Thread: Help Me Pick Some Heads For Christmas Present

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Originally Posted by firebird77clone

Wow, it just clicked: those cool mooneyes tanks that got mounted to the front bumper: that provided positive fuel feed at launch, didn't it?
Hell, all this time I thought it was just a fad.
Not completely non sequitur: it somehow clicked when tech was advising fuel pumps.

The hot shoes mount one gallon poly cells in the engine bay these days to feed N2O systems. They run pump gas in the main tank to feed the motor and then use race gas or methanol or E85 in the N2O tank.

You can still hang a Moon tank out front, but you have to have a simple tube cage around it or a crossmember in front of it to prevent rupture and spilling fuel if you drive into the wall.

Nuck, there's another idea for the truck, a 150 shot....... Those Gen III motors adapt easily to a turbo also. Do a google search for LS turbo and you'll find a plethora of articles about them. Seems it's pretty simple to make 600 to 700 horsepower with a turbo on one.
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Originally Posted by Nuckingfuts

I'll need to crash the boards tonight to get myself up to speed on what to know and look for when evaluating a pulled motor like this (which I've never done before). Any coaching tips?

The computer is a must. I hope he includes it and maybe a wiring harness. Aside from that, it's the little stuff that kills you, the fittings, nuts and bolts, fluid lines, connectors, etc. Of course, you'll need a complete factory manual and probably wiring diagram for the year and make of the vehicle the motor came from. I understand that there are some wiring harnesses that can be bought that make the swap a snap, but like I said, all my experience has been with carbureted vehicles.

All on this board can relate to the many, many trips to this store or that store to pick up the little stuff to finish off a project.

In post 23, firebird related the way that most of us do this, to buy a running car and take the parts we need for the swap from it, then sell off what's left (body parts, glass, wheel and tires, brakes, electrical that we don't need and any mechanical parts or systems that we don't need and interior parts.

You might check craigslist for running examples with low miles LS motors in them before you pull the trigger on the engine/trans. The ideal candidate is a car that has been hit in the side or side/rear and the owner just wants to get it out of the yard.

Phone your insurance man and ask it there are any candidates that he knows of, sitting beside the house.
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Originally Posted by techinspector1

The computer is a must. I hope he includes it and maybe a wiring harness. Aside from that, it's the little stuff that kills you, the fittings, nuts and bolts, fluid lines, connectors, etc. Of course, you'll need a complete factory manual and probably wiring diagram for the year and make of the vehicle the motor came from. I understand that there are some wiring harnesses that can be bought that make the swap a snap, but like I said, all my experience has been with carbureted vehicles.

All on this board can relate to the many, many trips to this store or that store to pick up the little stuff to finish off a project.

In post 23, firebird related the way that most of us do this, to buy a running car and take the parts we need for the swap from it, then sell off what's left (body parts, glass, wheel and tires, brakes, electrical that we don't need and any mechanical parts or systems that we don't need and interior parts.

You might check craigslist for running examples with low miles LS motors in them before you pull the trigger on the engine/trans. The ideal candidate is a car that has been hit in the side or side/rear and the owner just wants to get it out of the yard.

Phone your insurance man and ask it there are any candidates that he knows of, sitting beside the house.
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Yep, confirmed that it's a complete change over with ecm, wiring harness, throttle body (drive by wire pedal assm.).
I'm definitely temped but I'll be honest, feel like I'm in over my head with the electronics side of the swap. The mechanical stuff doesn't freak me out, relocating engine mounts, cross members and such.

The cost benefit comparison of spending approximately the same amount of money on either a) swap into a modern motor/trans or b) dialing in our existing sbc is what has me seriously considering the swap. In the end we'll have spent the same but have a better set up with the swap, its just a more difficult project that will need outside support (especially the wiring and tuning).

On the other hand the voice of reason keeps telling me to keep it simple and not make too much of this first round of engine tinkering on the boy's build. The beauty of the sbc is the simplicity, ease of tinkering/understanding, and cheap parts. In the end I need to keep the mission statement at the forefront, teach the boy.

Either way he'll be learning, just need to sleep on it before deciding on a game plan that works best.

Well, it has been an interesting thread so far and I'm looking forward to contributing no matter which avenue you decide to take.
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Originally Posted by techinspector1

Well, it has been an interesting thread so far and I'm looking forward to contributing no matter which avenue you decide to take.
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I appreciate you saying that.

Honestly I'm leaning toward the LM7 for all the reasons you stated above. It just makes more sense all around.

I still need to get my head around the additional costs to complete the project swap. Just spit balling here but feel free to add to it,

1. Motor mounts
2. Cross member kit
3. Driveline
4. Fuel pump (maybe a fuel cell?)
5. Hoses, fuel lines, wiring, etc
6. Someone to do the final flash/tune
7.???

Plus exhaust.

Originally Posted by firebird77clone

Nucking: dollar for dollar, unless you have a VERY good friend with a machine shop, AND access to swap meets: buy a wrecked car with complete, good drivetrain. Scrap/part out what you don't need and break even, or maybe come out plus a few dollars. Now you're only out of pocket for the installation, PLUS you have a stock motor and no problem getting parts, or having it serviced.

Like this? I can at least drive this one home
https://inlandempire.craigslist.org/...404630474.html

That's not a bad price for the whole car. It is reassuring to hear it run. I sold my last LM7/4L60E for $1200. It really isn't a hard decision to buy an LS anymore IMO. Just look at how much a new EFI kit costs. Right around a grand or more. Then you have to build the engine or have a good one to put it on. Just a great bang for the buck all around I think.

Originally Posted by Nuckingfuts

Like this? I can at least drive this one home
https://inlandempire.craigslist.org/...404630474.html

Bada Bing, Bada Boom....
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This isn't an LS1 as the ad states, its actually a gmc envoy with an LM4 and I'm not entirely sure what trans is in this vehicle. Not a lot of info or guys using it as a swap.

Ok an update is needed. I decided to put the LS swap on the back burner until I can get up to speed on all of the little details and costs, then draw up a plan. I feel rushed with Christmas almost here and I HATE making rushed decisions.

I executed the original game plan and went with the following:

1. Summit Vortec Heads: https://www.summitracing.com/parts/sum-151124
2. Summit Vortec Manifold: https://www.summitracing.com/parts/sum-226018
3. Summit Torque Converter: https://www.summitracing.com/parts/sum-g2702-1
4. Misc gaskets

Now the question I'm trying to answer at this point is which rockers do I need? I've read up on oem vortec heads requiring self aligning rockers (SARA) for gen I sbc 350 applications and these Summit heads, under the Q&A state they need self aligning rocker arms. But with that said, I've read that some SARA encounter clearance issues with either the retainers and/or the valve covers so I'm confused as to what works. Remember I have the Comp Cam kit (https://www.summitracing.com/parts/cca-k12-238-2 )

How do I determine what rockers I need for this set up? Standard or narrow, stamped steel or roller tip??

Originally Posted by Nuckingfuts

Ok an update is needed. I decided to put the LS swap on the back burner until I can get up to speed on all of the little details and costs, then draw up a plan. I feel rushed with Christmas almost here and I HATE making rushed decisions.

I executed the original game plan and went with the following:

1. Summit Vortec Heads: https://www.summitracing.com/parts/sum-151124
2. Summit Vortec Manifold: https://www.summitracing.com/parts/sum-226018
3. Summit Torque Converter: https://www.summitracing.com/parts/sum-g2702-1
4. Misc gaskets

Now the question I'm trying to answer at this point is which rockers do I need? I've read up on oem vortec heads requiring self aligning rockers (SARA) for gen I sbc 350 applications and these Summit heads, under the Q&A state they need self aligning rocker arms. But with that said, I've read that some SARA encounter clearance issues with either the retainers and/or the valve covers so I'm confused as to what works. Remember I have the Comp Cam kit (https://www.summitracing.com/parts/cca-k12-238-2 )

How do I determine what rockers I need for this set up? Standard or narrow, stamped steel or roller tip??

These are cast iron non-roller 1.5:1 narrow-body, self-aligning rocker arms that will work with the center bolt Vortec replica heads and are manufactured by General Motors. These are available in 1.5 ratio only.....They may or may not actually be exactly 1.5:1 due to manufacturing tolerances, but you can expect them to be less, not more. In days gone by, the stock and super stock racers would go to their local dealers and buy up all the rockers they had, take them home, test each one for the highest ratio, keep the ones with the highest ratios and return the rest of them to the dealer. Heck, they might still do that, I don't know.
https://www.summitracing.com/parts/n...5490/overview/

Here is a 1.5:1 ratio aftermarket narrow-body, self-aligning aluminum roller rocker, with a roller bearing trunnion and a roller tip. The roller tip is pretty much useless, as it is too small in diameter to effect a mechanical couple, but the roller trunnion could release up to 20 horsepower due to reduced friction. These roller trunnions will also reduce engine oil operating temperatures.
https://www.summitracing.com/parts/s...1035/overview/

Here is a 1.6:1 ratio aftermarket narrow-body, self-aligning aluminum roller rocker, with a roller bearing trunnion and a roller tip. Summit says that the heads you bought will work with up to 0.500" valve lift, so if you want to try 1.6 after reading Jerry's input, have at it. Your new valve lift with 1.6 rockers would be 0.493"/0.500". These Scorpion rockers were just over $200 a couple years ago, but have gone up significantly since I last looked at them. You may need help with the heads you bought, as they flow less than standard production 882 heads on the exhaust side, so you might use 1.5 on the intake and 1.6 on the exhaust. It's all up to you.
https://www.summitracing.com/parts/s...1036/overview/

With whatever you buy, check for alignment at all stations, including the pushrod to head clearance, where the pushrod comes up through the head, from valve closed to full lift. Check piston to valve clearance and shoot for minimum 0.080" on the intake valve and 0.100" on the exhaust valve, checked at 20 degrees before to 20 degrees after top dead center at 5 degree intervals, at overlap. If you use the Chevy rockers, check for pinch at the pivot to stud location. Stick a length of solder between the rocker and the stud as you roll the motor over. It's easy to see if the rocker is smashing the solder. Sometimes, a fellow will have to use a small grinder and stone to extend the slot in the rocker to prevent the rocker pinching the rocker stud. Check for at least 0.010" clearance between each of the 5 spring loops at full lift. Stud pinch or coil bind either one will destroy the cam in seconds. Here's an example of a long-slot rocker.....
http://www.grumpysperformance.com/longslot.jpg
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Good choices for the Christmas tree, Nuck!

Go to this link - https://www.summitracing.com/parts/cca-1417-8/overview/ and watch the video. It's 7 minutes well spent as he breaks down the math associated with rocker arm geometry.

You know that 1.5 will be a safe bet - 1.6 will probably be okay from a clearance standpoint, but as Richard advised, check everything. I like the solder tip a lot!

Let us know what you decide - and again, the best part of this is the time spent with your son making memories.

Merry Christmas!
Glenn

Thanks Richard & Glenn on the valuable feedback!

Now that the torpedo is in the water I'm wondering if I messed up. You've suggested that I target a SCR of 9.5:1 but with these heads on a stock sbc 350 I calculated I'll be 10.5:1 using the following variables/assumptions:

- Bore 4"
- Stroke 3.48"
- Combustion Chamber 67 cc's
- Flat top stock pistons (I'm not entirely sure what type of piston this '73 has)
- Deck Height 0.025" (assumed value as I haven't measured yet; I've read that stock height ranges from 0.023"-0.025")
- Head Gasket Thickness 0.015" (again I'm using this value based on the assumed stock deck height and if I'm looking to achieve a total quench of 0.040")

Have I put myself in a pickle??

EDIT: After some digging around I believe this year sbc came with dished pistons but I'm still trying to nail down the cc's as I've read anything from 12-16 cc's. If this is the case, and I use 12 cc's dished for example, then that brings my SCR to 9.22:1 using the same variables above. I guess I really need to crack the motor open to see what I've got. I think I'm going to pull the motor/trans out to work on since we wanted to paint the engine compartment (and repaint the engine block & trans).

I think the LM7 was only a couple years so numbers are down and also it was alum instead of cast iron 5.3