I have an ’05 GMC 1500 HD. It has 243,000 miles on it. It generally runs great but lately when I mash on the fuel to pass, it seems to bog down. But when I back out of it, it seems to pick up and go. Any suggestions?
Wow, 243,000 miles! When was the last time the fuel filter was changed? That would be the first thing that I would take a look at as the vehicle has the symptoms of fuel starvation. Then a fuel pump pressure check is in order. Electric fuel pumps don’t last forever and from my experience they usually start getting tired at around 100,000 miles. If the pump is not working up to its demand pressure rating, then there is a darn good chance it also needs replacement.
Do keep in mind that there could also be other issues that are causing the problem you describe but the fuel system is a great place to start.
Dirty Air MPG
I have just recently put a 4-inch Superlift suspension lift on my ’96 Explorer. I have the 4.0L V-6 engine and the gas mileage sucks. I was wondering about regearing. I’m gonna be using this vehicle to get to and from motocross tracks towing a trailer with a couple of bikes on it. It’s all stock underneath running 33x12.50 tires on 16-inch wheels.
Virginia Beach, VA
That is really a hard question to answer Matt because a lot of other factors are taking place. My guess is that you’re thinking that the engine is working too hard now that the overall gear ratio has been changed due to the larger diameter tires. Going to lower gearing, let’s say a 4.10 gear set, will put the engine back in the rpm range that the Ford people figured would get the best fuel mileage as well as improve the towing performance. So yes, you are right on that point.
However, you have to keep in mind a couple of other factors. One being that the larger tires have more rolling resistance due to more pavement contact as well as additional weight. The other is that your Explorer now sits higher exposing the underside to more airflow. The front axle, transfer case, and other components are now causing a lot more air turbulence or what I like to call “dirty air” that has a negative effect fuel mileage. Here is a classic example: A vehicle of mine started out getting about 18 to 22 mpg when driven on the interstate at a reasonable speed with 3.73 gears. A 3-inch lift and 31-inch tires caused the fuel mileage to drop down to the 15 to 18 mpg mark. More lift and 33-inch tires with a swap to 4.56 gears put the fuel mileage down to about 13 to maybe 15 mpg on a good day. Yes, off-highway performance was greatly increased but with a fuel mileage decrease. Life is nothing more than a big trade-off.
I have been trying to find information about lifting an ’89 Ford F-150. In the spirit of less is more I would like to go with a 2- or 2½-inch coil and new leaf springs. I would like to run 33x12.50R15LTs which I have run without a lift. They rub badly on the radius arms when turning and limit the turning radius a lot. I have contacted Rancho Suspension and asked if I could use the extended radius arms without a lift and they said that I couldn’t because the truck would need to be aligned. Obviously, modifying the suspension would result in the need for an alignment, so I ask you would it been possible to make a custom kit with 2-inch leveling coils, extended radius arms, radius drop brackets, traction beam drop brackets, and new leaf springs? Or how about any other combination to keep the center of gravity low but allow the fitment of 33-inch tires with no contact on the radius arms. Fender trimming is not required even in stock height.
Minden, Ontario, Canada
Sometimes it is OK to mix and match parts from different companies and sometimes not. Can you use the Rancho radius arms with another brand’s coil springs? Generally speaking, yes, I see no reason why you can’t use them. I assume that you want to use the Rancho radius arms because they tuck in a bit and allow more tire clearance when turning. However, I don’t think Rancho offers the radius arms separately.
Something that you should also look at is the backspacing on your wheels. A large amount of backspacing will put the tires in closer to the radius arms and cause rubbing at full steering lock. Less backspacing will move the tire outward for more clearance; however, you don’t want to go to an excessive amount as this causes all sorts of steering and suspension geometry problems.
The same goes with wheel width. If you keep the backspacing the same but switch to a wider wheel, the bulk of the tire is moved outward providing more inner fender clearance. But this may cause outer fender lip clearance problems. With today’s tires having a lot of sidewall tread compared to earlier years, a specific tire size that used to clear fine will sometimes contact now due to the sidewall tread lugs.
Home Job Stroker
I got a great deal on an ’84 305 Chevy V-8 engine that I plan to install in my Jeep. I have heard that I can take the crank out of a 400 engine, which my friends tell me is a boat anchor, and drop it in my 305 to make it a 383 stroker. Just what do I have to do to do this?
Well, your friend has got part of it right. With a 0.030 overbore to the 305 block and adding the 400 crank you will be just about 50 cubic inches short at 334 cubic inches. It takes starting out with a 350 block to get the 383 size configuration. First off, you’re lucky in that the engine you acquired has a two-piece crank rear seal just like the 400 engine has. I believe engines built after about 1986 use the later style one-piece rear seal. Yes, there are kits to convert it over but they are pretty expensive. To start off with, the main crank journals are too big so they have to be turned down to the 305/350 size. You have a couple of choices. You can keep the 305 pistons and use the short (5.565-inch) 400 rods, or you can also use the longer (5.7-inch) 305 rods with some custom aftermarket pistons. There may be some interference points within the block so some grinding there as well as on the connecting rods may be necessary.
I think that using the longer rod is the way to go as you don’t get as much sideways thrust by the pistons to the cylinder walls. You will also need the flexplate or flywheel as well as the harmonic balancer from the 400. Crankwise, I think that you would be better off buying one of the aftermarket cast cranks. It will likely be less expensive than paying to have the 400 crank’s journals turned and you don’t have to search for a good crank in the wrecking yards.
I really advise doing a dry run assembly of the engine to make sure everything fits properly. You may even have to make some minor oil pan clearances. When it comes down to power, why not just locate a real 350? It will save a lot of work on your part and make more power than your stroker 305.
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