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MFI cam towers, more big bore MFI questions

Will 2.4 MFI cam towers bolt up to 3.0 heads?

What kind of work needs to be done to 3.0 heads so that you can use MFI injectors instead of CIS injectors?

TIA
Old 11-28-2004, 01:07 PM
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thanks Noah!
Old 11-28-2004, 05:06 PM
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Sherman,

To use MFI on 3.0 Heads you need to do the following
1) have the part of the port where the old CIS goes in welded up
2 Machine a new hole for the MFI injector
3) Tap new hole with correct thread.

I had a local welder/ machinist do mine and it cost me $200 AUS.

I must say that I did supply him with a bare 2.0S head for comparsion.

Michael
Old 11-28-2004, 06:57 PM
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thanks Michael!
Old 11-28-2004, 07:00 PM
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Somewhat related - is it possible to use 2.4 or 2.2 MFI heads on 3.0 or 3.2 long blocks so that MFI can be adapted to these motors?
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Old 11-29-2004, 09:57 AM
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I think the head would need to be machined to accept the larger barrel

Michael
Old 11-29-2004, 01:42 PM
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No, the 2.2-2.7 heads have a different bolt spacing than a 3.0 head. They are not interchangable. the only way to get MFI is the modifications Walko outlined earlier.
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Old 11-29-2004, 02:19 PM
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Sherman,

The issue with cam housings is there are 3-bearing housings and 4-bearing housings. The MFI drive oil seal replaces the steel plug in the cam bore.


EDIT
Originally posted:
"As I recall (a stretch) you can use a 3-bearing cam in a 4-bearing housing if you plug the extra bearing oiling passage. You can use a 4-bearing cam in a 3-bearing housing with no mods. As I recall the cam housings were otherwise interchangeable. I don’t think the 3-to-4 bearing changed exactly with the 3.0 SC but slightly earlier."
Not so, I was in error. See the following posts.
There may be an intermediate configuration with small journals and 4-bearings. More research is needed.
END EDIT


Jamie is correct. The 2.7 has 80 mm cylinder stud spacing and the 3.0 SC has 86 mm cylinder stud spacing. See Bruce Anderson, 2nd Ed. p. 70.

Best,
Grady
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Last edited by Grady Clay; 12-01-2004 at 11:46 AM..
Old 11-30-2004, 07:26 AM
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Grady;
The cam bearing ID is different between the 3-bearing style (46.967-46.992 mms) and the later 4 bearing style (48.967-48.942 mms). I would imagine that you could use a 4 bearing cam in a 3 bearing carrier as long as you bored out the carrier the extra 2 mms.

I do believe that either carrier will bolt onto any style head.
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Old 11-30-2004, 07:38 AM
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Thanks guys!

So, ideally you would want to start with a 3 bearing MFI cam tower and a set of core MFI cams?

I talked to EBS today about the head work that would need to be done. Its just money

I just scored a set of mag '69 stacks. All I need to find at this point is a set of '69 throttle bodies.

This is actually starting to sound like a possibility.
Old 11-30-2004, 09:14 PM
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John,

The Forum comes through! Thank you. I’ll go edit the corrections.

My recollection the change to 4-bearing was possibly in ’77 (earlier?) Is there an intermediate configuration - 4-bearing, small journal? I recall discussions with my engine mechanics about what-would-fit-what some time in the late ‘70s. I looked in PET6 and didn’t find any obvious intermediate configuration.

This brings up the situation where, in order to use the larger journal, 4-bearing cams, you must have a MFI-suitable cam profile, the appropriate cam extension for the MFI drive, and a proper oil seal. It is certainly easier to use the 3-bearing cams and housings on the 3.0 SC.

Best,
Grady
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Old 12-01-2004, 11:38 AM
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I have a suspision that they bumped up the cam journals by 2mm in order to get more lift out of the cams. Would this make a difference in this case? Any confirmation?
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Old 12-01-2004, 12:13 PM
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I have heard of some 1975 to 1977 cam carriers that have 4 main journals sized at 47mm (46.967-46.992 mms). The engine
had 3 main journal camshafts and the extra main journal in the carrier was sealed from the factory.
Some of the early racing cams were 47mm and had 4 mains too.
If you wanted to retain the 3.0 49mm (48.967-48.942 mms) carriers, I can make a set of new billets with any available grind. These billets also have the MFI extension.
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Old 12-01-2004, 01:05 PM
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Quote:
Originally posted by Tim Walsh
I have a suspision that they bumped up the cam journals by 2mm in order to get more lift out of the cams. Would this make a difference in this case? Any confirmation?
That's basically true. They went to the four bearing cams for hte racing engines (I believe with the RSR in '74 - not sure) and soon adopted it for the street cars as well.

Performance-wise, there's really little difference between 3 and 4 bearing cam towers, and they can be used interchanged with each other. In general, I haven't heard of anyone using mistmatched cam towers with mismatched cams (3 bearing cams with 4 bearing towers), as it is relatively easy to find the proper cam tower for your cams.

-Wayne
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Old 12-01-2004, 10:37 PM
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Thanks again, everyone! I appreciate the help.

camgrinder, what do you think of running a GE40 cam with Max Moritz 98mm pistons and MFI? The pistons have already been cut for clearance and the engine ran in this configuration for years with carbs.

Would it be easier to use my 2.4 MFI towers and regrind my T cams, or to modify my 4 bearing SC cam towers and GE40 cams for MFI?

edit:
I should be able to get away with only modding the LHS cam tower, no?

Last edited by Shuie; 12-03-2004 at 06:30 PM..
Old 12-03-2004, 05:59 PM
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Sherm,
Since i cant talk you out of those mag stacks, I'll let you in on a little secret. The mag stacks on my 3.5 are 69's and they fit right up to my 73 S/RS throttle bodies.

Call Matt at Eurometrix. The last time i talked to him, he was trying to keep some popular sizes on hand for a quicker turn around. Plus, if you send them to him, he MAY match the ports for you. He is always adding new stuff to his can-do list.

Paul
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Last edited by Paul Thomas; 12-03-2004 at 10:34 PM..
Old 12-03-2004, 10:30 PM
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It is better to run the SC cam carriers and 4 main cams. The T cams would require hardwelding.
The GE40 style cam works great with MFI.
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Old 12-03-2004, 11:31 PM
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Paul, thanks for the heads up on the '73 throttle bodies. That will be a big help if I can use the -'73 throttle bodies. Im going to call Matt to see what he thinks I need to do. Do you know what cams and cam towers your 3.5 uses?

camgrinder, you have an incoming PM
Old 12-04-2004, 03:25 PM
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Sherm,
My motor has 4 bearing cams in SC towers. I just switched to a Wedcam grind, similar to a GE 80, that is alot of fun all over the rev range.

Paul
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Last edited by Paul Thomas; 12-04-2004 at 09:29 PM..
Old 12-04-2004, 09:26 PM
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