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Toymods Social Secretary
Location:
Sydney
Registered:
July 2002
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 18R-G head number answers, and more questions
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Thu, 13 February 2003 13:01
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well.. i have a bit of info on the head numbers on 18R-G's that has helped answer some of my questions....
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> Here's some head numbers off Al's 18RGs:
>
> 88250:
> - 49657 single spring early rgu single dump ex ok head small studs on ex
> - 52978 same as above
> 88253:
> - 73086 double spring late rgu good head to start with large studs on ex
duel dump man
> - 62744 single late rgu still good head may be small stud ex should be
single dump
> - 81784 double spring late also
> - 87278 double spring late also
> 88270: these are ale efi heads all double springs alll good heads these
are the ones you use
> - 35140 biggest ports biggest valves no smog ports best casting
> - 08037
> - 49383 very late head newest ive seen
> ?:
> - 81225 same as above double late rgu if the head is a 11111-88253 not a
11111-88270
> 88253 88270s would be the heads of choice since these need very little
work from the factory these willl make lots of power with little porting
they will make a lot more power with a lot of porting the castings are a lot
thicker around the ports so there is a lot of room
the 88250s can be made good but the ex studs should be changed up to 10mm
ones for best sealing
all of these engines should have 8.5s to 1 but the efi 88270 heads they
should have 8.3 to 1
just be glad you dont have any of those 11111-88230 or 88210 heads they are
good paper weights
hope this helps your info of what you got there sounds like my garage
i think i have 15-18 heads right now
cary
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now still i have questions.... should i use this worked 88230 head as seen below? it has 45/37mm valves, same size as 88250 heads....
or should i use the 88253 head which is currently bolted on the engine in the old car? Im a bit confused as to the main differences compared to an 88230 head.... did the 88253 have bigger valves? if so what were the sizes of the two?
anyway, all info would really help me out here... just trying to extract the most info before i dive too far into a rebuild 
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Location:
Mackay, Nth Queensland
Registered:
June 2002
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Re: 18R-G head number answers, and more questions
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Thu, 05 June 2003 11:02
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thanks for the info, just summing up your answer (a bit late yeah but i was doing some research and saw your post).
the difference between the 88250 and 88253 heads i can see are the different valve sizes. you've mentioned the valve sizes are 45/37mm for the 88250, well i just measured my 88253 valves and they're 45/39mm (using the vernier calipers).
anyway just letting you know,
jarrod.
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Toymods Social Secretary
Location:
Sydney
Registered:
July 2002
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Re: 18R-G head number answers, and more questions
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Thu, 05 June 2003 13:47
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thanks dude - but i have since already found that out! 
The 88253 head is identical to the last of the 18R-G's.. the 88270 (EFI) head, except for the reliefs in the intake ports for the injectors. So yeah... its the best head to use!
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