The fuel pump hole I use for my turbo drain, so its great that its there.

Front cover I leave alone, run a RiffRaff HPO res spacer so I can run the screened filter.

Change the manifolds over, flip it over, installed welded cooling jets, new pan (with my new weld in dipstick adapter) and go.

I dont have a fuel bowl, so mounting that is not an issue, up pipes are custom to my turbo mount...

Biggest issue is- Does it have 10 bolt intake manifolds or not, if its got the 8 bolts I am swapping heads, if not I'll install one stud at a time and leave it alone.

If I keep the heads on this motor I will install a new set of 910 springs and shims...

All sounds easy, but its several weekends worth of work, plus I'll be painting it Oregon State colors...

 

This is very useful information, thanks for sharing! I was looking at the intake plenum before and wondering about the bolt pattern - so now I have to reboot my reboot. Thanks for that too






I was contemplating arbitrarily doing a valve job on the OBS heads, but I decided to just do springs and seals. Now my options are gone - I need to rebuild Stinky's heads to install on this block. My 38R doesn't need that center hole, so I'm doing the freeze plug.

I've always known this will take me several weekends, but the plan was to have this ready to swap and plop (install Superduty parts and re-install engine) to keep downtime to a minimum. I now need to haul 7.3L heads around in a Prius. I guess this makes "Stingy" a tender for Stinky... not the first time.

 

Am I crazy for thinking drill and tap? What about skipping those extra holes - the plenum doesn't need the added support, does it? I think I just need studs for the GP relay bracket.

 

I was thinking about that myself, but began to wonder why IH added those extra holes in the first place. I would guess it was for boost leaks, as the stock plenum is sheetmetal, while the thicker billet flange on the RR plenum might resolve that. I was also wondering if RR had an upgraded plenum for the OBS you could use, but I didn't see one on their website.

 

Here's the odd part: The seals with RTV don't usually fail in that spot - they fail near the inlet due to the added strain of the boots and spider. I had the almost expected result of a failed seal near the inlet when I wrestled thick boots on there with an insert, then "turned the knife" by wedging the spider into that tight angle. Then... to drive the knife deeper, I threw the 38R on there with Stage II sticks for much bigger boost. Yes... of course my seal failed next to the inlet.

As for the area far from the inlet, I strongly suspect it's nothing more than making a strong mounting point for the relay bracket.

 

The main reason for the swap is because of the RiffRaff Plenums. They will leak at that hole. IIRC Clay was making some 8 bolt ones for the OBS, but I am not sure if he kept making them or not. Regardless, if you go to a standard stamped steel SD plenum I doubt you would have issues.

 

If you need any SD parts for the swap part let me know, I have 2-3 sets of manifolds (only the drivers side is different), fuel bowl, front cover, HPO res...

Lots of parts lying around.

Not looking to sell persay, just send to you, then you send me yours when your done with the swap. Just to make it quicker.

Also, when you do the swap, make your front end look like this...



Dont leave the bumper, dont dick with the core support, get all that crap out of your way... Dont know why people fight with some of that crap, 3-4 more bolts and you can nearly walk to the trans...

 

I will throw my .02 in here as well. Considering how many 3" plenums we have thrown on OBS LBs with 8 stud plenum mounts. If installed properly and torqued properly 8 studs will be fine. Yes 10 is preferred but I have not seen a failure yet with the 8s

My personal truck is the same way and sees 35+psi on 8 stud 3" non billet plenums without issue... verified for over 100k miles now. Others have more than that on their setups, and push more pressure.

It is pretty easy to get a 3/8 or thicker piece of steel strap, torch/plasma/waterjet the plenum hole and weld on some std schedule pipe and make a billet set of plenums in a matter of an hour or two for less than 15-20$. mock and drill your mounting holes and you are done. The effort put into fabrication will make it look professional or garbage. I have made quite a few sets for others.

Want it to look billet, hit your pipe with a quick spin on a lathe and run an endmill down the strap and there is your billet look if aesthetics is your thing :-) Tig welding with stainless rod will help bling up the weld a bit too...

 

RiffRaff Billet plenums are more then just a plate and tube design... Plus they use an O-ring seal rather then RVT.

 

I never said they were. They are an excellent part. I have installed many sets of those as well and would recommend them to anyone with the pockets.

Point is I do not believe its worth swapping heads over 2 studs... that was all. 8 is fine.

 

Rich, if I were you and had everything out in the open like you will/do... I would not even consider putting the GPR back into the valley. I suggest that you do what I did last winter when I moved it out to the PS fender wall with a custom cut piece of heavy 3"x3" aluminum angle. Since doing the hard mount on the fender wall, I not only have the change in brightness of my interior lights to indicate when the GPR kicks off, but I also now have a very audible "clunk" when the relay switches off as well, so I don;t even watch my lights any more, I just wait for the "clunk" and then start out of the driveway, and I now have no need for the GPR LED mod components I purchased but never installed several years back.

Here's the link to pictures from that work... Relocate GPR Mod

 

Hmmm... GPR mod. My ESOF solenoid sits there, but that doesn't mean I can't come up with a plan. I'd like to make room in the valley for some ideas I have kickin' around.

I appreciate the views on the billet plenum, this could end up being a vote thing. I plan to call Clay and start a conversation with him as well. I admit I don't feel warm and fuzzy about just taking it on faith that it will work - a reinforcement mod appeals to me more. While some people can fabricate a quick mod to an aluminum billet, I'm not exactly equipped to take on such a task on my own. I do know some people that may be able to help me out... maybe... but they are under the same time crunch I am.

 

Joe - that's very gracious to offer up parts swaps to speed the process up! You'll hear from me if I get into a situation. Thanks!

 

I'm curious - and it's not that I'm too lazy to look it up myself, I'm just only curious - are there any other differences between OBS and SD heads?

I just wonder why the change was made. I work for a company where our R&D will make a change that has us scratching our heads at times.. fortunately no one has invented teleneckringing..

 

Nothing worth noting. Just the 8 or 10 bolt change, which really happened somewhere in the 1996 range.

I'm hoping my new motor has the 10 bolts as well...

The last motor came out of a 1996 as well, and it had 10 bolt...