hi guys, I'm hoping someone somewhere can help with this little situation I have found myself in here.

I purchased this 5 carb Howard from US eBay, waited 4 months to get it to the UK to find it isn't as advertised. it was listed as a 270/302 intake, how ever the port spacing is off, the head on my 302 is 226mm and the intake is 218mm, both have 44mm ports.

the bolt spacing on the intake is very different to the 302 also, can someone confirm what this was originally for from the spacing on the bolts alone? it seems I have ended up with a super expensive wall hanger for time being.

I can't find any info on this particular set up online or in any books I have. any info, help or guidance would be great. Photos of this on my 302 are jus using 2 bolts to pinch it up for visuals.

click on the photos to make them larger, I didn't want to fill an entire page with photos.

Thanks Joe


IMG_3745 by joe curtis, on Flickr
IMG_3747 by joe curtis, on Flickr
IMG_3741 by joe curtis, on Flickr
IMG_3750 by joe curtis, on Flickr
IMG_3751 by joe curtis, on Flickr
IMG_3752 by joe curtis, on Flickr
[url=https://flic.kr/p/2cerEJ7]IMG_3753 by joe curtis, on FlickrIMG_3754 by joe curtis, on Flickr

Hi Joe . . .

I hate it when the hunt leads to bagging the wrong game. Done it a few times myself :-(

The port spacing on that intake suggests it's for a Chevrolet.

With the McGurk and Howard design one can fabricate elbows to replace the ones on the intake. The outer bits would have to cope with wider spacing found on the GMC.

In general the speed parts for GMC were made in less numbers then those destined for Chevrolet's. This typically leads to premium prices on the GMC stuff.

Have you approached the Ebayer about a partial refund given the mistaken ID?

regards,
stock49

The 218mm (8.583") pitch is close enough to the nominal 8-9/16" as being Chevrolet, but the 1.732" ports are bigger than any stovebolt head.
It's probably very valuable to someone who has the correct engine, but what...?
I can't think of any siamese L6 with such big ports, yet small cylinder spacing.

Unfortunately, in that era there was this mistaken belief that engines were literally 'starving' for air and that adding carburetors and opening up intake ports would assist in 'breathing'.

My guess is that the original alignment-ring bosses have been hogged-out/smoothed to match an equally hogged out intake port on the head.

As a result, the center-to-center dimensions are key - not the port diameters.

Stock49- I have emailed the seller through a new advert he has posted. As he sells a lot of engine parts. To no surprise I have had no response from the seller. I can’t do much through eBay as it’s taken so long to get the manifold to the UK as it come over in a container.

As for the elbows, a friend has offered to CAD and 3D print some for me. I didn’t consider the body of the manifold being the same for both GMC and Chevy. I could possibly email Patrick’s and see what the spacing and elbow set ups are on the repo Howard’s manifold they sell. There was me trying to get a nice vintage speed part opposed to buying a part that’s a lot cheaper but bolts on.

Panic- my thoughts being the same- of a good value to someone who could bolt it up. Only thoughts being 235/261 chevy motors. I can’t find any info regarding what Howard actually produced. Kind of pissing in the wind if someone has played with the port sizing too.

Thanks a lot for your help and info guys, off to eBay to try get hold of the seller again.

Based on the pictures I have (including Curt - thanks again) if you enlarge the stock 235 intake port to 1.732" you will get a bath.

Indeed. Bill Fisher's specs call for maximum of 1.375" when reaming straight back to branch. The ports on this piece are downright huge . . .

So it seems as if this is a very odd set up, port sizing for the big 302 head I have but port spacing for something different.

I shall go take a look to see if the 90* sections have been hogged out with a burr or these pieces have been cast as is.

Don't the elbows bolt on? even if they don't it would not be hard to make two new end pieces or modify the old ones. It's just aluminum, cut it, weld it, grind it, and weld some more if needed. It's a great old piece and will add to your engine.

Looks like they bolt on. There may be enough room to cut the flanged entry out of the bottom of the plenum. Make it 5/16" longer on the farther end, and reverse it, then weld. This will move the actual opening and the flange for the runner by the pitch distance difference (8mm).

The linkage should be examined: what is it now, and what do you want it to be?
No personal experience, but I would not try to run the engine on the center (#3) carburetor alone - that #3-4 port will drink all of it.
The most likely choice for race is all 5 in synch (all levers attach at the same length from the throttle shaft).
The street choice with progressive (staged) linkage is probably #2 & 4 for primary to attempt (!!) some mixture distribution. The progressive part will look very similar to any other progressive, even V8, as to how to calculate lever lengths. I have some more text on this here: http://victorylibrary.com/mopar/log-2.htm

IIRC Nicholson ran his 235 on #1, 3 & 5 carbs, with the #2 & 4 removed and the flanges blanked off, but that's a lot of work for a regular race-to-street change.
The problem is that leaving the "extra" carburetors alone with their linkage closed is that their idle circuits are still functional, and will both add gas and reduce vacuum to the other carbs.

yes the elbows bolt on, my first thought was get making some new ones. I was just hopeful someone had some info or a solution before I start making parts for this. Not as if I have to hack the main body about, this is the part I was obviously drawn too when purchasing

I'm hoping/wanting to leave the main body alone. I don't want to put too much heat in there and warp it. I was considering turning blanks and block all the holes up, and move everything over to suit the port spacing on the GMC, and buying new 90 elbows from Patrick from the new repo Howard manifold. I shall take a closer look at what meat is on the bottom of the body/plenum.

As for linkage set up, the car isn't a street car, our UK rags make it hard to build a car from parts and register it. Strictly event use, which by the sounds of it makes this a bit easy for carb set up.

Could you make spacers for the elbows? The center one straight and the end ones offset to line up with the head. You probably wouldn't need them to be more than 1/2 to 3/4" thick.

Will Willis

just an idea but I would unbolt the elbows and switch them around a few times and see what happens. casting on theses wasn't perfect.
Jay D.

That is a good idea. The difference in port spacing for a Chevy and a GMC could be accommodated by an offset in the end pieces. I may have even read that somewhere a long time ago.

I personally would avoid Patricks-especially about the GMC items.I had a bad experience purchasing items for my 302.

Maybe for advice only

There is a thread over at stovebolt that says Patrick's is out of business and other things. Not passing judgement just putting that out there. I have no experience with them.

I've had very good experiences with Patrick and some not so good experiences. It is too bad because he has some very good products that others don't.