120R vs 120ST

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Dec 3, 2015 | 05:48 PM

#11

abidzip

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Joined: Jul 2008

Posts: 70

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From: Central NY

Quote:

Originally Posted by fuelmoto

As several noted the ST is the emissions compliant version on the 120R engine. The only major difference is the ST motor uses SE-259E cams and includes some extras such as the throttle body, the 120R uses SE-266 cams. Both engines are very good platforms and are capable of making big power with just a few modifications. I would however recommend replacing the SE lifters before running either of these engines as we have seen several catastrophic failures, and we caught one here on the dyno just before before it expired. The valve springs are also a weak point.

Your scaring me Jamie, how many miles were on these engines when catastrophic failures occurred with the lifters and were the owners beating the crap out of it in you opinion?

Dec 3, 2015 | 07:42 PM

#12

Sierra977

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Joined: Jul 2014

Posts: 8,251

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From: Windwardside, Saba N.A.

The following were done to my 2014 120R before I took delivery:

1. SE roller rockers
2. Woods lifters
3. Offset rocker plate
4. 0.030" head gaskets
5. SE +1.5 quart oil pan
6. JAGG fan-assist 10 row oil cooler
7. Changed valve springs from 3-coil to 2-coil
8. SE Variable Clutch
9. Other things I can't remember right now...

Works damn good.

Dec 3, 2015 | 10:35 PM

#13

C.H.L.

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Joined: Feb 2010

Posts: 1,953

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From: Houston, TX

Quote:

Originally Posted by OldEnuf2NoBtr

There are tons of big inch motors running around that use the stock HD cam plate and oil pump with no issues what so ever. Matter of fact, a lot of builders swear by them.

My builder said he has good luck with these stock parts ....

Dec 4, 2015 | 11:29 AM

#14

fuelmoto

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Joined: Feb 2007

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From: Little Chute, WI

Quote:

Originally Posted by abidzip

Your scaring me Jamie, how many miles were on these engines when catastrophic failures occurred with the lifters and were the owners beating the crap out of it in you opinion?

Some have seen issues with less than 10K of normal use, we have one here right now that the lifter came apart and destroyed the cases.

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Dec 4, 2015 | 11:30 AM

#15

fuelmoto

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Posts: 7,287

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From: Little Chute, WI

Quote:

Originally Posted by Sierra977

Nice setup!

Dec 7, 2015 | 08:56 AM

#16

grbrown

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Joined: Jun 2007

Posts: 45,429

Likes: 2,898

From: Bedford UK

The 120R was launched as a promotional engine for drag racing. I suspect demand for it for road use, prompted the MoCo to capitalise on that and produce the 120ST version. That would also explain the lack of warranty on the 'R' and use of stock production parts on the 'ST'. The ST may possibly be helped by S&S T124 sales, as they also have two versions of that, with different cams and CR.