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058 is right on. Port matching the intake really doesn't do that much for flow, but it does do some. As long as you're careful you shouldn't have any prob's. Blend the bowls on both and REALLY open up the exhaust. It will definitely help! If you do put big valves in it you NEED to unshroud the valves in the combustion chamber. You take a head gasket and trace it's outline around the chambers. Then you blend(read:grind) the chamber almost all they way to the edge of the gasket(leave about .010 till the gasket). Only do this where the outside of the valve is. If you don't unshroud the valves then you won't get hardly any increase in flow.
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Thanks for the responses 058 and Mister460,
Based on your responses, I am going to clean out the exhaust ports, leave the intake ports alone, other than some smoothing and leave the current the valves in. I was wondering about the big step at the bottom of the exhaust port that seems to really reduce alot of flow area. How much, if any of that should I remove? Also, I remeasured the cam last night (I origianally measured the 0.050" duration at the lifter, when 0.050" is speced at the valve (duh!). 0.029" at the lifter is what I should have used for duration measurements. Anyway the intake (and exhaust) duration noe comes out around 234 deg at 0.050" (valve lift) and the total lift is 0.500 (intake) and 0.510 (exhaust). This cam isn't real high performance, but is good enough for my boating needs (cruising, skiing, going flat out every once and a while). Once I get the engine back together and the boat out, I want to try the gas peddle boost control approach (plug the pressure releases on the turbos) just to see (in small increments of course) what the engine will do. Thanks for the suggestions. Tim
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Tim, I would leave the floor of the exhaust port alone. Its already bad enough and unless someone has come up with something new that can be done then anything you do will only make it worse. Somebody suggested port plates but I've heard they only work on Cleveland heads and will do nothing for a 460 head. Personally I have never run them. As in my previous post I think the best thing that can be done to the exhaust is to raise the roof in the bowl as much as possible, cut and shape the valve guide and use a big valve. One last thing, have a cam ground for turbo application not just a shelf cam that some counterman suggests. Turbos like wide lobe seperation [114-116] and short duration on exhaust. If you want I can give you the specs on my cam.
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Just for some quick info on exhaust ports: 058 is right, raise the roof and grind the air injection knobs COMPLETELY OFF. Don't be afraid, there's plenty of iron to play with. On the floor, on the short radius turn, widen it out a good amount. Basically where the port makes the turn you want a "D" shape with the flat side of the "D" at the bottom of the port. This will help flow immensely. Port shape is just as important as port size. Probably more. Make sure you polish your chambers mirror smooth. It will broaden your torque curve and lessen the chance of detonation. If you don't understand what I'm talking about just shoot me an e-mail and I'll send you a pic.
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Is that a Turbo Kit made by somebody or did you make it yourself?
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Thanks for all the advice 058 and Mr. 460,
I am interested in your cam specs 058.
FoMoCo, the turbo setup was on the boat when I bought it. It is a PFM setup. The person I bought the boat from said it was on option on the boat when it was bought new. I unfortunately don't have any pics of it yet. Tim
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Beavertim, Sorry for the late response but I just got home from the lake. [Berryessa] The cam specs are: lift In- .595" Ex- .561" Dur. In. @ .050" 248 Ex. @ .050" 236 114 Lobe sep. The cam was done by Comp Cams Dyno shop. Grind no. FF 294-3/282-2 S14+4 The cam idles at about 750-800 rpm with about 12-14inches/vacuume makes good power to 7K+
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Originally posted by mister460:
058 is right on. Port matching the intake really doesn't do that much for flow, but it does do some. As long as you're careful you shouldn't have any prob's. Blend the bowls on both and REALLY open up the exhaust. It will definitely help! If you do put big valves in it you NEED to unshroud the valves in the combustion chamber. You take a head gasket and trace it's outline around the chambers. Then you blend(read:grind) the chamber almost all they way to the edge of the gasket(leave about .010 till the gasket). Only do this where the outside of the valve is. If you don't unshroud the valves then you won't get hardly any increase in flow.
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Originally posted by mister460:
058 is right on. Port matching the intake really doesn't do that much for flow, but it does do some. As long as you're careful you shouldn't have any prob's. Blend the bowls on both and REALLY open up the exhaust. It will definitely help! If you do put big valves in it you NEED to unshroud the valves in the combustion chamber. You take a head gasket and trace it's outline around the chambers. Then you blend(read:grind) the chamber almost all they way to the edge of the gasket(leave about .010 till the gasket). Only do this where the outside of the valve is. If you don't unshroud the valves then you won't get hardly any increase in flow.
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058,
What are you running as far as bottom end goes. I have what looks to be a stock bottom end (8.0 to 1, cast pistons/crank).
After removing the second head, I noticed a 1/4 x 1 inch piece of the piston crown missing on number 7. What was really strange was a few dings on top of the piston, but not a scratch on the head/valves. I think somebody just plunked another head on there and left the damaged piston inside.
Anyway, I was wondering what kind of boost and RPMs are safe on a stock bottom end. The Turbo system has a pressure activated washer pump H2O injection system to minimize detonation along with the original PFM intercooler. I'm wondering if a newer technology IC would allow more boost (safely). Looking forward to your response. Tim