Abby gets all the attention

[wasagachris]

5.7 Ltr - 350 C.I.D. - GM ENGINE 1971-1985 New 10067353

[slowmover]

Scoggin-Dickey has been (or still is) the "giant" in online GM crate engines. They're in Lubbock.

Try to find the HP/TQ graph on the cam in this GMPP HT-383 motor:

GM Performance Parts 12499101 - HT383 Performance Crate Engine, 340 HP, 435 ft lbs | SDParts - 1-800-456-0211

A 350 uses (needs) a slightly different cam, but this motor is the "ideal" for your application so far as the relation between compression ratio, cam lift & duration, etc. A 350 will come in lower on the numbers, but the area under the curve in a dyno graph is what I'd keep as reference in researching others. This one has the torque come on early and stay late. Flat.


http://www.chevyhiperformance.com/te...est/index.html

http://www.superchevy.com/technical/...mpp/index.html

With this kind of curve the point at which one shifts will have good recovery into the next gear (like a big block) without having to wind it out way out (as is the norm with a smallblock).

I strongly favor the vacuum secondary QuadraJet as the part-throttle adjustment makes for higher economy (vacuum readings) once the correct metering rods are chosen. This is a big deal, IMO, for a tow vehicle.

Other than that I'd really prefer a HOWELL TBI kit (which they can customize to your vehicle and use. They've been around for 25-years or more. Bulletproof. And that motor will last a lot longer.

Good luck.

.

[Colin H]

Originally Posted by Top

So, it seems the engine in my truck is near complete failure. I'm looking for a new engine. I'd like to have a 383 built (torque), but that would cost two arms and a leg, so I'm looking for a more economical crate engine that will last another 40 years.
I called the local GMC dealer. When I got the parts department, I asked what a Goodwrench 350 crate engine would cost. The noob on the other end of the line asked what it was for. I told him a 1970 C20. He replied with "Sorry, my catalog only goes back to 1982." I said, OK how much for a small block 350 crate engine? His reply, "What vehicle is this for?"

Hey Lance,
Pick up a couple of Street Rod/Hot Rod mags, there are a bunch of companies advertising in there that have all levels of small block crate motors. Pick your torque, HP & what you want to spend & away you go.
Colin

[Lance M]

Thanks for all the suggestions. I'd love to have the 383, but its just too much money. I do tow with this truck, but not enough to really need the 383. I think I'll be going with this one. This is the cheapest advertised price I can find for the 290 HP 350 crate engine. The Howell TBI kit looks like a deal too.
Time to go crack open the piggy bank.

[slowmover]

That's an easy-running high-vacuum engine good for mpg. Might be marginal for towing (as a business truck; I had this setup in a '77 Impala wagon with 3.08 non-stock gears @ 4,400-lbs). It's really more for a car than a truck, and in towing it has to work hard. In a truck, even harder without an effective rear gear ratio (engine rpm against tire revolutions).

I'd like to recommend the acquisition of the following information at present, before engine installation is done:

1] Vehicle weight
2] Tire height (and rpms per mile)
3] Rear axle gear ratio
4] Torque converter stall speed
5] Engine compression ratio
6] Camshaft specification
7] GPS check of speed against corrected rpm: 35, 45, 55, 65 mph
8] Vacuum readings of solo/unladen truck at same [corrected] speeds

Comparison of old engine and new engine will help with any future contemplated changes. (And with all ignition and fuel delivery timing). Depth of records is your friend.

The money, the power in an engine is in the heads. Air flow. In & out. The old first step in improving a motor (economy, not just hot rod) is in better head airflow specs. To take advantage of that one must have a camshaft to meet that ability and compression that can support it.

195°/202° -- .390"/.410" @ 112° duration. Part #12364050

Stock 350 8:2 Stock Ex Manifold & exhaust (dual)

Dyno TQ = 272 @2600, 283 @ 3000, 305 @ 3500

245-HP (@5k) is more likely 170-HP at the rear wheels. Peak TQ of 305 (@3.5k) may be 250. Where those numbers peak is great overall.

It's easy to swap a cam on a longblock prior to installation. Cams aren't expensive. Or, later, with a better set of heads and matched cam, make sure tire height, gear ratio, stall speed is compatible with a heavier and heavier work truck. All the above requested information must work together. Like hitch rigging, the better the info provided a builder or an aftermarket supplier the closer to ideal is met.

IOW, it can't hurt to ask around per online request forms what cam manufacturers may recommend. They will recommend something, so look up cam graphs to compare that area under the curve and look at it against your numbers (as above request). The cam in the motor contemplated has been around about 40-years.

If today your truck has 3.08 gears and you want to go to 3.54 (for those oversize tires you are running [?], IIRC, they hurt power, braking and mpg), as the truck is struggling when working for your business the above info is basic for any/all performance changes. 3.31 gears and stock sized tires might be perfect.

A single 3" o.d. mandrel-bent exhaust (no crimps) is ideal where the exit to the system is at or near the tailgate (angled at side) with a zero back pressure muffler (engine has to be tuned for this).

Someday, heavy-gauge headers (14-ga) in a Tri-Y configuration is a worthwhile upgrade with a hi-flow Y-connector for the exhaust join. It allows the engine to hang on longer when above 1,500-rpm (the optimistic number where airflow is slowed with stock manifolds), and are good for economy. Economy is best vacuum reading is highest when the engine is under load at the preferred road speed.

The old rule-of-thumb about towing is that the TV cruise at just under or near peak torque running the roads. Next to no throttle movement is needed to maintain the same headway when it is set up this way. It's also almost ideal for economy (short of an overdrive gear).

It could be that gears and tire size are changes that are of best benefit first if performance (mpg or grunt) is not what was expected. The HOWELL TBI unit is a good idea at any stage.

We're already looking forward to pics of the new motor.

.

[Lance M]

Thanks for the excellent post Ross. Lots of great information there. Hey, congrats on the new job!
The truck is a Custom Camper/20 so it has a very low gear, but I'm not sure exactly what the ratio is. It also has a Gear Vendors OD unit and headers.
The new crate engine arrived yesterday. I'm having CenTex Truck and Trailer install it for me, as I have lots of work to do at the shop. Hopefully they will be done with it by the end of next week. I need to get it broken in so I can use it to tow to the Lonestar VAC rally at the end of the month. Here is a pic for you.

[marzboy]

Originally Posted by Top

Thanks for the excellent post Ross. Lots of great information there. Hey, congrats on the new job!
The truck is a Custom Camper/20 so it has a very low gear, but I'm not sure exactly what the ratio is. It also has a Gear Vendors OD unit and headers.
The new crate engine arrived yesterday. I'm having CenTex Truck and Trailer install it for me, as I have lots of work to do at the shop. Hopefully they will be done with it by the end of next week. I need to get it broken in so I can use it to tow to the Lonestar VAC rally at the end of the month. Here is a pic for you.
Attachment 155711

Looks like fun! Reminds me of the good ol days at the pick and pull junk yards scabbing my crappy cars together. Except instead of a cherry picker I had an oak tree and a come a long.

[marzboy]

The guy that I grew up across the street from is doing this now. It was a bit of a gear head rodeo town, I miss it.

[3Ms75Argosy]

It really IS a crate! Can't wait to read about how it's doing for you! Should take about just a day to put it in?

[slowmover]

If you read around the Internet on car/truck sites some of these guys could do that during their lunch break . . after they finish eating.

[Lance M]

Originally Posted by marzboy

The guy that I grew up across the street from is doing this now. It was a bit of a gear head rodeo town, I miss it.

That is a cool dragster. "Blown Money" Sounds like some projects I know
I grew up on a farm in Iowa. My neighbor kid was four miles away and he is an accountant in Minneapolis now. The town you grew up in sounds like fun!

[Lance M]

Originally Posted by REDNAX

If you read around the Internet on car/truck sites some of these guys could do that during their lunch break . . after they finish eating.

I'd just like it to be done the right way with care and quality. Not speed and sloppiness.

[3Ms75Argosy]

Just kidding you.... for reference sake, (and contributing to my wife thinking I'm crazy), bought a '68 Dodge Powerwagon.... Not sure what I was thinking!! But, need a(nother!) project like a hole in my head.
Marc

[Lance M]

The good ol boys at Centex Truck and Trailer got the new engine installed without too many problems.

I got it back and started driving it everywhere I could to get it broken in.
Everything was going fine, except it needed some good tuning by someone that knows how to tune a Rochester Q-Jet. I took it back to Centex Truck and Trailer for the first oil change and have them do some tuning. When I got it back the next day, it was running better, but not really good enough. They did the oil change, replaced the brake master cylinder and put on new plug wires, cap and rotor. I drove away and it started burning up what I thought was some residual oil from the oil change. Well, by the time I got back to the house, oil was everywhere. I had hoped that it was a loose drain plug, oil filter or something. Nope. I took off the torque converter cover and it was full of oil.

I could see it was leaking from the rear of the oil pan gasket under the rear main seal. I tightened the bolts on the rear of the oil pan and it slowed it down some, but it was a steady drop every 120 seconds at idle.
I went back to Centex Truck and Trailer, but since I provided the parts, they weren't going to touch it. I called Scoggin Dickey and they told me that I needed to take it to a GM dealer for a warranty repair. The engine has a three year 100,00 mile warranty. I called a few of the dealers around here and they couldn't get it in to look at as fast as I wanted. This was on a Tuesday and I planned to tow to the Lonestar VAC on Thursday. Hmmm. I decided to tow up to Decatur with an oil leak and milk her along. On the tow there, it was over 90 degrees and the truck was really struggling. Getting hot, not running right, low power, leaking oil...
We made it to the campout and had an awesome time.


The tow home was better, but still not too great. It was very hot and windy. We got 9.5 MPG towing. Not too bad, but only going 45-55 most of the time.

I took the truck to Connell Chevrolet in Killeen to get the oil leak fixed on Monday. They called me on Thursday that it was ready. I went to pick it up and it was still leaking. From a different place, but still leaking. So then it became a blame game between all the parties involved for a while. So I asked the service manager why the tech would write "cleaned area and verified no leaks were present after repairs were made" if he was anything other than a liar. It seems that there was a plastic shipping plug on the right side of the block that was supposed to have a metal plug installed as it isn't used on older trucks. Interesting that it lasted in there for 700 miles then came out when at the Chevy dealer. Yesterday, they put a plug in it and I went and picked it up. No more leaks from the new engine.
I was talking with my friend Paul at Heights Lumber and he asked me how the new motor was. I told him the whole story and he said, "Oh yeah? When Mr. Curtis (The owner of Heights Lumber) put a new GM crate motor in his old Chevy pick up it was leaking from the same place!" I asked why he failed to tell me this little tidbit of information when he recommended I get a new GM crate engine. I guess he forgot that little detail. Oh well. Always learning...
I still need to find a good Q-Jet tuner around here.

[soldiermedic]

Bummer Lance.

At least it was taken care of in the end. Now get out to many rally and camping trips this summer.

Steve

[Aerowood]

Ah the infamous Quadrajet, I put one on my Willys Wagon small block Chevy. I screwed with it constantly to get it to preform and finally ditched it and put on a Holly, and all my issues dissapeared

[DKB_SATX]

I think the classic pejorative was "Quadrajunk" no?

[Lance M]

Originally Posted by soldiermedic

Bummer Lance.

At least it was taken care of in the end. Now get out to many rally and camping trips this summer.

Steve

Thanks Steve. Fortunately, we won't be towing Abby with the truck for a while. Maybe if I can get away to the RMVAC rally in Gunnison...

Originally Posted by Aerowood

Ah the infamous Quadrajet, I put one on my Willys Wagon small block Chevy. I screwed with it constantly to get it to preform and finally ditched it and put on a Holly, and all my issues dissapeared

Hmm that sounds like an option..

Originally Posted by DKB_SATX

I think the classic pejorative was "Quadrajunk" no?

Yes I hear that term often. When I google "Quadrajunk" pages and pages of how to tune or what to replace a Q-Jet with appear. Maybe I should ho with the fuel injection unit that Rednax suggested.

[Melody Ranch]

Wish you would have come by last week....we could have fixed up that carburation problem.

[slowmover]

The QuadraJet is one great carb. Nothing else close except the barely better ThermoQuad . . but it takes little from the ham-fisted and sausage-fingered to f'em up. Mainly the choke.

Doug Roe's book is great. But too many years for me (about ten) since I searched for rods, etc to get mine dialled in to know who to recommend. It'll be someone in Dallas or Houston that still remembers, and that has had enough customers to keep things alive. Check with car clubs, especially the Vette nuts who are into all original.

The Barry Grant Road Demon, Jr would be my second choice if I could have Don at FBO Systems set it up. Remember all the spec questions above? That and some more is what is needed to get fuel and ignition delivery dead-right. Throwing parts at something without knowing how to tune it all is the bane of the weekender enthusiast.

If you can confirm that the QJet you have was spec'd for a truck like yours (even where oversize tires throw off the tuning) it's what I would stick with.