Has anyone converted an original 307 car to a big block? I am changing to a 454 to be exact.

I am getting conflicting stories on the frame mounts. Are the small block and big block frame mounts the same?

I appreciate any advice.

If your 69 had a 350 in it originally....you bolt right up. If a 307 originally....gotta swap frame mounts. At least that's what I've read and been told regarding the 307. Mine had a 350 so I didn't have to do anything. graemlins/thumbsup.gif

as far as i know the only thing different that i could see was the webbing inside the frame mounts was different ...fairless hills thats were i am you wouldnt happen to be on collingswood rd would ya

I did it. went from a 307 PG, to a 307 turbo 350, then a 402 t350, now a 454 t350, looking for a turbo 400 to go behind this beast now.... back to your question, I didn't change anything except went to solid motor mounts.

I am near Collinswood. I have a dark green 69 clone shown here.

http://jmurphy333.home.comcast.net/images/chevy1.jpg

Purs - I have a 400 trans, short tail. It came out of an 84 Suburban 1 ton. It shifted hard when I disassembled it. I took it apart for the 454 going in the Chevelle. I also have a 2800 stall converter with less than 100 miles on it.
If you are interested, send me an e-mail at jmurphy333@comcast.net.

307 frame mounts are different. The rest of the small blocks and all of the big blocks are the same.... so if you go from 307 to anything else, you need to change them. You can mix and match motor mounts and make a big block go in there, but it won't sit level and will not be in the right spot. graemlins/thumbsup.gif

damm were almost neighboors. good luck wit the conversion. are you a member of the l-town street race website

by the way. the car is sweet lookin i havent seen it around before my uncle lives on your street along with some freinds also

Last name Matthews?

OK, does anyone know where I can buy these frame mounts? Ausleys does not carry them.

I swapped from 307 to 396. Transmission type does not matter, But since you brought it up I HAD a T350 now T400.

Anyway The frame mounts on a 307 are TALLER and can be used, BUT may give you hood to air cleaner clearence problems depending on your set up.

I got my frame mounts from a 350 powered 71 Monte Carlo junkyard car.

I have seen them in some of the car books, I think Ground up (our sponser) or OPG, can't remember, maybe both.

307 frame mounts are taller and slightly wider, HOWEVER when used with the matching 307 engine mount the engine will sit in the same place as the 350/BB mount setup. A 350 engine mount will not fit all the way down on a 307 frame mount which is why the incorrect info about the engine sitting high starts. I have done the swap numerous times, and this has been covered many times, a search will bring up the info.

martell

The 307 engine mounts will work on your 307 frame mounts , but are much lighter duty and I would not recommend it for a BB.
You need frame mounts from a 68-72 Chevelle 350 or larger engine car. Can be an El Camino, sta-wag, whatever as long as it's a Chevelle (A-body).
70-72 Monte Carlo are the same as well.
NO Buick, Olds or Pontiac mounts will work.

If you cannot find a set, I have several. Just email me.

I would highly suggest you use the Energy Suspension engine mounts. They handle the BB torque much better that the stock rubber mounts.

Nate

Thanks for all your suggestions. I am a newbie to the forum, and I really like it.

I will call Ground Up today (sorry - I did not realize they sponsored the newsgroup)

Thanks again!

I just helped a buddy with his yesterday. Out came a 350/t350 and in went a 427/t400. Same mounts, same framestands and same crossmember. I think we moved the crossmember back, but I was busy putting the rear diff cover on. No mods, just bolt-on.

I have a 69 originally a 307 now a 350.If the mounts were'nt changed when the 350 was put in,could this be the reason my fan hits the fan shroud? Thanks, Scott :confused:

Only if someone tried jamming 350 engine mounts down over the 307 frame mounts.

I have consulted with Dave(droptop) before on this issue. I am currently doing a 307-454 swap. His judgement is correct. However, I have not been able to find 307 specific engine mounts in a regular parts house. I've checked the big chains and the small Mom and Pop stores.

When you go to the store for a 307 mount, it is the same as the 350 or BB mount. Somewhere over the years the aftermarket companies have dropped the 307 mount and now just list 1 mount for all 8 cyl applications, or some companies list a SB and BB mount which doesn't make sense either.

What to do???

It's confusing. I called Ground Up on Weds. and bought a matching set of engine and frame mounts for a BB. I plan to compare them to the 307 mounts out of curiosity.

If I find anything noteworthy I will let you all know.

The 68-72 Chevelle 307 GM mount with the safety ears is 3990914. This is the same part listed for the early 283,327 (if you have changed to the 66-67 BB frame brackets, not an issue on the 68-72 307 frame brackets)
I just bought a pair for my 66 327 from GM Parts Direct, not cheap but they are new good quality parts made in Canada. I personally would not trust a super cheap off-shore SB mount for a BB.
I am sure any parts store can cross-reference this GM number for you.

Rene
66_Malibu

Is that Joe Murphy from Fairless Hills PA by any chance? I knew a Joe Murphy years ago who had a 69 Chevelle lost touch with him.

By the way when I converted my 69 from 307/glide to 396/400TH I used the factory 307 frame mounts that were in the car with Moroso solid motor mounts, never had a problem with fit or clearance.