too torqueeeeeee

[jwmbishop]

In my '86 C10 shorty (tow veh) I have a small problem. Every time I pull a load (or even just stomp on the pedal empty) I destroy the motor mounts. The rubber is sandwiched in the frame half of the mount set - it pulls the driver side up an inch and the pushes the passenger down an inch - and does not come back to center.

 

The engine is quite strong (C10 that will pull a 5000 lb trailer like nothings back there gives ya an idea of HOW strong) as I built it to be - at 387CI, 9.3\1 comp and a 450/470 lift X 260/270 dur cam with the small port/valve lg chamber heads. I've tried limiting the bottom torque by lashing up, backing off adv and running slightly rich. These all have noticeable effect while still letting it run strong - but i just noted this morning that the 2nd set of new mounts (not counting the original install new mounts) are trashed again - and all I have done is romp thru two gears.

 

I don't want to go to solid mounts and the vibration they transmit to the rest of the truck (or the torsions applied to the two bolt block) as when towing to Cal we spend 10 hrs a day in the thing - is there another way? On passenger mounts I have always thru bolted the mount - but on those the rubber is part of the engine side.

[Truck99]

Would the old chain trick work to limit but not totally eliminate the movement of the motor? Maybe if you used just the right length of chain from block to frame, you would get enough damping in the mounts to keep them effective but limit the motor travel enough to save the rubber.

[HiTech]

i did not do this with this typ of mount ..but maybe it will work ...if you can ..and have the space ..i drilled right through the mount and installed a bolt and double nutted it with enough slack or space .to let the mount move freely but not pull apart ....best of both worlds .....another way is something like 99 said .but use some cable straps .they seem to limit the viberation ..good luck.... on our thunders we use a chain to limit mount movement ... they have alot of touque .and wipe out stock mounts ..we ran a solid mount and chase came up with why we had problems on the track with our carb ..viberation ...so thats not the way to go .

[jwmbishop]

I know what you are saying hitech - thats through bolting. But on the truck mounts there is no way unless I cut a hole in the cross member to to get through it. (could be done if I pulled the engine - I like shortest path though) The chain "probably" would not stop it as we are only talking about an inch or two of "twist" - the chain limits lift. I am planning on trying it though. If I limit it too much I will twist the frame rails. I used to have a setup that bolted to the heads using the stock bosses - that way its removeable as in Cali if they see a restraint they can impound the veh as this is a "racing modification" - the kit was actually for corvette, as the 69-72 had a major issue and GM retrofitted to correct the recall.

 

Would love to find a single puck type (like on the Ford HD Trucks) that I could modify. Like this but was hoping someone already knew the demensioning and maybe even the part that would go right in without pulling the dang motor completely out, welding or having to go to the bone yard to measure to find the kit that comes close!

[CuttingEdgeRacing]

i did not do this with this typ of mount ..but maybe it will work ...if you can ..and have the space ..i drilled right through the mount and installed a bolt and double nutted it with enough slack or space .to let the mount move freely but not pull apart

 

I do this exact thing on pretty much all my mounts.

 

You cant unbolt the mount, jack one side of the motor and slide it out?

[jwmbishop]

You cant unbolt the mount, jack one side of the motor and slide it out?

Yes but This LINK is a stock mount - bolts down to the crossmember. No way to bolt thru it. No way to drill a relief hole for the throughbolt head (or tail and nut), or do any other mods to the crossmember without pulling the motor.

 

But duh... looking at the pic I just linked to I could drive in some 3/8" bolts on both top and bottom of the rubber insert (see the voids) so that it can no longer slide in the saddle! A quick tack with JB Weld to keep em there and done. Probably wouldn't even have to pull the mounts - its all the way one way now - do the wide side bolts then apply lift to the Drivers side and install the other two shimming bolts to tighten.

 

Of course the easiest way - if positive torque pushes them one way - I could just pull into low gear from 110 MPH to force it back the other.....

 

Man I love bench racin! Thanks guys!