venting... Vortec intake gasket failure !!

[ChrisWhewell]

Put vortec heads on my '67 last August. Been running it since then but on the highway a week ago I look in the mirror and I'm trailing a huge bog of smoke. So I'm thinking.... @#$@! oil ring is shot. Plug in #5 hole is all fouled up, but it turns out... of all things.... its an intake gasket leak. I started the motor and pulled the pcv valve and oil breather, and sure enough, a vacuum is developing in the engine. That explains why blue smoke only at higher rpms.

Well, I'm no novice at motors and never ever had an intake manifold leak on me. I used Edelbrock manifold 2116 and Edelbrock gasket set 7235, thinking all would be fine, cuz we sent a man to the moon and gasket stuff is easy.... right.

So, I could put back in another set of 7235's but the epitome' of stupidity is doing the same thing twice and expecting a different result, so I'm looking for options as far as intake gaskets. I'd like to re-use the brand new 2116 manifold I just bought in the summer, so it looks like the only gasket choice I have are:

1) Fel-Pro 1255's
2) GM 12529094; or
3) the ones included with the Fel-pro whole upper kit 98000T and use only the intakes from it and don't use all the other stuff in that kit.

I'm hesitant to use the GM's, cuz lots of folks claim when they tear motors apart, the plastic's always broken on those (overtightening or can't take the heat cycling). Plus GM had dexcool problems and their gasket re-design may have been motivated from that snafu and not necessarily sealing issues.

I guess its gonna be Fel-pro this or that, unless one of you all know of a better option perhaps....... Grr, my beast was running so nicely. Well, at least I don't have to do bottom end work on oil rings, so I'm kind of celebrating. Any and all gasket suggestions welcomed.....

[hugger6933]

I'd say run the GM intake gasketsand I know you are hesitant to do so but I feel they are the best choice. I have them on my Vortec headed small block and have had no problems. Since you are having sealing problems[are you having sealing problems or blowing them out?]you might want to consider the factory type intake manifold GM bolts,with the half ball shape on them under the head. The engineers put that there for a reason other than a conversasion piece.Also the torque settine on the intake is really something to watcxh for as well I weas told to pay really close attention to that when I installed my Elderbrock RPMAirgap on my motor. I think the setting is like[now this is from memory from like 7 or 8 years back] 12 to 14 inch pounds yes, inch pounds. I know I know, it does'nt sound right to me either so lookit upto be sure. Jim

[ChrisWhewell]

Originally Posted by hugger6933

I'd say run the GM intake gasketsand I know you are hesitant to do so but I feel they are the best choice. I have them on my Vortec headed small block and have had no problems. Since you are having sealing problems[are you having sealing problems or blowing them out?]you might want to consider the factory type intake manifold GM bolts,with the half ball shape on them under the head. The engineers put that there for a reason other than a conversasion piece.Also the torque settine on the intake is really something to watcxh for as well I weas told to pay really close attention to that when I installed my Elderbrock RPMAirgap on my motor. I think the setting is like[now this is from memory from like 7 or 8 years back] 12 to 14 inch pounds yes, inch pounds. I know I know, it does'nt sound right to me either so lookit upto be sure. Jim

Yeah, like 11 ft. lbs. What I didn't do is re-torque them after initial install. After the leak out of curiousity I put the Tq wrench on them and they needed a little twist to get back to 11, it could just be they need re-torque, which I didn't do.

Yep, I'm familiar with the GM bolts and the theory behind not bottoming out, but those bolts are designed for a GM manifold an unfortunately I don't have a GM manifold, rather, an Edelbrock that's supposedly made for the application. The balls on the end of the GM bolts ? Could be good but I don't know how the dimensions of the bolt boss's on the Edel compare to the GM ones so not sure the GM bolts with the balls on the end would achieve their effect. I may go with the GM's gaskets though, since its my understanding they have some kind of locator pins in them which is a good idea, and then just torque them to my heart's desire. I have a better feel than most for torquing evenly , once did heads on a 350 w/o a Tq wrench (!) and it was still strong 80k miles later when I sold it, lol. Haven't pulled the manifold yet though, still celebrating not having oil ring issues. Yee haw !!!!!

[clinebarger]

Fel-Pro MS98000T, Dont worry about the extra gaskets...Your paying for good intake gaskets.

[Lee H]

Yup, I'm on the second set of vortec gaskets in less than 10k miles.
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[oldblue1968chevy]

9800 felpro is what ive used twice now. no problems

[airdale94]

I would have your intake manifold surfaced. I've seen new Edlebrock manifolds need as much .060" machined off of them to get them flat.

[Bob B.]

Originally Posted by clinebarger

Fel-Pro MS98000T, Dont worry about the extra gaskets...Your paying for good intake gaskets.

I have worked on a lot of '96-'00 Vortec 5.0L and 5.7L's. The Fel-Pro MS98000T gaskets are the the best, no question. They are silicone with a metal spine and have torque limiting washers around the bolt holes.

[ChrisWhewell]

Clinebarger & Bob B. -- just bought the MS 98000 T , Advance Auto had them in stock.

I'll pull the intake and see the mode of failure. Hopefully I won't have to machine the intake as airdale94 suggests might be necessary.


My ole '67 seems like almost as fast off the line as my 454SS p/u was, headin to pull the manifold now.

Have a great day guys (and gals)......

[jaros44sr]

Vortecs also suggest three steps of torque, three to four in/lbs apart...something like 5, 8,11in./ lbs

I can measure my gm intake bolt holes, its not fully installed, just the four oem fastners in the corners. If this would help.....

Dont forget the thread sealer on the thru bolts

[ChrisWhewell]

yeah, I went in three steps like that - the instructions said so but I do that as a matter of habit on anything, even when changing tires.

Hey jaros44sr, don't bother. I'm gonna try these 98000 t gaskets from Fel-pro. If it fks up again, I'll buy the GM manifold.

[jaros44sr]

Originally Posted by ChrisWhewell

yeah, I went in three steps like that - the instructions said so but I do that as a matter of habit on anything, even when changing tires.

Hey jaros44sr, don't bother. I'm gonna try these 98000 t gaskets from Fel-pro. If it fks up again, I'll buy the GM manifold.

Post back when you get a result, ill be heading down your road on my scroggins dickey baseplate

[ChrisWhewell]

ok, will do.

Scoggin-Dickey vortec heads are a great value. On mine, I just had to do my own valve seat cutting just once in my life. Took me a long time b/c I wanted the seats perfect and at the right place on each valve. Plus I did it for myself. lol, what a way to burn my precious time, something must be wrong with me..... Oh well, it was a success. Too bad I trusted the danged Edelbrock manifold and gaskets , but I figured those guys would have their act together on this by now. I don't discount that maybe I did something wrong, but I seriously doubt I did since manifolds are relatively easy and I've done over 20 of em in the past.

[jaros44sr]

Originally Posted by ChrisWhewell

ok, will do.

Scoggin-Dickey vortec heads are a great value. On mine, I just had to do my own valve seat cutting just once in my life. Took me a long time b/c I wanted the seats perfect and at the right place on each valve. Plus I did it for myself. lol, what a way to burn my precious time, something must be wrong with me..... Oh well, it was a success. Too bad I trusted the danged Edelbrock manifold and gaskets , but I figured those guys would have their act together on this by now. I don't discount that maybe I did something wrong, but I seriously doubt I did since manifolds are relatively easy and I've done over 20 of em in the past.

Cool...
I bought the GMPP heads, cant believe they could stuff those valves in there. SD makes a TPI intake/baseplate that i am running, they then allowed edelbrock to make it as well.

Good luck

What carb are you running?

[ChrisWhewell]

Originally Posted by jaros44sr

Cool...
I bought the GMPP heads, cant believe they could stuff those valves in there. SD makes a TPI intake/baseplate that i am running, they then allowed edelbrock to make it as well.

Good luck

What carb are you running?

One of the best carbs ever built - Quadrajet !! Just have to get everything right on that carb, and start with one from a good year. Late 70's is best, mine's a carb # 17059520, orig equip on a '79 truck with a 454 in it, but was made in "emissions" years. So I went back to the charts of the muscle cars in the late 60's and looked at the metering rod diameter and jetting on the motors with the most advertised torque. On my carb it was kind of simple, I just upjetted it from a .072 jet to a .074 jet. Lucky the throttle bushings on mine werent wore out, most of the Qjets you see guys have them sitting on a bench on the throttle cam and most need to be re-bushed. There's a guy Cliff Ruggles in Mount Vernon Ohio who's pretty savvy on Q-jets. They're capable of accurate metering all across the rpm range which is a slight advantage over the holleys. But lots of people hate Q-jets, there's a learning curve.

[ChrisWhewell]

Originally Posted by jaros44sr

Cool...
I bought the GMPP heads, cant believe they could stuff those valves in there. SD makes a TPI intake/baseplate that i am running, they then allowed edelbrock to make it as well.

Good luck

What carb are you running?

Yeah I have a 93 vette with the LT1 heads which were the predecessor to the vortec's. the ports in the vortec heads are superior to those in the LT-1's, I had to do extensive re-work on the LT-1's (using David Vizard's wisdom) to get them to even be close to the vortec's.

One big area of improvement is the ridge around the valve seat where it meets the combustion chamber - on many production and aftermarket heads there's a noticeable ridge there, about 0.010" high that sort of fks low-lift flow. By making that a perfect transition, you pick up as much as 40 ft lbs of Tq. But its hard to get it all correct b/c if you remove the ridge before cutting the seat, you're going to have to remove the ridge again later after you make the top cut. So cut the seats first, then remove the ridge. I used a dremel carbide grinder, jeweler's headpiece magnifier, and a steady hand but got my transitions baby-ass smooth all the way around. Lots of rough surfaces in there, esp the spark plug thread area and those sharp areas are local spots that can get hot, trap hot carbon embers, and cause pre-ignition,
so I put in a plug on each cylinder then ground the excess spark plug hole threads that remained exposed so they were smoothed or gone. Smoothed other areas too, any rough areas in the chambers I smoothed. On a lot of those GM heads when they cut the valve seat there's a brow that's pretty sharp where the chamber meets the quench or flat larger part of the head. I smoothed that also. My pistons are flat-tops in my 350, with four eyebrow cutouts. Static compression measures exactly 10:1 on my gauge - yee haw !!!!! Just what I wanted. I run initial timing of 11 degrees on a GM HEI. 12 is too much. 11 is perfect. Cam is in my signature, its basically a no-overlap cam that gives me 21 inches of vacuum at idle and is ground for low-rpm torque. I live in the low rpm world 1800 - 4800 or so rpms. My wild guess on the Tq at my rear wheels is about 380 ft lbs. but I never dynoed it. Some sources suggest flywheel Tq can be as high as 450 ft-lbs with my setup. I'm not too much into numbers, just hauling a trailer and a tractor and my 67 is a friggin Champ at it !!! I can accelerate going uphill carrying a 93 olds cutlass supreme that weighs about 4500 pounds on my trailer that weighs about the same. Go team Chevy !!!!!

[jaros44sr]

Good info., sounds like you did your homework...youre far more advanced in your knowledge of head design than me, but maybe someday ill go down that road. Im just looking for good numbers in the low end torque

[ChrisWhewell]

You'll get it, those are great heads out of the box.

Just got all the bolts out of the manifold and all the other stuff out of the way. A smoke break, and then I'll go lift that manifold off.

[ChrisWhewell]

Failure mode was that the gasket had become buckled, enabling oil/vapor from crankcase to be sucked between the manifold and the gasket and into the #5 intake port. Center bolts in the manifold/head would have prevented this. Possibly a thinner gasket would have been better than Edelbrock 7235. My engine's nothign special, just a late 70's 350 chevy block with 062 vortec heads on it.

[ChrisWhewell]

Originally Posted by Bob B.

I have worked on a lot of '96-'00 Vortec 5.0L and 5.7L's. The Fel-Pro MS98000T gaskets are the the best, no question. They are silicone with a metal spine and have torque limiting washers around the bolt holes.

You're right. No question about it, much higher quality than Edelbrock 7235. Wish I'd have known that last summer when I put the motor together, cuz Edelbrock 7235 not only cost me to waste the money I spent on them, but also a sunny afternoon that I can never re-coup. Maybe Edelbrock ought consider hiring a gasket engineer from Fel-pro, as it stands I'm going to avoid anything that says Edelbrock on it.

[ChrisWhewell]

Originally Posted by airdale94

I would have your intake manifold surfaced. I've seen new Edlebrock manifolds need as much .060" machined off of them to get them flat.

Geesch, what did Edelbrock do ? Outsource its Quality Assurance department ??

0.060" to get them flat is absolutely unacceptable in this day and age of computer-controlled CNC, & cet.

In-house spec should be on the order of 0.010" at the most, I'd imagine. Oh well, I'm done venting now

Thanks everybody for your thoughts !!

[jaros44sr]

Originally Posted by ChrisWhewell

Geesch, what did Edelbrock do ? Outsource its Quality Assurance department ??

0.060" to get them flat is absolutely unacceptable in this day and age of computer-controlled CNC, & cet.

In-house spec should be on the order of 0.010" at the most, I'd imagine. Oh well, I'm done venting now

Thanks everybody for your thoughts !!

lmk, if you decide to change intakes, i have a new gmpp intake im not using

[ChrisWhewell]

In all fairness, I really have no qualms with Edelbrock. Vic is probably more than a heck of a Man, starting that company and all, keeping lots of folks working, doing their best. Vortec heads are a trick kind of swap I suppose and nobody's perfect - even GM did multiple gasket changes on vortecs. I bet the people at Edelbrock are top-notch, and sometimes issues can slip thru the cracks. Just wish I didn't have to burn a day re-doing the job. Live and learn. Peace.

[jaros44sr]

Originally Posted by ChrisWhewell

In all fairness, I really have no qualms with Edelbrock. Vic is probably more than a heck of a Man, starting that company and all, keeping lots of folks working, doing their best. Vortec heads are a trick kind of swap I suppose and nobody's perfect - even GM did multiple gasket changes on vortecs. I bet the people at Edelbrock are top-notch, and sometimes issues can slip thru the cracks. Just wish I didn't have to burn a day re-doing the job. Live and learn. Peace.

Just trying to give you an option.....i am using the gm gaskets, so well see how that works out. Plastic, dont think they will squish

[clinebarger]

Iron LT1 heads are almost identical to the Vortec port design, Though the aluminum head left alot to be desired.