Keith, I would like to give you some more input. The aussie 2V heads that Mike mentioned will help low end torque with increased port velocity but there not going to improve HP numbers. Also, if you consider the swap to closed chamber heads be aware that depending on your pistons and the chamber volume of both heads you could increase your compression as much as 2 points. The following web address is for Keith Black piston info.
http://www.kb-silvolite.com/page45.htm#SECT2 You don't need torque in a 2500lb straight shift car you need horse power.
You asked about the exhaust port plates and would they help? I think they will because the exhuast port on a cleveland 2V or 4V is a bad design. The exhaust exits the chamber going up into the port and then has to turn down to exit the head. The plate will actually even the port out and make it a more uniformed size. The aftermarket world has figured this out and raised the exhaust ports dramaticly to improve exhaust flow. Just for you information the exhaust ports on 2V & 4V heads are almost the same size at there smallest point were they turn 90 degrees in the head. The 4V head exhaust port is a little wider but is the sams hieght. (see atached photo).
As for carburetors, any custom carb shop will tell you vacuum secondaries are for automatics and mechanical secondaries are for straight shift transmissions. Edelbrock carbs are good for daily drivers but they are not for high HP applications. They don't respond well to the low vaccum signals that big cams tend to produce. I would stay with your Holley for now and just try to tune it a little more. By the way my carb specs are as follows:
Flow(cfm) 880
Main jets: pri. 73 sec. 83
Power valve: pri. 6.5
Nozzle size: pri. .028 sec. .031
You also said that you were a bit perplexed with your Desktop Dyno. I'll tell you what I have found to work with mine. Input head flow information instead of using there generic selections. If you do a search on the web you will find sites that have head flow information for a cleveland. It may not be exactly what you have but it will make a diference in the end results. You can also get all the information you need from Cranes web site to input diferent cams.
http://www.cranecams.com/CraneCams.htm I have built a library of head and cam information in my Desktop dyno and it helps when I want to experament with different ideas. You will probably find that your cam is on the smaller side and that changing it will yeild the biggest results but use your Desktop Dyno to compare different cams. It really does work.
I figure you will need to perform a compression check just to make sure all 8 cylinders are good. Then I would start working with the carburetor and the distributor. A vacuum gauge is also a very useful tool when fine tuning. I would like to know what kind of advance curve your distributor has been set to, and do you have a vacuum advance or is it just mechanical?
Bottom line is don't be afraid of those 4V heads. They will make horse power and lots of it even on the street. You just need to optimize everything around them to get the best performance. Thats what your Desktop Dyno is for.
Tim
Hybrid Mode
