'75 SR5 with 21R motor - Tune-up info?

[fj40Dave]

Hi All,

New guy here - been searching the site without finding anything about tune-up specific to the 21R (Japanese exchange) engine that's been placed in my (new to me) '75 SR5 truck.

Any links or outrigh info would be great!

Thanks,

Dave

[fredk]

Well, since it is an R motor, probably quite similar to a 20 and 22r, I would just go with the specs of a 20r. I am guessing your motor has a carb, I would just go with the specs on the 20r carb too

[fj40Dave]

I was thinking that would work......found that the valve clearances are 0.20 Int & 0.30 Exh

Point gap is .017

Gonna go with that and see what happens.

I took the smog pump off and all that vaccume line stuff - runs better - gonna try and "dial it in" a little better this weekend.

Thanks!

Dave

[fredk]

you got any basic engine info on the 21r?

[fj40Dave]

No particular info on the 21R that's in the truck......just what I'm trying to find on the web.

I've assumed that it's a Japanese engine swap - probably one of those deals ya hear about where ya buy a 30k mile motor from Japan for cheap.

I just got the truck last Friday for $500 "as is".......

[fredk]

20R SOHC 2 74-78 2189 ? ? 3.48 3.5
20R SOHC 2 75-77 2189 96@4800 120@2800 3.48 3.50 8.4:1
20R SOHC 2 78-79 2189 95@4800 122@2400 3.48 3.50 8.4:1
20R SOHC 2 79-80 2189 90@4800 122@2400 3.48 3.5 8.4:1
21R-U SOHC 2 82 1972 105@5200 120@3600 84 89 8.5:1
21R-U SOHC 2 86 1972 101@5400 114@4000 84 89 9:1
21R SOHC 2 78-87 1972 105@5200 116@3600 84 89
21R-C SOHC 2 ~82-85 1972 90@5000 116@2400 84 89 9:1
22R SOHC 2 80-89+ 2366 ? ? 3.62 3.5
22R SOHC 2 81-83 2366 96@4800 129@2800 3.62 3.5 9.0:1
22R-E SOHC 2 83-86 2366 105@4800 137@2800 3.62 3.5 9:1
22R-E SOHC 2 87-89+ 2366 ? ? 3.62 3.5
22R-E SOHC 2 90+ 2366 112@4600 142@3400 92 89 9.0:1
22R SOHC 2 90+ 2366 108@5000 138@3400 92 89 9.0:1
22R-TE SOHC 2 84-88 2366 135@4800 173@2800 3.62 3.5 7.5:1 6 psi

[fj40Dave]

[21R-U SOHC 2 82 1972 105@5200 120@3600 84 89 8.5:1
21R-U SOHC 2 86 1972 101@5400 114@4000 84 89 9:1
21R SOHC 2 78-87 1972 105@5200 116@3600 84 89
21R-C SOHC 2 ~82-85 1972 90@5000 116@2400 84 89 9:1



Thanks Fredk.....