1966 GMC P1000 (C10) Build

Bdsankey

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Well the time has come that my wife and I finally picked up one of our dream projects (we initially wanted a 58 Apache but those are insane in price) for a deal that we would've been fools to pass up. It is a 1966 GMC P1000 (C10) with 66k original miles. With it we got a NOS rear GMC tailgate, NOS grill/headlight bezels, reproduction header panel, 99 6L/4L80e (iron heads) with some valvetrain goodies to throw in it. Are there any better/more user friendly swap kits/parts available than what I have listed?


The plans are to get it running/driving first then work on the exterior of the body.

Engine Swap Plans - Subject to change but this is what I've found thus far
1) Holley or Dirty Dingo engine mounts (leaning dirty dingo as they're a slider and allows me to use the nice and cheap speed engineering long tubes)
2) Holley or React trans crossmember (leaning toward Holley as it offers awesome exhaust clearance)
3) Holley Terminator X Max to control everything
4) Dakota Digital RTX gauges
5) Entropy LS swap radiator with trans cooler (hopefully it's enough cooler)
6) Vintage Air heat/AC system
7) Dakota Digital digital climate control interface for Vintage Air system

Engine Plans - These are subject to change but this is what I'm leaning on at this moment in time
1) Swap on some AL heads (I have to look at what I have here, I have 2 sets but don't know the numbers on em)
2) Swap on a TBSS intake with a Holley or FAST 92mm TB
3) Holley "Blackheart" LS swap long tube headers (1 7/8) or Speed Engineering LS swap long tube headers (1 3/4)
4) BTR "Truck Norris" cam
5) Comp Cams rocker trunnion upgrade (13702-KIT)
6) Comp Cams beehive springs (26918CS-KIT, 0.695" max lift)
7) New lifters (undecided?)
8) New high volume oil pump
9) Motion Raceworks steam port kit
10) Texas Speed pushrods
11) New timing chain/gears
12) Ceramic spark plug boots
13) Holley 2 piece valve covers to hide the coils a bit

Transmission Upgrades - Once this stock-ish trans fails I will overhaul it
1) FTI or Circle D or Pro Torque converter
2) Dual feed the direct clutches
3) Jakes recalibration kit
4) TransGo AFL ream
5) Sonnax lube regulated pressure valve or drill a line-to-lube hole in the pump case/body
6) Rollerized output
7) Cheap billet input
 

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Chevy1925

don't know sh!t about IFS
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if you ever plan to add more heads and cam flow down the road, get the holley headers. then you know you got that headache out of the way.

beyond that, you pretty much nailed what id do!
 

Bdsankey

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if you ever plan to add more heads and cam flow down the road, get the holley headers. then you know you got that headache out of the way.

beyond that, you pretty much nailed what id do!

Holley it is then. The Speed Engineering seem like a nice piece and save ~$580 but that's nothing crazy. The Speed Engineering are available in 1 3/4" and 1 7/8" but state they require use of slider engine mounts (Holley mounts are not) and that I may have to grind my 4L80e case ears to fit (not a fan of that either).


The plan is get it running/driving first then start knocking down the bodywork (within reason, obviously patch the door holes to keep water out). I have no problem cutting some ply wood for a bed floor and painting it black for a year or two while we finish the body work but you bet your ass that thing will be driving next year. I will be painting the engine bay/frame/underside of the cab relatively quickly as that is a job that can't really be done in the cold. Wiring can be done in our unheated garage with a simple space heater easy enough but paint will never dry properly in that environment.


I am trying to figure out what rear axle I'd like to put under it. Currently the front already has a 5 bolt CPP disc brake conversion. I can get a disc conversion for the OEM axle but I don't know if I am better off using something newer or if this old hunk of iron will hold up to this driveline (I'm guessing it'll be sub 500hp to the tire).
 

Chevy1925

don't know sh!t about IFS
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Oct 21, 2009
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i doubt that old rear end is worth saving. wouldnt hurt to look it up though.

if you wanted to keep chevy, you could find an old truck 12 bolt and build it but its really hard to beat a 9" bought as a whole package from a shop. the amount of R&P ratios offered is absurd and they work. very likely to find parts for them too if you ever did drag week or something like that.
 

Bdsankey

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i doubt that old rear end is worth saving. wouldnt hurt to look it up though.

if you wanted to keep chevy, you could find an old truck 12 bolt and build it but its really hard to beat a 9" bought as a whole package from a shop. the amount of R&P ratios offered is absurd and they work. very likely to find parts for them too if you ever did drag week or something like that.

I certainly would like to do drag week/power tour. Any 9" shop's you'd recommend? For now I'm going to use the drums and OEM rear axle (as long as it's not hurt) just to drive the darn thing but long term it will absolutely need something else.
 

Chevy1925

don't know sh!t about IFS
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Oct 21, 2009
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These guys have always been the best bang for the buck imho. In the off road world, the 35 spline and 40 spline units hold up well. i coulda bought the 31 spline axle for my tracker for what i have in this damn 8.8. oh well

 
Last edited:

Bdsankey

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These guys have always been the best bang for the buck imho. In the off road world, the 35 spline and 40 spline units hold up well. i coulda bought the 31 spline axle for my tracker for what i have in this damn 8.8. oh well
If you were sending a link it didn't attach/post.
 

1FastBrick

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Dec 1, 2016
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Junkyard
Stay away from the Comp Cams Rocker Trunnion retrofit.

Personally I would look elsewhere for springs too... BTR and Texas Speed have good spring kits with titanium retainers for less money.

For Lifters, At least a Morel drop in, If not Johnson's. The only issue with Johnson is they just stopped production earlier this year on there standard lifters and you can only get there lifters with the axle oiling feature which makes them more expensive... If you use standard roller lifters, Get New Genuine GM trays only!!! The Generic ones will fail...


Push rods, Wait to order them till everything is assembled. Lifters will affect this. If the heads or block are surfaced this will affect it it also. Every one always tries to cram 7.4 lengths in there cam and spring packages. The factory push rod is like 7.38 ish and depending on the combo of parts you may need 7.375, 7.350, or even as low as a 7.325 to achieve proper Preload like in my truck with milled heads.

Since you will be replacing the heads with Aluminum, I would go with a 243/799 head if you have it. If not, A 317 would work as a replacement but I would mill them from 71CC down to 68CC to get the compression up a bit.

As for the Oil pump, You only need a standard replacement pump. A regular M295 will work just fine.

Timing chain. Personally for the money JP Performance or the Rollmaster Billet Single Roller Timing set. The both feature a billet gear set and an IWIS chain as well a a Torrington bearing were the cam sprocket rides the retainer plate. The whole kit is just over $100.
 

Bdsankey

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Feb 1, 2018
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Neenah, Wisconsin
Stay away from the Comp Cams Rocker Trunnion retrofit.

Personally I would look elsewhere for springs too... BTR and Texas Speed have good spring kits with titanium retainers for less money.

For Lifters, At least a Morel drop in, If not Johnson's. The only issue with Johnson is they just stopped production earlier this year on there standard lifters and you can only get there lifters with the axle oiling feature which makes them more expensive... If you use standard roller lifters, Get New Genuine GM trays only!!! The Generic ones will fail...


Push rods, Wait to order them till everything is assembled. Lifters will affect this. If the heads or block are surfaced this will affect it it also. Every one always tries to cram 7.4 lengths in there cam and spring packages. The factory push rod is like 7.38 ish and depending on the combo of parts you may need 7.375, 7.350, or even as low as a 7.325 to achieve proper Preload like in my truck with milled heads.

Since you will be replacing the heads with Aluminum, I would go with a 243/799 head if you have it. If not, A 317 would work as a replacement but I would mill them from 71CC down to 68CC to get the compression up a bit.

As for the Oil pump, You only need a standard replacement pump. A regular M295 will work just fine.

Timing chain. Personally for the money JP Performance or the Rollmaster Billet Single Roller Timing set. The both feature a billet gear set and an IWIS chain as well a a Torrington bearing were the cam sprocket rides the retainer plate. The whole kit is just over $100.
Already got the comp stuff here, came with the truck. Same with pushrods.

The rest I 100% will look into. Hopefully I have some 243/799 here as I know they seem to be pretty darn good on these engines.
 

1FastBrick

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Dec 1, 2016
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Already got the comp stuff here, came with the truck. Same with pushrods.

The rest I 100% will look into. Hopefully I have some 243/799 here as I know they seem to be pretty darn good on these engines.
Because people only look at flow numbers and for a stock cathedral head, they have the highest flow numbers. Doesn't mean you can't make any of the other heads flow the same though... People used to junk the 706/862 heads until Richard Holdner showed them making more power on a stock 6.0L But most people fail to look at the whole combo like what the compression ratio is with a 61 CC chamber. Vs the 71 CC on the 317 heads....

If I remember correctly, it goes from stock 9.5:1 with a 71 CC to around 10.5:1 with 61cc...
 

Bdsankey

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Because people only look at flow numbers and for a stock cathedral head, they have the highest flow numbers. Doesn't mean you can't make any of the other heads flow the same though... People used to junk the 706/862 heads until Richard Holdner showed them making more power on a stock 6.0L But most people fail to look at the whole combo like what the compression ratio is with a 61 CC chamber. Vs the 71 CC on the 317 heads....

If I remember correctly, it goes from stock 9.5:1 with a 71 CC to around 10.5:1 with 61cc...
I’ll see what heads I have and report back. Anything’s got to be better than the iron heads on it.

Now I have to find a TBSS intake, a FAST LSXR102 is real pricey. It makes more power but not lightyears more than a TBSS.
 

Bdsankey

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CHE trunnions are highly recommended in the corvette world. https://www.cheprecision.com/part/trunnion-kits/ The Compcams ones fail at an alarming rate from all Ive read.
Well poop on the comp cams trunnions, I paid $150 for em as part of the package.

You can find 243/799 takeoffs on Marketplace pretty regularly.
I'll see what I can find! Hopefully that's what I have here and I can just have them gone over/through.

You could always go LS6/later LS1 intake if you cant find a TBSS.
I just snagged a loaded TBSS intake in great shape for $120 (manifold, DBW tb, injectors, fuel rails). Now I need to decide if I am truly going Holley or if I'm going to try using the OEM ECM/make a harness.
 

1FastBrick

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Dec 1, 2016
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@1FastBrick, is there a downside to running the Melling high volume/high pressure other than the few dollars between them? Or even the GM high volume?
Sorry I missed this. I personally have not tested it, but I suspect there is more oil vapor whipping around inside the motor. With the LS having such short valve covers, alot of people find they need to run a catch can to reduce the oil being sucked through the PCV system.

The standard replacement M295 will put almost nearly 50-60PSI at idle and upwards of 80PSI in an Iron block with stock like clearances. I typically Port the pump openings so there is no sharp edges and you can shim the Pump relief with some small washers to increase the relief bypass pressure.
See attached PDF it covers the mods on an OEM pump but the same principals still apply.

Some claim you can pump the Oil Pan dry under heavy acceleration with high volume in an application that doesn't require it. But From What I understand that's Physically impossible and it's more probable that its introducing to much Air. The bubbles can not dissipate fast enough and you get cavitation. The oiling system in the block has alot of sharp edges.

Good deal on the intake score.

And the CHE is one of the best rocker arm conversion kits on the market. Have yet to see 1 real actual failure unlike every other kit on the market. I have them in my daily driver as well.