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stock 782 vs the stock 655 8v heads

23K views 115 replies 28 participants last post by  Glhs60 
#1 ·
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This head I was told by Gary D flows less than a 782 at low lifts and therefore sucks. Clearly I wasted a lot of time on that BS. The 655 starts pulling away from a 782 at .100" lift on the intake and .200" on the exhaust.

On the being fair factor the 655 was machined 10 years ago and has the single angle cut seats and valves. The 782 in question has the muilti angle grinds and seat hone that is standard today.
 
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#3 ·
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Here we have the POS 782 head complete with muilti angle seat and valve grinds rebuilt with no casting marks on my flow bench. Woohoo, no wonder there isn't a power difference most of the time between a 1 and 2 piece stated by people. The head flows worse than the intake. The way it should be though, an intake should always flow a little more. This wasn't even a fair baseline, it had things working in its favor and still dropped the ball.:(
 
#4 ·
Thats funny, I was running a ported 655 head on my CSX which I purchased on ebay and everyone over on turbo mopar told me that head was junk and only an idiot would try and port one. I just sold it to pay for a LWP 782 head.
 
#5 ·
87OmniT2 said:
Thats funny, I was running a ported 655 head on my CSX which I purchased on ebay and everyone over on turbo mopar told me that head was junk and only an idiot would try and port one. I just sold it to pay for a LWP 782 head.
The LWP is going to really out flow a stock 655. Extensive shaping and adding of matterial to a 782 vs a simple port job the 655 needs will make an expensive 782 work better. For most people the garage port job will take very little time to do. Then comes intakes. Port and polish a 2 piece and it kills 15 CFM on my head. If a lone wolf head really flows 30 CFM more than my head great, but if you stick a factory modded intake on it it will turn into a that flows no better that mine. The 2 piece can be opened up height wise in the runners to get air past the injector, but only if it is on the 655. I'll see pretty soon the results, But on my flow bench the ported 2 piece dropped flow to 166 per port. If I can get it up to 175 or 180 on a 655 it won't, matter how much CFM the 782 runs over the 655. The 655 would do better because of a better intake, not because it does better by itself. When you buy the LWP head be sure to add the $500-$600 more for the intake or you won't be able to use it.
 
#6 ·
The Pope said:
The LWP is going to really out flow a stock 655. Extensive shaping and adding of matterial to a 782 vs a simple port job the 655 needs will make an expensive 782 work better. For most people the garage port job will take very little time to do. Then comes intakes. Port and polish a 2 piece and it kills 15 CFM on my head. If a lone wolf head really flows 30 CFM more than my head great, but if you stick a factory modded intake on it it will turn into a that flows no better that mine. The 2 piece can be opened up height wise in the runners to get air past the injector, but only if it is on the 655. I'll see pretty soon the results, But on my flow bench the ported 2 piece dropped flow to 166 per port. If I can get it up to 175 or 180 on a 655 it won't, matter how much CFM the 782 runs over the 655. The 655 would do better because of a better intake, not because it does better by itself. When you buy the LWP head be sure to add the $500-$600 more for the intake or you won't be able to use it.
Im gonna play around with making my own intake. Ive got a one piece cut apart now and I plan on porting the runners not that the top hald of the plenum has been cut off. I will then enlarge the plenum substantially and TIG weld it all back together. We'll see what happens.

My 655 flowed 181/131 @ .500" The LWP head will hopefully be flowing 190's/178 @ .450" So, yea....there wont be any comparison. But it cost a few bucks more than the old ported 655.
 
#7 ·
87OmniT2 said:
Im gonna play around with making my own intake. Ive got a one piece cut apart now and I plan on porting the runners not that the top hald of the plenum has been cut off. I will then enlarge the plenum substantially and TIG weld it all back together. We'll see what happens.

My 655 flowed 181/131 @ .500" The LWP head will hopefully be flowing 190's/178 @ .450" So, yea....there wont be any comparison. But it cost a few bucks more than the old ported 655.
I haven't seen anyone sell a completely port big valve 782 for less than $1,500 done right. A guy could port a big valve 655 for $600 out the door and make money. In fact I could do 3-4 655 heads in the time to do one 782 right, and thats just cutting. The guys adding matterial and flow benching during porting have to really be spending time. A few bucks?
 
#9 ·
The Pope said:
I haven't seen anyone sell a completely port big valve 782 for less than $1,500 done right. A guy could port a big valve 655 for $600 out the door and make money. In fact I could do 3-4 655 heads in the time to do one 782 right, and thats just cutting. The guys adding matterial and flow benching during porting have to really be spending time. A few bucks?

Mine is a stock valve 782. My 655 was a big valve head. The LWP stock valve will out flow the large valve 655 though.

What makes the 655 so much easier to port?
 
#12 · (Edited)
87OmniT2 said:
Mine is a stock valve 782. My 655 was a big valve head. The LWP stock valve will out flow the large valve 655 though.

What makes the 655 so much easier to port?
for starters there is no real combustion chamber work other than to polish a bath tub head. Then comes the massive intake port cutting on the 782. The 782 port gets 3/16" wide from gasket to bowl. Then it is raise 3/32" at the gasket to .300" at the guide, at that point your using straight edges to make sure there is no wave in the walls or the roof. Then there is measuring constantly to keep each runner exactly the same size, which you must do when making a huge cut and change in port shape. I use a caliper to check depth within .01" of each other and the same on the floor. I get the last .05" with 120 grit roles. Then when you get the seats done the machine cuts the combustion chamber and leaves a bump in the angle cut you have to take out.

The 655 needs the gasket matched on the exhaust which is a big cut but easy. Then the intake gets blended, removing the bumps and smoothing of edges. The intake is large enough that you don't make it really any bigger. Both will get very little in the bowls as well. My tool cuts 1/8" deep per second with aluminum so even the exhaust is a "quiky". The head just doesn't need much, less than most any other head needs. In fact porting wise I am going to do about the exact same thing to the 655 that I do to Edelbrock 440 RPM heads.

I would like to get the Powre Lynz tool and cut the intake. Big companys like Indy and others use this to create a boundry layer in huge ports. The air that is on the edge or the port is dead and slows flow, thats why polishing creates CFM. The Powre Lynz tool can create a boundry layer of air. This is like adding grease for the air to slide on that makes the port, from the airs eyes smaller and slicker. Some of there cuts are extreme. I want the CNC lined look which is very mild cuts to a polished runner. Again just on the intake but I think it is a good idea on the 655
 
#15 ·
#16 ·
Brian Putman said:
That's the way the ports look on my 445 casting, except probably a little larger still. I know my exhaust ports are larger.
The head pictured is stock all the way around ... never been on a block. When I got it, the size of the intake ports really surprised me. I don't think that the 445/287 intakes are this big .... the exhaust ports are bigger like you noticed.
 
#17 ·
puppet said:
The head pictured is stock all the way around ... never been on a block. When I got it, the size of the intake ports really surprised me. I don't think that the 445/287 intakes are this big .... the exhaust ports are bigger like you noticed.
Stock they are not. I did a ton of work on a 445. Check out the pictures on the post (782 with the intakes bolted on).
 
#20 ·
puppet said:
Heh, not your head ... the one I linked to. That's stock size 655 intake ports.

Edit: Looks nice Brian. What are you using for an exhaust manifold? ... those ports are huge :)
A ported TU header for now, driving an SC6152 turbo. I have plans for a tubular. I really couldn't get the flange on the TU header as large as I would like. I like for the flange to be a little larger than the exhaust port for anti-reversion.
 
#21 ·
It's starting to run really good. I should be knocking on the door of 100mph in the 1/8th on pure street tires (not DR's) next year. I was already hitting 90mph with the boost staged to 20psi and with a mild tune. I have been tuning it for 28psi here lately. BIG difference!!!
 
#25 ·
no extra ones. They are a bone yard find. Some people still have them lying around. Cindy had a couple some time ago, might see if she has one to sell at FWD. The 655 uses all the same stuff the 445 and 287 G castings do, valve springs so on. Some machine shops have them in old stock, my machine shop had mine for over 8 years collecting dust. They only fit the 81-82 cars because of the port size. I got lucky on one of my castings, brand new in a Mopar box, been waiting for big valves its whole life :thumb: I also got one off Ebay pretty cheap too. They're out there.
 
#26 ·
I this sneaky feeling you got that one of puppet, if you did, I will have a monkey throw poop towards your general direction. j/k. For the magnum springs and ls1 titanium retainers, are they interchangable between swirl and g-head? I will have to give Cindy a call again tomorrow and see if we can make a deal for for my complete t3 head with good cams for a 655 head and some parts. Yes I know I am nuts for dumping the t3 head, I just want to tangle with the import boys with a 8 valve.
 
#28 ·
Cindy said she sells crane springs, I believe they are conical too. Why buy Ti retainers? The stock steel ones weight nothing, there is really no need.

The wolves will after you about the T3 head soon, they haven't seen the post yet lol. Much is still pretty cheap and easy with an 8v. You need to spend a grand on a T3 before it is safe to drive anywhere. The need at least +20s, T2 injectors to 100% stock sucks. The lifters need to be changed right when you get one, or a rocker can fail and destroy the top end. The head needs to be plugged on the end so water doesn't squirt out, then add aluminum plugs. ARP studs and Cometic MLS gasket. Lastly I would drive around the block without changing the timing belt, oil pump and oil pump pilot shaft that strips out.

In the end you need to rip the engine out and rebuild the whole thing and up grade it to drive it.
 
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