Which head on 351W?
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From: Northeast, OK
Which head on 351W?
Got the bad news f/the machine shop today - one of the heads I sent in is cracked, badly. So, the question I have is what head to go back with.
The existing head(s) is a D80E-AB casting. Obviously, if I can find another large chamber/small valve/small port head to match I should go with it - assuming the cost is right. But, a guy has a pair of '74 Cougar heads that should be 60 cc chambers & a bit larger valves. In addition, these heads should not have the Thermactor bump in the exhaust ports if they are truly from a '74.
My calc's say that going from 69cc heads to 60cc heads would raise the CR from 8.5 to 9.25. Is that too much? The truck is a 2WD w/3.50 axle ratio and a C6. 2 barrel carb and single exhaust. Not looking for a hot rod, but don't mind better perf and gas mileage.
The existing head(s) is a D80E-AB casting. Obviously, if I can find another large chamber/small valve/small port head to match I should go with it - assuming the cost is right. But, a guy has a pair of '74 Cougar heads that should be 60 cc chambers & a bit larger valves. In addition, these heads should not have the Thermactor bump in the exhaust ports if they are truly from a '74.
My calc's say that going from 69cc heads to 60cc heads would raise the CR from 8.5 to 9.25. Is that too much? The truck is a 2WD w/3.50 axle ratio and a C6. 2 barrel carb and single exhaust. Not looking for a hot rod, but don't mind better perf and gas mileage.
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and any pinging (should it occur) could be dealt with by adjusting the ignition
timing or re-curving the distributor's advance curve (if necessary).
I have something between 9.5 & 10.0 CR on my M-block 400 and I generally run
mid-grade unleaded fuel..
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FTE Legend
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It isn't computer-controlled, at least not any more. 
But, the guy w/the Cougar heads wants $200 for them and they aren't ready to go. Found a guy w/D7 heads, which are essentially the same as my D8's, that wants $40 for the pair. Think I'll go that way to minimize any hassle. All I have to do is to drill the bolt holes out to 1/2" as these are 302 heads.
But, the guy w/the Cougar heads wants $200 for them and they aren't ready to go. Found a guy w/D7 heads, which are essentially the same as my D8's, that wants $40 for the pair. Think I'll go that way to minimize any hassle. All I have to do is to drill the bolt holes out to 1/2" as these are 302 heads.
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OK, I got the D7 heads and am in the process of drilling/reaming the head bolt holes. But, the heads have different rockers than my D8's. These are cast units, and the heads have studs with lock nuts.
So, are these adjustable? And, is this configuration better than the stamped rockers with a bolt? Thoughts, please.
So, are these adjustable? And, is this configuration better than the stamped rockers with a bolt? Thoughts, please.
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They are still not adjustable. There is no way to lock the nut down if you back it off. They do make kits though, with extra tall nuts and a set screw in the middle. So you back the nut off for adjustment, and then while holding the nut you turn the set screw in the middle to lock it.
What you have are the "rail rockers". Be warned, I don't think you are going to be able to use your old pushrods that went with the newer "sled rockers" and bolt system. If you do some research, I think you will find each system takes a different length pushrod.
The deal with this whole rocker mess is Ford always needed something to keep the rocker lined up with the valve tip. These older heads you just acquired used the "rail" or a u-shaped looking rocker tip and fit over the valve tip, and kept it from walking off the valve. The newer "sled" type rocker system used a groove machined into the head, and the fulcrum fit into this groove and kept the rocker straight.
What you have are the "rail rockers". Be warned, I don't think you are going to be able to use your old pushrods that went with the newer "sled rockers" and bolt system. If you do some research, I think you will find each system takes a different length pushrod.
The deal with this whole rocker mess is Ford always needed something to keep the rocker lined up with the valve tip. These older heads you just acquired used the "rail" or a u-shaped looking rocker tip and fit over the valve tip, and kept it from walking off the valve. The newer "sled" type rocker system used a groove machined into the head, and the fulcrum fit into this groove and kept the rocker straight.
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Bummer! The more I learn the more I realize I have to learn. I'll research the pushrod length issue. Thanks for warning me, but is there somewhere you can point me to re this?
Also, I have a Motor's manual that describes adjusting the valves on the engines that had the stud/nut combo, the 260'S and 289's, and it has you set them at TDC. Wouldn't this allow me to compensate for a different pushrod - assuming there's enough adjustment range?
And, I'll research the nut issue. But, my nuts have indentions on the sides to make them locknuts. (Oddly enough, the nuts on one head spun off w/my fingers while those on the other head took a wrench.) Wouldn't new locknuts work and allow adjusting?
Also, I have a Motor's manual that describes adjusting the valves on the engines that had the stud/nut combo, the 260'S and 289's, and it has you set them at TDC. Wouldn't this allow me to compensate for a different pushrod - assuming there's enough adjustment range?
And, I'll research the nut issue. But, my nuts have indentions on the sides to make them locknuts. (Oddly enough, the nuts on one head spun off w/my fingers while those on the other head took a wrench.) Wouldn't new locknuts work and allow adjusting?
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From: Virginia
When trying to use just the nuts on these heads, they are prone to back off after awhile, and it will start clattering. The locking type with the set screw is just extra insurance that they will stay put.
Yes, the old 260's and 289's had the system like a chevy uses, and they were adjustable. Yours are not.
Yes, the old 260's and 289's had the system like a chevy uses, and they were adjustable. Yours are not.
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Thanks for the tip, Dave. Here's what I've found:
The book How To Rebuild Small Block Ford Engines (which I won't have until it arrives on Thursday, but which I read bits of on-line) says that I have "positive-stop" rocker arm studs. And, they aren't adjustable. Further, that those rockers require 8.170" push rods and heads with the stamped rocker arms use 8.180" rods.
But, the Ford Racing pushrods.pdf says rail-type rockers take 8.152" rods and stamped steel rockers take 8.182" rods.
Obviously, I don't know which is correct. But, there is a difference. However, it is at most 30 thou and at the least 10 thou. If my heads were milled slightly to clean them up, that might do it. Thoughts?
The book How To Rebuild Small Block Ford Engines (which I won't have until it arrives on Thursday, but which I read bits of on-line) says that I have "positive-stop" rocker arm studs. And, they aren't adjustable. Further, that those rockers require 8.170" push rods and heads with the stamped rocker arms use 8.180" rods.
But, the Ford Racing pushrods.pdf says rail-type rockers take 8.152" rods and stamped steel rockers take 8.182" rods.
Obviously, I don't know which is correct. But, there is a difference. However, it is at most 30 thou and at the least 10 thou. If my heads were milled slightly to clean them up, that might do it. Thoughts?
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Let's revisit this issue, please: I got both the D8 awa the D7 heads back from the machine shop. Turns out that the rocker pedestals are exactly the same height. And, the D8's don't have a channel cut in them. Instead, there's a u-shaped sheetmetal channel that sits on them.
So, I could use the later, better style of rocker by simply pulling the studs and tapping the pedestal for the bolts. BUT, the machine shop did me a favor by throwing all the rocker parts in one bag - meaning they didn't keep the mated parts together.
QUESTION: Is it worth it to do the work to convert over in order to get away from the rail rockers? When I don't know which parts go together? Even when I've already gotten the Comp Cams adjustable kit for the rail rockers/positive stop?
So, I could use the later, better style of rocker by simply pulling the studs and tapping the pedestal for the bolts. BUT, the machine shop did me a favor by throwing all the rocker parts in one bag - meaning they didn't keep the mated parts together.
QUESTION: Is it worth it to do the work to convert over in order to get away from the rail rockers? When I don't know which parts go together? Even when I've already gotten the Comp Cams adjustable kit for the rail rockers/positive stop?
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I know the guy in the book says the rail rockers can wear and knock the keeper loose on the valve, but you would think you would hear more about it happening if it was a common problem. I would check them for wear and use them. Being adjustable is more of a priority than anything else. If you have no adjustment, then you have to rely on the machine shop guy to get everything right. When the valves and the seats are re-worked, that changes the height of the assembly and the proper amount has to be ground off the valve stem so the valve lash is correct and the hydraulic lifter pre-load is about midway. Add in a possible head re-surface, and there are a lot of places to make a mistake, and you will end up with tapping lifters. With your adjustable setup, you can be sure to get it right with a little time spent turning the engine by hand and adjusting each set of valves.
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That's my thinking as well. Just wanted to hear someone else say it. Will put it together as is and set the valves according to the "adjustable valves" process. And, since that process has me stopping at TDC for each cylinder, I'll run a leak-down test at each stop. If all cylinders are in the 4-8% range I'm "in" and can put the intake and exhaust manifolds on. Thanks!
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