74 NovaMan's 1979 Chevy Truck - LS Swap - 5/6 Drop

[SuperBuickGuy]

those work by simply tying the pairs together

[74NovaMan]

Another choice for rockers (thanks SBG) - $222.75 from a couple of sources

https://speedmaster79.com/Chevy-LS1-1.7-Ratio-Aluminum-Pedestal-Mount-Roller-Rocker-Arm-Set?page=1&fbclid=IwAR1CrRo9w9bzK3Ktf4fFu1OMtH5a_FpaIMRtXxjlwI-VhtQ2EXEfpIwyvFI

These don't need guide plates but it's not clear if they require a special bolt or if the stock bolt will work. I like these over the speedway ones.

[SuperBuickGuy]

I bought bulk AC delco off ebay.

[74NovaMan]

Seeing as I'm in the spending mood I've been looking at the last of the valve train parts I need.

Lifter options:

GM lifters from EBAY. $200

https://www.ebay.com/itm/New-LS7-LS2-16-GM-Performance-Hydraulic-Roller-Lifters-4-Guides-12499225-HL124/302718223703?epid=75243328&hash=item467b698557:g:DUQAAOSwhQJc~ndk#rwid

Summit brand lifters $154
https://www.summitracing.com/parts/sum-htlskit

Both come with new holders and the Ebay lifters seem like the way to go if they are actually GM

Rocker Options:

Summit Brand for $226

https://www.summitracing.com/parts/sum-141556

Some nice looking Speedway motors ones for $270 (once I buy the studs and guide plates)

https://www.speedwaymotors.com/Stainless-Steel-Roller-Rocker-Arm-1-7-1-0-375-Inch-LS,326882.html

For the price difference I'm leaning towards the Speedway.

On the other hand, summit is running a 10% off Summit branded stuff (got that deal on the pistons and springs).

Not really looked into pushrods yet.

As always, I would love to hear your thoughts. Thanks.

[oletrux4evr]

And there is lots of swill available out there.

[SuperBuickGuy]

same decision path as I made... 10.9 is fine if you're not going to boost it, heck you could boost it, however 9.7 lets you run swill

[74NovaMan]

Well I finally laid eyes on the other set of heads. They are 823 castings and very nice pieces. From the link SBG provided above:

"LS7 Heads - These were the first heads to bring race car quality and technology to the OEM side. Although common in the aftermarket, CNC-porting of the intake and exhaust runners is usually too costly for a factory head. Titanium intake valves and sodium-filled exhaust valves were previously unheard of in a domestic factory engine, which revved to 7,200 rpm, another anomaly for a pushrod V-8. Right out of the box, these heads have supported more than 600 hp naturally aspirated and substantially more with forced induction. The large, raised runners and 12-degree valve angle enable substantial flow that supports large cubic inches ... the large valves necessitate a 4.125-inch or larger bore"

In addition to being rectangle port intake heads (the intake I have is for cathedral port) the 4.125 inch bore requirement will not work on a 5.3.

So we are using the 706 heads and our compression choices are 9.7 or 10.9. 10.9 seems a bit much and will be kind of on the edge for boost for me. 9.7 is the winner.

[74NovaMan]

I have not been paying attention what was the reason for the rebuild? Is it getting boost, or maybe some day?

Go with the small chamber heads.

https://youtu.be/gJCT5RvPCwM

I was planning on a cam swap and found some milkshake in a corner of the passenger side head. So far we have not found a source for that as the head pressure tested fine. It may have been a head gasket issue. Teardown revealed the need for new pistons and it's snowballing from there. I'd like to leave the option of boost open since I'm so far in anyway.

[74NovaMan]

LS motors are a different animal - the same cubic inch compared to a gen 1 can live with much higher CR.... on swill, a gen 1 could run 10:1 with careful tuning. Yet the LS you can play at 11:1 without a fear. As with any motor, though, what a motor will tolerate requires a solid knowledge of the parameters (air flow, cam duration and timing, and how the fuel is put in - efi/port, etc).... the common rule back in gen 1 days was 7 or 8:1 compression on a boosted application, now? 9-10 is considered just fine.

heads..... https://www.lsenginediy.com/ultimate...r-heads-guide/
there's the numbers for each and every LS head.....the 317/243/799 all flow basically the same with the difference being the combustion chamber size

and if you don't want to read down to see the flow works on the 5.3 head (despite the smaller valve)... here's this - say you send off any of those heads to a lingenfelter or such.... the same CNC program is used to port them, to me that speaks volumes about how similar they are (and how some trolls want you to believe their version is 'the best')....

Good insight as always. Thanks again. The reading I've done so far backs up your statement above. The more I look into the different heads, the more it appears that there is very little difference at the power levels I'm contemplating (given i have this cam in hand: https://www.summitracing.com/parts/nal-12638427) and that the combustion chamber size is probably the most critical detail.

[74NovaMan]

I run 11 - 1 on the street in the wagon but not on 87 octane.
I run 9.7 -1 on the street in the truck but not on 87 octane (it has cast iron heads).
What is the truck's main purpose - you looking to kick some ass or are you going the thumper cam and flowmaster route?
Those other heads sound like a good choice for a forced induction build so if that is probable then you might consider the best combination for the future.

How much ignition lead do those LS engines like?

The trucks main purpose is summer daily driver. Before the rebuild rabbit hole I was planning in stabbing a moderately hotter cam in it and hoped for 400 hp with cam, intake, headers and tuning. The 87 octane requirement is self imposed because I believe that it will be easy enough to tune for that with the flexibility of the fuel and ignition controls. Mostly I'm tired of the ever increasing cost of premium gas over 87.

Now that I'm spending more with the rebuild, I'm looking to maximize the potential I guess. I should probably focus on building a sound 350-400 horse motor with the flexibility to turbo it later.

[Deaf Bob]

Fuel rating... 350 small block, headers, intake, cam, big coil drives fine empty on regular fuel, but with loads, I find it likes premium better.. Lugs better, pulls better..empty less downshifting as well.. I might be running too much timing..

[Russell]

I have not been paying attention what was the reason for the rebuild? Is it getting boost, or maybe some day?

Go with the small chamber heads.

https://youtu.be/gJCT5RvPCwM

[SuperBuickGuy]

I see how you are! Making me do my own research!

Seriously, I very much appreciate your input on all of this stuff even if I end up going another direction.

I'm not much into, when I don't know, googling then acting like a solid resource... If I know, I'll tell you, if I don't I won't (unless you're my wife and you ask the same thing twice... then I'll give you the same advice I give here which is "under any circumstance do not follow my second bit of advice - even if it were possible")

Here is an interesting article on stock head choices that would seem to indicate that the 706 head is a better choice when all else is equal (on an NA motor).

http://www.superchevy.com/how-to/eng...nder-head-test

Question for the gallery: Is a compression ratio of 10.9 too much for 87 octane for this motor? Is 9.7 a better target? It appears to me that the tuning available with the fuel injection and ignition that too high a compression ratio (as long as its not crazy) is less of a concern.

LS motors are a different animal - the same cubic inch compared to a gen 1 can live with much higher CR.... on swill, a gen 1 could run 10:1 with careful tuning. Yet the LS you can play at 11:1 without a fear. As with any motor, though, what a motor will tolerate requires a solid knowledge of the parameters (air flow, cam duration and timing, and how the fuel is put in - efi/port, etc).... the common rule back in gen 1 days was 7 or 8:1 compression on a boosted application, now? 9-10 is considered just fine.

heads..... https://www.lsenginediy.com/ultimate...r-heads-guide/
there's the numbers for each and every LS head.....the 317/243/799 all flow basically the same with the difference being the combustion chamber size

and if you don't want to read down to see the flow works on the 5.3 head (despite the smaller valve)... here's this - say you send off any of those heads to a lingenfelter or such.... the same CNC program is used to port them, to me that speaks volumes about how similar they are (and how some trolls want you to believe their version is 'the best')....

[cstmwgn]

I run 11 - 1 on the street in the wagon but not on 87 octane.
I run 9.7 -1 on the street in the truck but not on 87 octane (it has cast iron heads).
What is the truck's main purpose - you looking to kick some ass or are you going the thumper cam and flowmaster route?
Those other heads sound like a good choice for a forced induction build so if that is probable then you might consider the best combination for the future.

How much ignition lead do those LS engines like?

[74NovaMan]

Here is an interesting article on stock head choices that would seem to indicate that the 706 head is a better choice when all else is equal (on an NA motor).

http://www.superchevy.com/how-to/engines-drivetrain/1712-surprising-hp-numbers-from-our-stock-ls-cylinder-head-test

Question for the gallery: Is a compression ratio of 10.9 too much for 87 octane for this motor? Is 9.7 a better target? It appears to me that the tuning available with the fuel injection and ignition that too high a compression ratio (as long as its not crazy) is less of a concern.