Big block mounting alignment questions - Team Camaro Tech
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post #1 of 12 (permalink) Old Oct 29th, 05, 08:13 AM Thread Starter
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Dave
 
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Big block mounting alignment questions

I'm rebuilding the 454 in my '68 SS. This car was originally 350 equipped. I had the running 454 in there before and I noticed (when assembling) that the tranny crossmember would not line up. I had to pry the trans over to bolt up the trans mount to the crossmember.

So, now I have my engine at the shop and am using a spare 454 block and tranny case to check the fit of the engine and get things aligned correctly. If you look at the pic, I have drawn a white line in the approximate center of the chassis. The engine is clearly offset to the passenger side by about 3/4". Is this correct?

I AM using the correct BB frame mounts, and I'm using interlocking '69 style engine mounts. How does the driveshaft end up perfectly straight to the crankshaft? If not, it seems like it would cause vibration.

There may already be a good thread talking about this. I've been searching and can't find any that specifically talk about this. If there is, and someone could post a link, that would be great.



thanks

Dave F. in Rhode Island
'68 Camaro SS Accel DFI 454 (SOLD - I'm a boring Corvette owner now)
Bought my first big-block Chevy in 1970

Last edited by Chevy-SS; Oct 29th, 05 at 08:51 AM.
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post #2 of 12 (permalink) Old Oct 29th, 05, 08:42 AM
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Re: Big block mounting alignment questions

You need a big block crossmember. The mounting holes are offset.
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post #3 of 12 (permalink) Old Oct 29th, 05, 08:48 AM
 
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Thumbs up Re: Big block mounting alignment questions

OR just use a three hole poly tranny mount and install the needed Grade-8 bolt and washers in the center hole through the pass. crossmember hole AND you will be fine.

That's how I have mine.

pdq67



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post #4 of 12 (permalink) Old Oct 29th, 05, 08:55 AM Thread Starter
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Re: Big block mounting alignment questions

Thanks for replies.

But if I do what you guys suggest, won't the pinion angle be off a little sideways?

Dave F. in Rhode Island
'68 Camaro SS Accel DFI 454 (SOLD - I'm a boring Corvette owner now)
Bought my first big-block Chevy in 1970
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post #5 of 12 (permalink) Old Oct 29th, 05, 09:03 AM
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Re: Big block mounting alignment questions

Yes, it will but as long as the engine is aligned to the center of the car you won't have any issues. Thats why there are big block crossmembers to match the offset of the big block motor mounts.

Mark Canning
1969 Indy Pace Car
350/300HP RPO Z11

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post #6 of 12 (permalink) Old Oct 29th, 05, 10:18 AM Thread Starter
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Re: Big block mounting alignment questions



Thanks for tips. I never really paid attention to the difference, but it's clear in this pic from Rick's First Generation that the big block crossmember is offset.



I had actually ground a little offset into the frame mount holes. I moved the driver-side mount 1/8" forward and the passenger-side frame mount 1/8" back. This got the tranny mount lined up perfectly with the small-block crossmember. Can I use this method, or is it really necessary to get the offset in the crossmember itself?

It seems like no matter which way you do it, the pinion angles will always be slightly off sideways.

Dave F. in Rhode Island
'68 Camaro SS Accel DFI 454 (SOLD - I'm a boring Corvette owner now)
Bought my first big-block Chevy in 1970

Last edited by Chevy-SS; Oct 29th, 05 at 10:28 AM.
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post #7 of 12 (permalink) Old Oct 29th, 05, 10:42 AM
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Re: Big block mounting alignment questions

for the ujoints to work as designed, the 2 things the driveshaft connects have to be parallel. That is, the engine/trans centerline and the pinion gear centerline. The u-joint angles must be "equal but opposite" So, no, you shouldn't run it the way you have it. The trans mount must offset the same as the engine mounts are. The engine will be off-center, but still be parallel to the car's (and the pinoin's) centerline.





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post #8 of 12 (permalink) Old Oct 29th, 05, 11:21 AM Thread Starter
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Re: Big block mounting alignment questions

Quote:
Originally Posted by JimM
for the ujoints to work as designed, the 2 things the driveshaft connects have to be parallel. That is, the engine/trans centerline and the pinion gear centerline. The u-joint angles must be "equal but opposite" .....
Yes, yes, very good explanation. Makes perfect sense. I will get new crossmember, or grind old one, or do as pdq67 suggests and use one grade 8 bolt in center hole of poly mount, since I already have a poly mount..

Thanks for help gents

Dave F. in Rhode Island
'68 Camaro SS Accel DFI 454 (SOLD - I'm a boring Corvette owner now)
Bought my first big-block Chevy in 1970

Last edited by Chevy-SS; Oct 29th, 05 at 12:04 PM.
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post #9 of 12 (permalink) Old Oct 29th, 05, 03:24 PM
 
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Thumbs up Re: Big block mounting alignment questions

Back again,

I think that you will find out that a BB will sit fine like I said b/c the center hole put's the tail-end over the needed about 1" towards the pass. side.

And the reason for the three holes in the first place is b/c the newer cars only use one rear mount bolt!

pdq67



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post #10 of 12 (permalink) Old Oct 30th, 05, 06:27 AM Thread Starter
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Re: Big block mounting alignment questions

pdq67

Check out this pic:



Was your poly mount taller than the stocker? Do you (or anyone here) happen to know which height is correct?



thanks

Dave F. in Rhode Island
'68 Camaro SS Accel DFI 454 (SOLD - I'm a boring Corvette owner now)
Bought my first big-block Chevy in 1970
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post #11 of 12 (permalink) Old Oct 30th, 05, 07:47 AM
 
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Smile Re: Big block mounting alignment questions

I don't think so.

Mine fit fine.

Anybody else want to add anything that I may be missing?

pdq67



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post #12 of 12 (permalink) Old Oct 30th, 05, 08:27 AM Thread Starter
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Re: Big block mounting alignment questions

Quote:
Originally Posted by pdq67
Back again,

I think that you will find out that a BB will sit fine like I said b/c the center hole put's the tail-end over the needed about 1" towards the pass. side.
.......
Perfect fit! After I put frame mounts back to stock position, the center hole of poly mount lined right up to passenger side hole in crossmember.

Now my only quandary is the poly trany mount maybe being too tall.


thanks again

Dave F. in Rhode Island
'68 Camaro SS Accel DFI 454 (SOLD - I'm a boring Corvette owner now)
Bought my first big-block Chevy in 1970
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