Topic: 22R fuel consumption Problems

[Gewehr43]

I have an '82 Toyota pickup with a recently rebuilt 22R.  It has about 1,500 miles on it.  I have a rebuilt Aisan Carb, Downey header, Northwest 2 1/4" exhaust, and a performance cam.  My problem is that the truck is getting about 13-14mpg.  Before I rebuilt the engine it had 326,000 miles and was getting 19-20 mpg.  The timing is dead on and it seems under powered as well. Any clue what's wrong?  Any help would be greatly appreciated.

[WHITE_TRASH]

You have the timing set at factory specs dont you.  Once you start to modify things such as cam and header all the specs change from factory.  You'll have to keep playing with your timing or just set it by ear.

[79coyotefrg]

what cam do you have??  aisin carbs are bad about going lean, chunk it and get a weber.   has it been low powered since the rebuild,  sounds like the cam timing, ie  NOT ignition timing is off
pull valve cover , watch intake valve #1, rotate crank by hand from tdc,aka12 oclock,  if intake opens befor 9 oclock,aka 270* give or take, retard cam

pull valve cover , dist, dist drive gear,  carefully remove cam gear and move on chain one tooth

back me up WT   its been along day i might have forgot something 

[Gewehr43 [OP]]

What type of Weber would you recommend?  The truck is a daily driver and must pass emissions in NM.  Where should I look for one?

[79coyotefrg]

LCEngineering.com ,  a 32/36 weber kicks butt

and i think they have emission legal thingy numbers for you guys,  they are in AZ

[79coyotefrg]

check that cam timing too 

[Shamb]

Anyone suggest the 02 sensor?  a bad 02 can cause it to burn fuel as well..


Im wondering where i can pick up a STOCK 82' carb?!

[BigMike]

Hey,

Did you have those mods on the engine before you rebuilt it? Those mods will result in more performance at the cost of fuel efficiency.

[WHITE_TRASH]

How is the powerband now?  Does it have lots of low end or top end?

[Gewehr43 [OP]]

The only mod that I had on the truck before the engine rebuild was the 2 1/4" Exhaust system.  The carb was in horrible shape, and the engine barely ran.  After the rebuild I expected about 18-19 mpg 'cause of the cam and other parts, but it's getting about 13.  I also had the engine converted to a double timing chain.  Where can I find a good adjustable cam gear for it?

[BigMike]

Lc makes a nice adj. cam gear, and this might be your only option to regain your mileage. However on a single cam engine, you won't be able to take advantage of varing the overlap/underlap like you could on a true twin cam (Toyota desigination "G" as in 4A-GE, 7M-GTE, or 2ZZ-GE, not "F", F is a poor man's twincam, as in 3RZ-FE, 3VZ-FE, and 5VZ-FE).

The adj. cam gear will allow you to alter the overlap/underlap's timing with the piston, and I would recommend trying to retard the cam to allow the piston to have fully escaped exhaust gases before opening the intake cam. This would reduce the time that the intake valve is open during the exhaust stroke, and hopefully preventing some of your intake charge from dumping out with the exhaust. If done correctly, you will gain bottom end and loose some top end, but will improve your gas mileage.

But remember, the overlap/underlap is SET by the cam itself, since this is a single cam, and can not be altered unless you regrind the cam.

[79coyotefrg]

my truck was the same way,  i checked the cam and it was advanced 1 notch on the gear,  thats why i said ,check your cam timing 

[Gewehr43 [OP]]

I just bought an LC engineering dual roller adjst. cam gear.  Should arrive in about 10 days!  Thanks for the advice. 

[BigMike]

HOPEFULLY that works......

[hawaii500_1999]

my money is on the cam being the culpret for the lack of milage.

yes maybe the cam might be out of timing, but also i'm wandering.  what lift, duration and overlap specs your cam has.