Hemi street intake gasket clearance on end wall?

AR67GTX

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Anyone with a stock Hemi street intake ever measure their end wall gasket clearance when changing gaskets or cams? Sitting loose on .062” side gaskets, my front is measuring .130” to .0135” range. Hard to measure the back but seems pretty similar. From the positioning of the gaskets on the head with studs holding it and on the intake and with the intake on the engine, port and bolt alignment seem to be pretty good. Breakdown for any machine work is not in my immediate plans.

Trying to figure out my best bet for getting the 1/8”(+) end wall gaps to seal. Are the end wall gasket pieces with the Fel Pro 1234 gasket set that thick?

I’m thinking the problem I had sealing with RTV may be due to out of date stuff - but not sure.
 

PasiR

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.130 is not bad gap at all. I always use there a sealer called Right Stuff, never gasket.
 

Beekeeper

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Yep delete the gasket and use permatex ultra grey or right stuff on it.
 

AR67GTX

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Well, the reason I’m asking is I had a ultra grey failure. After an engine start after about 28 hours of curing I had an oil leak an when I pulled the intake again about 50+ hours after, I found only the outside of the RTV had cured. Inside it was like it just came out of the tube - just no cure at all.

I thought it might be out of date RTV but date is the middle of last summer (or 2011 but I doubt that). I have a fresh tube of black Right Stuff but I’m leery of it now As the most recent date I could find in the stores was last July. I made 4 test pieces up (2 ultra grey and two right stuff) sandwiched between bars of aluminum and will watch to see if they actually cure out after 48 hours. But would almost trust an end wall gasket more right now, but the gasket would need to be .180” thick to seal up with 40% compression. Are they that thick in the FelPro gasket kit?
 

6PKRTSE

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The tubes do have expiration dates on them. We received a bad (expired) batch direct from loctite before and it did the same as you described. We had to reseal numerous engines once we learned about the issue after dyno.
 

AR67GTX

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From what I gathered off the web, the number etched on the bottom of the tube - the first numeral is the year of manufacture - ie, a 2 is 2022, 3 is 2023. I hope nothing as old as 2012 or 2013 is out there. The next letter is the month with A being Jan. Permatex recommends a 2 year shelf life but that seems optimistic to me based on my experience. I went to 3 stores this morning and couldn’t find anything more recent than June/ July on the shelves. I also found some 2021 stuff on the shelves.
 

pnora

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I will tell you this. That is a big gap to bridge so you need a big high bead. Guide pins are a must. Surface must be clean. I use brake clean. No contaminants. Oil can not drip off the manifold onto the silicone. This can happen if the intake has been upside down. I flip it over and wash it down good. Simple test with the silicone you think failed. Run a 1/4 inch bead an inch long and let it sit overnight. It should be pretty solid.
 

AR67GTX

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I’m going to let my 4 test strips I discussed in post 5 above, cure 48 hours and then cut in to them to see if they have cured out. Odd thing, I started the motor after letting it sit for 26-28 hours and ran the motor for 15 minutes +/-, water was up to temperature. And another 24 + hours later when I pulled the intake off, that RTV inside was as fresh as if I just squeezed it out of the tube. I would have thought the engine heat would have helped kick it off and cure it, room temperature or not.
 

Fran Blacker

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Front of my intake gasket it's blue . chrome is coil bracket left thrermo bolt blue of gasket comes out of head of thermo bolt.
IMG_2235.JPG
 

AR67GTX

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Yeah, looks fairly thick compared to the thermostat gasket.
 

dvw

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Well, the reason I’m asking is I had a ultra grey failure. After an engine start after about 28 hours of curing I had an oil leak an when I pulled the intake again about 50+ hours after, I found only the outside of the RTV had cured. Inside it was like it just came out of the tube - just no cure at all.

I thought it might be out of date RTV but date is the middle of last summer (or 2011 but I doubt that). I have a fresh tube of black Right Stuff but I’m leery of it now As the most recent date I could find in the stores was last July. I made 4 test pieces up (2 ultra grey and two right stuff) sandwiched between bars of aluminum and will watch to see if they actually cure out after 48 hours. But would almost trust an end wall gasket more right now, but the gasket would need to be .180” thick to seal up with 40% compression. Are they that thick in the FelPro gasket kit?
The leak failure wasn't from the center being soft. It was from the RTV not adhereing to the metal itself. How do you know if the metal is clean enough? Wipe a very thin layer of RTV on all the metal surfaces first. It should spread smooth and thin adhering to the metal. If it rolls off or there are bare spots it's not clean. Then apply your bead and assemble. Letting it skin gives it less chance to adhere. I learned this early on as a dealer tech. Early GM sealer was the worst. The stuff leaked right out of the factory. If we repaired it and it came back, it was a freebe on us. Working flat rate you make sure any job that leaves has the best chance of zero failure. To be honest most any quality RTV will work. The difference is down the road how well it holds up. I'm telling you from experience, taking a part off thats been sealed with Ultra Grey a year or two later is tough. I could pull all the bolts out of the oil pan on my racecar and it wouldn't fall off or leak. The stuff is that stout. I worked in auto repair over 45 years. still building hot rods. I've used the mopar black as well. Worked at Chrysler Engineering my last 10 years. So it was readily available. I still liked Ultra Grey better. Which ever sealer you use the clean and wipe method will provide a good seal. Good luck.
Doug
 

AR67GTX

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I appreciate your earnest advice and I know you know your stuff but I‘m still skeptical. It could have been compromised by poor adherence - I cleaned 20 times if once with Prep Sol and denatured alcohol. Now I’m skeptical of the denatured alcohol as I’ve never used it before and I’m noticing masking tape doesn’t adhere as well to a surface cleaned with it it does to one cleaned with lacquer thinner or acetone. I wouldn’t have suspected it, but it may leave some sort of film on the surface. Next time I’ll wipe down good with brake cleaner.

But today I cut open one of my test coupons I made 48 hours ago with Right Stuff and it was cured right at the contact point with the aluminum and maybe 1/8” thick on the exposed surface, but the entire center was as fresh as when it came out of the tube. Sort of like a chocolate with a marshmallow center. I’m having a hard time accepting that. How damn long does it take this stuff to thoroughly cure out? At least with a gasket I know I’ll have something solid in there.
 

AR67GTX

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I’m really torn on this. Pulling a Hemi intake isn’t the worst job in the world but it is a pain to do over and over. I may give the Right Stuff a try with the shields I made. If I do, I’m not starting it up for at least a week.
 

Dragon Slayer

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I am sure everyone has an opinion on this, but old super stock racer who still builds motors. If gap is big and your not going to machine, would glued down the included gasket to the wall. Then use RTV on top to seal to the manifold. Glue intake gasket to head also.
 

AR67GTX

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I opened up one of my test samples of Ultra Grey at 96 hours and it was cured about 1/4” deep around the perimeter and just goo on the inside. Since the end wall gasket seals are about 1/2 - 5/8” wide, the RTV may be pretty much cured after 4 to 5 days so I’ll probably give it that long before starting the motor.

FCCE795F-62C5-4727-AE95-55E6543CB762.jpeg
 

AR67GTX

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Well, I wimped out. After cutting the rest of my samples open at 96 hours and finding the same thing as above, I went with the Fel Pro cork end gaskets. Used RTV on the ends and applied Permatex gasket sealer to gasket and metal surfaces and dropped the manifold on it. Also put end wall shield plates I fabricated on to minimize oil spray on the joint areas. The more I thought about trying to separate Right Stuff and cleanup if it leaked again, the less I liked the idea. Stuck with what I’m comfortable with. We have crappy weather now so may be a few days before it gets tested.
 

AR67GTX

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So far I think my intake joints are staying dry. It took about 2 weeks of daily retorquing the bolts before they finally stabilized. So the rear of the engine finally seems dry as does the bell housing and transmission. Last drive included a pretty much full bore blast in first to a little past 5,000. When I got underneath later I noticed a faint, thin trail from the front of the pan and a drop on the bottom of the sump. First time I’ve seen this. Can‘t find anything wet up front and pan gaskets seems tight - hard to see around the K- frame and pulleys, balancer, etc. Could be the front seal or timing case gasket but it’s pretty minor so unless I find something definitely leaking, I guess I’m good for now.
 

Fran Blacker

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So far I think my intake joints are staying dry. It took about 2 weeks of daily retorquing the bolts before they finally stabilized. So the rear of the engine finally seems dry as does the bell housing and transmission. Last drive included a pretty much full bore blast in first to a little past 5,000. When I got underneath later I noticed a faint, thin trail from the front of the pan and a drop on the bottom of the sump. First time I’ve seen this. Can‘t find anything wet up front and pan gaskets seems tight - hard to see around the K- frame and pulleys, balancer, etc. Could be the front seal or timing case gasket but it’s pretty minor so unless I find something definitely leaking, I guess I’m good for now.
The tighten process crossram manifolds is needed.
 
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