Looking at old Hilborn mechanical injection intakes. Anyone know the bore size on the Pontiac intakes? I heard they were small. sm-all. Anyone with experience can say whether they perform small or not? Any workarounds to get bigger bore?
Hi Monkey Give a call to the good folks at Hilborn they will help you a bunch, what are you going to use them for street or ? Ran Hilborn's on my gasser 50 plus yrs ago, was and still is a great product DND
Thx - I've heard Hilborn has great customer service. I'll shoot an email. I run an original Pontiac motor and I fit MPFI onto it. Runs awesome, but I'm just dying to get an original Hilborn and convert it with injectors. 462 motor. I'm thinking I'll need 2.25" - 2.375" (57-60mm) holes, and for some reason I suspect the Hilborn are much smaller? I think Hilborn (and others) do new full custom ITB setups, but that starts to get out of my $tyle. I'd really like to convert something original.
If this is a street car and runs great with the MPFI package you really should not need more throttle area than what you have. With the Hilborns you will have twice the number of openings (assuming that your current deal is a four barrel butterfly on a regular manifold) so the overall area may be greater with even a small bore Hilborn. https://www.google.com/webhp?sourceid=chrome-instant&ion=1&espv=2&ie=UTF-8#q=area+of+a+circle Roo
I have run early Hilborn injectors on a Packard. But they were made for a Pontiac. I don't remember the size, but like all early Hilborns they were small. I have a Y block set here and it's 1.670 dia. I have also run later Kinsler injection on a 455 Pontiac and they were 2 1/2 as I remember. Look the same as Hilborn's new castings and use a lot of Hilborn parts. Y block and Packard construction picture for referance
New Hilborn injection. 2 5/8. Also SBC intake modified to fit Lincoln. You can do the same for your Pontiac. 2 7/16. Hope this gives you some ideas about fitting whats available instead of wishing you could find a rare Pontiac casting. The Pontiac is a Valley cover engine, so it is very easy to adapt the Chevy Hilborns. I wanted to cut up a BBC intake for the 455. But the owner insisted on spending $3500 for the Kinsler. I would have saved him $3000. I also trimmed the water pump housing on that motor. Removed the water pump and that part of the casting the pump bolted to. Used a remote electric pump. looked a lot cleaner. The 2 5/8 castings are for a MoPar 360 sprint car head. Magnesium casting and cost me $400 on Evil Bay recently. I made the bells.
Actually, it occurs to me that the guy who owns the pictured Packard is currently running a 440 MoPar tunnel ram and may well be willing to sell the Hilborns. If you really want the early tiny early ports. He is on here V8Packard. Also home made intake using Motorcycle EFI throttle bodies. There is a lot you can do if you want to.
Awesome pics and ideas. I am not only looking at using the Pontiac intake, in fact it seems clear that it just won't work. I'm open to unusual ideas (heck, my crank trigger is a 36 tooth motorcycle sprocket with a tooth knocked out lol). My mind keeps trying to create a cross-ram ITB setup instead of down draft for air cleaners and hood clearance. The second to last pic (labeled img149.jpg) has the TBs canted inward and the stacks could route across instead of up. What TBs are those? rooman - for some fancy engineering reasons that are too complicated for me, the area of the circle approach does not work. In fact, the 4150 style TB I have on there now, flows 1000 CFM with 4 each 1.75" barrels. This is at the top of single plane plenum. Each of those 4 barrels are a lot smaller than the 8 each of 2 7/16" to 2 1/2" that Hilborn is recommending. Things change with the ITB throttle down low. Pretty interesting huh? Hilborn response: "Thank you for the inquiry! It looks like the butterfly sizes for our Pontiac injector manifolds ranged from 1-11/16 to 2-1/16. These in my opinion would be considered extremely small for an engine with 462 cubes and the power potential today. A 2-7/16 or 2-1/2 would be more ideal and possibly even larger if you are making big power (800+). Unfortunately we do not offer a bolt on manifold for the Pontiac applications but we have had customer use our SBC throats that are then adapted to the Pontiac head, with fantastic results. If this interests you please be sure to let me know and we can go to the next level. I appreciate the interest and if you have any questions please be sure to let me know..." See pic of my current setup. I'm very happy with it, but I can't stop what's cooking up in my mind.
The above picture(labeled img149.jpg) is an early Hilborn made for a Pontiac. Same engine as in picture img 66 on top. But adapted to a Packard. Very small. I made the stacks. Here it is with short Hilborn stacks. Also TBs from a 4.6 Ford sohc V8 being used as Hilborn MFI throttles. Cheap and big.
The Jalopy Journal
