On a lokal Dutch e-bay-ish website I found an Edelbrock STR10 crossram intake for sale in realy good shape...(on the other side of the country :D)

What would be a good combo for it,...I know the best way to go is a screamer, but how to make one? I have a bare 350 4bolt in my shed which I could use, or my 305ci ;)

Or I would build a 383 stroker, or a screamer using the crossram. Most of the time I will be cruising so a 383 would be best, but I realy like the looks of the crossram :) and I have never seen one.
I know a guy who is selling his 283ci, so could this be an option?

I have searched the internet, but I trust answers comming from this forum more, so any ideas?
Or is it not worth buying the crossram intake?

thnx, David

look here for some info:
http://www.camaros.org/crossram.shtml

I think this manifold would be easier to live with on a larger engine like the 383. It's complicated to deal with and requires syncronizing the carbs/linkage for equal air flow and some careful tuning of the accelerator pumps, -so I'm told. If the manifold bolts to head need re-tighening the whole top must come off, this requires the carbs to come off first, THEN the top can be removed because two of the top cover bolts are under the carb bowels. Removing the carbs will mess up your linkage adjustments which must then be re-balanced for equal air flow at idle using a unisyn device.

This is just my opinion from looking at them, I haven't wrenched on the system, - yet...
David

Thanks David, I am happy to hear I can use a 383 for this crossram. I was planning to go for a 383 and then I saw that crossram....

Otherwise I had to build a 383 and a 302 :) and I only have one car...

Should I use DP's or vacuum secondarys? Didn't they use DP's normally? I have 2 vacuum secondary carbs laying around here...so I am hoping I can use these.

They used DPs and you would probably be better off using it on a hi rev setup.

GET IT!!

It will make a great swap/trade part in the future IF you don't use it, imho..

pdq67

I talked to an Edelbrock crewman at the vintage races. Edelbrock runs that manifold on his Smokey Yunic Camaro. The report was, the Edelbrock produces more power than the GM manifold. I think he said it was worth 20 hp more. The port approach angle was slightly better on the Edelbrock than the GM manifold. The ports are way too low for optimum flow. The Smokey Ram has a much better port approach but is taller overall.

Manifold runner velocity is relative to horsepower produced, so the greater 383 engine displacement will produce more velocity at a lower rpm than the 302 (aprox 1000 rpm lower). With 81 more cubic inches sucking on the runners I'd guess instead of "coming on" at 4500 rpm's and up, the manifold would "come on" at just above 3500.

With identical camshaft and heads, a 383 will also make peak horsepower and torque 1000 rpms lower than a 302. A 302 cammed for 7000 rpm's would rev 6000 if it were a 383, using the same camshaft and heads while making aprox 60 hp less than a 383.

I think it would be very easy to over-carb an engine with this manifold so keep the carbs a bit smaller like 500 to 550 cfm. Vaccum secondaries were recomended to me by the Offy representitive I talked to. The large plenum makes a small carb act bigger and besides with two 550 cfm carbs, you have 1100 cfm of flow which is way more than single carb setups you see on the street.

Thanks again guys...this is what I want to hear :hurray:

David, still have a small question. You wrote:



A 302 cammed for 7000 rpm's would rev 6000 if it were a 383, using the same camshaft and heads while making aprox 60 hp less than a 383.



Am I correct if I read it like this:
A 302 would rev 7000 rpm's and have, lets say, 400hp... While a 383 with the same camshaft and heads would rev 6000 rpm's and have 460hp.


So because of the bigger cubic inches the manifold would do its work on a narrower rev-band. As I remember correctly the manifold 'works' best between 3000 and 7000 rpm, so for a revvy engine.
But because of the bigger displacement it could be used in a more streetable way like 2500 and 6000rpm.

If this is correct I would be in 7th heaven as this is the range I was hoping about...

Sounds about right!

Probably be even more streetable on a 406/412 motor to!

Guy's, aren't some of the early AFB's like 450 cfm or so?? Or just maybe a pair of 390 cfm Holleys too..

A pair should be dandies here, imho to keep from over carb'ing it is all..

pdq67

Yes, you will see more hp and torque with the larger engine. The larger engine can and should use a different camshaft to optimize performance of course, but hp gains would be along those lines.

The larger engine can burn more air and fuel mix at a given rpm. This works out to a bit over 1000 rpm's lower than the 302. The engines I compared were 530hp for the 302 and 590hp for the 383. A lower horsepower engine would show less hp difference between the two displacement engines. The 302 could catch up by revving higher, but it would take a more agressive camshaft to do it.

Average port velocity for 302 at 4500 = 212 cfm.
Average port velocity for 383 at 3000 = 209 cfm.
I did this very quickly so there may be some differfences I didn't come up with.

It should be pretty easy to build a 383 with 450 hp and a hydraulic cam that would have loads of torque. Just use good cyl heads like the aluminum fast burn, or AFR.
David

Thanks guys, I think I will read the 'how to hotrod your small block chevy' book and see if I can come-up with a good 383 combo.

I'll probably gonna ask you guys for advice on the engine very soon, but for now I've got some reading to do.

David