I’ve got 500 miles on a total rebuild on my 87 22R, but I’ve had so much trouble tuning it I did a compression check, which had all four cylinders at 160-165 psi, as expected. Also did a vacuum test, I got a new gauge for it. The needle bounces back and forth between 19 and 21 inches extremely rapidly. The instruction manual says rapid oscillation could mean weak valve springs or a few other things. However, the test of bumping the accelerator to 2000 rpm dropped the vacuum to 14 inches. The instructions say that only indicates one issue: weak valve springs. So I’m wondering if I should go ahead and pull the head and check the springs or is there another test I can do of some kind.
BTW this head was rebuilt 9 years ago by the shop that machined the block. It’s the original head. He line bored the main journals. Thanks for any suggestion testing springs in the engine.,

 

so the head was rebuilt and run for xxx miles before it was put on the rebuilt short block?

did it sit with some springs compressed for years at a time, as in, it wasn't run for quite awhile? i was wondering why the springs would be that weak.

 

No, it’s 500 miles into it’s second long block rebuild. I don’t know if the springs were replaced on either rebuild. I assembled it the second time 9 years ago but can’t remember if the springs were replaced by the shop. I’m pretty sure I don’t have the work sheet on either rebuild. It’s the OE head.

 

Are you saying that springs weaken from sitting more than from being run occasionally?

 

it sounds like you are saying that it's a longblock that sat for a long time without being driven, aka, some of the springs were held in compressed positions for long periods of time.

fwiw, i've seen people debating whether or not that weakens valve springs... seems like a long shot tho.

what about a valve lash adjustment?

 

Might pull the valve cover and check valve adjustment. could do a visual on the springs at the same time.

You say trouble tuning, but what symptoms/troubles exactly?

 

Thanks very much, that’s a good idea to check the valve adjustment. Don’t know why I didn’t think of that. Can do it in a couple days. I wouldn’t say it sat for a long time without running, six months at the most.

 

The tuning trouble has been with the idle and timing. Which I had attributed to the Weber 32/36 carb I put on it when I rebuilt it. One big discovery with that was when I discovered I could get the timing mark into view in the timing light by turning a screw on the carb that I had never noticed until I searched meticulously for it. But still I had to make another major change on the usle speed adjustment when the weather warmed, which is not normal. And the engine never has been able to idle below about 900 rpm, even warmed up. Altho once I got it timed right it idled much slower. The idle vacuum being at 20 is a good indication the timing is close to being on spec. 5 before.

 

You have the old Toyota carb?

 

No, why? I don't have enough room to save everything I would like to

 

The factory carbs were very good.

 

That was before there were forums or YouTube vids for advice. Have you ever rebuilt one? Maybe I’ll find one

 

Rebuilt the one on my Samurai. I bought a reman unit because my old one had design issues and Suzuki had a newer version with some improvements. Supposedly the reman had those revisions.
But they did a horrible job setting the float level. My first smog test should have been my clue. It passed, but close to max allowed. Way higher than my old unit. Few years down the road and it failed the test, and decided to open it up myself. Reset the float and everything was fine after that. It's not that imposing if your methodical.

My recommendation is to not feel the need to overdue it. Pull the horn and carb dip the pieces. Then simply replace the needle and seat, along with the float. Pay particular attention to setting float to the height specified in your rebuild kit. Do that, and it should go fine. The factory manual has good tips for setting all the adjustment screws. If you try and remove a lot of those brass pieces/pipes inside the carb things may snowball on you. The carb dip should do a good job cleaning them out without needing to remove.

 

Thanks, I’ll try that if I can’t get the Weber to work or if I find another Toyota carb. What is the model number of the carb?

 

I need your model number and production date. The model number is on a metal plate mounted on the firewall under the hood

 

Thanks very much. Model # RN66L-MDCA

i adjusted the valves, 3 were way too tight, it idles a lot slower and smoother, and the needle bounces half as far but just as fast. So instead of bouncing over two inches it bounces from 19.5 to 20.5. I forgot to check for loose springs so will do that later.

 

I didn’t see a production date anywhere

 

production date should be on the VIN plate at the driver's door jam.
But just the year will suffice. Fortunately, any carb off a 2wd or 4wd mtm 1986 or 1987 will work. How the atm carb is different I don't know,
Toyota typically put a metal tag at the base of the carb with the last five of the part number. Yours should be #35291

The model# helps narrow your choices in EPC-data.com or Amayama. Go check it out.

 

From my experience not just any carb from 86 or 87 will work. I rebuilt mine and a second one 3 years ago. Initially I decided to purchase refurb instead of rebuilding myself. I purchased a refurb carb for an 87 from a vendor in CA that specializes in refurbed carbs. When it arrived it didn't have the same number of vacuum ports as my original. So after a hassle with the vendor who insisted I had a California carb, he sent me a second carb. I asked for pics before he sent it but he assured me it would be right. It too didn't have the same number of vacuum ports as my original and was different from the first carb sent. At that point I dove in to rebuilding mine. In the meantime I picked up an 86 carb from a guy. It is way different than my original. There are also different wiring connectors.

If going back to an OEM carb from a Weber, to go stock one would need the hard vacuum lines which I don't believe is used with a weber. Also needed would be the air filter assembly and all that attaches to that. That is unless you desmog the OEM carb.

 

Yep, my bad. There are some Calif spec ones in 86-87 that are different.