I've done this mod many times, nothing to it. Made my own tapered spacers out of 1/4" scrap aluminum or steel. Your just modifying the four center bolt holes. zman-- The vortec head is a completely different animal and most early intakes won't match the raised ports on the Vortec heads even if the heads are redrilled and tapped for the early style manifolds.
Hey, JC & Rustednutz! Do you guys have a photo of how the holes are drilled and of the tapered spacers? Thanks, Kahuna John!
I think when your saying JC you mean me? Here you go http://www.summitracing.com/parts/PFS-52001/?rtype=10
Forget the 2x4 set up. There's a guy that runs a t-bucket with a small block Dodge in central Minnesota. It looks kick-ass, black with flames, bg old meats and triple 2s. It looks like the 340 six pack motor from across the street. I took a close look, and it's a stock 2 bbl. manifold with a 1/2" spacer that's big enough to hold the outboard carbs inline. He's got a pair of carbs that don't do anything, they don't even feed the manifold. They're just hangin' in the wind. Looks great, and he's got good economy and enough power for his 'bucket. Maybe 3 dueces is an easier solution.
That mod takes less than 1 hour for all 4 holes and 4 wedge spacers on an aluminium manifold. You can try it out on a used Craigslist manifold for an older sbc first if you are worried. Usually 50.00 for an eldebrock performer type manifold I have heard of not using the center bolts at all but not personally tried that nor do I think I would.
OH IT'S YOU AGAIN!! still struggling with English I see ? ? Wait, do I hear banjos? Keep paddling!!! You just can't type with a Tennessee speech draw and communicate effectively. 400 plus posts ???
Thanks, JG! I have a intake on the way I bought off Ebay I need to see how the holes are re-shaped and what the spacers look like? Thanks, KJ!
I wish I had a picture, If you have your manifold off, drop the bolts in the holes and note the angles. Your tbi manifold will have the center bolts vertical. The pre 86 manifold's bolts will all be at the angle. The hole modification consists of ovaling the center holes so that the bolt can be at the angle of the tbi manifold. It will be slightly ovaled on the bottom (almost round) and largely ovaled on the top. The spacers (actually washers) are a wedge to take up the difference of the newly angled bolt head and the older manifold. I used some 3/4 hollow bar with a 3/8 hole. Cut the pieces about 3/4 of an inch, disc sanders to square up one end and then sanded the other to a wedge. It's about 30*, once you get into it you'll see exactly what needs done.
Thanks, JG! Went there not much to read! I wish I could see what the washers look like, so I could make some! KJ
The washers simply make the stock angle of the intake adjust to flat. So if you look at the angle at the bolt flange of a stock SBC intake, then imagine a line from the edge out it will be the angle. I believe the angle is around 23 degrees, so that would be your cut on a piece of say 3/8" pipe to make a spacer washer, then put a regular washer on top of the sp[acer for the nut to tighten against. I'm still worried about whether the center port will seal with an old intake on a Vortec style head. You should check the gasket against the head and the intake before doing anything else, just to make sure it fits both before starting.
The Jalopy Journal
