Edelbrock xc-8! tips and tricks to a crossram.

Wow that's a nice camaro, especially a original z/28 my dad has a 68 its in pieces right now, just received new quarters, roof, doors, fenders.

 

I don't know how much difference it makes to tuning, but the Edelbrock xc-8 separates both cylinder banks completely.
There's no connection between the right and left plenums on the xc-8, while the Chevy "Crossram" uses a common plenum shared by both carbs.

 

Oh yes that right, ive that's the reason the xc-8 and similar cross rams weren't that great of a design.

 

I was told they runners were so long they had problems with the fuel droplets falling out of suspension which would explain the flooding and backfires. I did have a friend in high school with a 454 and a cross ram. He had it running on propane though and it ran like a champ. Drove it like that for several years as his daily driver, we went on trips in it, it was cool as shit.

 

I believe that what the previous poster meant by limiting backfires with a starter button was simply clearing the cars throat a bit and having it spinning over fast before giving it fire. A lot of advance and a balky start with a regular key setup could give you a backfire.
I don't think he meant the intake was worse for creating backfires...just dangerous if it did backfire due to the large plenum volumes.

 

Yes, that's what I was trying to say...

 

Hmmm ok i understand what you are saying, interesting, as for performance this intake wants high rpms right? my engine wont see past 6500 rpms its a stock 350 bottom end.

 

I have an X-C8 on my 350 SBC and have had it on various SBC's since 1971 when I bought it on trade for my '58 'Vette injection. Like one of the guys said, MATCH THE CARBS. I bought two from the local NAPA guy way back then, and didn't figure out why it was so antsy until I discovered much later one that one was a 118 venturi, and the other was a 108. Now I have 2 holley 600's dialed down and it was and will be a lot of fun. I am still in the process of dialing this 350 in (forged 10:1 domes, Crane, Strange 3:91 dodge, M20.) I've used this combination before with a 327 punched 10 over, and it was a blast to drive light-to-light on the street. (We did a lot of that in the 60's and 70's) With this newer 350 setup, I want to keep my Corvette signature covers, so I have been reading about venting the covers without damaging the original '60 chevy take-offs I got from my older brother back in '69. Dialing this combination is key and takes time, but it is worth it. It fills my engine bay and is very impressive for a carb'ed engine.

 

The 400 will use more air so the power band should come down some, any one running one on a big inch small block?

 

Chubs was last seen about 5 years ago. I hope he got it together by now.

 

I hope so too, but I thought I'd throw my two cents in just in case anyone else needed to hear about someone who has real life exposure to the XC-8 manifold.

 

Yep, the XC-8 and other two separate plenum cross-rams badly need some sort of fabricated plenum connection passage to help equalize pulses. It can be a full aluminum fabbed and welded passage, or as simple as a couple of 1-3/4 to 2" tube stubs welded on and reinforced radiator type hose connecting the plenums.

The Chevy Z28 factory deal and the Mickey Thompson Cross-Ram are the only two I've seen that address this in their design.

In it's current form, it turns the engine into two completely separate, non-even firing pulse 4 cylinder engines in one block, and that's the root of the problem.

You could search crossram threads, there is a post here on the HAMB somewhere of a member doing the fabbed plenum connection deal...might have been the BBC version(tech info still applys though) ….might have been over at SpeedTalk engine forum where I saw it recently too

 

Building a 400 sbc with a x-c8 on the top for my fiat with a pair of 450 holleys with vac secondarys...had a x-c96 experimental unit on top of my 62 nova 427 Chevy..40 + years ago... Pic of 400 on stand collecting parts..also a set of hooker headers to cut up..gonna be funny in the fiat i hope it was a blast..hopefully i can get the sbc version under control...