DC manifold

Will a manifold from a 800 or 830 fit on a DC? I have a DC for tractor pulling and the vertical pleium always frost up on it. It pulls well until about 190 to 210 then always sputers out then it will pop back up to full power then drop off again. Was wondering if manifold is to small? I have 4 in pistons in it. When I put it on the dyno it says 68 hp. looking for ideas thanks.

The frosting of the manifold above the carb is perfectly normal, The closed throttle plate causes a venturi effect and the fast flow at idle speed through a very small area at the edge of the plate causes a refrigeration effect, you will see that frequently on many different makes, last pull I seen an M frosted 6 in above the carb.

You have an issue other than the manifold with your miss, you need to go over every area of the engine, I would make sure your manifold gaskets are good, Go over the ignition system, (Are you using a mag or a distributor) to make sure you do not have a spark issue after warm up, check the valve setting as tight valves can cause problems on warm up, go through the complete fuel system from the tank to through the carb. If your association allows high revving a richer mix is required. You obviously have access to a dyno and that is the perfect tool for diagnosing the issue.

I am jealous however, I have a 48 4 1/16 flat top piston DC that won 3 farms stock championships last year at our local pull that runs very well and can only manage 49 honest HP at 540 on a M&W 400 dyno. If I had a engine with your HP I would go up to a higher class and pull against hotter stuff.

Good luck with your problem, OH, I am not sure that a later manifold would fit although they look similar the port locations could differ, it would be interesting to see the difference

I put an aluminum flashing shield over the outside of the manifold to collect heat off the engine block on my 300 to help this problem. I assume that you have adjusted the valves?

68?-BS

B 49 DC, I was being kind!