LUVTruck.com

There is a lot of discussion here about increasing the performance of the G180/200 engine, but I have some questions on a different approach.

What sort of improvements can be made to increase fuel mileage in this engine? Currently I'm satisfied with the stock power on my beat up, low compression '78. It's a daily commuter with the occasional trip to the dump.

It's not a heavy hauler, rock climber or quarter miler. It may do some duty over the mountains (the Siskyous, Oregon coast range, The Blues), but probably not with a significant load.

The truck is generally driven about 30-50 miles a day at between 55-70 mph, with some stop and go in between. I rarely take it over about 3500 RPM (I'm afraid it will come apart...hahaha..).

I've got a 32/36 here, and a 77 G180 block, but I'm considering setting up a G180 head for this specific application. What cam grind makes the most sense? Has anyone adapted EFI to this engine using stock Isuzu/Chevy parts? How about a Motorcraft 2100/2150 series carb? These carbs perform very well using vapor feedback and deliver power on demand as well. I'm not very proficient on carb jetting so a primer on this would be much appreciated.

I know the 5 speed is probably the best upgrade for this purpose with a stock engine, but what about gearing or tire size? Would a 2nd gen diesel rearend go in my truck? Can I just put the gears in my existing diff? Where do I find an online calculator to sort out HP/Tranny/Gearing combinations?

Is a later model EFI 1.9-2.3/5 speed an easier approach?

Thanks folks! Looking forward to your ideas

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"If we did the things we are capable of, we would astound ourselves" - Thomas Edison

The thing you need to look at is operating RPM and what you plan on driving and it seems you have that already planed.So for my 2cents worth just for starters is i would go the G-200 block asy. a G-180 head or higher comp. pistons in the G-200 block, but lets look at budget build G-200 block,G-180 head, header. stock G-200 cam(Impulse), your 32-36 carb, and a 5-spd with 3.73 gears or 3.42s if there are any.As a big power motor it wont be but as a torq and fuel efficient motor it sure will be. Now remember this a cost effective way and there are allot of other ways to make this happen.For the best fuel economy is a good torq motor not a high horse power motor.More later as the flaming should be good reading.

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1978 pro street step/side 455Buick, 4sp,4.11s, 31/18.5s

Yah, I guess I sort of opened myself up for flaming...hahah...
Thanks for the low buck ideas, that is right up my alley.

Just to be clear, the 1.8 is the G180, 1.9 is the G200, right? Is there a year demarcation? I'll check other threads here for clarification...

How do I identify rear diff gears? I know the 4by guys talk about counting ring gear teeth, etc. Is there a stamp or something on the pumpkin?

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"If we did the things we are capable of, we would astound ourselves" - Thomas Edison

you can get an estimate by jacking your pickup up and turn the right rear wheel a full revolution and count how many times the driveshaft turns I used a piece of chalk for a line on both. Oh and get someone to watch driveshaft its not easy by yourself

you can get an estimate by jacking your pickup up and turn the right rear wheel a full revolution and count how many times the driveshaft turns I used a piece of chalk for a line on both. Oh and get someone to watch driveshaft its not easy by yourself

not to be a jerk, but you can take the RPMs a lot higher than that! you dont have to worry about it coming apart. i missed third gear and put it in first when i was racing a ricer, it revved to 6500, and nothing happened ( oh and i still won lol)

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(PLATINUM STREET RODS)
Deming, NM

luvprojects - wow, what a simple, effective idea. No wonder I didn't think of it. hahaha...Thanks

off road - I'm not so sure you'd do that with my engine...haha..it's pretty tired. I haven't figured out exactly what the sound is that it makes at speed, but I'm pretty sure it's days are numbered. Piston slap, maybe? Whatever it is, is doesn't purr...it sort of hollers...

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"If we did the things we are capable of, we would astound ourselves" - Thomas Edison

A torq or milage motor will rev up high but it won't have the power up high. Clue look at the difference between the Edelbrock performer and the performer rpm. The main key is to build your motor to make the power in the rpm range you plan on running.I haven't seen the difference in the G180 and the G200 head to say for sure but if there is on the smaller motor will have smaller combustion chambers and smaller runners all witch is conducive to add more compression and low speed performance.Example a small block chev with fat tops,72-74cc heads, edelbrock performer cam and intake ,and a 600 cfm carb setup will be about 9.2-9.4 compression and be real fuel efficient from 0 to 5500 rpms.Now the same motor with a performer rpm set up and it won't even start to run good until about 1500-1700 rpms.Here is the kicker the performer rpm motor will make more total torq but at a rpm level that may not work for you, and the performer set up will make more torq at the rpm level that you are looking for. Are you confused yet as there are allot of variables and theories so keep asking and compile all the info until you have it figured out.

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1978 pro street step/side 455Buick, 4sp,4.11s, 31/18.5s

Can you describe the noise? I had a weird noise in mine right after I installed a Weber carb, it would make kinda a shrill metallic noise at high rpms shifts, and sometimes just cruising at high rpm. Worried about it for about a week thinking something was about to go. Turns out, it was the warm air deflector, thin metal shield that is bolted to the exhaust manifold... took it off, no more noise.

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FIAA: Color Guard

tj - Thanks. Not too confusing, yet. An engine is basically just a big air pump anyway, right? So it makes sense to tune the air flow (rate) for various performance objectives. To be sure I build the engine where I need the power, I should probably put a tach in the truck and record where it actually runs day to day. My RPM statements are seat of the pants right now.

'79-Luvr - I'm not sure how to describe the noise. It just sounds like something is loose inside the engine when it's at about 3000 RPM. It's one of those things that's especially hard to describe when I'm not actually in the truck listening to it. I think it's called skirt slap (?), but it may be rod bearings or wrist pins. It hums at idle, but when it's not under load it's noisy. The noise quiets significantly if the engine is under load with no noticable effect on power. It doesn't sound like it's the valvetrain to me, but I'm no engine expert...

I could definately use some lessons on jetting a two barrel carb though. The first several carbs I rebuilt were all big one barrels. The only 2 bbl I ever worked on was a Carter WBD (?) which was a factory option on the Rambler 196 six. I have a lot more recent experience with Saab's mechanical fuel injection set up on their 8v engine. My '86 900 had 430,000 miles on it when I finally sold it...

Start talking about roller cams, lift, duration, end play, 60ft times and stall converters...then you'll get me confused...

Try to go easy guys, the first dozen cars I owned and worked on were Ramblers, and for the last several years I've been pretty much a Saab 900 guy...

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"If we did the things we are capable of, we would astound ourselves" - Thomas Edison

Be carefull with the Saab stories.

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1978 pro street step/side 455Buick, 4sp,4.11s, 31/18.5s