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Dual quad intake to fit under smooth hood
I'm assembling a smooth hood ERA roadster with an FE engine. Keith Craft proposed a Blue Thunder intake combined with a set of early, re-worked high performance heads. I assume the intake is a medium riser reproduction and the heads are typical of low riser heads. Bob at ERA showed me pictures of an ERA car in their shop with a medium riser dual quad intake and it requires a hood scoop - lacks clearing by about 1 inch. Sooo - what dual quad intake did Shelby use in the Street Cobra Roadster that managed to clear - a low riser seems to be the default answer. Are there any reproductions comparable to the low riser or do I need to be shopping Ebay? Or, am I missing something else here?
Dan |
honestly i don't think the low riser will fit either. the difference isn't in the height of the head and intake themselves but the height of the port.
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Surely the low riser dual quad intake clears a smooth hood OK. I hope. After re-checking the web site I see that they list a 8V model for the 428 CJ which is a low riser head (#IM-428CJ-8V). This must be the one he plans to use. I need to either drink more wine or less before posting. Dan |
Hey Dan, persevere on your mission, street cars are beautiful! I have a couple of dual quad manifolds here and the first one I tried fits under my hood with S&H aircleaners on it. That is an old Offy. If you need height measurements off that or the Ford one let me know. You need to chat with Frank about this a little more, he knows street cars intimately.
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"The intake ports for the MR measured 1.34 x 2.34 in. wihile the HR's ports were 1.34x2.72. Actually, the MR's port dimensions weren't anything really new, being the same as on the 1960-1962 HP 352 and 390 cid engines. The same heads were later used on the 1968 - 1970 428 CJ eninges but with smaller valves. The difference between these heads and all the others is that the MR heads used much larger valves, 2.195 in. intake and 1.73 in. exhaust." So the 428 CJ dual quad intake that I hoped was lower than a mid rise dual quad intake, is actually the same as a mid riser intake. Blue Thunder confirmed to the builder it and the MR intake are the same height. They also said it duplicates what was used in the original Cobra (Street or SC I don't know). Bob at ERA says a MR dual quad intake won't fit under a smooth hood so I'm not sure where I'm going with this. Dan |
Medium risers have unique port entry size and shape....the Edelbrocks mirror those. Cj heads are decidedly different...
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Barry is the expert on the motors and I defer to his experience on port sizes/angles etc. The dual quad was typically used on the street cars where the comps used a MR with a single 4. I'm sure ERA has the car shape and height etc about as accurate as anyone. The trouble is with these cars it's 10 pounds of poop in a 5 lb bag. If it's not touching rubbing or against something it's in the wrong place. The oil pan should be the Aviaid type or depth, 6" front 5" rear. The pan bottom should sit level with the bottom of the frame rails and not quite hang below. That all being good a dual quad should fit under the hood with a low profile air cleaner like the S&H.
http://img708.imageshack.us/img708/6...ctures004u.jpg |
Dan, I have an ERA with a smooth hood. My intake is an old Holman & Moody medium riser with 600's on it. the only thing you will have to worry about is the rear molded bracing on the hood that will just barely touch the air cleaner. Just trim that back (neatly prior to painting) about .25" and you will be good to go. If you'd like I can send you pictures measurements or what ever you need.
Regards, Frank |
LR's, MR's, HR's, like what was stated before pertain to intake port height and shape.
LR's were the first port, with the improvement being the development of the HR's, C3 and better C4 designs. I think the HR was outlawed by Nascar, so Ford designed the MR, with a raised floor as compared to the LR, but with the same overall height of the port. The CJ head I believe was based off the LR head. I would think the carb height on the LR's would be equal to or less than that of the MR. I think Offy makes a dual quad with a low carb height. You may want to call Carl's Ford Parts, as he has a lot of these parts, and may know the specifics |
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I wonder if there is any relatively fixed point on a manifold that the height up to the front carb pad could be measured - and then compared to another manifold. Like to a valve cover bolt or something. My engine builder is trying to help but he's primarily into engines and not ERA street cobras and he doesn't have a good yardstick to compare to. I finally figured out these 390 HP heads are pretty much the same basic casting as the 427 LR head, except for smaller valves. Port dimension appears to be same as for both MR and LR 427 heads. But, from the posts by Anthony and Barry above and from what I can find - It sounds like the MR port is physically raised a little higher up in the head. I guess I really need a LR 2x4 intake if I can find one. It doesn't sound like a MR intake should even match up with these heads (?) Thanks - my FE education continues. Dan |
I don't know why you care about the intake ports on the head.
"Low-riser", "Medium-riser", "High-riser" all pertain more to the intake than the heads and describe the angle of the runner between the head and carb flange. Low riser's had the carb mounted relatively low, to fit under T-bird hoods. High-riser's had a straighter shot from the carbs into the chamber due to the raised carb pads on the intake...they were much higher than a low-riser's. Medium risers were just that. They mounted the carb somewhere between the extremes of the high riser and low riser intakes. They also reconfigured the runner shape. A low-riser's intake port in the head is actually taller than a medium-riser's port. The only way to answer your question definitely is to lay a straightedge along the carb pad, and measure. Or rely on your builder. Just make sure your builder knows specifically the application the motor is going to be installed. I would think Keith Craft might have a few measurements available to him as well as a little experience as to what will or won't work/fit. |
If I better understood the interchangeability of FE heads and FE intakes I probably wouldn't care as much. But on the theory that a litlte knowledge is a dangerous thing and that there appear to be short port, medium height port, tall port, standard floor, and raised floor heads - not to mention the TP heads, it's all been quite confusing. I fear paying a good sum of money to have a nice engine built only to find I can't close the hood. But - it appears to all be boiling down to needing a LR dual quad intake. Or, as the builder put it - looking for a needle in a haystack.
Dan |
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Dan |
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