For the last year or so I've been working on the Chinook. Before I get her back on the road, I wanted to put some money into freeing up some horsepower. At the moment it can be a struggle on bigger hills. I'm not expecting miracles, but anything would help at this point. I'd also like to clean up the engine bay and make more room so it's easier to work on. Here is what I have planned: -Weber 32/36 Carb (seems to be the best option for more power/mpg) -Remove as much of the emissions/desmog system as possible (no testing in my area) -Aftermarket Header -Larger diameter exhaust (current one needs replacing anyways). Unsure on size... 2.25in? -Eliminate the A/C System completely (saving weight, freeing up room and one less belt on the engine to deal with) From what I've read, even adding the weber will wake it up a little. I don't expect anything amazing, but with the weight I'm hauling around, anything would be helpful. Hopefully the other supporting mods will also show some improvement along with the carb. So with the list above, would it also be beneficial in anyway to get an aftermarket intake manifold. Example: Downdraft Intake Manifold-20R (2-bbl Single Plane)
My vote is always port the stock 20r intake manifolds. They really flow awesome. The mods you listed will get a solid puller motor for ya. You should change the ignition coil to a better one too. And better than stock plug wires. Taylor makes a nice 8mm set for 22r which is the same fitment physically.
Not sure why I didn't add the ignition system to the list. That would also be something I'd want to address. What ignition coil do you recommend for the 20r? Have a link for those plug wires?
Summit racing has the plug wires. I think they come in a few colors too. No link for them right now. As for coil, an accel super coil or an msd blaster 2 works great. I have had a blaster for years. And those Taylor wires. Revs to 7k smoothly with no ignition issues. Stock wires and coil could barely pass 4k smoothly.
They have always been a great coil on my Toyotas and all my dodge trucks. Only time I fried one was when I bypassed the stock ballast resistor on a dodge and it got too much voltage. The mounting could have been an issue. Dodges its usually sideways on the firewall above the motor. Pretty hot engine bay area. And MSD recommends they stand as vertical as possible. Just rotate it on the stock mount to point upwards.
That's a nice manifold ., it would pair well with a torquer cam .. That's we're your going to actually make a improvement in acceleration and long strides up hill or grades .. Won't effect idle or gas mileage much but will loose some high rev power above 4k rpm Cam isn't a necessary item but if your loaded down with gear and gas Maybe a canoe on top .. . It will get you up to speed with less struggle
Gotta remember guys, its for his Toyota motor home not just a pickup. They're pretty non aerodynamic.
The above upgrades header and larger exhaust would ideally move your torque curve into the mid to upper area . Not really optimal for a rv . The rv cam is designed for this purpose to move all the torque from idle to about 4000 rpm It's ment to get ya off the line and keep torque at a lower rpm were I'd imagine it spends most of its time This is also a popular mud truck cam for turning heavy large tires That is if you want to go with a cam swap Weber* cam* . Header optional a good flowing quiet muffler dyno max rv mufflers 2.25 piping. . If the trucks a four speed I'd consider the cam even more
You make a good point about moving the tq around. I'll definitely keep that in mind. Would a header and stock diameter exhaust change the tq curve that much? I could understand it might if I were to enlarge the exhaust diameter.
EFI is a **** ton of work to upgrade to on the early trucks. I hadn't thought about the torque curve moving around. The 4wd guys like the 4-2-1 style headers. Says it helps better down low, but they don't flow as good up high. Might wanna consider that instead of a 4-1 style. Also I would recommend a 2.25" exhaust diameter through your choice of muffler. Will allow good flow without losing too much backpressure and scavenging. 2.5" is more for high revs.
You may want to measure your exhaust at different points like right after manifold then half way back then tail pipe.. On mine it went 2" to 1 5/8" then 1.5" at the end, and just making it all 2" with a glasspack was a big improvement
I'm planning to go over the exhaust soon. That will be taken care of once I get the engine back up and running. I probably won't enlarge it over stock.
20r and 22r headers are the same more or less. Air injection ports are a bit of a change year to year. Some of the 4wd guys like 4-2-1 for torque. Not sure who makes them still