Planning my next next project...engine?

[Chris64]

OK, my current project is suspension and getting the rig to feel comfortable to drive. Right now it's scary at 45mph. I can't imagine going freeway speeds, but I'm not sure if it could go freeway speeds.

Then maybe body work...or...

I keep watching videos on improving the performance of the 350 (and there are a ton of them). My truck really drives like a tired old 50 year old truck. I'm not expecting it to be a race car, but it could be a lot better. What are peoples thoughts on doing a mild cam? According to google, this truck in 1974 was around 175hp. That's nothing crazy but I'm sure I'm nowhere near that. For all the menacing noise this thing makes, it would be nice if it drove a little more like it sounded. I see these videos where the stock lobes are worn down to almost nothing. This wouldn't surprise me.

Anyway. Thoughts?

 

[Ricko1966]

Run compression on ALL 8.(gotta add that part now.) Also check oil pressure with a mechanical gauge. How many miles are on it?

 

[Chris64]

Run compression on ALL 8.(gotta add that part now.) Also check oil pressure with a mechanical gauge. How many miles are on it?

Compression on all cylinders is the same - I do have a compression gauge, I just don't know what number it's supposed to have. It reads 135 on each. Oil pressure seems fine on the stock gauge (it has a direct oil line. It goes to zero when it's off and goes to about 70% on the gauge when the engine is running). I have no idea how many miles are on it. The Speedo cable was broken when I got it and the odometer wasn't working. It read 49,999.

I know those aren't very specific.

 

[Ricko1966]

If it were mine it would get different heads,rings,rod bearings,headers,and a cam. You've got 76 cc heads,you don't have enough compression to run much cam. Yep I'm going to get cruzicified here but A pair of TBI heads that nobody wants, would be dirt cheap,bring compression and torque up a bunch,stay with a small cam,929,edelbrock performer,MTC 1,so you got all your power below 5000 rpm. Yes there are lots of better heads than TBI heads but for a dirt cheap low rpm build they'd fill the bill. You can ring and bearing the block in the truck,if you aren't pulling the engine.

 

[Camar068]

I'd go LS (injected or carbed) or big block. Money no object, an Oldsmobile diesel 350 converted to gas. Link below. Or diesel lol.

Olds Diesel 350 to gas

 

[Chris64]

OK - Money is an object. My whole reason for asking is that I want to spend wisely. I have a new Edelbrock AVS2 so I wanted to stay carbureted. If I went EFI I'd probably just go with an LS which I may do someday, but for now, I'm enjoying the process of learning about this motor.

I was thinking about pulling the motor so I can clean up the engine bay/firewall (and paint the cab - which I want to do sooner than later because the windshield is leaking). I was thinking a mild CAM, maybe heads. I guess my compression is low? So pistons and rings (and bearings). I wasn't sure if heads would be needed or if I could just reseat the existing valves. So the stock heads are just not salvageable?

Camar068 - what's the difference of a diesel 350 converted to gas?

 

[Snoots]

A mild cam would help but there are a lot of other points to ponder. My main one would be to get rid of the '74 heads and get a set from earlier years.

 

[Edelbrock]

Exactly 135 on all 8 cylinders? You should buy a lottery ticket.

As for engine performance, start with stoich. If you ain't got that, you ain't got nothing at all.

 

[Ricko1966]

OK - Money is an object. My whole reason for asking is that I want to spend wisely. I have a new Edelbrock AVS2 so I wanted to stay carbureted. If I went EFI I'd probably just go with an LS which I may do someday, but for now, I'm enjoying the process of learning about this motor.

I was thinking about pulling the motor so I can clean up the engine bay/firewall (and paint the cab - which I want to do sooner than later because the windshield is leaking). I was thinking a mild CAM, maybe heads. I guess my compression is low? So pistons and rings (and bearings). I wasn't sure if heads would be needed or if I could just reseat the existing valves. So the stock heads are just not salvageable?

Camar068 - what's the difference of a diesel 350 converted to gas?

The reason I said heads,and the reason I picked those heads. Your engine was built as a low compression engine. It has 76cc combustion chamber heads,the TBI heads are 64cc combustion chamber heads. Swapping heads is going to take you from 8 to 1 compression up to 9.5 to 1 ,rough numbers. That's going to make a cam work better. More lift more duration bleeds off low rpm cylinder pressure. You don't have any to give away.The rings and bearings are just because they are easy while the heads are off,and you won't have oil consumption problems 10,000 miles down the road.The rod bearings take the most abuse and if a bearing fails its usually a rod bearing the rod bearings will be in your hands while you are doing the rings. Earlier heads as mentioned in another post,Chevrolet went 76cc heads 71 up,yes the 70 and earlier and specific 71-73 heads were 64 cc. The early heads weren't unleaded fuel capable they generally are so worn out that it would be cheaper to buy new aftermarket heads than to fix them,and most won't have bolt holes for your accessories (alternator,ac,power steering etc) They went back to small chamber heads like 81 in some applications but all 350 tpi and tbi will be 64cc,just like old double humps. All that bump when you put double humps on your 72 Camaro 1/2 of it was the compression ratio went up. Everyone bags on the TBI heads and they are super,super common so they'd be a dirt cheap upgrade. ( they don't make hp past 5000 rpm) so everyone hates them,but if you aren't planning on seeing 5500 rpm ever or often they are good, they also take less total timing so they make better torque and mpg.

 

[SquareRoot]

Rabbit Hole approaching fast. You can nickel and dime it or you can buy once and cry once. Please don't waste the $$$ on a flat tappet cam from 50 years ago. At least get a junkyard core that accepts modern parts. Get a used LS and run it with a carb. No matter what, you're still gonna get 10 mpg. Buts it's drivable and reliable.

 

[Ricko1966]

I keep having this weird dream that myself and 90 percent of my coworkers friends,and family drove cars all across the country on vacations,hours at a time,and we drove to and from work,school,the grocery store, everyday,rain,shine,hot,cold and the weird part was almost all of these cars were carbureated,with primitive HEI ignitions. Even my 69 GTO with points was reliable it just took maintenance. This is so bizarre. Some crazy basta*ds even bought giant motor homes powered by carbureated big blocks and drove them cross-country. Towing another car behind it.

 

[Chris64]

Exactly 135 on all 8 cylinders? You should buy a lottery ticket.

As for engine performance, start with stoich. If you ain't got that, you ain't got nothing at all.

Do they make a stoich-o-meter?

This is something I haven't even looked into, but I think the carb came pretty close. I say that just based on the plug color (Disclaimer: I really only know the colors of 2-strokes). It's cocoa brown and dry-ish. I only checked plugs 1&2. When I get on it, it doesn't feel like it's lean (I know that feeling), it could be a tiny bit rich but I don't think so. It's just weak.

 

[Ricko1966]

Do they make a stoich-o-meter?

This is something I haven't even looked into, but I think the carb came pretty close. I say that just based on the plug color (Disclaimer: I really only know the colors of 2-strokes). It's cocoa brown and dry-ish. I only checked plugs 1&2. When I get on it, it doesn't feel like it's lean (I know that feeling), it could be a tiny bit rich but I don't think so. It's just weak.

You can buy a wide band O2 sensor,and Air Fuel Ratio monitor. But there's pretty good Edelbrock tuning information out there that will get you very close without it. That and a little street tuning,a vacuum gauge,a stop watch a speedometer and 2 landmarks on the road,using speed to distance,and E.T. to distance. An AFM can say whatever it wants if the car traps 3 mph higher,at a different setting,that's what the engine really wants.

 

[TotalyHucked]

What gears does the truck have and what size tires? A gear ratio change is the best bang for the buck seat of the pants "HP improvement" you can make.

 

[SquareRoot]

I keep having this weird dream that myself and 90 percent of my coworkers friends,and family drove cars all across the country on vacations,hours at a time,and we drove to and from work,school,the grocery store, everyday,rain,shine,hot,cold and the weird part was almost all of these cars were carbureated,with primitive HEI ignitions. Even my 69 GTO with points was reliable it just took maintenance. This is so bizarre. Some crazy basta*ds even bought giant motor homes powered by carbureated big blocks and drove them cross-country. Towing another car behind it.

When the speed limit was 55 and gas was $.99/Gallon. What about the other 10%?