Been asked before: MM

[arkracing]

Well I have a question that i'm sure has been asked before...but I searched for it and can't seem to find the answer that I need:

I have a 6cly truck that will get a V-8. I know that the V-8 will mount to the 6cly stands - but may have some clearance problems with an HEI dizzy.

so the question is...on a stock V-8 truck how much further foward are the Motor mount stands than in a 6cly truck.
I noticed that there is another bolt hole further foward on the top side of the frame about 2.5" infront of the first bolt of the 6cly mount...
do i just move the mount to that position and drill a new bottom hole?
or do i have to drill some new top holes too? - and if so..what distance from the stock 6cyl holes?

Thanks guys

[arkracing]

ttt

[67ChevyRedneck]

I wrote this a while ago, probably more than you need, but someone wanted to know about converting from I6 manual 3sp to V8 automatic.....

I recently put a 350 crate enigine with a 700R4 in my 67 pick-up that had a 250 six banger and 3 spd manual. The straight six motor mounts are taller than the stock 350 mounts, I think you can use the I6 mounts, but chevy must have used lower ones for the V-8s for a reason. But they DO need to be slid forward to the next set of holes in the frame, or your distributor will be hittin the firewall. Mine are slid forward and it's tight now! There is also another hole in the crossmember so no drilling is necessary. DO NOT reuse rubber motor mounts. I did and the passenger side broke after 2 miles. I think they are only 8 dollars each at a local autozone. The original manual crossmember is rivveted in and needs to be torched out. I cut out the mount itself and then it was easier to torch the bolts to get the rest out. I scoured local junk yards and pirated the 350 motor mounts and an automatic crossmember from a 72 Cheyenne. The automatic mounts were bolted in, not rivveted. The easiest thing to do is get the motor and tranny in the truck and then slide in the tranny crossmember and bolt it to the tranny. I did this on my truck because only 2 stock holes lined up, I had to drill the others, but I did use a 700R4. All chevy manuals were "short" so you will need to take your driveshaft to a machine shop to be shortened, but I have heard if you use a TH350 you don't need to do this, but don't forget to take out some length for suspension travel, you don't want the shaft slammin into the tranny when you hit a bump. You will also need to install a tranny cooler in front of the radiator, you don't have to, but you run the risk of burning up the tranny. For shifting it is easiest to buy a shifter, I put a LOKAR in my truck, VERY EXPENSIVE! You might get lucky and find an original column shift in a junkyard....but GOOD LUCK. I went to 9 yards and didn't find one at all. Also, I suggest a new radiator and electric fan. For the motor you will need a new accelerator rod to connect to the carb. I couln't find one so I made one using 1/4" rod. I also ordered a 2 1/4" dual exhaust kit from LMC truck and it installed fairly easy. I think that's all the "conversion" stuff, but it is A LOT of work, it IS NOT easy to do. I have been working on vehicles since I was a kid, I'm 23 now, and the swap took me 3 weeks working after work and on weekends. I don't mean to scare ya, but it IS VERY WORTH IT. If you want mileage my last suggestion is to trash the 350 tranny and pick up a 700R4. You will need to get a stock TV cable mount that goes on the intake manifold near the carb and a lock-up kit for the converter. My truck gets 15.5 mpg highway, 13 avg and it has a 3.73 rear...which is next to go to get some better mpgs......

[arkracing]

Thanks boss. I didn't know that the V-8 mounts were shorter than the six clyinders..i would figure the other way around because the mount spots on the 6 are low...near the oil pan...guess not as much as i thought though.
I already got an Auto Crossmember so i should be all set there
i plan on the same swap..small block with a 700R4 tranny.


anyone got a pair of small block mounts for sale?

[arkracing]

anyone else know the answer...i'm sure more than 1 person on the board has done this??? no?

[Tx Firefighter]

I've also done that swap several times.

A V8 with an HEI distributor will set right onto the 6 cylinder stands without moving them at all AND the distributor will clear the firewall. I've been there personally and done it. Ask Dubie, here on the board, he has good pics of a V8 on 6 cylinder stands in stock 6 cylinder holes. The distributor will clear the firewall.

[gmc67swb]

Mine is sittin' in the driveway right now with a 350HO and HEI on the I6 mounts. Need a pic? I can get it if you like.

[arkracing]

yeh that would be great if you could.
Thanks!!!!!

[1969K10]

Yes it fits, and YES its TIGHT!!! I had to install the back 2 or 3 plug wires on the cap, and then tighten the cap to the distributor body. And on top of that, I had to turn the dist on direction to get to 1 of the clamps, and then turn the dist the other way to tighten the other clamp in the back. Then rotate it to the correct place...

[67ChevyRedneck]

I did my swap about 16 months ago. It was just me and my dad. We knew the mounts were different and that on a V-8 that they were slid up, so to be safe we went with what Chevy had originally done. With the V-8 mounts and a flex fan my distributor is about 2" off the firewall and my fan has about 2" of clearance from the radiator. I like where the motor sits and happy with what I did. With moving my mounts I don't have to mess with doing what 1969K10 had to do. If you can use the I6 mounts, why not take the bolts loose and slide them up to the next hole to get clearance??????

[67ChevyRedneck]

Forgot to mention I'm using an HEI distributor as well!

[67ChevyRedneck]

MOTOR MOUNTS

Now I understand the difference, the I6 mounts can't be moved forward. If using the six mounts puts the motor so close to the firewall and causes difficulty with the distributor, why not just put the proper V-8 mounts in the truck in the first place? I got mine for $20 from a local yard. Even in the north they should be somewhat rust-free and usuable. I say do it right and put in the V-8's!!! JMHO

[1969K10]

If the '72 was still driveable, I would probably mess with it, learning what I have on this board. On the other hand, wouldn't I have had to move the tranny, and gotten a longer drive?

[Tx Firefighter]

Originally Posted by 67ChevyRedneck

MOTOR MOUNTS

Now I understand the difference, the I6 mounts can't be moved forward. If using the six mounts puts the motor so close to the firewall and causes difficulty with the distributor, why not just put the proper V-8 mounts in the truck in the first place? I got mine for $20 from a local yard. Even in the north they should be somewhat rust-free and usuable. I say do it right and put in the V-8's!!! JMHO

That's the deal dude. If you move the engine forward onto the V8 mounts, you have to lengthen the driveshaft, redo the shift linkage and move the transmission crossmember forward too. This can even cause problems with tranny cooler lines. All that adds up to bucks spent and hours worked.

Most times, guys like to remove the 6 cylinder and drop the V8 in and use the old transmission, driveshaft and all from the 6 cylinder. For the money and hassle saved, most guys can tolerate the distributor being close to the firewall. Like I said, Dubie got tired of all the talk about this and took a good picture of his HEI and how it sets in relation to the firewall. His picture shows his hand between the distributor and the firewall to prove how it really fits.

[67ChevyRedneck]

Thanks for the info Tx! For some reason, I'm usually under the impression the truck is going from an I6 and 3sp to a v-8 700R4 auto. When I did my truck, with the mounts moved forward, I had to have my driveshaft shortened a good bit. I see that if your sticking with the same tranny its worth the distributor hassle to keep the same lines/driveshaft/shift linkage etc.... very informative thread!

[arkracing]

Close...
it was a 6cylinder 250 with a 4speed granny - removable hump floor (must have been a special request or something)

going to a V-8/700R4
If i can't find a good running V-8 soon i might put the six back in it with the 700R4 who knows i'm crazy enough to do something like that.
i already know that i have to have a driveshaft made cause the stock on had a u-joint on each and and did not have the yoke on the tranny (i.e. Big M.F'n 4 speed)

heck my buddy had a 318 Mopar with 22k orginal milles that he was going to give me to put in the truck, but after a couple of days of thinking about it i said..."if i ever want to sell it, it won't be worth anything"
besides that's just wrong....not as bad as putting a Ford in there though??? just kidding....chevy guys put chevy's in everything so i guess a ford guy can put a ford in whatever he wants...

[Longhorn Man]

it was a 6cylinder 250 with a 4speed granny - removable hump floor (must have been a special request or something)

The high hump came in all 4 speed equipped trucks regardless of engine size.

[arkracing]

yeh i knew that the high hump was for all 4speeds. but i thought that the 4speed would have been special order...cause most of the 6's are 3 on the tree aren't they?

[Longhorn Man]

just an option...nothing special.
Most had the 3 speed becouse it was cheaper, and ost who were getting an inline were getting cheap vehicles.