. I've had this problem before on this motor so either I'm doing somethign wrong or something isn't straight.

Questions:

1. How do I verify the intake and heads have the correct angle (machined properly)? Straightness is no problem but angles???

2. Proper use of sealants??? I looked through the service manuals I have laying around. 83 Cadillac, 71 Chevrolet, and 96 F-body... All had different procedures:

One said use RTV around water ports only.

One said RTV where end seals and intake gaskets meat, but nowhere else.

Last one said RTV corners and waterjackets on head side only.

Also, experiences with different brands of gaskets??? I tried Fel-pro 1212 and MrGasket ultraseal. Both left me unimpressed. Felt cheap to me and leaked. Going to try a GM gasket this time. No idea if they are any better...

Engine is a 454 BBC with aluminum heads & Intake.

/Markus

If your heads are milled it lower's the intake ports and your intake will need to be milled to match it. It is probably only a problem if you had to slot the intake bolt holes just to get the intake to bolt on. I just put a lil silicone around the water jacket's, and a 1/4" bead on the front and rear rails instead of the gaskets. Did you torque the bolts according to the correct sequence, and to the correct spec? Maybe your aluminum head require a specific gasket?

The heads were milled by Edelbrock, but I have not done any machining. The heads are Edelbrock RPM's that were angle milled by edelbrock to decrease the chambers to 100cc. I'm hoping edelbrock did the machining properly and all the angles match but it would be nice to be able to verify. The intake bolts fit fine.

I did follow the tightening sequence. I have not found a way to get a torque wrench on the 4 center bolts though. Any way to do this? Also, in the past I've used 25 ft-lbs on the outer bolts but I noticed the 96 f-body spec is 35 ft-lbs with aluminum heads/intake.

remember check the intake bolts every time the car cools down at first. in my experience they can be like header bolts and i have a suspicion that it can be worse when reusing stock bolts.

also if there are any intake bolts holding accesory brackets make sure the bolt is long enough to get enough thread in the bolt hole- keep an eye on them, i think they take longer to seat than the other bolts do.

make sure intake and head surfaces are clean as hell. use a high tack spray on the whole gasket and head. still use rtv on water ports. and read the intructions from edelbrock twice... just in case.

I have the same setup as you, Edelbrock 100cc heads and alum. intake.
I put a beed of silicon then the rubber pieces(to take up space), then another beed of silicon on each end.
The intake bolts just sliped into place on mine also, so I dont think there are any alignment problems.
But I havent started mine yet so I cant tell you if it leaks or not.
I did clean everything really well with laqure thinner before assembly.

If I may ask, and not to change the subject, how does your motor run?
What cam,pistons,ect...........?
T.C.

Small block Ford's are notorious for intake leaks. When I had the Mustang Conv, a few years ago, I found the only thing that worked were the Mr Gasket compressed composite gaskets sprayed liberally with HyTack on both sides and additonal sealer (good ole Permatex #2 soft set) at the water ports.

HyTack sounds like a good idea. I think I'll use it this time around (never used it before).

I'm using ARP intake bolts but I noticed I don't get very much thread engagement because the intake flange is so thick. I actually stripped 4 bolt holes in the heads and had to helicoil. :(

Maybe I should give up on the ARP's and get regular, longer, bolts.

TC: Motor runs real well except a unstable idle and slight chugging that I think is due to the intake leak. Power is good, IMO. Dynoed 393 rear wheel hp and 440 rwtq with a baby cam (224/229 hydraulic roller on 114 LSA, 0.573/0.585 lift). Pistons are stock LS-5 flat tops so CR is about 9.3-9.5.

/Markus

You don't have to give up on the Arp bolts...just get longer ones. Hillco fasteners have Arp bolts the the piece, you pick the head, thread then length.
I ran into that when I bought a all-in-one engine bolt kit and the valve cover bolts were just long enough for stamped steel covers and I had cast alum.

I use the Mr gasket and the Felpro just fine. My procedure is always the same.

I use Permatex aviation sealer and brush it around each port on head and on water passages. I let it tack up and then stick gaskets to it. I then put a relatively thick bead of RTV on the end rails and let it tack up. I NEVER use the ruber or cork end seals. Then I brush sealer on the intake manifold side of the gaskets and let it tack up for a minute or two. Next I drop manifold on and start all the bolts.

I lightly snug them all up starting in center in an X pattern. Just barely get them tight. Then I progressively work around them tightening more and more each time. May take me 4-5 times in increments. I don't use a TQ wrench for this, but my gut estimate is that I am in the 35-40 lb range minimum.

I also retighten them at least once after the initial start up. I do it when it is still warm, and then again after it cools overnight.

The next day, I trim excess RTV off end rails with a razor blade to make it look pretty.

I can tell you I don't think I've ever had an intake gasket leak. I know I've never had an end rail even seep or blow out. RTV is great stuff.

MY ARP intake bolts are pretty short too. The Edelbrock is much thicker than the old Weiand was. So far so good, but eventually I will dig up some slightly longer ones.

I would hope Edelbrock milled intake face of heads to match the angle milling too, but who knows. My heads have been whacked pretty hard, but they did intake face of head too and it works perfect. To check, try laying intake in "V" without gaskets and center it up. Look real close at the angles/gaps. You'll have to look closely to see if it's off, but it will be visible.

You can also use the extra thick ones that are pretty soft. These raise intake slightly and then allow it to imbed deeper to seal up well and make up slight angle mismatches.

JIM

I do the same as 540Hotrod,Permatex Aviation sealer. Might not be fun to loosen up and take off, but it seals well. The instructions with my RPM Airgap said to use it and lightly ring the waterjacket holes with silicone.I also never use the front and rear gaskets, just a bead of silicone and allow it to start to set before applying the manifold.

Originally posted by 540Hotrod:
I can tell you I don't think I've ever had an intake gasket leak. I hate you. :D

Where can you buy the aviation sealer?

Good advice from all the above but let me add my 2 cents: because of the RTV I let my stuff sit at least overnight before adding water/antifreeze and starting the beast. I also like the copper spray gasket sealer. Some gaskets tell you you don't need RTV around the water jackets--BS

So do you use RTV on BOTH sides of the gasket or just the head side? The 96 F-body service manual calls for RTV on the head side only for some reason.

Try the NAPA Performance gaskets, very nice looking intake gaskets. They seem to have thin layer of some type of metal on them. They're nice looking, but about 10 bucks more than the Mr.G Ultraseals.

Alright, here is my plan of attack:

Obviously I'll clean everything up.

Check straightness by placing intake sans gasket on engine and poke feeler gauges inbetween.

Spray high-tack on both sides of gasket.

Use permatex #2 (non-hardening) around waterports on both sides of gasket.

Let car sit overnight.

Will report back with results...

Originally posted by Slowpoke70:
Try the NAPA Performance gaskets, very nice looking intake gaskets. They seem to have thin layer of some type of metal on them. They're nice looking, but about 10 bucks more than the Mr.G Ultraseals. Are you talking about the Victor Reinz nitroseals? Yes those are nice but covered with teflon and you are not supposed to use any sealer anywhere on them.

Don't know, I just got them from NAPA and the packadge said NAPA Performance on it. I put an RTV bead on the rails, some on the water ports, put the gasket on, put some on the gasket around the waterports, put a dab on the corners between the rails and heads. Sealed fine. But I was working with all stock components, just resurfaced light if at all.

Good luck

Why do you think you have a vacuum leak?

Do you have a cracked intake? Are any holes plugged that are leaking? Hoses? Do you see antifreeze?

Does anyone use either soapy water sprayed on suspicious areas to check or any oil spray?

Originally posted by zwede:
The heads were milled by Edelbrock, but I have not done any machining. The heads are Edelbrock RPM's that were angle milled by edelbrock to decrease the chambers to 100cc. I'm hoping edelbrock did the machining properly and all the angles match but it would be nice to be able to verify. The intake bolts fit fine.

Pretty easy to verify the angles.
Before you put anything on, bolt the intake to one head with a couple of bolts & check the other side with feeler gauges at the top & bottom.
If it is off the angle will be double as you are measuring it all on one side..
You will need a pretty good stack of feeler gauges but if it is off enough to cause a problem you can damn near see the difference by eye.
If the heads were done right you shouldn't be able to measure much of anything.
If you get say .020 difference top to bottom I would correct it. anything less shouldn't cause a problem with seal as this would only be .010/ side.

".....with a BABY CAM...(224/229 hydraulic roller on 114 LSA, 0.573/0.585 lift".


Jeez.....I love the "new you'!!

Coming over to the Dark Side!! Just waiting on those new Voodoo's???


JIM

Originally posted by Wolfplace:
Pretty easy to verify the angles.
Before you put anything on, bolt the intake to one head with a couple of bolts & check the other side with feeler gauges at the top & bottom.Mike: That's brilliant! Why didn't I think of that? Thank you!

Jobberone: Why I think I have a vacuum leak: Several reasons. It does sweat some coolant on the front drivers side. Not enough to make a puddle, but there's some there.

Some (not all) plugs get a black spot on the insulator pointing towards the intake valve. I replaced valve seal, no difference. Disconnected PCV temporarily, no difference. Only leaves intake gasket. Finally, idle rpm surges.

Jim: My Baby cam statement was adig at YOU! You kept calling your old monster cam a baby cam. I'll show you what a baby cam really looks like! :D

But yeah, those voodoos do look interesting.

[/qb][/QUOTE]Mike: That's brilliant! Why didn't I think of that? Thank you!
[/QB][/QUOTE]
=
You are welcome graemlins/beers.gif

Hey,,, sometimes even us "shadetree types" have a fit if sanity graemlins/hurray.gif

Just wish they came a little closer together :(

I'm in the process of putting it back together again. Intake is back on and torqued. I ended up like this:

High tack on heads & gaskets around intake ports. Permatex #2 around water ports. Also used permatex #2 around intake ports on intake side. Reason is I was worried about using high tack on that side and possibly move the gaskets when I lower the intake. China walls got Ultra black RTV instead of rubber end seals. Of course all intake bolts got a smear of permatex #2.

I'm crossing my fingers!

I used GM gaskets from a 1990 chevy 454 truck. Seems like a nice gasket. It has a steel core with some sort of fiber around it.

has the block ever, to your knowledge been decked? my son and i had a time with a 400sb that had been decked and the manifold actually sat on the enrails of the block and would fall onto the heads when you pushed it back or forth off of the endrails. wound up having the manifold endrails shaved so it would sit on the heads. (hope i explained that right)

I now use a product called "great stuff" I think it is called. It's not your regular black RTV - it will setup even when surfaces aren't clean and dry and it would seal a duck's a$$! I have to use a long bar under the runners to pry the intake off though. I bet once it's setup I could take out all the (dry) intake bolts out and it would still never leak.

Sounds to me like your bolts are simply not long enough. Get longer ARP bolts and I bet your problem is solved.

Status:

Engine is back together. I started it up for a short time to set timing. I will take it out for a drive in the next few hours and see how it does. 34F but sunny and dry here.

mechcanic427: I know what you mean; the intake would contact the china walls before it contacted the heads, right? I verified that this is not the case on mine. With gaskets I have the proper 3/16" gap between intake and china wall.

66 283: Where can I find this stuff?

Originally posted by 66 283:
I now use a product called "great stuff" I think it is called. It's not your regular black RTV - it will setup even when surfaces aren't clean and dry and it would seal a duck's a$$! I have to use a long bar under the runners to pry the intake off though. I bet once it's setup I could take out all the (dry) intake bolts out and it would still never leak. =The "Right Stuff" & you are right, you need a damn hoist to get the intake off :D
Good stuff graemlins/thumbsup.gif