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I've been tagging along other threads long enough, so I started my own to request help on my assembly.
Right now I'm looking to install a set of Edelbrock Performer heads that I got used from someone who had been running a supercharger, putting out I'm guessing close to 600HP. So I'm wondering if the heads need to be reconditioned. An area of concern are these dark patches on the outer regions of the two inner cylinders. Do they indicate head gasket failure, and possibly warped head? If so, should I a full valve job done, or is is sufficient to just have the heads planed?
The other head also had gas escaping from the sides and between cylinders, and both heads had valves that failed a simple leak test. Full valve job under way.
The other head also had gas escaping from the sides and between cylinders, and both heads had valves that failed a simple leak test. Full valve job under way.
Likely to find other problems there too. Just me but I'd have steered away from those heads subjected to probably too much boost.
Indeed, if I had known that the heads were so abused, I would have re-negotiated the deal. But buying used heads, I knew the a valve job was probably needed.
Heads were warped, but good now after full valve job and planing.
As I continue with my assembly, I noticed that the intake ports on the heads are quite a bit bigger than the outlets of the intake manifold. Fel-Pro 1250 on Edelbrock Performer Same gasket on Edelbrock F4B intake.
Would it make a big difference in flow to expand those openings in the intake to match the gasket? I can't port myself, in fact, I'm not sure if I can even do the port matching. So I would have to have someone do it. Would a full port add significantly to flow?
Port matching the intake would be labor intensive, if you have to pay somebody else to do this you would be dollars ahead just buying another intake that matches better. Gasket matching is never a good idea.
Port matching is just that. Matching the ports to each other as opposed to the gasket itself. Without a bore scope to see the end result after it's all torqued down, it's a crap shoot as to how it ends up on each port. If anything just take a grinding bit and chamfer the edges of the intake ports out to better fit the gasket and call it good.
I spent a good part of today checking/setting lifter pre-load; it's hard to set up the dial indicator with a magnetic base on a stable platform when the heads are aluminum. I measured about .020 to .035 with the shims that I have. Should I try to increase the .020 preloads to .030? I'll have to get some thinner shims to use with my existing ones.
OK, looks like I should leave it as-is, and change it if I experience ticking.
With roller rockers you will have some noise no matter what. More like a sewing machine noise. I have them on my 96 E150 van's 351, this is the first time I couldn't hear it, but it's got the engine cover's insulation deadening the sound. Every other vehicle I've had them on you could hear it
What I read was the preload was supposed to compensate for block and head expansion from heating up, so there is a spec for that. It's more with aluminum, such as the Edelbrock Performer I have, so I was thinking maybe I need a little more preload than the specs for iron heads.
My 87 5.0 HO with roller lifters always had a slight ticking noise, and for a short while after I installed 1.7 rockers it turned into a loud tapping before it went back to normal. If I start hearing tapping on this new build, I'll try thinner shims to see if I can get rid of it.
Got it all together today, after dealing with some leaks, got the engine running. The lifters made some noise initially, but quieted down after a few minutes. After adjusting carb for maximum vacuum and setting timing to 10 BTDC, it idles kind of rough at 700 rpm. It's pulling only 15" of vacuum, and I'm pretty sure there are no leaks.
Had a satisfying road test; whereas the old stock heads had a hard time pulling past 5000 rpm, these heads pulled right up to 6000 effortlessly, and probably would have gone past if I had not let up. I don't know how the engine will hold up much past 6000. First gear is pretty useless; trying to accelerate past about 1/4 throttle, and the open diff just spins the right tire. It does give a nice chirp fast shifting into 2nd without my even trying. So I need to install the LSD next, otherwise all this newfound power is wasted.
