Magnum 5.2 & Doug's D453 Header Fitment Issues

-
N

Nate@BLI

Member
Joined
May 23, 2016
Messages
20
Reaction score
4
Location
SoCal
hey all, long time lurker first time poster. i have a 67 valiant that was originally a slant 6 car. enjoyed it for a few years with the stock engine and stupid Holley 1920 single barrel but got tired of dealing with carb issues and wanted a v8 anyways so i swapped in a 5.2 magnum with 42rh trans. want to give a big thanks to those that posted their a500 swap pics and stories as that really helped me figure out how to do it myself. short story: i sectioned the cross member way down until the trans fit under it. did not have to completely cut it out like others have done. for a mount, i started with the Hooker blackheart mount and modded it.

anyways, the real reason why i'm posting is i'm struggling to figure out if my engine is in the right spot or not which may help resolve the Doug's header fitment issues i'm having. short story: i think if i came up and forward slightly with the engine, i'll gain some decent room. i have a whole bunch of pics to share that show the current fitment situation.

first, steering on the right side.
PXL_20250212_013730747.jpg

luckily the motor mounts aren't bolted all the way down right now because when i turn the steering, it actually bumps the header and lifts the engine up about a 1/4 inch!

another view of the right side steering. also shows how close the headers are to the torsion bar.
PXL_20250212_013827065.jpg


can see that the idler is also hitting
PXL_20250212_013836424.jpg


here's the drivers side. this is probably something like 1/8-3/16 inch clearance between the header and the torsion bar.
PXL_20250212_014008099.jpg


another view showing clearance to the torsion bar
PXL_20250212_014029617.jpg
 
and here are some pics of the motor mounts.
PXL_20250212_014129200.MP.jpg

i'm aware the bolts are a little short since their for a LA engine and not a Magnum. i'll get some longer bolts eventually.

passenger side mount
PXL_20250212_014135104.jpg


header fitment on passenger side. looks mostly okay.
PXL_20250212_014415736.jpg


here's the clearance i have on the steering box. can i come forward some?
PXL_20250212_014435978.jpg


and here's a top view showing the side clearance
PXL_20250212_014511507.jpg


now up at the column, this is what i'm dealing with
column clearance collar.jpg

whatever the outer most steel part is on the column is just barely not in contact with the header. what's the best course of action to remedy this? i would like to keep the stock column shifter. also, what does the collar part (blue arrow) do? looks like a stop maybe. for whatever reason it had an incredibly long set screw in it that stuck way out and the first time i went to turn the steering it smashed into the header and left the ding that you can see there.
 
i should also probably note that when the engine went in, it kept settling into a spot on the k frame mounts that had it offset to the driver side and had the driver side slightly higher than the passenger side. i messed with trying to position the engine just right but each time i put the full weight of the engine on the mounts, it just slipped right back into the same bad spot. it's acting like it needs an 1/8" thick shim under the passenger mount.

also, i have a "mini" starter from a '97 Dakota and it definitely would not fit through the window in the header tubes. seems like the only way it might fit is if i take the steering links off. is that expected?
 
couple more motor mount pics just to give more context.

driver side
PXL_20250212_014632303.MP.jpg


passenger side
PXL_20250212_014720559.jpg


clearance at the firewall
PXL_20250212_014741681.jpg
 
here are some pics of the swap in progress and the fab work i did on the crossmember.
PXL_20241227_213352533.jpg

PXL_20250103_185357970.jpg

PXL_20250103_185406405.jpg

PXL_20250103_185423650.jpg

PXL_20241228_234235739.jpg

PXL_20241228_234231177.jpg
 
Did you grind the truck mount pads?

Probably in the above linked article.
 
DS mount looks wack. like something is pushing the motor toward the PS and twisting it. the trans mount looks very low and that may be contributing to the issues at hand. you may need a shim on the mount, that's not unusual.

firewall clearance looks fine.

i'm guessing you've got death by 1000 cuts going on here: this is a little low, this needs some adjustment, that is just off enough, need to make shim here, etc.

the column will likely need to be trimmed back a hair or loosened and ajusted. that's just how those things are sometimes.
 
Your engine looks a little too low and far forward to me. There are published values on TTI’s website about how high the centerline of the crankshaft should be from the k-member and also values about how far from the left and right in order to make their headers fit. I am sure that these values represent a stock A body so they would also apply to Doug’s headers.
At an initial glance if your motor was higher and back about another 1/2” you wouldn’t be having any of these problem. Seeing as you have the 46 rh trans you may have been overly focused on making the trans mount solution without placing enough value on where the motor is ‘supposed’ to be.

The pictures I have posted here may or may not be of value to you but this is a magnum 360 mounted in 1970 v-8 k-member.

I believe there was also something funny about 1967 k-member idler arm mounts/position too. This is something else you should make sure isn’t giving you grief.

IMG_6012.jpeg


FullSizeRender.jpeg


IMG_6014.jpeg
 
I had to make a cross member for my TKO and I have Doug's and power steering and a Z-Bar. Once the engine is set at the correct angle I had to shim both motor mounts as show above to get the headers off the steering box and my 1" torsion bars. I won't even discuss what I had to do on the zbar side after it was revised to Doug's specs. Biscuit mounts seems to be an issues with Doug's for some people.
 
One FIRST thing I'd do is obtain, from a member, a "stock" V8 install dimension from say, the front wall of the crossmember to a known point, such as the rear of the engine bell face, or such that you can access, to establish the stock front/ rear dimension of the engine as in place. This should not change. If, example, you had a stock trans, such as a 904, etc, you could locate the rear mount "as original" and that would be that. I don't know if the 42XX are the same dimension, etc.

(I cannot tell you that because mine is apart)

I assume the Shoe mounts came with destructions as to how they are oriented etc? I don't remember the years, there are truck pillow mounts that are thicker than 67. I tried to use them on my 67 with stock mounts but they were too tall. In your case they may be what you eed
 
Looks like you have a truck mount isolator on passenger side and a car mount on driver side . Like saiid above try using 2 truck ( thicker ) isolators. Or flipflop the 2 you have now .
 
He has a /6 k member and is using conversion mounts.

I would try to find a V8 cross member and get stock mounts.

The mini starter should come in and out easily with douga headers.
 
mbaird said:
Looks like you have a truck mount isolator on passenger side and a car mount on driver side . Like saiid above try using 2 truck ( thicker ) isolators. Or flipflop the 2 you have now .
Click to expand...
He has a 6cylinder k-member with schumaker conversion mounts. This is roughly how it ‘should look’
 
thanks everyone for the replies. i found the TTI chart with the dimensions so i'll start by checking there.

someone asked if i ground the truck mount pads - i'm not sure what that means. i don't know what the truck mount pads are but i didn't grind anything motor mount related.

the isolators i have are exactly what come in the Schumacher kit. you can see the instruction HERE. i'm sure i have them on the correct side.

as far as the transmission mount goes, it's not especially low. i spent many weeks scouring every A500/42R_ install on this forum and studied every photo i could find very closely. i also took reference measurements from the old 904 trans and the stock trans mount to establish a relationship between the output shaft and the crossmember mounting holes and i maintained that same dimension when i made my mount. i don't think mine is any lower than the USCT crossmember.

i did not check the longitudinal engine angle. it should already be pretty close figuring an off the shelf mount kit and making sure the trans is roughly in the right spot. if it's off, it's not off by more than a couple tenths of a degree.
 
swapping k members isn't in the cards. seems like that'd be way more work, effort and expense. i'll work on adjusting/shimming/trimming things as i can.

i'll trim back the outer "shell" on the steering column. and while i'm in there, i'll snap a pics showing that the starter motor definitely isn't going in. i'll dig up the starter part number too.

so what's this collar do?
column clearance collar.jpg


i don't know why it had a 3/4" long set screw in it. guess i can just put a short one in right?
 
with these mounts and the tiny bit of clearance i have between the headers and the torsion bars - how likely is it that they're going to hit when the engine is running? wondering if i should just bash 'em in now or wait.
 

Nate@BLI said:
schumacher
Click to expand...
The brackets might be but that driver's mount biscuit is smushed flatter than hell. Look at how much difference in thickness there ie between the driver's and passenger's side mount biscuits.
 
that DS biscuit is no flatter now than it was when it came out of the Schumacher box. did you look at their instructions? it shows a thick and thin biscuit. might be worth point out again that this a sbm going into a slant 6 k member.
 
You must log in or register to reply here.
-
Back
Top Bottom