DIY4X Crossmember with a BBC

[Mr Banshee]

Been a member of this site for about a year now and found this a wealth of knowledge in addition a great resource for parts for my 72 K5 4x4 build and just wanted to say thanks to members that I have been in contact.

Moving forward on my build or should I say I am at the point de-rigging 40 + years of mechanics in training on this truck. I’m currently reworking the Big Block 396 placement in the chassis. The current drivetrain is a turbo 350/205 trans/transfer combo with a 14 bolt floater out back and Dana 44 up front. Current plan is to install a Turbo 400 Trans and rework the 205 transfer to mate with it.

The engine installation at best would considered hacked. The frame and cross member was mutilated to clear the headers which who knows the header application should have belonged to. I decided to go with the DIY4X Engine cross member. What a great fit this member has been. Read a lot about pan clearance on this site but with the one I received there was plenty of clearance with the stock pan, maybe a different story with an aftermarket one. For round one of mock-up, the cross member was installed in the small block mounting holes. During attachment of the cross bar the frame pulled in somewhat however the engine dropped right into place. With this position, the engine is right at the fire wall. No chance to put valve covers on without serious firewall massaging. In addition with the turbo 400 bolted up and the transfer case adapter on, I noticed that the orientation for the transfer case shifter will enter into the cab about 3 ½ inches back from the original hole basically putting it right thru the floor cross member.

Round 2 of mock-up, my plan is to move the engine cross member up to the next set of holes basically moving the engine forward about 2/12 inches. This should give me ample clearance for valve covers without chopping into firewall and putting the T-case shifter close to the factory hole in the Trans hump. 2 things that I am struggling with are the header selection and the cooling aspect. So this leaves me at the moment a couple questions to ask. Header Selection and Cooling. I have been reviewing a lot of threads and it seems that the Hooker Headers 520-2463 series has been used more and with better fit. Has anyone that has used the DIY4X member and what was there best header option? On to the second question. I currently have a pristine 4 core brass radiator that I will be using. The plan is to use a clutch fan. The water pump and brackets are of the shorty water pump style to give the most clearance. From my initial measurements of the engine placement with the factory cross member, this fan style was going to work out great with a 2wd fan shroud. Now using the DIY4X member and shifting the engine forward for the added Trans length this is not in the cards. My thought is to come up with a happy medium for engine placement so I can use a clutch fan with perhaps a Big Block fan shroud. This will force me to punch new holes in the frame and rework the Trans hump. So this question maybe more of what is your opinions and suggestions for cooling ideas. I’ll get some pics posted after this weekend. Thanks….Mike

[turp mcspray]

On my Blazer build I swapped to a big block and th400. I moved the transfer case back 1 inch. This put the shifter in the same location as it was stock. The engine ended up being about 2 1/2" forward from stock. I used a short water pump setup, with a clutch fan. The fan ended up half in, and half out of a factory 2wd shroud. Everything looked and fit like a factory install.

[Mr Banshee]

Thanks for the info. I reviewed you build thread. Nice work!!!! Gives me alot of ideas... Well detailed with pictures and information. I like your shift linkage, I was thinking on the same lines. In regards to your fuel tank install, is that a 31 gallon unit? Also what kind of work went into it for the installation? Thanks Mike, Look forward to seeing more on your progress....

[turp mcspray]

Yes, it is a 31 gallon tank. I moved the rear 72 crossmember back untill it was about even with the body crossmember. I used a 73 and newer, front crossmember to attach the front of the straps to. I also used the filler neck from my original tank on the newer tank, in the 72 location. It was all pretty simple and straightforward to do.

[madkmart]

Mr banshee i live in warren too would to see ur blazer
Post some pictures

[Mr Banshee]

Hey madkmart,

Thanks for the interest. I will get some pic's posted here soon. Worked on getting the engine/trans set in where I think it will be in the best position over the weekend. You have a project you're working on? Thanks again, Mike

[madkmart]

Not yet soon been looking hoping buy the end of year had a 72 jimmy at one time lost it in divorce

[Mr Banshee]

Turp Mcspray, have a question for you regarding your Fan clutch and big block shroud setup. For your set up what size fan (dimension) are you running and did you have to modify core support height, shroud height or engine height to obtain center clearance for the fan blade to shroud?

Here’s what is going on with mine. During what I thought was my final my mock-up I had the fan out of the shroud 1 inch roughly using a Big Block 2wd shroud and a 19” 6 blade Big Block Fan assembly. In order for me to have a centered fan in the shroud I needed to raise the engine 1 5/8” at the engine mount location and drop the transmission cross member ¾ of an inch to achieve this. While this seemed perfect and would improve the driveline angle at the rear of the transfer case, it made the driveline angle worse for the front output. Keep in mind I am using a DIY4X member instead of the factory member so that may be causing me some issues however before I replaced this member with the DIY4X unit I took some measurements of the factory member and with the big block in and with using the DIY4X and engine in it has the engine setting roughly a ¼ of lower in the engine bay. Stumped at this point as I would prefer to run a Fan/Clutch with Factory Big Block shroud. Any thoughts?? Thanks Mike

[turp mcspray]

I used a factory bb clutch fan. I don't have any pics of it mocked up with the radiator and shroud, but when I mocked everything up, the fan fit in the opening fine, with no height adjustments required. I don't know what the fan diameter is off the top of my head.
I can only guess that the problem lies in the crossmember, since that is the only non factory piece. Do you have the core support bushings installed?

[Mr Banshee]

Yes when I began mocking up I purchased a new set of core support bushings. I have an orginal cross member from another parts truck since the one I had was butched beyond belief for the headers they used. I will try a factory member this week. I wanted to use this DIY4X member since it does have a better mount system over the factory pads. Did you use a better engine mount with a molded saftey bar in the mount or just a standard replacement rubber pad mount? Thx Mike

[turp mcspray]

I bought some poly engine mounts.

[Mr Banshee]

I ordered up a set of Poly Mounts and installed them today with the factory cross member and I didn't gain much. In fact the Poly mounts are 5/8 taller than the oem rubber ones but even with this it didn't help much in centering the fan. From the inside lip of the fan shroud at the top to the center of the water pump it is 11''. From the inside lip of the shroud at the botton to the center of the water pump it is 9 1/2. Far cry from being centered. In the pictures you can see the fan is touching the shroud at the bottom and at the top I have an 1 1/2 + gap. I could use a small block fan to gain clearance at the bottom however the top side would increase and over all affect cooling. I also could raise the engine as I have attempted already which works out good for centering the fan and helping my rear output driveshaft working angle however it greatly increases the working angle of the front driveshaft. As anyone ran into these issues installing a big block and using a clutch fan? Any suggestions are welcomed. Thanks

[Chulisohombre]

Cool build. Ill be watching to see progress.