'65 GMC 1500 project. From the Netherlands

[Prowbar]

Thanks for the pictures, Ed. That is not the typical Sun tach I've seen in other 60-66 trucks. You're making me want to cut a hole in my dash

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First I'll have to get the thing converted.

[Prowbar]

Good news! Delta Cam (finally) finished the camshaft!

This is the custom grind that I wrote about earlier. Reground lifters are also on the way!

Hope to have camshaft here in about 1.5-2 weeks.

Fingers crossed...

I'll tell ya, when I have that bumpstick in my hands, that thing is going into the engine ASAP

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[Prowbar]

Received the reground lifters yesterday. They are very nicely ground and then polished with ceramic media, resulting in a very nice finish. The correct radius has also been ground in, if you put two lifters with the faces against each other you can rock them back and forth. Thank you very much, Steve.

Also installed the missing gun rack. The holes were there, and I like the touch as a firearms enthusiast. Just something an old pickup should have. Can't drive around with guns in the rack though

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Need to remove that duct tape in the cab, but it is stubborn stuff... Been on there for years.

Also did some mocking up to check all the carburetor linkages. Made a steel fuel line as well. The fuel filter is placed between the frame rail line and this steel line. This prevents the gas in the filter from boiling and flooding the carburetor. I had problems with this in the past.

[Prowbar]

Here are the modifications to the 305 manifold. I received the Mr. Gasket adapter. To clean up the gasket surfaces I fly cut them on the mill.

I then opened up the manifold to match the adapter opening. I also radiused the edges of the manifold where it transitions into the runners. It is easy to rough in with the carbide burr, then followed up by a shoeshine motion with a thin strip of sandpaper to dress the edges.

Both modifications should aid in flow tremendously.

As you can see I also installed the block-off plates for the heat riser. They are a light press fit.

Also got new 73 jets for the Holley from a local guy, he had a set of Holley jets. Said I could come back if I need another size.

I have plenty of hood clearance now, but I don't like the look of the stock Impco mixer filter. Toying with the idea to adapt a 1-inch or more dropped base air cleaner adapter on the mixer and use a 14x4 or 5-inch filter to correct the proportions.

The camshaft is on the way, hope to avoid any unnecessary customs intervention so I can install it ASAP.

[James]

Originally Posted by Prowbar

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I then opened up the manifold to match the adapter opening. I also radiused the edges of the manifold where it transitions into the runners. It is easy to rough in with the carbide burr, then followed up by a shoeshine motion with a thin strip of sandpaper to dress the edges.

Both modifications should aid in flow tremendously.

I had done the same modification to my intake manifold that you had done for the carburetor flange. However I did flow testing with a head on a flow bench, intake manifold bolted to it, and a Holley carburetor on top of that. The result that I had found is the center cylinders did not flow as much as the end cylinders. However with the stock carburetor all of the cylinder flow about the same (and flow alot less than the Holley). The center intake runner make a sharp turn toward the cylinder. To resolved this, I removed the runner divider between 3-5 and 4-6. Now with the Holley all of the cylinders flow rate are close together.

The other reason I'm improving the flow was I modified the combustion chamber and intake port to improve the air flow and cylinder swirl. Before there was no swirl. Now with all of the modification I had improved the overall flow rate by 10 cfm at .450" lift and the swirl inside the cylinder is 900 rpm at .450" lift.

[Prowbar]

Now that you mention that about the runners, James, it reminds me of an old post where you posted some pictures:

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Post 6.

Looking to do the same thing to my manifold, since you've proven it works.

Curious how you removed the divider. Just roughed it out with a carbide burr from both sides?

Also curious about your head porting work. I figured the stock ports should produce some swirl, but apparently, they do not. 10 cfm is a nice gain though. Was that with a 3-angle valve job?

[James]

Originally Posted by Prowbar

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Looking to do the same thing to my manifold, since you've proven it works.

Curious how you removed the divider. Just roughed it out with a carbide burr from both sides?

Also curious about your head porting work. I figured the stock ports should produce some swirl, but apparently, they do not. 10 cfm is a nice gain though. Was that with a 3-angle valve job?

I used a 6" length carbide burrs and worked it from both ends. I have this intake on my truck now. Road testing it I can pull a steep hill and still have power to accelerate up it. Before I would slow down. I'm planning on placing my truck on a chassic dyno to compare to the stock pull (stock carb, intake manifold, and breather).

First off I have not had the time to see what the results will be from this point on, life happens. All of the work that I have done so far was over a year ago. And I been wanting to get back to finishing it.

In the intake port valve pocket I reshaped the short radius, and some smoothing of the port. After a 3-angle valve job I made sure the transistion from the port to the bottom angle was smooth.

As far as the swirl, I had bolted my flow bench adapter onto the head and scribed the bore onto the head opposite side from the sparkplug. It basically convert the sharp edge (that shroud the intake valve) from the edge of the cylinder to the top of the combustion chamber into a ramp. Making a smooth transistion. The only major problem with this is it lower the compression ratio. There is two processes I will be performing to help bring the compression back up:

1.Cutting the head deck and the block deck. I believed the decks is thick enough not to cause an head gasket sealing problems. Will also need to make sure the block head bolt holes is fully tapped and clean to allow the bolts to go in without bottoming out.

2. Then I am going to offset grind the crankshaft from standard to .030" under to increase the stroke. Then mill the top of the piston to get the deck height back to zero, this will remove most of the dish from the top of the piston.

Both processes should raise the compression to approx. 9:1, hopefully or close to stock.

On another note: Doing the same thing on the exhaust valve (but on both side of the valve) will improve the exhaust flow by 15 cfm, with an open exhaust port. Not able to test this with the exhaust manifold bolted on because the flow bench is in the way.

[Prowbar]

Thanks for the reply, James. Time to rework the intake... Seems you gained some hp and torque performing those modifications.

Hope you get around to performing the dyno testing, would be interesting to see. A dual exhaust would also help in your case I would think.

I did the same as you to the 478 heads. The short side was a sharp ledge going transitioning into the valve seat area. I radiused it. Also added the 3 angles.

I like your idea, but how much do you need to take off of the deck to get rid of the dome in the piston? The offset grind sounds good but a lot of work. Then you run into the intake manifold and water cross-over fitment problems...

[James]

Originally Posted by Prowbar

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I like your idea, but how much do you need to take off of the deck to get rid of the dome in the piston? The offset grind sounds good but a lot of work. Then you run into the intake manifold and water cross-over fitment problems...

I hoping to get about .020"-.025" longer stroke, so the piston will move up .010"-.012" higher in the bore. I facts you might not need to mill the piston if the head gasket thick enough (.055" stock thickness) and it would raise the compression ratio, currently the stock piston deck height is 0.00". I've seen other engine with a piston deck height above 0" because of the gasket providing clearance. They did this because they needed more space for the top land and using a short piston pin height.

The intake flange on the head will need to be milled to allow the intake manifold to sit properly. This way the heads and intake manifold can be swapped with another block.

[Prowbar]

Got the camshaft in Saturday! Delta did a good job, but the results ticked me off a little at first as they measured them as a hydraulic camshaft. Therefore the opening and closing points have to be taken at the 0.012" and 0.018" lash settings. Seems they had a core with a little flattened intake lobe, as the intake lift isn't as high as I hoped it to be. I believe the stock rockers are 1.5 as opposed to 1.73 which is written down. We'll see how it runs.

Anyway, this probably being an earlier cam(?) it has very small oiling grooves for the heads. I milled them out and also increased the oiling duration to the heads. I am a firm believer that this is better for the engine and positive valve seals. I will try to bleed the trapped air from the rocker shafts when priming the engine by loosening one of the end bolts.

The camshaft and reground lifters have been installed since.

I am also modifying the intake manifold as per James' instructions to remove the 1-3 and 4-6 dividers. It is a hassle to do, but should provide equal flow to all runners. Should have gotten a Magnum manifold, since it already has the dividers removed. But it would have to be imported and freight will cost me an arm and a leg. Anyway, hope to fire her up this week.