Engine Placement - Classic Gas Coupe

[Plainview]

We will putting a GM big block in our 1954 Chevy coupe (115 inch wheelbase).  According to the rules, we can move the engine back 2%.  That works out to 2.3"  Am I to assume I can move the engine back 2.3" measuring from the center line of the front crankshaft?  Or do we measure from the original 6 cylinder motor mount position back 2.3" (which have already been removed,making it hard to determine their original position)?

Second question, the motor should be mounted down, as low as possible to the frame rails (dependent on steering swaybar/rack & pinion, oil pan/ground clearance).  Any rule of thumb on how low?

Sorry, for the rather naive questions.  I hope the wealth of experience on the LS webpage can assist us as we move along.

[RichFox]

The engine location is measured from the front spark plug. Going from a six to a V8 may actually mean moving the CG foward. I put my crankshaft centerline about where it was with the original engine. The car having been lowered quite a bit and a deep sump pan gets the crank out of the oil. Puts the pan about as low as it can be and still load it on the trailer.

[Plainview]

THX, Rich.  I have lost my guide posts, since both the 6 cylinder engine and the original motor mounts are gone, so I am trying to figure out the best way to place the motor in the correct location to past tech.  You are right the CG will be more forward with the big block, so we are striping off any excess weight in other locations, and will then add weight further back.

[SPARKY]

Should be measured from the sme centerline of the frt. spindles that is going to be used to determine the WB.

[Sumner]

................. so I am trying to figure out the best way to place the motor in the correct location to past tech.  You are right the CG will be more forward with the big block, so we are striping off any excess weight in other locations, and will then add weight further back.

As you probably know you don't need it in the right place to pass tech, but to get through impound if you set a record, which of course I hope is the case  .

................. so I am trying to figure out the best way to place the motor in the correct location to past tech.  You are right the CG will be more forward with the big block, so we are striping off any excess weight in other locations, and will then add weight further back.

Don't be too quick to worry about taking weight off the front of the car sometimes it can be good there.  I've put down some thoughts on the subject and it has been discussed here and might be old news to you, but here are a couple links....

http://purplesagetradingpost.com/sumner/bvillecar/bville%20-%20LSR%20Thoughts-3.html

........... and....

http://purplesagetradingpost.com/sumner/bvillecar/bville%20-%20LSR%20Thoughts-3.html

I'll bet if you post on some of the "6" boards or restorer boards you could get some measurements that would help you with the set-back question

The best of luck,

Sum

[Plainview]

THX Sum. Good answer on asking some of the guys that have restored 54's and getting some of the lost measurements from them.

[4-barrel Mike]

I'll bet if you post on some of the "6" boards or restorer boards you could get some measurements that would help you with the set-back question

Am I misinterpreting the rules (as usual)?  Engine set back 4.AA says that distance from the spindle traverse centerline divided by the wheelbase.  115" wheelbase gets 2.3" max set back, right?  Doesn't make any difference where it was originally, does it? 

I'd bet big (Monopoly) money that the front-most spark plug on a '54 Chevy is several inches in front of the spindle centerline.

Mike

[SPARKY]

ONE of the 3 qualifers for Classic Gas Coupe can be an engine swap:
I feel sure that the set back is based off cars original wheelbase dimension and the spindle centerline---you have the exact opsite with late model vech. with V-6 and V-8 engs., The frt sparkplug is different for the Production Class but would be the same if an eng swap were involved.

[Sumner]

......................
Am I misinterpreting the rules (as usual)?  Engine set back 4.AA says that distance from the spindle traverse centerline divided by the wheelbase.  115" wheelbase gets 2.3" max set back, right?  Doesn't make any difference where it was originally, does it?.................

I'll bet you are exactly right.  Now he can forget going to those restorers that won't be happy with him anyway for messing up a perfectly good car  and you should have bet real money on this one  .

c ya,

Sum