PROJECT: How would a Chevrolet dealer build a shop truck in the early 1970s?

[mattfranklin]

Here's what I'm thinking...

I love stock trucks. I love radically modified trucks. I love the middle ground, too.

Suppose your local Chevy dealer were to build a shop truck in the early 1970s, with mostly stock parts. What would it look like?

I'm thinking it would have a '70s 'Vette LT-1 and Rally wheels. And maybe a Muncie 4spd. It would be minimalist. Maybe it would get a disk brake upgrade by swapping in '71 truck parts and convert to five-lug bolt wheels?

I think my project will be in the spirit of that, but not necessarily to the letter of the law. For example, my budget doesn't allow me to get an original LT-1, but I can follow the specs. Instead of the Holley 4150 with 780cfm, I'd use the 770 Street Avenger (which is basically a 4150 with 770cfm). I can find some 2.02 heads. I can copy the cam specs. I might keep my Sanderson short headers or look for the 'Vette model of rams horn exhaust manifolds. Maybe in the future I'd look for a somewhat correct set of valve covers and air cleaner. If I can find the correct intake manifold inexpensively, that would be cool, otherwise, my existing Edelbrock Performer will be fine. And I might allow it to have 2" drop spidles, though those would not yet have been available. ;-)

BOTTOM LINE: Kind of stock, but with parts that would have mostly been available off the dealer's shelf in the early '70s.

Maybe it would have a clean '70s vintage door logo from a performance-minded dealership. Maybe Yenko, maybe something else. Maybe it would have something from long-gone rural dealership.

Anyway, that's my vision. This build will probably go slowly as I'm on a budget.

[mattfranklin]

Put on a new Holley 4150 today (Holley P/N 0-083770), taking me one step closer to LT-1 specs.

It idles much better than that cobbled Rochester ever did. No adjustments needed. I still need to find a good 12v source for the electric choke. And I need to install a new throttle ball (also known as a ball stud) because the 5/16" one from my Rochester didn't fit -- it's cobbled right now, using washers and the big hole of the Holley arm, just to help it amble around the driveway. I've ordered a throttle ball kit so I can get the proper 1/4" stud screwed into the proper 1/4" hole of the Holley arm.

I learned that the cam I need is the 3972178 (or the '178 for short) to get the valve action and valve sounds of an LT-1. But that may have to wait until the engine gets a full rebuild.

One small step every weekend.

[BMERDOC]

Lets see some pics and inspirational photos!! Sounds like a good idea to me.

[mattfranklin]

The truck has been on the back burner while the kids and I built a go-kart. But I almost ordered a Grant Walnut steering wheel today (trying to clone the 'Vette teak look on a budget).

Still thinking about new tires. I really want to keep the same size front and rear. Current thinking is to go with 255/60/R15 like the existing fronts, because the 255/70/R15 rears just seem too tall with the current ride height. I'm tempted to go wider, but the prices start kicking up pretty quickly the wider you go.

[mattfranklin]

Removed the old choke heater and electric choke hardware. Installed the block-off, Edelbrock 8901. Unfortunately I had neither the right choke coil spring nor the right linkage. With each incremental step of engine upgrade I'm trying to replace things with the 1970 LT-1 spec parts. I think this step won't be good until I replace the Edelbrock Performer intake with the right stock part. Unfortunately, eBay thinks those manifolds are made out of gold. I'll keep looking. And in the mean time, I'll patch together a divorced choke setup functionally equivalent to that of the LT-1, if not yet with the proper part numbers.

BTW, if anyone has part numbers and/or close-up pictures for the carb/choke setup on a real 1970 LT-1, please post. I thought the parts pictured would do it, but it's looking like I didn't know what I was doing.

[mattfranklin]

Since the choke conversion hit a dead end I shifted to the steering wheel downgrade. The PO had put in a 13" wheel. It looked pretty good, but this is a truck. With wide tires. That sometimes (always) lose air. And no power steering. I found one on eBay a couple of weeks ago and won it for around $140. Pretty sure it's a reproduction. It's in perfect shape and has no GM part numbers. I would have preferred a real stock one in this shape and price, but that's probably impossible. Anyway, I'm happy with what I got.

It needed doing because my plan is to restore it in a stock direction, except for the LT-1 motor and wheels/tires, so this was an obvious step toward that eventual goal. My memory is just not that great anymore to remember what got modified and which spec I'm following. Stock is stock and easy to remember -- and easier to find proper parts for.

[67_C-30]

I like the direction of this build! I look forward to see it come together.

[Bomp]

I'll jump in and follow along.

[mattfranklin]

Hey, thanks for the interest!

To get my carb and choke straightened out, I stumbled across the key number 4555. It may not sound like much, but that's the version of the Holley 4150 that was in the LT-1. Armed with that secret code I found quite a few close-up photos and even a conversion kit that will (I think) give me the right linkages to make an original LT-1 style divorced choke work.

The new challenge is to figure out which way to take the fuel pump. To fit the stock LT-1 fuel line exactly, I need the Vette fuel pump and 90deg 1/4"NPT to 3/8" inverted flae adapter . Unfortunately, that pump is taller to include the vapor separator and fuel return system. I really don't want a *return line* going back into my in *cab* fuel tank. And a more standard pump might not fit the line. I'm waffling right now between just capping the return line and putting in a normal height pump without the return. In one case I'd be going against the original engineering by capping the return. I'm trying to rationalize this by saying that there was a lot more vapor pressure in 1970 gasoline than now, so I might get away with it. Some of the guys in the Corvette forums are doing that. In the other case, I'll have to modify the fuel line. That goes against my self-imposed rule of using only stock fitting parts. If I'm lucky there may be enough slack and flexibility in the fuel line to just use a more standard pump. If I'm unlucky I'd wind up kinking the line and having that 90 deg adapter not fit.

[67_C-30]

This is just an observation here, but if the carb is modern and the engine has HEI, why sweat the all factory fuel line thing so much. A zinc plated carb with glass float sights isn't ever going to look like an original LT-1 carb, so I'd just go with the best way to get it going. I'd buy a '67 Z28 302 fuel pump and let it ride. They have no return line, will perform as well as the stock LT-1 pump. I've been using these on street/strip engines for years, and and used them on hotter engines than the factory LT-1 ever was.

Just my humble opinion on it!

[mattfranklin]

Good point. That may well be what I wind up doing, but I was thinking of ways to minimize exceptions to my stock-only rule. Out of curiousity I checked on the proper part number and date code matching carb for this combo: $700-1400. And the real distributor is around $1,300 -- yikes!

For the most part I'd like to walk into my local Napa store and ask for stock parts and get what I need without extra cutting or bending.

But thanks for the feedback, that may well be what I do.

[Mister-B]

See if you can find one of those original step bumpers that has the dealership name stamped in the front lip. Then, find some original dealer license plates to the same dealership (or have some made), get original vintage license plates from the era. Restore the rest of the truck to stock, and then put some of those paper floor mat covers with the shoe imprints on, and call it a day lol.

[mattfranklin]

Hey C30, I just ordered the fuel line, fuel line support, and fuel pump for a 1970 Z28. So it will still be 1970 LT-1, but in Z28 trim rather than Corvette trim. Thanks for the suggestion.

MrB, if I can find one of those bumpers it would be cool. Thanks.

[Mister-B]

Originally Posted by mattfranklin

Hey C30, I just ordered the fuel line, fuel line support, and fuel pump for a 1970 Z28. So it will still be 1970 LT-1, but in Z28 trim rather than Corvette trim. Thanks for the suggestion.

MrB, if I can find one of those bumpers it would be cool. Thanks.

This thread might be helpful http://67-72chevytrucks.com/vboard/s....php?p=5718022

[mattfranklin]

These bumpers are interesting and cool in a way. But it's so hard to find bumpers that I really, really like to see on the stepsides. No wonder most guys go without. I wonder if you could cut and weld one of these to make it look really good in a stepside.

[Mister-B]

I didn't notice you have a stepside. Yeah, that makes it harder. I don't think I've ever seen one on a step side. I suppose you could probably cut and weld a fleet bumper to work

[mattfranklin]

While I was trying to figure out the choke issue, my Z28 fuel lines and fuel pump came.

The pump bolted up just fine. I was pretty quick to slip my finger out of the way and slip the pump into place before the fuel-pump plunger slid back down. In all of my decades of *reading* about small block Chevys and a few years of running one on a laboratory dyno (never used a pump because the dyno fuel tank was high mounted and the carb was gravity fed), I never realized that you were supposed to pack the mechanical fuel pump cavity with heavy grease until I actually installed one. That gap between reading and talking and actually doing is a funny one sometimes.

Unfortunately, I still don't know what I'm doing when I mess with the fuel lines. They didn't quite fit. I think the 3972110 (stock LT-1) intake must have been a high-rise manifold and my Edelbrock Performer intake manifold is not. Edelbrock says the standard Performer "A" measurement (see their A/B measurement system for more details) is 3.5", while the performer RPM is 4.2". Anyway, the Performer intake, which I have, is not tall enough, so off to Monument Auto to pick up a Mr. Gasket 1" spacer. It was a lot cheaper than the Holley, Edelbrock, or Spectre spacers, at about $25. Then I saw where it was made. I hope it fits and lasts a while -- at least until I can find a good 3972110 for less than an arm and a leg.

Oh, and I had to change a valve cover to make the fuel line fit. The Moroso tall-deck covers that the previous owner installed were just too high.

Tonight I plan to try to fit the new lines in again, this time with the spacer and see how everything plays together.

I'd better hurry up and get it driveable again. My wife's minivan has been out of the garage for a couple of weeks now and this is the rainy season.

EDIT: All screwed back together. It all fits. I'll post pics later.

[mattfranklin]

Ok, here are some of the pics...
1970 Camaro Z28 fuel pump (from Rick's Camaros).
Proper mounting bolts with captive washers (also from Rick's Camaros; for decades of Chevy small blocks).
1970 Camaro Z28 fuel line support bracket (from Rick's Camaros; added in later years to prevent leaks, they say).
1970 Camaro Z28 fuel line kit from Rick's Camaros (but actually made by and shipped from Classic Tube).

And the bottle of the aviation shellac I used to glue the valve cover gaskets to the valve covers.

[mattfranklin]

And here are a few more...
The NAPA guy said these "high temperature" gaskets were probably the right ones, although they had thicker ones as an option, too.

Cool 1970 vintage stock valve covers for the LT-1 in the Z28 and Corvette (cooler looking and absolutely necessary because the fuel lines would not clear the Moroso sky-scraper tall-deck ones).

Nice shot of the fuel lines and brass block (ordered separately), playing nice with surrounding parts. NOTE: There is a proper direction for the L-shaped tubes. The direction that puts their centerline spacing closer together and puts the brass block further from the carb worked best for me. EDIT: In looking at my pictures I see I'm missing one that shows the fuel line support bracket installed. It screws to the rear passenger side carb mounting stud and the other end wraps around the rear L-shaped tube and is fastened to itself with a hex-head sheet-metal screw. I'll see if I can put up a pic in later postings.

One more shot of the fuel line showing it routed *behind* the water pump. I believe the Corvette puts its line to the side of the water pump, so that's a difference between the Corvette and Z28 parts.

In other good news, it looks like the Weiand "Stealth" 8016 is nearly a drop-in replacement for the rare, expensive, fragile LT-1 intake. It seems like it has a reasonably-close-to-correct carb flange height and has the same divorced choke coil/thermostat mounting shape. Most if not all aftermarket intakes do not have that style of mounting for the divorced choke. And on eBay they are about a quarter of the price of a good 3972110 intake. More of a back-burner issue for now.

[jhama78]

Subscribed! Definitely a cool idea!

[mattfranklin]

Swapped out the front torched springs for the proper drop springs. Those torched springs are pretty ugly. Now 2" drop in the front so I don't over-do it. The rears were already at a 4" drop. This is in anticipation of getting new rubber for it. Here's one place where I'm departing slightly from the purist minimalist restored shop truck vision. The front tires are 255/60/15 and the rears are 255/70/15. The fronts look a little too short and the rears look a little too tall for the wheel wells. Then I swapped front and rear tires and saw that the 70s were too tall for the front and the 50s were too short for the rear. CONCLUSION: 60s will likely be best for front and rear. I'm also kind of glad that it looks best with same size tires all the way around. Some vehicles look great with a rubber rake. But on the practical side, having all the 4 the same makes life simpler. And I do like them a little wider so it will be 275/60/15 all the way around when I get money for tires.

[sduckworth13]

Do have any pictures of the truck? Just curious to see what the machine looks like.

[mattfranklin]

Originally Posted by sduckworth13

Do have any pictures of the truck? Just curious to see what the machine looks like.

Good point. I guess I don't *yet* have many "big picture" views of it, only detail shots. There's one here and I'll post a few more later...
http://67-72chevytrucks.com/vboard/member.php?u=106603

[67cheby]

sounds cool !

[mattfranklin]

Originally Posted by 67cheby

sounds cool !

Thanks for the kind words. I enjoy reading your builds.