Irish_alley

i reported the bot two days ago and hes still here. idk whats going on, granted the site that i mod on is smaller but he wouldnt have made it two post and heres going on 31 post in two days

Kazoocruiser

Shalom and welcome to the forum.

What kind of car do you drive? Do you control the car from the right seat? How much does the car weigh?

As far as your Winnebago goes, there is no getting around the fact that it a concrete-filled Twinkie, with a huge motor, pulling a loaded trailer and all of the fun that makes your life exciting when the adrenaline kicks in.

You could wire in a wide-band O2 sensor and tune your exhaust stream to minimize fuel waste. A rich idle creates fuel dump at highway speeds. A vacuum gauge can help in leaning out a rich mixture. It can also help you detect vacuum leaks and general engine health.

It's likely that the carb you using right now on the truck has dried out gaskets and possible worn throttle shafts, given that it may be the original carb on a 35? year-old-vehicle. That and Ethanol fuel being used in a vehicle never designed for it makes the carb. and all the other rubber fuel lines suspect.

What kind of mileage numbers are you pulling currently?

David Green

By that year, the 454 engines were "pathetic" for both performance and fuel economy. They had a "huge" combustion chamber and possibly dished pistons that yielded less than 8 -1 compression ratio.

I have a 454 powered mid 80s crewcab into which I installed an earlier (about 1975 vintage) 454. The mid 70s 454s had about 8.5-1 compression ratio.I was able to squeeze some fuel economy out of it by advancing the cam timing by about 10 degrees using both an offset button on the cam gear and a step key on the crankshaft. I run a quadra-jet carb. I do not recall the jetting. This one trick actually raised my fuel economy by about 15%. There is a possible downside to this as oxides of nitrogen emissions go up as well as the peak horsepower will occur at several hundred RPM lower than the factory rating.

One other thing to do, if you "dare" is find some closed chamber heads and install them. The compression ratio will be bumped up to about 9.6-1 (or possibly higher depending on the thickness of head gasket you use). The performance is suddenly "incredible" but you will, in all likelihood, have detonation issues without using higher octane fuel. I had done this for several propane fueled vehicles many years back. Propane likes higher compression and the fuel economy on propane gets pretty decent with this "trick".

Now, I presume your motorhome is automatic transmission equipped. One thing that I discovered about motorhomes is that they seem to be equipped with very high stall speed torque converters (3000 - 3200 rpm). With the much increased lower end torque from the aforementioned cam timing change, the stall speed can be dropped with a torque converter change. I do not know which actual converter to recommend.

Anyway, it all costs money and time. Do a bit of research ...and - Good luck!

texrex

I would check to see if the if the bottom Welch plugs are not leaking fuel . On every quarda jet carburetor overhaul we would replace then with a set of Tomco that has orings .

Tomco-inc Home Page

oilcanhenry

It would be nice if one of the pickup and larger manufacturers would add a two-speed rear axle on a two-wheel drive vehicle, just as you can get with a medium duty truck, as an option. Not sure if they would work with an automatic transmission as most medium-duty trucks that have a 2-speed use a 5-speed stick-shift transmission. You can split gears and really get a heavy vehicle up to speed with a 2-speed axle. The six-speed automatics on a medium duty truck never some with 2-speed axles and they blow anyhow.

oilcanhenry

As someone who knows carburetors of all kinds and has rebuilt more then I want to think of,, Tomco is a very good brand of carb rebuild kit that I have used many times.

Hate the R-C Quadrajet with a passion, however. If it's not a Holley, it's not the best carburetor on your vehicle, period. Eldebrock-Carter comes close, however.

Joe Surefoot

Hi All!

My '86 Chieftain's final drive ratio is 4.56:1. I'm planning on installing a B&M 4L80E transmission, which is basically a TH400 with an added overdrive gear and a lockup torque converter. I've confirmed that the first 3 gears are identical to my current TH400, so pulling ability should be unchanged, but will have the OD when needed. Does require shortening the forward drive shaft and an aftermarket (or donor) controller, which isn't cheap. Will the swap ever pay for itself in terms of fuel economy? Well, certainly not in dollars, but if I ever find myself just a few miles from the next gas station and running on fumes, I might consider the investment paid in full.

As to the 454s of this era being "pathetic," there is certainly some merit to this position, however, they are not irredeemable. I'll not address the low compression ratios, because that's a question that brought me to this forum, but I will observe that from what I've been able to glean, even a basically (internally) stock smog-era 454 with the much maligned 'peanut port' heads can produce 400HP and lots of torque. Coupled with the 4-bolt main caps (on mine, at least), that makes for a basically strong engine.

So, here's my question:

I know compression == power. I'm and old (and I do mean old) hot rod guy, from when "street" meant 10.5:1, and even 11.5:1 wasn't all that outlandish if you were willing to buy the right fuel.

On the other hand, I've seen old B&W photos of nineteen-fifties Jeep FCs, probably powered by flathead 6 cyl engines, pulling flatbeds loaded with logs, so high compression has a history of being eschewed for gas-powered heavy haulers.

Anyway, I'm starting out with a nearly pristine 1-owner vehicle with documented 24,570 miles on it, so I'm being a bit circumspect when it comes to cracking that engine open any deeper than is absolutely necessary. Moreover, while I have good friends with lifts and professional garages, neither of them can accommodate my motorhome, so there are many operations I wouldn't hesitate to tackle on a pickup or even a van, but approach with some trepidation with respect to this coach.

My plan includes a Banks Power Bundle (headers, exhaust, air intake), Wieland Street Warrior manifold (dual plane, and specifically matched to peanut port heads), and a Comp Cams Xtreme Energy, XR252HR Kit, whose 600rpm - 4600rpm range seems ideally matched to the flow capacity of the small-port heads. Moreover, I think that low-end grunt will be ideally suited to getting the most out of the transmission's overdrive gear, not to mention delivering crisp throttle response where I realistically anticipate doing most of my driving.

Already have a Jacobs (multiple discharge) ignition system waiting to be installed, and will likely match it with an upgrade distributor, curved to my requirements.

Okay, so far I'm pretty confident in my configuration choices, but here's the question:

I know that with my flat top (no, not dished) pistons, I can install a set of closed-chamber (100cc) oval-port heads, and the resulting compression will be a street-friendly 9.2:1 or so.

Acknowledging (but ignoring) the fact that making this change would entail a different cam and intake, better suited to the capabilities of the oval port heads, the question is then whether the difference between 8.0:1 and 9.2:1 -- taking into consideration both horsepower and torque, as well as nature of the vehicle -- would be significant, or indeed, even desirable?

Remember, I'm and old fart, and no longer interested in wowing the other seniors at the gathering with my growling idle or ability to squeak the tires. What I do want is something that won't be a drag to drive, will be able to merge with traffic without raising my blood pressure, and will let me climb reasonable grades without becoming a hazard to navigation....

Also, for the reason stated earlier, I would like it to be as fuel efficient as is possible. No, don't expect to get 20+mpg, but having driven rigs pulling similar weight with similar displacements and gearing, I am highly confident that I'll be able to achieve 12 or better.

Anyway, tried to get an answer in an RV forum, and several folks suggested here, so here I am.

Irish_alley

my opinion is get a donor 1 ton that has the 4l80e (1991+) with a newer motor and run that setup. i dont know why but when i see a BB i just see a gas sucker with moderate power. you can grab a BB (or whatever) out of a 2000+ CHEVY with a 4l80e, take the computer (as the 4l80e needs a computer to shift), engine and trans and run it. you will get more power out of the newer engine and prob better MPGs. by time you buy all those parts for the BB you have now and a 4l80e+a TCU (transmission control unit), it might be cheaper in the long run to find a donor setup that has most the parts you need right there

Joe Surefoot

I will certainly consider a donor for the trans, especially since I have a local junkyard that's very reasonable. I'm not considering an engine swap 1) Because I don't have access to a facility that can accommodate this vehicle, and 2) because I really couldn't bring myself to replace a well-running low-mileage engine. (Although I'll admit to having briefly toyed with the idea of an aluminum 502...).

I've owned rigs with big blocks -- pre- and post-smog years -- and my experience suggests they can all be made to perform, particularly in truck applications where low and mid RPM operation is the norm.

Your advice, however, is well taken -- I have reached the conclusion that swapping heads (which is, after all, the topic of the post) is probably not justifiable when compared to just swapping in a higher compression engine.

While this is my first motorhome, I did own a 1984 F350 flat bed with the 460/4bbl/4-speed manual/4WD, and by my calculations, when towing my 4-horse trailer, the weight was right about where the Winnebago is with the water & waste tanks empty. I used to drive that in the Blue Ridge mountains near Asheville, and it would take some of those hills, fully loaded, without having to downshift, and would always give me around 10mpg -- up to 12 without the horses. No modifications whatsoever to the truck. Based on that, I don't think it's unrealistic to aim for similar performance and economy from this.

Irish_alley

look into the tcu you trans will need to shift if you go with the 4l80e. it needs a few signals from the engine.