906 Vortec Heads with Ramhorn Manifold?

[tsmith8]

I am currently working on a 383 for my '58 Apache and will be using 906 Vortec heads and would like to use my Ramhorn exhaust manifolds. Has anyone done this combo before? Any issues i should be aware of with final install?

[paulspickupparts]

http://www.clubhotrod.com/chevy-smal...tec-heads.html


This answers a lot of your questions. You might catch some flak for using them on a performance engine but your call. One guy said its like throwing a blanket over a light bulb.

[mr48chev]

That link confirms what I was thinking when I read the question yesterday. The ramhorns aren't going to be a direct bolt on. I'd have to wonder the reasoning behind spending all the money for a stroker motor and then choking it down with stock manifolds though.

If you want cast manifolds there might be better flowing stock truck manifolds for that engine that go with one of the larger trucks that uses that engine.

[tsmith8]

I am restricted on what i can add for manifolds or headers as i am still using the original manual steering box. (this doesn't bother me, i actually like it). So i am tight on space on the drivers side with steering box. I have read several posts about headers just not working at all with the original manual steering, any truth to it???

As for the 383, my brother collected all the parts for it about 5 years ago for is '95 chevy but it caught fire and burnt entirely. So the engine and new parts have been collecting dust and we have guy that owes us a favour from an engine machine shop, so the machining and assembly is all payback from old favours before we sold the business a few years back. Everything just fell into my lap for this swap out. I like my current 327, but a 383 is just as cool. No to mention it will have a Tri-Carb setup as well.

So back to original questions. What should i do in regards to exhaust?????

[tsmith8]

http://67-72chevytrucks.com/vboard/s...hlight=headers

[1project2many]

If you draw a line through all of the exhaust manifold bolts on an old SBC head, the center of the ports lines up with the center of the bolts. But on a Vortec head the line through the bolts is higher than the ports. In many cases the pre-Vortec manifold will bolt up and often it will seal but the mismatch exists and the potential for leaks and reduced flow with an older manifold is real.

There are aftermarket rams horn style manifolds that offer larger ports. There may also be the option of using a Corvette LT1 exhaust manifold. That manifold is shaped roughly like a Ram's horn but is designed for a higher HP engine than the original Ram's Horn.

http://67-72chevytrucks.com/vboard/s...65&postcount=7

[paulspickupparts]

Originally Posted by 1project2many

If you draw a line through all of the exhaust manifold bolts on an old SBC head, the center of the ports lines up with the center of the bolts. But on a Vortec head the line through the bolts is higher than the ports. In many cases the pre-Vortec manifold will bolt up and often it will seal but the mismatch exists and the potential for leaks and reduced flow with an older manifold is real.

There are aftermarket rams horn style manifolds that offer larger ports. There may also be the option of using a Corvette LT1 exhaust manifold. That manifold is shaped roughly like a Ram's horn but is designed for a higher HP engine than the original Ram's Horn.

http://67-72chevytrucks.com/vboard/s...65&postcount=7

1project2many is entirely right .

http://www.hotrodders.com/forum/head...-204140-2.html

I think this artcle on hot rodders even shows a picture of a vortec headed engine (scroll down to lower posts to see the pictured engine) with the correct information. As stated you want to make sure you run a gasket (if you use one) designed for a Vortec head. As you can see in the photo it matches the Vortec head while one for old small block head will not. You may have to enlarge or move the bolt holes of your exhaust manifolds downward ( to move manifold or header upward ) . You can make any header of manifold work to its potential buy taking a vortec gasket and laying it on your header or manifold and see how it ligns up . Good chance it will not line up thus blocking the flow out of the exhaust port. Kind of like having a flood gate 1/8 closed . Many people do not know this and think one size fits all. Actually you should always check this with any head you buy . You could take 10 different heads. New , used , aftermarket and not all exhaust ports will be in the same location. Most people assume if the bolt holes line up and the header bolts on its the correct one. Not

[tsmith8]

I will have to check my manifolds in reference the the vortec heads i have. Even that forum has the line about adding to confusion about some earlier vortecs have the bolt holes centered with the exhaust ports.

[paulspickupparts]

Exactly , same rule applies to every head , not just a vortec . And now with all the Chineese heads who knows which one they copied.