Moparts Brain Trust,

I'm building a Magnum based 408 for my 73 Barracuda,using EQ heads (Hughes prepped). Compression will be right around 10.25:1, forged pistons, Hughes 3034 cam. Primarily a street engine, but Power Tour is on the calendar and I'll be sorting the car out at the drag strip and on a local circuit. I am compromising almost everywhere in favor of durability over power output.

Question on head gaskets. FelPro 1008 or Cometic CGT-C5916-036?

I've always had success with FelPro, and never used Cometic. But the cometic option is listed specifically for the EQ heads. It also has a 4.04 bore as opposed to 4.108 bore, and .036 compressed thickness instead of .039". Final finish bore is at 4.020"

Can anyone offer a compelling reason to spend 2x the cash on the Cometics? They are ostensibly designed/optimized for use with the EQ heads.

My assumption is that the top layer finish of the gasket is optimized for the modern cast iron and finish machining of the EQ heads.

I should add that this is my first build in a decade, and first ever doing anything but the getting the best power I could out of factory hardware, on a budget. My last setup was a 333ci 318 based, Erson hyd mid-range flat tappet and 302 heads with big valves and a fancy valve job, LD4B and an AFB. It peaked at ~240HP @ 5200 and 290ftlbs @4600 on a chassis dyno at 5280'.

Any advice appreciated.

Thanks
Chris

Dang, "brain trust" leaves me out...

Never had a problem with the 1008s (or BB 1009s) on alum heads, and Cometic's quality has a good reputation, but if there's some unique feature on EQs that only Cometic has addressed, I don't know.

So, a bump for the real guys.

Chris -- I'm a former Fel-Pro aftermarket engineer and was involved with the development of the 1008s, etc... my 340 engine was a test engine... lasted past 30+ years with the 1008s.. came off clean.. held 10.5 CR a-ok. The 1008s (as the balance of the wire-ring design FP race gaskets) are a high CR sealing design, typical from diesel designs that seal easily over 16-18-20+ CR. (and far superior to the standard 8553 FP passenger car head gaskets, for CR sealing and resistance to detonation/pre-ignition = burnout). The fiber-facing seals fluids much better than a metal-faced design (the metal faced design, such as the MLS gaskets in the marketplace, requires ultra-smooth surface finishes -- most machine shops cannot provide, or don't spend the time, to make that ultra-smooth surface finish).

For our old iron engines, even with optional aluminum heads, you can feel confident that the 1008s are excellent. The MLS gaskets are over-kill for most applications, pending the engine design. Save your $$ and use the 1008s... they are the only head gaskets I'd ever use on my SB mopar (likewise the 1009s for the BB).

Thanks Mitch! I was hoping to hear something along those lines. I'll stay with the 1008's.

Have you got the front end back under your T/A yet? Mine is all bolted up, just waiting to get over this winter crud and for some warm weather to get the bigger fuel pickup/line installed, new a/c condenser in and trans cooler fan mounted/wired, then it'll be a roller.

I used Cometic head gaskets on my 408, But, it was a supercharged motor. When the head gaskets blew due to bad timing/octane combination, the multi layers of the metal Cometic head gasket blew into my motor. That is the only bad thing about Cometics, if you blow a head gasket, pieces of the metal gasket will end up somewhere in your motor. Something to think about.....

Remember, the Magnum head is just a " touch" different than the old LA, but directly from EQ:



The production Magnum head gasket is a unique design, however the changes from the LA series are primarily to corral the pushrods into position during assembly. Regular LA engine gaskets can be used here.