The Stovebolt Site Forums The Shop Area The HiPo Shop Intake&Headers for 270

Ok my Clifford Intake has arrived. The "GMC" headers that I ordered arrived today. When I opened the box; inside was a paper taped to the inside lid. From "Patricks' ". If I had known they were coming from them I would have bought them directly instead of using "The Truck&car shop". What issues am I going to have with installing the headers? Paper talks about grinding in acouple of places for fitment. Also can/should I drive from my house to muffler shop or not? About 5 miles.
Thanks 4 the advice ,

They look like Chevy headers but they are "stamped" "GMC" in a small spot on each header. Are these Chevy headers that I am going to mod to make work with my 270??

Presumably, you have no manifolds now on your head?

If that is the case, see if the new intake lines-up/bolts-up properly on your head (with no exhaust manifolds/headers in place).

What exhaust manifolds/headers are you using? Do they mount up properly to the head (with no intake in place)?

If the intake and exhaust manifolds mount up OK, then you will have do whatever grinding needs to be done. Be careful.

I still have original intake exhaust on engine.

Was wanting advice before I take off the old to add the new...

so I need to check : Intake fit first. Then those headers , right

Well, you will have check fitment of the new components.

I have been able to do that on some sixes by unbolting the old intake/exhaust as a unit and moving it aside. Then, check the fitment of the new manifolds.

I can only really relay what I've been told about the reproduction Fentons. From what I was told, the headers are the same, the main difference from the originals being the rear header no longer having the heat riser cast to it, which required different castings for Chevrolet and GMC due to the length difference. I could be incorrect about that, I've never had the opportunity to compare a Chevy to GMC as far as port spacing goes.
Now, as far as the fitment and grinding mentioned, even the Chevy version requires some grinding to fit. Most of the grinding will be on the mounting tabs, as they need to ground to match whatever intake you're using. It's not really that bad to do. I ended up not only grinding the headers, but also made my own clamps out of 3/8" stainless, as the stock clamps did not really work all that well.

It does not matter which fitment you check first.

If they both can be attached separately, you then see if they attach together (this might be when/where the grinding begins).

BE CAREFUL - take off a little at a time - you do not want to grind through to an internal journal/passageway.

On 216/235/261 engines, the Offenhauser intake and Fenton headers had to be ground in order to be attached together (their bodies rubbed/interfered with each other).

That intake/exhaust interference grinding was in addition to the grinding needed for head-mounting clamps to line-up on both manifolds.

On a second installation, I ground the bolt-clamp faces (on one side of each clamp) to produce a tight head-mounting.

So I will be grinding where the "bolts" go ? Not sure I guess til I get the old outta the way ...

I bought the Fentons that had been "modified" to fit GMC heads. The only modification I could find was where they ground the flats to stamp 'GMC' on them.

Here's what I had to do to make them fit.

Thanks for the advice. will try to just move old set up out of the way for fit test. When these catalogs stated GMC ; thought they were designed for it--backside says chevy. Hindsight I woulda spent the extra $$ at Buffallo if they just bolt on without modifying.

Just got off the phone with Steve at Buffalos'. He stated both headers- his and Patricks need "tweeking" His are "made" for GMC;; where as patricks are made for the CHEVY but will work.

Which is the way to go?? Sounds like I will have to" grind to fit"
Charlie did an awesome job of showing "how to" grind to fit

What are the sizes of those openings in the Fenton headers and the Clifford intake. Would I use black pipe(gas) fittings or copper? Center of the intake I need to block off.

Thanks 4 the advice ,

Will it hurt my engine if I drive 5 miles with only headers hooked up to the muffler shop?

I wouldn't hook up the headers to the muffler shop (sorry - bad joke).

You will most likely not hurt anything but eardrums if you drive 5 miles with no exhaust system parts connected to the header.

THANKS
do I need adapter rings?"Patricks" stated it would help ...

What kind of adapter rings?

Intake manifold-to-head alignment rings - some come as adapters for mis-matched intake manifold to head port/hole size?

yes, do I need alignment rings.Or "nice to have"but can still bolt up

I used a 302 military intake and the Fentons on my 1950 GMC 270 with H head. The Fentons I got from Patricks also required grinding inside the ports to open 2 ports up to align with GMC ports. Also had to grind on outside a couple places to get enough clearance for socket and wrenches. Back bolt is still very tight to get to. Also made some "clamps" that span intake to exhaust with clamp bolt in middle from flat stock. Saved my stock clamps in case wanted to go back stock. After seeing Buffalo manifolds wished I had gone that way myself.

My intake also had alignment rings that I reused. Made it easier to align obviously.

Well Eagleuh1 I have the same headers. Thanks for the insight."Patricks" said bolt Em on and go....anyways am going to see if I can align without the "rings" for now.Can order a set later-but buffalo stated the rings would do no good if the intake isn't setup for them. Dont know what head I have.

If the alignment rings weren't needed why did GM put them on millions of vehicles? They could have made millions more bucks by leaving off un-necessary parts.

Also, what are you saving by doing it wrong the first time and having to go back and do it right later?

I have been informed that those headers from Patricks require grinding to fit. I want to bolt it on.
Which header goes in front towards the radiator?

Patricks told me