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Unread 05-29-2009, 07:22 AM   #1
chill254
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1984 CJ8 
 
Join Date: Feb 2009
Location: Georgia
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1978-1980 Cam Specs

Got myself into an argument and I need some help. I have the cam specs for the 84-86 jeep 258 and I need to compare it with the pre computer jeep (79 preferred). I would like to get these off an fsm. The specs I need are as follows. They should be located under the 258 engine section. The heading will be specification.

Cam lobe lift
Valve lift

Intake valve
Opens
Closes

Exhaust valve
Opens
Closes

Overlap

Intake duration
Exhaust duration

Please give all measurements in inches and include position like bbdc, btdc, atdc, abdc.

Thanks in advance.

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Unread 05-29-2009, 08:50 AM   #2
Mike Romain
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I would also like to find out what engine I am running so I can maybe micro tune my distributor advance as I have a mix of an older engine with an 86 distributor and am part of the above discussion I believe.

Where do I find the list for the engine numbers? I have numbers below #2 cylinder on the block I believe.
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86/00 CJ7 Laredo, 33x9.5 BFG AT's, 'glass nose to tail in '00, 'New' frame,wires and plumbing in '09. Carter BBD Carbed 4.0 HO in '10.
89 YJ Renegade. BBD Carbed 4.0 HO. Locked front and rear with 33x9.5 BFG AT's
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Unread 05-29-2009, 09:01 AM   #3
chill254
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Mike I have the fsm for the 84-86. The link is bellow. You should be able to find the numbers in the 6 cyl engine section or post the numbers and I can give the inof to you.

http://www.jeepforum.com/forum/showt...=750127&page=2

I think the numbers are only a couple of pages in.
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Unread 05-29-2009, 09:06 AM   #4
Mike Romain
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Quote:
Originally Posted by chill254 View Post
Mike I have the fsm for the 84-86. The link is bellow. You should be able to find the numbers in the 6 cyl engine section or post the numbers and I can give the inof to you.

http://www.jeepforum.com/forum/showt...=750127&page=2

I think the numbers are only a couple of pages in.
As soon as it stops pissing rain I will go look. I was 'told' it was a 78 by the shop, but the bozos that sold it to me were shaky at best. Thankfully they are now one 'less' POS jeep shop ripping folks off.
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86/00 CJ7 Laredo, 33x9.5 BFG AT's, 'glass nose to tail in '00, 'New' frame,wires and plumbing in '09. Carter BBD Carbed 4.0 HO in '10.
89 YJ Renegade. BBD Carbed 4.0 HO. Locked front and rear with 33x9.5 BFG AT's
Some Canadian Bush Jeep Runs and Build Photos: http://mikeromainjeeptrips.shutterfly.com (10 new albums added Sept 16/10)
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Unread 05-29-2009, 09:33 AM   #5
Mike Romain
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Quote:
Originally Posted by chill254 View Post
Mike I have the fsm for the 84-86. The link is bellow. You should be able to find the numbers in the 6 cyl engine section or post the numbers and I can give the inof to you.

http://www.jeepforum.com/forum/showt...=750127&page=2

I think the numbers are only a couple of pages in.
That FSM doesn't seem to have the engine numbers that I could find, I have it too.

Here are the numbers from below #2 and 3 plugs: 103C19. I believe I found someplace that the 'C' meant the cam was for a 2BBL at least which may be why my 86 distributor works well with it.
(after checking, I have the old engine's distributor in it)
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86/00 CJ7 Laredo, 33x9.5 BFG AT's, 'glass nose to tail in '00, 'New' frame,wires and plumbing in '09. Carter BBD Carbed 4.0 HO in '10.
89 YJ Renegade. BBD Carbed 4.0 HO. Locked front and rear with 33x9.5 BFG AT's
Some Canadian Bush Jeep Runs and Build Photos: http://mikeromainjeeptrips.shutterfly.com (10 new albums added Sept 16/10)

Last edited by Mike Romain; 01-13-2010 at 12:42 PM.. Reason: more info
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Unread 05-29-2009, 10:07 AM   #6
chill254
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Well I can't say for sure because the numbers are in a different order. It is possible that they used a different numbering system before. The normal numbering would be say 3 10 c 19 and would indate a 1983 2v carb built on October 19. Since the numbers are laid out different I can't say for sure without knowing the numbering system for models before 1980. I will try to check mine this weekend as it is a rebuild.
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Unread 05-29-2009, 10:12 AM   #7
chill254
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Also the compression went up from 8.3:1 to 9.2:1 after the 81.
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Unread 05-29-2009, 10:24 AM   #8
chill254
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Check out this web site.

http://www.amcrc.com/tech/engine.html

It is also possible that it is a 1979.
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Unread 05-29-2009, 10:27 AM   #9
chill254
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Here is a site for the casing numbers.

http://www.geocities.com/cantwait_fo...ers.html#block
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Unread 05-29-2009, 10:53 AM   #10
fuzz401
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from 78 service manual

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1978 cj-7 had since 1979
401 .030 over- full floating flat top pistons
crower solid cam 292 dur .500/.510 lift
turbo 400 tranny 2500 stall
model 20 transfer case
aj delux glass body
4" lift
dana 30 frount
dana 44 rear
4.56 gears
http://img2.photobucket.com/albums/v...slideshow=true
http://photobucket.com/albums/v31/fu...slideshow=true
13.461 @ 92.45 mph on 37" super swampers on 1/4 mile
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Unread 05-29-2009, 11:33 AM   #11
chill254
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They are slightly different.


.................................84-86..... 78 2 bbl..... 78 1bbl

Cam lobe lift..................0.0253..... 0.0248..... 0.0232

Intake Valve
Opean ...................9 BTDC..... 14.58 BTDC..... 12.12 BTDC
Close ...................73 ABDC..... 68.79 ABDC..... 64.80 ABDC

Exhaust Valve
Opean.................57 BBDC..... 55.59 BBDC..... 53.12 BBDC
Close..................25 ATDC..... 27.78 ATDC..... 23.80 ATDC

Overlap......................34....... 42.36....... 35.92

Intake Duration.............262....... 263.37....... 256.92

Exhaust Duration...........262....... 262.37....... 256.92


I guess the next question would be if they ran different mechanical advance limiters in the 2bbl vs 1 bbl distributor.

Last edited by chill254; 05-29-2009 at 01:59 PM..
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Unread 05-29-2009, 11:37 AM   #12
John Strenk
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Looks like the 84 cam is a little more retarded (14* vs 9*)than the 78 but that makes sense since it's more designed for emmisions. THat would make the most impact i would think. Redrill the pin holes on the gear? .

What is the rocker arm ratio on the 78?
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Unread 05-29-2009, 11:37 AM   #13
chill254
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Thanks fuzz 401.
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Unread 05-29-2009, 11:38 AM   #14
chill254
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They were probably trying to take out some of the overlap.
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Unread 05-29-2009, 11:44 AM   #15
fuzz401
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Quote:
What is the rocker arm ratio on the 78?
same as the V-8

1.6:1
__________________
1978 cj-7 had since 1979
401 .030 over- full floating flat top pistons
crower solid cam 292 dur .500/.510 lift
turbo 400 tranny 2500 stall
model 20 transfer case
aj delux glass body
4" lift
dana 30 frount
dana 44 rear
4.56 gears
http://img2.photobucket.com/albums/v...slideshow=true
http://photobucket.com/albums/v31/fu...slideshow=true
13.461 @ 92.45 mph on 37" super swampers on 1/4 mile
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