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Old 08-11-2004, 02:04 PM
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68 Firebird engine/ trans mounting

I have 68 Firebird conv with org 350th trans and org driveshaft(org engine was a 350) and a Pontiac 400 from a 1975 Catalina(engine codes reads 74 engine). Orig crossmember is still mounted in car. From the measurements/ comparision that I have made from the eng and trans to the motor mount and crossmember I will be approx 7" short on he eng and trans... I would rather not have to move the crossmember if I dont have to, and from what I read the 350 and 400 eng blocks are the same...so Im not sure now...any help is greatly appreciated.....Thanx Pete

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Old 08-13-2004, 12:28 AM
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Pontiac made some changes in their motor mount setup in the early '70s. Your 350 probably has 2 bolts on each side, one in front of the other down by the oil pan. Many of the later ones had 3 bolts, 2 down low (but not at the same place as the other 2), & another an inch or two above the others on a raised boss. Some of the later 400's & 455's had all 5, so check & see if you're lucky. If not, Indian Adventures has mount adapters.

The '75 Turbo 400's in the big cars had a longer tailshaft housing than the smaller cars. Even short-tail T400's used in smaller cars use a different crossmember (it's tubular, although slightly flattened, & positions the mount farther to the rear) from T350 cars. I don't know if it will work with the long-tail T400, though.

www.chiefmanyhorses.com click on "online catalog", then on "motor mount adapters" in the left-hand column
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Old 08-13-2004, 12:34 PM
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Thank you for responding ..but Im still confused

The engine I want to mount is the 400 and it does have the 5 hole mount pattern. The engine mounts that I have been taken off the frame of the car and match up using three of the holes and pe rthe measurements I made to the firewall will work giving the dist enough room. So I guess my dilema is the trans and the crossmember..or is it....again if I use the th350 that org came with the Firebird and the org driveshaft the cossmember is too far back and would have to be moved, although I thought that my eng block was the same dimensions as the org 350 engine and with the org trans and drive shaft that it would all line up....but again with eng and trans mounted the total length is not long enough to line up with the crossmember........whew...I hope this isnt confusing......another question will the th350 work wih the 400 engine...? Thanx in advance...Pete
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Old 08-14-2004, 12:51 AM
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Yep, the T350 will work. But I am confused. Pontiac 350, 400, & 455 engines have the same external dimensions, and one of them with the 5 mounting holes can replace any of the others using the stock mount setup specific to the car. Early Firebirds that I've seen have all used the two-bolt mount setup, but maybe somebody changed something. There's a pic of the original setup here:

http://cgi.ebay.com/ebaymotors/ws/eB...category=46098

Last edited by jimfulco; 08-14-2004 at 01:10 AM.
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Old 08-16-2004, 10:50 AM
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True...sombody could have changed something...

That could be true someone might have changed something...I am goning to have to check into this a bit more....I am also assuming that the guy I bought the car off of is teling me the truth, its possible someone alrady moved the crossmember, I actually havent inspected the undercarriage too closely yet...THat mounting kit link from Ebay that is in your reply is the mount that is on my Firebird...Thanx Again fo rthe info....if you come up with anything else please let me know.....Pete
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