newschoolers

I just built my first 20/22r hybrid and the compression numbers seem low af I’m wondering what I should be seeing before taking everything apart again

261 cam from bill (redline)
.020 piston
.7 intake .9 exhaust lash also tired .8I and .11E and.3I .5E no changes
Domed pistons
Canon intake w/ Weber 32/36
LCE headers
Msd 6al w/ coil blaster 2 .55 spark gap
Roughly 16 advance in timing played around with this both ways seemed to like this area best

It’s giving me super low compresssion and absolutely no power after 3k RPM which is okay for initial break-in but worries me its something worse

Melrose 4r

What’s the compression reading? Cam timing(not ignition timing) affects static compression. If your cam has much overlap that would effect compression readings. A stock new 22re spec is about 170 psi, iirc. For a point of reference.

newschoolers

the compression on the best of tests is 130psi goes down about 20 psi hot.
the 261 has 6° of overlap

i did the 20r head on the 22r block from all the talk of getting higher compression and built around that im getting the same numbers as the junk 22r had before the rebuild....

the complete power loss at 3k is more of a concern because the power band of the cam is supposed to just starting there its timed according to the cam card and marks its TDC across the board

millball

Put a wide band o2 sensor in the pipe and see what you're getting for fuel and air at speed.

newschoolers

ive never built or kept an O2 sensor there must be a universal one i can read the numbers from? any links or what i do with this information?

millball

What you will do with the information is determine whether your carburetor is suitably jetted.
Google is your friend.

newschoolers

i usually judge my air/fuel mix based on the spark plug color this is just the first toyota ive built is the spark plug method not accurate enough for these trucks?

millball

You complain of loss of power at higher revs and fuel mixture issues need to be ruled out.

newschoolers

i agree that my weber isnt exactly perfect yet but gotta test it each time i change something on it to see if it helped or made it worse....

that being said the carb wouldnt solve my low compression issue shouldnt my hybrid engine easily hit stock compression numbers?

Melrose 4r

20 psi is ridiculous. Hook your compressor up to the spark plug hole at 100 psi. With the cylinder at tdc you will hear where the compression is going- past an intake valve, past an exhaust valve, past rings or past the head gasket into the cooling system?

Either way, not good.

Melrose 4r

Do you have the right followers for the cam? I recammed one once with a Crane cam and the wrong rockers and immediately ate the cam. 20r and 22r are different.

newschoolers

its a 20 psi and up loss when the engine is warm which isnt normal to me every compression test ive done on other engines it generally goes up....

ive been searching my area for someone with a leak down kit.... no luck yet the stores dont even have one im probably gonna have to order one and wait....

newschoolers

followers? or rockers?

i bought the cam and the rockers at the same time from redline (Bill) given hes been making cams for 25+ years i ordered the correct ones for his cam i told him my set up

Melrose 4r

screw the leakdown. This is a 5 minute test. Yes, compression should improve when hot, and if you think about it, we don’t drive around with engines cold so cold numbers are less significant. Sounds like your cam is fine, was the bottom end rebuilt(new rings, pistons, bored) or did you just swap the head?

newschoolers

the compression gets. worse when hot....
yeah bottom end with new domed pistons cylinders bored .020. the deck was resurfaced .005" on both the head and block

how would I attach the air compressor w/o the leak down kit?

Melrose 4r

I used the hose in my compression tester.

newschoolers

yeah we would have to make an adapter for our hoses to work on the compression tester hose, or change the fittings on one of then ends. Ill see what we have i didnt even think of that

newschoolers

ok little uodste.... did another compression test 130 again, checked the cylinders with a camera noting bad looked brand new as expected.... put a little oil down compression went up to 140... guess the pistons havnt seated yet?

on the 3k problem changed the air jets up 2 sizess primary ans 1 on the secondary helped but still not great....

newschoolers

any one have any tips on the weber i seem to go be stuck at either the idle is too high and no backfire or idle is set and backfires on deceleration... ive tried retarding the timing then it diesels when i turn it off for a second.

are some of these quirks normal on a rebuilt 22r?

Punjab

Can't help much on your compression numbers though I also wonder if your rings just aren't seated or maybe your ring gap is a little wide.

My 22R is bored .020 over, I run a 261 Crawler cam, headers, and factory valve lash numbers.
Each truck is a little different so Weber settings are going to be unique for everyone. A simple vacuum leak can change all of this.
However, here are my daily driver 32/36 settings. Once warmed up, I get great throttle response and solid power throughout with no backfire.


I made this .pdf file a while ago to keep track of my jet settings. You can download it from the link below if you'd like. I just print one out and write jet numbers next to the icon.
https://www.dropbox.com/scl/fi/cu2sa...3eqpm7vuh&dl=0

Hope this helps!