Well I guess Tim at the shop who did the heads knows what he is doing, he said 2.02 and 1.60, he's been there a long time, and stays busy so he should know. When I went to pick mine up he was starting head work on a single head that weighed more than my entire engine! he said it was from an engine on a 45 foot pleasure yacht it was 8 inches thick and maybe 6 foot long and a foot or so wide.
I hate to tell you this, but that head design ('66 289 heads) will not flow well with those valve sizes. That's why aftermarket performance heads are so popular. They are designed to flow with the larger valves. Simple porting isn't good enough. It's the size and shape of the runners that matter the most. You might be disappointed.
Nah for no more than I have in them, it'll be fine as long as I can outrun my wifes tri carbed I6 in her Maverick, not building a drag car just a street car.
Next time you see him ask him if that engine is a " Nordberg ". We had a boat with two of them. Sounds like the size of the head on them. You need a crane to get it out of the boat! I can't even guess what the weight is!
couple of quick comments in no particular order. you can get a 2.02 valve into these heads.. but shrouding becomes so excessive that they can actually hurt airflow over a smaller 1.94 valve while also simultaneously reducing swirl(which is already an issue to be dealt with on factory valved SBF heads in the first place). Only way around it.. to some small degree(besides lifting the bejesus out of the valve for long periods of time).. is to cut the chamber wall out to the cylinders perimeter. Those heads have not been deshrouded. The exhaust side can also benefit from that as well. But.. it's still better than any factory valved head from a flow standpoint.. so.. just enjoy what you got. PTV clearance is more about the duration figure than raw lift.. but you'll definitely need to check it due to the intakes size/minimal valve seat to head deck margin. From mine and others experience with these particular heads.. sub 50cc's for those smaller chambers really is a piece of cake and you generally figure about 1cc for roughly every 7 thou of flat milling. And as you'd expect.. angle milling tightens things up even quicker. IIRC.. my 289 hi-po's were into the low-mid 40's after a .135 angle cut(cc removal is not linear due to progressively increasing wall slope).. and ended up right at 52 cc's after sinking the intake seat, heavy deshrouding to a 4.060 cylinder/gasket line, some clover leafing to help the short side flow, and slightly laying back the chamber wall to promote swirl, high lift flow and also improve pressure recovery just a tad. The exhaust port has been substantially improved over stock and they easily flow well enough to support over 425 horsepower. With a decent enough cam.. those heads will make adequate power. I won't candy coat it for you at all here.. and I just call em' like I see em' with no disrespect intended to anyone who see;s it differently. Your quench height flat out sucks. That hurts performance and efficiency in so many ways that I won't even go into much detail here. That makes for a dirtier motor and more detonation sensitive environment as well. Bigger duration cam will help reduce the dynamic compression ratio at lower rpms to help lesson that tendency somewhat.. but without a doubt, power and efficiency will be lost. Not much you can easily do to close that gap at this juncture short of thinner shim stock style.. or custom MLS head gaskets. Just have to tune around it the best you can with a bit more initial ignition lead, is all. Achieving more than adequate compression on these small motors is no easy task with flat tops.. but trust me here.. you won't be disappointed with those heads and they'll really wake that little motor right up.. shrouded intake valve.. or not.
I've done a TON of flow testing on these heads with various valve sizes. Even moving the chamber wall out to the very edge of the head gasket a 2.02 valve will be so shrouded it won't flow past .385" lift. Flow will actually stall. The optimal valve size for these early heads is a 1.85" intake and a 1.55" exhaust. 1.94/1.60 will fit but, again, flow will be hurt. And putting these heads on a 351 is an exercise in futility. Out of the box iron Dart Windsors are fairly affordable and allow a 351 to really breathe.
lol.. whoops.. I didn't forget.. I just flat out breezed by that important little tidbit as I read through the thread too quickly. That does change things. And as for these heads not performing past .385 lift?.. well.. my 1.94's do just fine up to about .500 or so and I have the flow sheets to prove it. I've seen many others on the bench flow decent numbers at higher lifts too.. mainly because that's all we had to work with at one time. Also good to keep in mind that there are still a few super stockers out there making WELL over 500 horses with these little heads. Shrouded or not.. at high rpm/high lifts the flow will skip right past this heads miserably squished short side and over to the long side of the bowls anyways. While it should go without saying that aftermarket heads would certainly be an improvement here.. with the right cam choice, the OP's usage and power requirements seem to make these heads entirely feasible. There have been many thousands of damned good running street motors using this exact same combo through the years.
We've raced these heads on dirt stock cars and modifieds before the aftermarket heads were available. We prefer the 64-65 heads. Never waste money to put a 2.02 valve in these heads, you don't pick up flow and the flow you have is very disturbed due to shrouding, as others have discussed. 1.94/1.60 pretty much says it for these heads. We have run cams up to .578/.589 lift and turned them 7600 with no problems with these heads. If they are well ported they can actually flow fairly close to a set of Windsor Jr. heads. We milled ours to 46 cc chambers to gain compression since we ran race gas. As for 1.5 compression on the street with iron heads, plan on the best gas you can find and retarding the timing a few degrees to get rid of the pings. Also plan on a good ignition. SPark
Gotta be a little better on flow than the stock 351w heads I have...... Ok, this is coming from Haynes Ford Engine Overhaul Manual. For a 351: @4000rpm - 325cfm @4500rpm - 345cfm @5000rpm - 405cfm @5500rpm - 445cfm @6000rpm - 490cfm @6500rpm - 525cfm These are stock numbers based on a carb'd 351w. With a stock, carb'd 351w engine and a 4 barrel carb, what I had, any improvement will be fine.
My guess is that's carb flow, not port flow. We ported the intake side to take a 1262 gasket but it gets really tight around the pushrod tunnels and on the floor at the radius. We also went up to the bigger Mr. Gasket header gasket on the exhaust side. We have thrown away a few heads over the years learning where the thin spots are! SPark
Ok finally got to cc'ing the heads, and well they are for sure 50 ml, thats with the spark plug in place, now to hope the intake fits ok, can't you buy thicker intake gaskets? I'm pretty sure I'm not the first to wonder about this, I know I can get thick head gaskets, I do have two intakes to choose from, the Edelbrock Performer and the 1969 Factory 4v intake.
I recalculated the CR using +18 cc dish pistons and a .040 head gasket thickness, with the 50cc chambered heads and came up with 9.66 : 1 CR and that sounds a little better, the +18 dish will also help on clearance for those big valves.
