460 Header Gasket

[PurpleVenom]

I have a header gasket leak on #8. Need to replace the gasket, but not sure what port size to get for the Cobra Jet Heads that are installed. Here are my choices (from Summit Racing):

http://summitracing.com/parts.aspx?sku=PHP-66035

http://summitracing.com/parts.aspx?sku=MRG-5954

http://summitracing.com/parts.aspx?sku=SUM-111436

http://summitracing.com/parts.aspx?sku=FPP-1420

Thoughts/suggestions?

[xlr8or]

Get the copper ones. They will leak the least.

[Silverback51]

Originally Posted by xlr8or

Get the copper ones. They will leak the least.

I agree. I ran it through a heat cycle and went to retighten the bolts and they were still tight. I have close to 2500 miles on the gaskets and have checked the bolts 3 times. Always tight.

[kitcarbp]

I went to the source, I contacted the 460 SCJ crate engine head designer (Jon Kaase) for my SCJ head from Ford racing and he confirmed they use FEL-PRO # 1420 on their racing engines. I confirmed they match the ports nicely on mine. I decided to use ARP stainless studs for all but one fastening point on each side (due to clearance). I can't comment on leaks, I am still in build mode. Leak potential will depend on so many factors such as: flange material, flatness & thickness and then the stress/load the side pipe movement places on the entire 16 bolt flange which will depend on how the side-pipes join the header collector (slip joint, flange joint etc.) and how the side pipes are hung/supported from the chassis.

[PurpleVenom]

Thanks, I had ordered the 1420 prior to your post kcb, looks like I will be ok, however, I am going to check torque on my bolts first.

[Garage10]

Kitcarb
Did you buy the SS headers and sidepipes from WCC ? If so, did you check to see how large an opening the headers have where they fit to the heads ? do they have any restriction ?
Thanks
Brent

[PurpleVenom]

Pulled the header last night and have confirmed that with the COBRA JET heads the FPP-1420 is the correct gasket. Now, there may be others with the same port measurements of 2.35" Tall x 1.55" which I'm sure there are many. The 1420 is what I will be using on my application. The old one was leaking on #8 and appears the gasket had hardened to a point of cracking. I recently had a dyno tune done, wonder if the added horsepower/dyno had anything to do with this gasket failure as it wasn't there prior to the dyno tune.

[kitcarbp]

Purplevenom,

Hard to say why #8 leaked, dyno tuning and the higher exhaust temps likely accelerated the failure, not sure how many hours on your rig but, max power will test your exhaust joint for sure, thats where oems test exhaust manifold joint designs, at max power for hundreds of hours. A good exhaust joint will outlast ( no leaks or bolt torque loss) the engine on a 400 hour durability test. #8 was gonna leak eventually, your dyno session made it happen sooner.

Brent,
I checked my header joint condition using feeler gauges without a gasket first to find the lows and highs of the flange/head face when cinched up to torque. Mine are far from perfect. Mine is a WCC. Each side had one port that had .035" gap, so that port was tightened last during header install and checked with a feeler gauge to confirm no-gap. Yes there is restriction, but I wont notice this on the street, mufflers are the low hanging fruit to pick up easy HPs you can notice. I really need to have new custom header flanges cut with a better alloy steel to better match my port dimensions and that distorts less during welding. Another question for JK Racing, he most likely makes his own flanges. It appears my header flanges were made for std 429 CJ ports or other and do not match the Jon Kaase SCJ head exactly. Another optimization project down the road.