The Stovebolt Site Forums The Shop Area The HiPo Shop Block huggers on an SBC.

During my recent rebuild following a fender bender I decided to replace the header gaskets on my '50 while the front clip was off.
They're generic block huggers,i'm not even sure what make.
Long story short,they now leak even worse than before!

All the flanges and cylinder head ports were thoroughly cleaned,new Fel-pro gaskets fitted (dry) and all header bolts were evenly torqued.

Buying new,better quality headers is NOT an option at the moment.
Or fitting an original Stovebolt motor for that matter....

Question: Can any of you recommend a high temp sealant that I can use or would basic exhaust assembly paste suffice?
Suggestions/advice please....
Thanks.

I would bolt the manifold on without the gasket and check out where the gaps/high spots are. A feeler gauge works well for this.
Carl

Unless the header flanges are at least 3/8" thick (1/2" is better) leaky header gaskets are simply a fact of life. At full throttle the temperature of the exhaust gas leaving the cylinder head can be as much as 2,000 degrees F. There's a reason factory exhaust manifolds are made of thick cast iron. 30-something years of building race engines has taught me that there is no magic sealer that will prevent header leaks- - - -just keep a good stock of gaskets on hand and change them frequently. Some people use two gaskets stacked on top of each other to help seal slightly warped flanges.
Jerry

I used to have a lot of problems with manifold gaskets on 292 6 cyls. in step vans. I used Permatex copper RTV. on them It worked real good.

It is also worth noting the port shape and size. I have seen cheap headers with round header tubes that won't seal too well on rectangle head ports! (expensive ones too for that matter!).

You might check the port size and shape on both heads and headers (using the gaskets) and see how much gasket material is actually hitting both the heads and the headers, you might be surprised how little surface area on your headers actually mates up with the surface of the heads! It is pretty easy to take a mig welder to the headers and add more material where it would hit the gaskets so you have more surface area contact. (you will of course need to grind/file it flat again)

Simple solution- - - - - -find a set of ram's horn exhaust manifolds and toss those headers as far into the nearest scrap iron heap as you can fling them!

The only time I've ever seen headers outperform ram's horns on the dyno has been at full throttle above 4500 RPM- - - -something you're not likely to see very often.
Jerry

I glossed right over the "header" part of the original post.
I have to now agree with HRL and chuck them for ram's horns. They look cooler anyway.
Carl

Thanks Jerry I can always rely on you for straight to the point advice,you're not the first person to suggest this solution.
That's something I will consider in the future,right now my financial status won't allow the purchase of such things,there's also the availability problem here even second hand.
There's also the alteration to the actual exhaust downpipes to mate up with them to consider or are the collectors normally in the same position for huggers?
If so that simplifies the problem greatly.

I DO like the o/a look of Ramshorns and i'm pretty sure GM did many,many hours R&D to develop them to work well too,function rather than form is more important to me right now.

Look and no doubt run cooler too.
Thanks Carl.

Thanks,I picked some up yesterday and will give it a try,I do realise it's like wallpapering over cracks but if it works,it'll do meantime.

One solution I used many many years ago was: purchase 2 of the thin metal type gaskets and a thicker fibre gasket. Make a gasket sandwich along with some copper coat sealant. Torque it good and go for it. Hope you can find a solution cause leaky headers don't sound cool.

Me too,just spent another 4 pointless hours bustin' knuckles etc and they still leak!

I've got the feelers out for a set of Rams horns as Jerry suggested.

It's been off the road since Christmas eve,I finally got all the damage repaired and get everything buttoned up and now this....
The worst part is I can't just pop round to the FLAPS and buy more gaskets...

You're right about the sound too.....it's embarrassing.

jockbolter50,

I have always had GREAT performance out of "Percy's" header gaskets. These are guaranteed not to leak. When I couldn't get the standard header gasket not to leak, the Percy gaskets saved the day!! They are a little pricey, but they pay for themselves in the long run. Got mine from Summit Racing. I also suggest the "dead soft" aluminum collector gaskets. Once tightened they form and you start the engine to get the header hot,, re-tighten and they won't leak either. Hope this helps!

Tim

Thanks for your input Tim,my problem seems to be the actual headers,not so much the gaskets.
I may have found a pair of cast manifolds local to me,well... 80 miles away.
Still a wee bit closer than you guys....

I'm just waiting on confirmation that they will actually fit my engine.

I'll certainly keep those Percys gaskets in mind though.

Jockbolter, I don't know if you are running a generator or alternator. If you are running a generator, the manifolds in the photo will work for you.

Thanks for the additional info,I have had it on good authority they will work in my instance,if I have to do some clearancing/grinding work to the cast bosses then so be it....

The alternator mount i'm currently running is a cast alloy 'vette C3 one mounted to the left hand drivers side head as seen from the pilots seat.
I'm also praying they will be a direct interchange without any radical exhaust work...the headers were fitted and mounted to the original '81 C3 donor cars exhaust so i'm hoping my stainless exhaust will do the same.

Function rather than form is more important for me right now.
My truck's a driver not a show queen....

This true, they're just for looks. Most of these trucks will never see the advantage of a set of headers. That being said, I run equal length headers and doubled up my gaskets, crappy flanges seal like crap...

Well look who's back. About time you woke up from your nap. Good to see you posting again.

Yeah,i've been informed they don't usually come into their own until around 4500rpm and higher.

Good for smoky rolling burnouts then?

Until the pump seal goes kaboom. Pm me and I'll send you a video.

Ballooned torque converters are a definite possibility, also!
Jerry

Got to get myself a 'proper' trans with a clutch, 5 or 6 cogs and get my three pedals back....

I'll be picking up my 'new' cast headers tomorrow so i'm looking forward to a quieter and fume free future.....

On an extended drive yesterday I got a fuzzy head and stinging eyes....not good!

Could that possibly be a case of "single malt syndrome"?
Jerry

Sadly no Jerry,carbon monoxide syndrome unfortunately!
Hopefully these will cure the problem.
The heat riser assembly on the right was fubar so i've removed the inner heat tube and plugged the holes,I also removed the cast generator boss on the left hand one as it would interfere with the alternator on mine.
Gave them a slathering of POR-20 VHT paint,they'll not win any prizes but as I said before function rather than form is more important to me.
As you mentioned i'll need to have the downpipes modified,i'll be seeing my exhaust guy today.

I don't know what the ports on your 350 look like, but I'm using an Earl's pressure master gasket on my 383 (cylinder head exhaust port is traditional 23 degree square port Air flow Research / Brownfield Racing). The pressure master gasket is an aluminum frame with a graphite impregnated steel insert. I have never had a leak with these gaskets. And up until I changed starters, my full length headers touched the starter housing. So I never knew if that caused an excessive gap.

Jockbolter....what did you use to plug the holes on that heat riser?

I ran a 9mm drill through it and tapped it out for a 10mm x 1.25 socket capped stainless bolt,simply because that's what I had to hand,I used a smear of assembly paste and screwed it in.
I still haven't installed the headers as I need to change the exhaust downpipe flanges.
I just haven't had time to get it to my exhaust guy to have the pipes done.
As yet I have no comments on if it works or not.....time will tell.

Are you referring to the piece of tubing that goes through the passenger's side manifold at approximately a 45 degree angle? That was intended to be an air passage for the choke heater on an automatic choke carburetor. The heat riser passages go through the cylinder heads and intake manifold. Unless you have the add-on flapper valve in one of the outlets, there's very little flow through those passages, and virtually no carburetor heating during warmup.
Jerry

Jerry, any I've seen have the heat riser (flapper) on the driver's side. On my one car I bought a cheap spacer off eBay to replace it, and it works great. Without that there's no taper on the bottom for your donut to seat into.

Looks like he plugged the little hole you're talking about as well, though.

Jock, I love your truck, I noticed in your album you had previous replaced exhaust type stuff or has your album been updated..

love seeing that you drive this baby

Jerry the butterfly assembly was fubar and had been previously removed/butchered so I also removed the riser pipe and as you saw plugged the holes,i'm running an Edelbrock 1406 4bbl with electric choke and have never had any issues without preheat,even down as low as the mid 20s degrees.
It was simply an easier option for me than trying to find a functioning set up here in Blighty.

Thanks Fred,you've most likely noticed the title of that picture is "Daily,not seasonal".
The previous exhaust mods were to realign the silencers for clearance when I changed out the rear suspension.

Regarding the daily driver status to be honest my hand was forced due to redundancy (it was never my intention) so lacking the funds to buy a daily hack,the old truck was pressed into action.
I'm commonly known as the dude with the old 'Yankee' truck round these parts now.......it does tend to get you noticed!