Hi everyone! New guy to the site here. I signed up awhile back actually, but this will be my first posting. I'd seen the topic mentioned before by other members, but it seems to hit a dead end. I bought a '55 Pontiac off of ebay last September with a '68 400/t400. It runs and drives well with quite a bit of power, but the engine & ****** seem precariously mounted and I'm afraid I'll romp on the gas one day and see the motor blow the hood open and shoot out across the road. Up front it's mounted on the timing cover with the oe '55 mount, and the ******'s mounted at the back with what looks like a prefab piece which sits nicely between the X members. I'm guessing this was made to be used for tri 5 Chev convertibles, but I could be wrong. Anyway, what's keeping the whole thing from twisting out from under the hood when you mash on the gas are two 'torque chains' I'll call them. They're heavy chains bolting the T400 bell to the frame on either side. Originally I thought to make up a set of brackets similar to what Danchuk offers to mount a Chevy T400 in a Tri 5, but there's still the issue of the single front motor mount. Now, the question is, what do I do? I'm ok with the mig welder, but have no experience in bracket fabrication. Does anyone make a set of brackets I can use to mount the engine at the side mounts to the frame? Thanks in advance for any input! PS-please excuse the ****py chrome parts on the engine, I bought it this way.
The saddle mount was used up through 59 (and possible later?) on engines up to the 389, so I'd think it would be strong enough to handle the power. Of course, your motor isnt meant to be mounted that way, and I don't know the deal with the chains... so you're probably correct in questioning some of the engineering that went into the motor swap. You might want to try to get a better picture of the actual motor mount. PS, I;m jealous. My bone stock 287 is ticking over 130,000 miles and it's getting pretty tired. I'd love to do your exact swap (or find a '59 389 to drop right in).
Oh to have the descriptive vocabulary I used to have before brain cells started dying... Nice pontiac! The original mounts on these cars were: One at the front (like it already has), and one on each side of the transmission bellhousing that went the crossmember that's apparently been taken out. I sold mine on ebay last year, or I'd offer it to ya. The original one went about where the bell met the block, with clearance on the p***enger side for a single exhaust. If you could fab one up (not too hard to do) or have someone make one for you, all you would need is a couple of L shaped pieces made from some decent angle steel that allow a couple of bellhousing bolts on each side to attach to the bellhousing, and a single bolt through the bottom that used the typical rubber donut bushings to attach to the crossmember... here's a quick (and cheesy...my good software is on another computer) sketch of what I'm talking about just a rough sketch of a rough idea, but it works.
the chains are probably there to keep the engine from torquing over and breaking something...I've seen that a lot on some of the redneck engineered "drag cars" in these parts, but it's usually one end of chain to the block, the other to the frame for the engine to pull against under full throttle. Seems to me like the way his is set up that it would be pulling against both sides, downward, causing stress on that aluminum bellhousing? edit: I'd love to do that swap too! I wish there were more pontiac donor cars close to my home town...
I've actually seen that done before and am kinda torn. On the "it's OK" side drag cars use motor plates without mid mounts all the time your front mount is a fairly proven unit in your power range Ultimately it doesn't seem very different from some tri-5 chevy conversion mounts Chains may be redneck but are extremely effective to control engine roll On the "holy ****" side we've got Motor plates do a better job of controlling tilt, leading to less stress at the bellhousing 4x4s that cantilever a th400 with t'fer case weight also use a secondary transmission brace. Failure to install said brace results in a broken bellhousing. If that's my car the concern is a broken bellhousing more than the engine actually pulling loose. Ever taken apart a th350 or 400 case with a sledgehammer? I have. About 4 hits and you can lift the rotating ***embly right outta the case. They're WAY weaker and thinner than you would think after beating on one from the driver's seat. The mid mounts suggested above will get the engine's weight off the bellhousing. good luck!
'59 had side mounts. My only worry with the chin mount is - is it new, or old? When they get old, they come apart. We pulled a motor out of a '56 a few years back and I never had to touch a bolt, it just popped loose. The early (59-60) side mounts are the same way, except there's two of them and they usually break one at a time. Here's the deal. You can run either the 59-60 type mounts which use one bolt vertical through a hole, or use the later mounts which use a horizontal through bolt like most anything else. This is what I would do if I was building one. I'd go to the junkyard (well, my backyard) and get a pair of '81-'87 Chevy pickup mount plates. They're angled plates the mount sits on. They'll take a standard GM lower mount for the through bolt. Bolt on some stock '68 side mounts, use the through bolts to mount the whole works - lower mount and plate - and see what you have to trim off it to make it work. If you can drill holes and bolt it, bolt it. If you have to trim it, weld it in. Have a pro do the welding with a stick welder. I'm thinking you might be able to trim them or add material so you can use these and clear the A-arms. A company called Indian Adventures used to make a mount kit for late V8 in 55-57 cars but it's been taken off the market. Also, what steering is in this car? How's the clearance around it? With stock steering the factory ran the dump out the front of the motor, it was that tight.
No matter how hard I try, I can't wash the red off my neck What does one expect from a person whose alma mater had a muzzleloader totin', overalls wearin' hillbilly as a mascot? I hope nobody gets offended at my using that word to describe the chains, LoL...simple but effective. Thanks Shifty, I KNEW there was a proper name for "mid-mounts." In my pain med altered state, I couldn't think of it!
Any side mount brackets would have to be made. Here's some pics of what I built with 2x2 1/4" thick tubing cut at a 45 than 1/4" plate welded w/my 68 GTO frame brackets. But for a cleaner more original look, I got a 60' cover (last year for steel cover) and an early Hurst mount I picked up. I also picked a 60' cover because 55-59 engines were reverse cooling. Of course just the 60 cover and an early mount would work, but with the biscuit mounts on the Hurst mount would be a stronger set up IMO. I believe the earlier cover would work on the newer engines, it's also bored for a newer type seal instead of the cork/spring deal. A centering fixture has to be made to mount this cover to the engine also. Than either put in a mid plate and tie in to the original trans crossmember or build some more brackets for the trans if your staying with the timing cover mount. If you build some side mounts than that and the rear trans mount would be enough. The first 2 pics are my mounts, 3rd pic was borrowed from here on a Hurst mount thread, last is the 60 cover w/Hurst mount.
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