Help me fill in the blanks.

[Kapdin]

Hey Gents, I am going to start accumulating parts for my 79 K20 single cab rebuild and I need some input from guys that have more knowledge than myself.

So my goal for this truck is solely "work truck" / "weekend warrior" / "trailer hauler". The most important to me is reliability and smooth runner and second is MPG while still having great torque.

Here is what I know I have and or getting for sure.
1. 400ci sbc out of my 77 1 ton.
2. TH400 also out of my 1 ton.
3. 35" tall tires
4. NP205
5. 4:10 gears
6. FAST-EZ multiport EFI system (so their is no question on tuning)
7. MSD Ignition Kit
8. Electric cooling fans
9. Trans cooler

http://www.fuelairspark.com/fas/ez-efir-multi-port-efi-kit-w-fuel-system-small-block-chevyhtml/

90% of the time I'll be going 55-65mph or less so that is the sweet spot I would like to have. So with the TH400 at 1:1 and 35" tires, 65mph puts my motor at 2627rpm's and at 55mph 2223rpm's.

(fill in the blanks)

The motor is (400ci sbc), The heads are (cast iron vortec heads http://www.jegs.com/i/GM-Performance/809/12558060/10001/-1), The cam is (_____), The valve train is (_____), The ignition is (MSD ignition Kit http://www.jegs.com/i/MSD/121/85551K/10001/-1), The exhaust system is (_____).

Please read and review my decisions and if you think I'm off on my decisions so far please let me know. Again money is not a huge concern but I'm more bang for buck .

 

[bucket]

Howdy dude! Haven't seen you around much lately! If reliability is the goal, I'd suggest a roller cam setup. Something mild, and not too much lift, partially because of the vortec heads.

 

[Kapdin]

Hey Bucket indeed its been a while, I finally finished my house and am moved in and settled ! (LONG time coming) Also I know for a fact you know more about building motors than me so point me in a roller rocker set up. Also I'm completely torn between headers or "Ram Horn" manifolds. Currently my Jegs shopping cart looks like this.

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[77 K20]

Hey Bucket indeed its been a while, I finally finished my house and am moved in and settled ! (LONG time coming) Also I know for a fact you know more about building motors than me so point me in a roller rocker set up. Also I'm completely torn between headers or "Ram Horn" manifolds. Currently my Jegs shopping cart looks like this.

I went with ram horn manifolds just because the cast iron they are made out of should last the next 30 years or so without me messing with them. The one drawback was the clamshell part of the driver's side motor mount will get in the way. The exhaust shop I went to knew about this and cut part of the clamshell off to provide clearance. They then welded in an extra chunk of metal to provide strength again to it.

I'd also recommend a roller rocker setup. I've had a flat tappet cam go flat and I suspect it was from lack of zinc in the oil. With a roller rocker you wouldn't have to worry about zinc or ZDDP additives.

 

[Kapdin]

Hey 77 K20, I have heard a few similar stories on the lack of zinc taking out cams but the question than arises..... aren't all sbc up till 96 flat tappet??? And if so that's still a ton of autos on the road using the same oil. I'm not arguing at all I just don't know. Also I really dig your manifolds, is their reason to believe thos give better low end power than headers?

On a different subject I already admitted incompetence on cam selection but I learn quick with research and to the best of my current knowledge with the setup I previously posted I mite be looking at way to high "compression ratio".

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[rich weyand]

The Hooker headers will last quite a while. Headers get so hot they boil out all the condensation even on a short trip. That's why tail pipes rust out but exhaust pipes typically last twice as long. Headers last even longer. As long as the vehicle is used weekly, the headers will last quite a while. BTW, those are the correct Hooker headers for the K truck SBCs.

I strongly recommend against that cam. It was designed for a high-compression engine, and is an old design with very slow ramps. It's the cam from the L-82, I think. The 64cc heads will only give you 9.5:1, which is not enough for that cam. You will have dismal torque at low rpm due to very low dynamic compression. Trailer towing will be a nightmare, and it will be a pig off the line without a 2200+ rpm torque converter. BTDT.

There are a lot of trade-offs in cam design. The issue is that compression only begins when the valve is completely closed, and the burning charge and it's pressure on the piston is dumped as soon as the valve opens at all. But you only get good flow when the valves are open .050 or more. In between .050 and fully closed, you get none of the benefit of the valve being open and none of the benefit of it being closed. So the faster you can go from open .050 to closed, and from closed to open .050, the better.

Old cam designs have a difference between the "advertised duration" (completely closed to completely closed) and the .050 duration of 70 degrees or more. Modern computer-aided cam design has gotten those ramps much faster without excessive wear or floating valves, and the difference between advertised and .050 duration on a modern cam is usually in the 40 to 50 degree range. The additional torque and horsepower that can be achieved from these faster ramps compared to old designs should not be underestimated.

Download the Comp Cams Camquest software (just google Camquest download), enter the engine parameters and try out some cams. Look at the 12-300-4, 12-235-2, and 12-238-2, for example. It's pretty easy to use, but if you need any help setting it up, PM me. You can send me all the specs on your parts, and I will program in the engine parameters and send you the data file for Camquest.

One dead giveaway: the spec for that cam says operating range 2200 rpm and up. Which means no torque in the bottom. Look for 1500 rpm and up.

 

[rich weyand]

Hey 77 K20, I have heard a few similar stories on the lack of zinc taking out cams but the question than arises..... aren't all sbc up till 96 flat tappet??? And if so that's still a ton of autos on the road using the same oil. I'm not arguing at all I just don't know. Also I really dig your manifolds, is their reason to believe thos give better low end power than headers?

On a different subject I already admitted incompetence on cam selection but I learn quick with research and to the best of my current knowledge with the setup I previously posted I mite be looking at way to high "compression ratio".

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Our posts crossed in the mail.

Added zinc is easy. One bottle of ZDDPPlus per oil change. That basically gets you back to where everything was before they took the zinc out.

That compression number looks high. But, if it's right, then that cam might work. The dynamic compression you give up at low rpm will prevent detonation, but it will come on like gangbusters as the rpm comes up. That was one of the tricks to high-compression engine builds back in the day.

I would still run some simulations and see what a modern cam would give you.

 

[77 K20]

Hey 77 K20, I have heard a few similar stories on the lack of zinc taking out cams but the question than arises..... aren't all sbc up till 96 flat tappet??? And if so that's still a ton of autos on the road using the same oil. I'm not arguing at all I just don't know. Also I really dig your manifolds, is their reason to believe thos give better low end power than headers?

Supposedly some of the TBI motors newer than 1987 could have a roller rockers. But as far as I know it finally became a standard with the vortec motors in 1996. If you were going to use the vortec heads then I figured you'd just run a roller. There is a ton of info about how the EPA has been reducing the zinc and phosphorus levels in motor oil for the last few decades. The biggest thing was making sure you have enough to break in the cam. After that is done is might survive on a normal oil. I just know I had 3 lobes get rounded off on my 400. Some oils have a higher level than others. Mobile 1 high mileage oil (for older engines) has higher zinc levels than their other types.

http://www.enginebuildermag.com/2014/08/preventing-flat-tappet-cam-failures/

I did a bunch of reading on the 2.5" ramhorn manifolds vs headers. Seems headers can make a bit more power, and most gains were above 5,000 RPM. I didn't think a small gain would even be noticeable in a 5600 lb truck. The ramhorns were cheaper and shouldn't rust thru or leak for decades. Sometimes my truck will sit for a month or two outside without me driving it (I sometimes travel a lot for work). They use a lot of salt and chemical de-icer up here also.

This was one article I read that had actual data on headers vs ramhorns.

http://www.chevytalk.org/fusionbb/showtopic.php?tid/256915/

 

[bucket]

I feel it's a toss up between ram's horns and headers. Sure, that manifolds themselves will last longer, but the down pipes and flanges often won't last any longer than a set of headers. And I seem to blow out donut gaskets more often than quality header gaskets. It could very well be extremely inaccurate, but my own personal butt dyno says long tube headers make more mid range power too.

I still think a roller cam is the way to go these days. You're risking a lot of money if a cam goes flat. I also believe roller tip rockers are a good upgrade, I think they put less wear and tear on the valve guides.