A/C Delete Options for 3400's

ronaconda · Post by **ronaconda** » Sun Dec 25, 2011 3:36 am

So this post got me thinking...

3X00-Modified wrote:This is a diagram I found for the MPFI motors without AC... This is not possible on a 3100 install due to the way the motor mount is setup, you need a AC delete pulley to get the job done, but its not a big deal really.

...which sent me to my "lab" (aka junkyard) this morning and this is what i learned. The 3400's from a Grand Am, Venture van, Montana van, Silhouette van, and the 3100's from the Malibu all share the same belt routing - tensioner on the alternator bracket that tensions the belt toward the firewall and has a ribbed pulley - all have this stub on the front cover:

This is where a smooth idler puller resides on the vehicles mentioned above. The smooth pulley can be replaced with the grooved pulley that is utilized on the tensioner and thus bypass the a/c without the use of the a/c delete pulley as shown:

Some important tidbits...

the bolt used in the above pic is the bolt from the smooth idler pulley and will need to be used on the grooved pulley.
For those of you that grabbed your 3400 from an Impala, those 3400 covers, from what i have been told by someone that got his 3400 from an Impala, DO NOT have the idler pulley stub on them.
I do not know how this will work for 3100 swaps using the mount that Jon mentions in the above quote/diagram. This WILL however work for the older (87-90 2.8/3.1) swaps.
Actual belt-to-water pump pulley contact will vary from the pic above - i believe that it will have more contact with the pulley. The 'lab rat' that i was playing with no longer had it's p/s pump.
These 3400 covers have the holes/threads for the 'typical' tensioner installation.
Dimensions (pulley OD, bearing ID) are the same between the smooth pulley and the grooved pulley.
This setup will use a shorter belt.

Alpinestar10 · Post by **Alpinestar10** » Sun Dec 25, 2011 4:14 am

common knowledge with z24 guys, With the grooved pully on that "boss" and no underdrive balancer its a 600k6 belt lenght...

ronaconda · Post by **ronaconda** » Sun Dec 25, 2011 4:41 am

Alpinestar10 wrote:common knowledge with z24 guys, With the grooved pully on that "boss" and no underdrive balancer its a 600k6 belt lenght...

I bet it's common knowledge with those guys...didn't even occur to me to search this over there. A parts search of the belt for a non-a/c 88 Beretta showed a 615 length belt which is nearly an 1-1/2" longer than the 600...not questioning what you posted, more thinking 'out loud'...

Post by **3X00-Modified** » Mon Dec 26, 2011 11:05 am

If you have the AC bracket in there, then the $28 bypass pulley with the right size belt seems to be a better option if you ask me...

Alpinestar10 · Post by **Alpinestar10** » Tue Dec 27, 2011 3:46 pm

ronaconda wrote:
Alpinestar10 wrote:common knowledge with z24 guys, With the grooved pully on that "boss" and no underdrive balancer its a 600k6 belt lenght...
I bet it's common knowledge with those guys...didn't even occur to me to search this over there. A parts search of the belt for a non-a/c 88 Beretta showed a 615 length belt which is nearly an 1-1/2" longer than the 600...not questioning what you posted, more thinking 'out loud'...

For some reason the parts on the older timing cover are in a slight different location, I was running a stock balancer no power steering (had a stock size pulley used on a custom bracket to make sure it would use the same belt as normal) and a bypass pulley on that boss and it was 600 and then i went to a newer alternator from the 3500 engine with the bracket and iirc it was 610 or 615 can look later the belt is still brand new and in my basement. Personally the cast bracket that you can buy jon in my opinion is not worth it since its more of a pain to deal with if anything breaks on that. Heck even a brand new pully and belt is cheaper the 28 dollars.

Post by **3X00-Modified** » Tue Dec 27, 2011 7:25 pm

It wasn't a pain for me, I'd rather just work with it the way it was designed to be run. I'm not a fan with how little the belt is touching the WP in that setup above so I will always keep my AC or put an AC delete pulley, or centrifugal SC there to ensure proper contact.

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