Inliners International Forums General Discussion Hi Performance 250 intake manifold woes

I'm back.

I just procured my TBI set up for my project, complete with attached truck lol.

The stock manifold does not really work the best with the TBI. I would like to upgrade, my preference would be the dual carb Offy with dual 1bbl TBI's. Looking around, it's $400 and delivery date is 'maybe September'!!!

Looking for Clifford or Offy 4bbl, again cost about $400 and delivery dates 'TBD'.

Actually looked at Marshall's FI manifold, would skip TBI and go Megasquirt. Website is closed down.

Noticed that there are a few Aussiespeed manifolds available, same price point but ships today. Anyone have experience with these on a street motor? Currently have both a 250 w/307 pistons and mild cam, and a stock 292. Will use a 305 TBI w/4.3 ECM (adding 4L60E).

Mine are still available. Got another batch of the EFI intakes coming!

And wouldn't you know.... up pops a heated Clifford on FB market. Nabbed it for under $200. Now to make a TBI plate. Any guesses, should the holds just be bored straight or tapered?

Next a SPA T4 manifold, run with just exhaust until I can afford a turbo and plumbing.

Been working on this thing 10 years, at some point I'll get it together.

That was a good deal!

Deals are always out there if you have time to find them. I'm glad you found it when you needed it! I'm still looking for the guy with the 12 port GMC head looking for scrap aluminum price. It's out there!

I would bore the holes, turn the pate upside down, and radius the edge with a radius router bit or with a milling machine.

I bought a TBI plate that bolts a GM TBI to a 4 bbl carb pattern. I had to cut the center out of my Clifford manifold.

I'd still like to hear any input on the Aussiespeed intake manifold.

It will work better then either the offey or the clifford.

I used to make billet Stromberg 2bbl carb spacers years ago and had them featured several times in some magazines. One was a dyno test on an early Chrysler Hemi that used 4 of them on a 4 x 2 intake. They did before and after tests with and without my spacers and saw a 20 HP increase with them, or 5 HP per spacer basically. I radiused both the top and bottom edge of the throttle bores on each spacer and it does make a difference. I also made a 60MM spacer for a sheetmetal intake for a friend of mine years ago also that I radiused both sides of the bore. He asked why, so I made another one that was not radiused and sharp on both sides. We took both of them to another friend that has a flowbench and asked him to compare the flow on both of them. The radiused one flowed 125 CFM more than the unradiused one. Both were the same bore size to within 1/2 a thousandth, and the spacers were the same thickness to within that same amount as well. Radii make a huge difference..... That's why many cylinder head race teams use radius seat cutters for valve jobs instead of angled seat cutters now....

I say now, but they have been doing it for more than 20 years now!

any body tried 3 two barrel carb Offenhauser tri one barrel intake with two inch spacers "adapters" from 3 bolt to 4 bolt

I have seen on many other motors but I never ran one. Other then the 3x4 I built for my motors. Getting the carbs over the intake ports I feel work better to start with as I have seen. I have ran Both the offey and clifford single carb set-ups The dual clifford worked better then either single but my 3x4 ran better then the others. And the track showed me the prof of that.

I would also like to add That this why the Webbers work so well because they are right in line with the Ports, Yes for some or many they are heard to keep tuned. This is also the reason I think the dual intakes work better then most single Because the carbs are better divided on the intake. Just some of my 2 cents.