I have got square port heads and I think the Flowtech headers are round (Not sure...?).
Do I have to use gaskets with round or square holes?
Do I best use some sealant to prevent leaks? Which is the best?

 

For the most part as long as the header openings are bigger than the head port openings you'll be OK. Gaskets....everyone seems to have their favorite, as long as you get a good seal it doesn't matter if they're square or round. Most people do NOT use sealant, There are few tricks to get a good seal...good bolts, retorqueing, special cuts on the header flanges etc....

 

Thanks for the info.
Do you know of some good gaskets for headers and collector? Maybe Mr; Gasket or Percy's
I'm not a drag racer...
I have the original heads on my L48.

 

I did a search some time back on Summit Racing to determine the difference between a $20 header gasket and a $40 set. The cheaper units are usually a fiber board material. Some of those will eventually burn through. Then I found Percys aluminum flange gaskets. When the package arrived from Summit it appeared that they sent too many. I believe I counted 16 layers which are to be separated into one pair of 8 layers each header. They crush down nicely, are re-usable, can not burn through and conform to rough surface flanges. A little pricey, but a excellent product.
On the collector gasket itself, if either flange is rough, some use copper, some use the fiber Mr. Gasket pcs.

Gaskets should be ordered by the exhaust port shape on the head, not the shape of the header tubes. No sealant is needed, use good 12 point bolts w/ washer and re-torque after several heat cycles.

The special relief cuts Jim refers to are needed in extreme cases where the header refuses to seat tightly against the head. This is usually due to old warpage from extreme heat rather than poor manufacturing. The cut is done on the "backside" of the header flange so as not to be exposed to the eye. The cut barely is half the thickness of the flange, known as a kerf and can be done with a hacksaw. One kerf goes between cyl 1 & 3. The other goes between 5 & 7. Then do the other side if necessary. This relief cut allows the warped flange to twist ever so slightly to get a good seal.

 

 

Ok, I want to spent about 30 dollars on gaskets in TOTAL.
Will I need 'stock port' or 'square port' gaskets.
https://www.summitracing.com/parts/fel-1405
https://www.summitracing.com/parts/fel-1444

What about these collector gaskets?
https://www.summitracing.com/parts/php-66002

What brackets will I need? I have A/C, powersteering. Will I also need a bracket for the alternator?

What stainless steel bolrs do you prefer for headers? ARP?
​​​​​​

 

$30 is a little short for quality, but hey . . . . the Percys are $38?

Stock port will work.
None of those links go directly to Summit.
If you have A/C I believe you will need just one long header bolt with spacer up front for your existing bracket.
P.S. is not involved with headers.
ALT is not involved with headers.
ARP bolts are top-of-the-line, come with a built in washer. Order SBC "header" bolts and they will be the correct length. 12 point is easier to torque, your choice of black or stainless.

 

I only could find the Percy's 66012.
https://www.summitracing.com/int/par...reviews?page=2
It is for 'square ports'. Wil they work or are these square holes to big for the stock heads?

The Percy's 66120 are supposed to fit the 'stock ports' but the strange thing is they are round... they also get overal bad reviews.

Also found these ARP (12-point) bolts 400-1201
https://www.summitracing.com/int/par...make/chevrolet

 

Fel Pro 1444.

Jebby

 

I have not read through all the comments but the easiest, most sure fire way to make sure header gaskets do not leak or burn through is to double up on each side with a quality gaskets (Felpro^^^^^^^). I am sure some of the suggestions will work if you have leaks from warping such as grinding, cutting the flange, Percy's and others, single gasket with RTV sealant BUT the simplest method that I KNOW works on badly warped headers that I have used on 2 different sets of gasket on 2 different cars (C3/Mustang GT) is:

Buy 2 sets of Felpro blue Header Gaskets for your headers-About $15-18 per set depending on Gasket type-which hits your $30 target solution

Put 2 gaskets together with red High temp RTV and clamp them until dry..

Both sides with double gaskets

Install as usual and normal. NO OTHER SPECIAL procedure required.

NO LEAKS for years now on the 2 sets of badly warped headers........This method is cost effective and works..........

 

Any suggestion for collector gaskets?

 

I believe you are not using the Summit part search correctly. Under "gaskets" , then engine gaskets, then exhaust, then header / manifold. Enter SBC first generation or year make, model.
Percys 66011 is $28 a pr. and received 4.5 star rating. Aluminum, sq port, will work for you. I doubt Percys ever received a bad review but maybe.

The 12-point ARP bolts makes it easier to get a box-end wrench in there and torque it. Just make sure the bolts are for headers. Should be 12 in a pack. You won't have to worry about snapping off an ARP, super strong.

 

I have LTH headers on my C3 now from XSpower and used the hooker collector gaskets . I have no leaks from the collectors.

BTW-I did try Percy's on the Shorty warped BBK shorty headers on my 5.0 V8 mustang, and the Percys did NOT seal the headers which are/were warped. Only The Felpro double gasket method worked and solved the problem.......

 

Thank you all guys for the info! My list is almost finished.
I still need two things:
-Brackets (???) or one 'longer bolt' for A/C: How much longer? Or are the ARP's long enough to get the spacer(s) in between?
-Collector gaskets

 

Where the collector flanges on you Flowtech 31106flts welded in place or where they movable?
Can't find anything on Summit's item discription about this.

 

For the A/C bracket that would normally be bolted to the exhaust manifold, you might be able to re-use that one bolt. I believe it was close to two inches.
(Header bolts are around 3/4") I had a steel tube for a spacer and maybe the spacer was 1 3/4" long. Don't remember, my A/C is dismantled.

 

Novusuhu - I cut off the regular header flanges and welded on some of these.... they've been fantastic. A bit expensive but it eliminated that annoying gasket at the collector and actually gives more room between the exhaust collector and the road since there is no "flange" sticking away from the exhaust pipe.
https://www.summitracing.com/search/...s?autoview=SKU

 

I'm going to buy an extra set of bolts for the use of one longer bolt.
What is a cheaper but still good quality brand other than ARP. ARP is too expensive when you only need one bolt from the set.

 

I think I just go with the use of collector gaskets and see how that works out for me.
Any suggestions on collector gaskets?

 

I purchased the bolt and spacer for my headers from Corvette Central for my AC bracket. Search for Air conditioning compressor mount bolt and for Air conditioning compressor bracket spacer. Cost will be less than $20.00 for both before shipping.