Engine mounts further forward? 73-87 front swap related

[J1MMY]

I've got to the point where the truck is completely torn-down and the '79 front crossmember is bolted up with a view to dropping the 292 and 5 speed in, so I can make sure everything is lined up before blasting and painting the frame.

I've run into a few issues and have a few questions - they're not likely to be anything that hasn't been picked up before but typically all my bookmarks were kept on my old (dead) computer and I can't find them again so, in no particular order here is what is holding me up:

1. I am unable to source any C20/30 engine mount towers (? I think you call them, the brackets that bolt to the top of the frame and the crossmember) so I am having to use the C10 ones. However, I recall reading that using these moves the engine away from the stock mounting point? If so, by how much and can that be negated by the slotted mounting holes on the crossmember and the mount towers? This info will help me to avoid cutting any more metal from the top of the frame than is necessary.





2. I ordered a Davidson Performance 292 engine mount adapted through 12bolt Tom which arrived last week (beautiful looking piece of metalwork) which I have bolted to the engine, so now the 292 can mount up in the 250's mounting points.The original mounts and brackets are now obsolete. Sadly I don't have the '79 I6 motor mount brackets. what is now the best type of motor mount brackets to use?



Finally, is this gap between the outside of the frame and the sides of the crossmember consistent with a '73-'87 swap?





Thanks

[Chevy Fleetside]

Stock mounts will work still with the later model cross member. Have you tried that?

[padresag]

http://www.persh.org/pickup/perches.htm
the first picture show 2 sets of perches. the top 2 are for 230-250 I6 and sbc. the second set is for a 292. the passenger side perch is shorter and i don't know if that adaptor that you have compensates for that enough. check with the manuf. these are the stock perches for your truck. 292s in later years were not as popular so makes it more difficult to find the later style 292 perches. there is really no need to move your engine forward nor benifit. HEIs are just a closer fit is all
do you have the steel part that goes between the eng block and the insulator
if you use the earlier perches then you have to use the earlier style of insulator
ron

[J1MMY]

I have the 63 perches and insulators but not the frame-crossmember mount (the stock crossmember went to another forum member so he could convert his 60-62 to 63-on suspension).



I borrowed this pic from the web for reference - I believe that it shows the mounts that I need. If you compare the location underneath the pushrod covers to the mounting point given by the adapter it would appear that it is pretty well spot on.....



Once I have obtained these I think I'm in business mounting the engine and gearbox. One of my main concerns was that the later frame mounts would bring the engine forward, something that I want to avoid.

[J1MMY]

Ok, so I've gotten a bit further with this (life gets in the way sometimes but I'm in no hurry) and after having dropped the engine and trans into the frame - note that the trans mount is fitted but the engine is sat on timber while I look at trimming the frame for the motor mount towers - I have found that the engine mount brackets on the 292 are BEHIND the crossmember.

When I fitted the gearbox and crossmember the 230 was still fitted, along with the '63 front suspension/crossmember. Therefore I can only think that the 63 crossmember does sit further forward. There is ample room to drop the sump pan which I don't think was there before. There are also additional holes already in the crossmember which I could use to bring the towers in line with the mounting brackets on the motor. However, this means that the rear of the tower will be hanging behind the crossmember and I will have to drill the top of the frame to bolt the towers down. Is this another difference in mounting points for I6 and V8?

I have tried to take pics....

Tower hanging from the back of the crossmember but lined up with mounting point:


Tower sat over the mounting points on the crossmember, the motor mount position is behind the tower:



I have shown pics from the passenger side - the drivers side is the same and that adapter plate does bring both mounting points in line.