351c cam, heads, and intake questions

[dbgrigsby93]

I've got a Cleveland 2v in a 1973 mach 1 and have recently come across the opportunity to buy a set of cast iron 4v heads that a guy pulled off of a car in a junk yard. If I get them I'm going to rebuild them with new valve stems, springs, and probably rocker arms. My engine doesn't need rebuilt and I don't want to have the car down for too long anyway but I'm going to replace my cam and don't know very much about them. I also need to know what to do about the push rods... will I need to get new ones? I don't know what these heads came off of but I need to know what kind/size of cam I should put in my car and how big of an intake/carburetor I should put with it and the 4v heads. My compression ratio is 8.6:1 right now and that'll remain since I'm not rebuilding the engine. I'd like to get up around 350hp at around 4000-4500rpms. But I want to achieve that from cast iron 4v heads, new cam, intake, and exhaust. Any suggestions?

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[Flash70]

Why not replace with Aluminum Heads if you are going to all that trouble?

[THUMPIN455]

Because there is no need to buy an aftermarket head if you can find a good set of iron heads. Its often cheaper to rebuild the old heads than buy new ones, with new valves and springs it only costs me $400-$500 to refurbish iron heads. The cost of the aluminum heads isnt always justified by the performance.

Depending on what year the heads are from you will either have nearly the same compression or higher. If they are 70 or 71 heads, you can have well over 10:1, they lowered compression with the 72 heads to run unleaded gas. For the most part its a bolt on deal, you need to change headers, intake, and the heads. Pushrod length comes into play when you change cams or if the heads have been milled. Its something you need to check on any Ford engine after you swap heads. They lowered the compression by making the chamber larger in the head, not by using dished pistons.

Depending on what you want to do with the engine will make a big difference in what cam and intake you choose. 350hp is pretty easy to get, but 4500 is rather low for a Cleveland, they have huge ports that make power in the higher rpm ranges, but you can still make decent low end grunt. With a good set of valve springs a stock Cleveland will run over 6500 rpm no problem. The weak links are the rod bolts and valves, replace both and its a pretty stout engine. You only need oil mods if you are going to be running it over 4500 rpm for extended periods, or running it over 7000 rpm such as drag racing.

I had very good results with a comp cams 270H in a 4V Cleveland, its an old school cam that you can use with a stock converter and a set of headers really wakes it up. Stick to the dual plane intakes, dont get a single plane unless you have a 3000 stall and 4.10 gears along with higher compression and a comparable cam. For a carb a holley between 650 and 750 with vacuum secondaries. A quick change kit will allow you to swap secondary springs around quicker for tuning.

It seems like you want a cruiser with a bit more power, not a full on race car. A cam with 220-224 duration @ .050 works very well in a 4V with highway gears, and a stock converter. You can go dual pattern or single pattern, but dont go over 234 duration if you can help it. Too much cam and the 4V head doesnt make any power down low, keep it on the small side and you will have traction problems. Traction problems are a good thing compared to a huge bog. Remember, dual plane intake not a single plane and you will like having the big heads on your ride.