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Shoe-horning a Mammoth under the hood:

38K views 328 replies 68 participants last post by  TonyS 
#1 · (Edited)
For those who might be interested in following my big inch engine 70 SS clone build-up, here's an update. The big tall deck block 632 inch engine is finally in the car, but boy did it take some doing! The big monster wouldn't even fit, and I had to cut the frame!

Take a look at the engine shots below, and notice how deep the front of the oil pan is. Not the sump in the rear of the pan, but the front of the pan.
The reason for the depth of the front of the oil pan, is because of the massive 4.75" stroke of this engine. The pan had to be made that deep just to clear the connecting rod caps while also using a windage tray and crank scraper, because of the huge throw of the big stroker crankshaft. The reciprocating parts of this engine are literally busting out of the block, and a really deep pan had to be used as well as the block being relieved to clear the crank and rods.

It's because of that, which made it neccessary for me to cut the front crossmember which as you know is part of the frame. The oil pan wouldn't clear the crossmember, and it bottomed out on it before the engine was low enough in the compartment for the motormount holes to line up with the motormount frame bracket holes.And because of close hood clearence, I didn't want to attempt to raise the mounting points of the motor mounts. So in my next post, I'll show you pics of what I did to get around this obstacle....
 
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#3 · (Edited)
...then it was time to have some steel pieces cut and welded in, to box the crossmember back in again in order to restore rigidity. The frame is .125" wall thickness, so I decided to use steel pieces that were of a .250" thickness, so that the frame would be stronger than it originally was.

I used pieces of cardboard to make up templates, that I would then use to trace the patterns onto the sheet of 1/4" thick steel that I bought ( just like I did when I made up the pieces for boxing in the control arm brackets).

I brought the steel to someone who had the equipment to cut the pieces out of it for me that I had traced the patterns for. And then I got the welder back over again, to weld them in.
 
#8 · (Edited)
...and, while I was at it, I also did some more things to the frame in other areas of the car, to beef it up more, to prevent it from being twisted when I put my right foot into the pedal. I cut and welded 1 5/8" diameter steel tube with a .134" wall thickness to the frame rails so that they would run parallel to them on each side of the car. Now in essence, the car has four frame rails instead of two. I also intend to have welded in gussets to the steel tubes, in the four places where they meet the frame.....
 
#9 · (Edited)
...and here's a couple shots of the rear wheel & tire combo I'll be using, that's sitting next to my brother's Harley, just to give you an idea of the size of the rear meats..... that's all for now....next, I have to figure out how to get the steering linkage to clear the deep oil pan. I'm going to try and find a pitman arm with a greater drop to it than the stock one has, and if I find one, then I'll also drill two holes lower in the frame rail for a lower mounting point of the idler arm, so that the centerlink will rest lower in order to clear the oil pan. After that, the transmission, and headers go in, along with the 3.5" diameter exhaust......
 
#11 ·
Very nice, I have never heard of a 632 .. ?

Thats a lot of inches !
Thanks....it's a tall deck block ( 10.2" deck height) with a 4.600" bore, and a 4.75" stroke. It's an aftermarket block ( a "Merlin III" block) which is a beefed-up version of the Chevy mark IV block which also has thicker decks. This particular version that I have runs on pump gas.
 
#13 ·
Holy cow......I know of the 632, a friend has one in his 68 chevelle....it makes 900+ hp and almost the same in tq.

I think he has around $14,000.00 invested, his is also a merlin III block.

Have fun keeping any kind of tire under it without roasting them to the cord in a hurry......
 
#15 ·
Holy cow......I know of the 632, a friend has one in his 68 chevelle....it makes 900+ hp and almost the same in tq.

I think he has around $14,000.00 invested, his is also a merlin III block.

Have fun keeping any kind of tire under it without roasting them to the cord in a hurry......
Yep, the 900 HP version is the high compression race gas one, and the one that I have is the pump gas 800 HP version which has a 10.5:1 compression ratio.
 
#17 · (Edited)
That's what I'm going to find out. It's sold as a "street" motor and even comes with a 2 year/24,000 mile warranty. Unlike their 13.5:1 compression ratio 632 race version one. I plan on running this car on the street, and once in awhile at the dragstrip. But it will be primarily a street car.
 
#24 · (Edited)
Like i said in my previous post, no the centerlink will not clear, and that's my next mini project. I wanted to get a rack & pinion set-up especially for Chevelles, by a place called "Steeroids", but I called their tech department and they told me that they will not have the GM A-body set-up ready until next year, so that's out. And I don't know of any place else that makes a rack & pinion set-up for GM A-bodies. I don't want the steering to become a major project either if I can help it, so I haven't any desire to attempt to design my own rack & pinion set-up for this car.

I plan on trying to find a pitman arm that has more of a drop in it than the stock Chevelle one does, and relocating the idler arm mounting holes lower on the frame rail also, in order to drop the cemterlink down so that it will clear the oil pan.
 
#28 · (Edited)
Harold,

I forgot to answer your other question about the choice of rear end that I made. I'm using a Strange "S-60" rear which is their Dana 60 rear with a Detroit locker, 3.73 gears, 35 spline axles, a chromemoly 1350 series yoke, and a heavy support cover with a girdle. And I chose a built up TH400 transmission rated for 950 HP with a full manual valvebody that has a reverse shift pattern, along with a 3,200 RPM stall speed on the converter. Below are some pics of the rear....
 
#29 ·
What street yoiu going to run that thing on???

Don Garlits Ave..????


That is even a mad motor for Gratiot Ave. or Woodward around here....I think..!!

Good luck with tires..what brand are you going ot explode first?? I might just buy some of their stock.
 
#30 ·
What street yoiu going to run that thing on???

Don Garlits Ave..????


That is even a mad motor for Gratiot Ave. or Woodward around here....I think..!!

Good luck with tires..what brand are you going ot explode first?? I might just buy some of their stock.
I have a supercharged low 12 second pump gas daily driver, and have been using that car for the commute to work for the past three years. This car had to be a cut above that one in performance, otherwise this restoration wouldn't have been worth the time and trouble for me. I'm already beginning to stock up on tires. I have a stack of the M/T drag radials. I'm gonna need em'. ;)
 
#32 ·
If all you have to say about my project is some wisecrack about the oil filter, than that is pretty lame. What's next? An argument about the choice of oil? :waving: I guess you're not really much of a car enthusiast.
 
#34 ·
Billy,
Don't worry about these jokers. :boring:
They said the same thing over two years ago when I first built my pump gas, street driven 540...never get it to hook, can't use all that power, bla, bla, bla...
Now, everyone is building a BIGGER big block it seems like. ;)
I for one have enjoyed your posts on this project and look forward to seeing more details in the near future. :thumbsup:
 
#35 ·
Bill,

you're one of the guys that I was looking forward to seeing weigh in on this thread of mine. I have a lot of respect for you, and the way that you conduct yourself on this board. Guys like you help to give this hobby and sport of ours a good name. You sir, are one class act, and not merely because you've paid me a compliment. I consider some guys on here, to be assets to this board, and you sure are one of them. Thanks for your post my friend, and for all of your advice so far!
 
#38 ·
Wow that is a buncha work. Should be quite impressive when you are finished.

I would be concerned about strength and flex of the cross member personally. Doubling the thickness of the new top metal is ok but misses a lot. The strength of something built from stamped steel like the cross member is more the result of the distance between the shells than it is of the thickness of the shells. If you move the shells closer together by half you have reduced strength to perhaps one fourth. Doubling top shell thickness to compensate will just focus the stress in the lower shell. At a minimum I would add reinforcement to the bottom side of the cross member.

Another area I would be concerned about is the shape of the inset. It appears from the pictures to have fairly square corners to it. If so, these will serve to focus stress into the corner. You will often find corner gussets in sheet metal structures to add reinforcement for just this reason.

You may not get much out of your frame side reinforcments either. To reduce twist you need to tie the two sides together into one box. An X brace is one way to do this. A full cage would probably be the best way to reduce torque flex on this monster ;-)

You are also flirting with disaster with your plan to lower the centerlink. The vertical alignment of the pivot points on the outer tie rods relative to the lower control arm is a very critical factor in bump steer. By lowering one of these points (the centerlink to tie rod pivot) you will create a strange steering response as the suspension moves. I might be inclined to fabricate a custom centerlink with a dropped center rather than change pittman arm and idler arm locations. Especially on a street car.
 
#41 ·
Wow that is a buncha work. Should be quite impressive when you are finished.

I would be concerned about strength and flex of the cross member personally. Doubling the thickness of the new top metal is ok but misses a lot. The strength of something built from stamped steel like the cross member is more the result of the distance between the shells than it is of the thickness of the shells. If you move the shells closer together by half you have reduced strength to perhaps one fourth. Doubling top shell thickness to compensate will just focus the stress in the lower shell. At a minimum I would add reinforcement to the bottom side of the cross member.

Another area I would be concerned about is the shape of the inset. It appears from the pictures to have fairly square corners to it. If so, these will serve to focus stress into the corner. You will often find corner gussets in sheet metal structures to add reinforcement for just this reason.

You may not get much out of your frame side reinforcments either. To reduce twist you need to tie the two sides together into one box. An X brace is one way to do this. A full cage would probably be the best way to reduce torque flex on this monster ;-)

You are also flirting with disaster with your plan to lower the centerlink. The vertical alignment of the pivot points on the outer tie rods relative to the lower control arm is a very critical factor in bump steer. By lowering one of these points (the centerlink to tie rod pivot) you will create a strange steering response as the suspension moves. I might be inclined to fabricate a custom centerlink with a dropped center rather than change pittman arm and idler arm locations. Especially on a street car.
Thankyou for your input. I am planning on reinforcing the bottom of the crossmember also, so I hear what you're saying about that. Good point, and one that's well taken!

As far as the bump steer issue, I know that is a very important issue, and I do appreciate you bringing that up. I figure that I'll only have to lower the center link about one inch. Do you think that a small amount like that will cause bump steer? That's a sincere question on my part ( no sarcasm intended). As for the left and right frame rails, I've seen race car frames offered for A-bodies, that have double frame rails made of steel tube, so that's where I got the idea from to do what I did with the frame rails.

I realize that going across from one rail to the one on the other side would be ideal, but with the 3.5" exhaust that I'm going to have, that won't be easy. Again, thankyou for you well thought out input. :thumbsup:

BTW, I really want to have a custom made centerlink, I just don't know where I can go to have that done.:confused:
 
#40 ·
Christ you need to lighten up...most my comments were meant to be a joke.

I've been on this site a lot longer than you and the long time members know who I am and how I treat others. I go out of my way to help folks when I;ve gone through similar things and can give first hand input.

good luck with your project...you just need to lighten up a bit and not take comments so serious. What ever happened to some friendly rib poking and joking?

EDIT: I appologize if my prior comments offended you. But I still feel you need to rethink your oil filter choice ;)...that and lighten up a bit.
 
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