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Author Topic: '91 Capri XR-2 Resto-Mod  (Read 12821 times)

Aus Capri

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    • 1989 Capri Turbo
Re: '91 Capri XR-2 Resto-Mod
« Reply #255 on: October 05, 2021, 07:59:51 AM »

https://www.ebay.com.au/itm/Cometic-C4122-051-051-Cylinder-Head-Gasket-suits-Mazda-B6T-Turbo-DOHC-16-Va-/303237388641?mkcid=16&mkevt=1&_trksid=p2349624.m46890.l49286&mkrid=705-154756-20017-0

This is the cometic multi layer head gasket I used. I think this one is thicker and will lower your compression ratio, but I'm pretty sure you can get it in the standard size as well. I wasn't concerned about it dropping the compression ratio due to thicker head gasket as the pistons I used raised it to 8.6.

Using fresh decks on the block and head, apr head studs  and the cometic gasket is a very strong seal. I even torqued the arp studs a bit more than they recommend. I have been running 30psi and had 0 problems with it, it even accidentally saw 40psi last week and didn't complain 😂. The last composite one I had let go after a couple of weeks at 20psi. 
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EShepherd

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    • 1991 Capri XR2, 1991 Capri XR2 Rusted out Shell
Re: '91 Capri XR-2 Resto-Mod
« Reply #256 on: October 05, 2021, 06:38:37 PM »

https://www.ebay.com.au/itm/Cometic-C4122-051-051-Cylinder-Head-Gasket-suits-Mazda-B6T-Turbo-DOHC-16-Va-/303237388641?mkcid=16&mkevt=1&_trksid=p2349624.m46890.l49286&mkrid=705-154756-20017-0

This is the cometic multi layer head gasket I used. I think this one is thicker and will lower your compression ratio, but I'm pretty sure you can get it in the standard size as well. I wasn't concerned about it dropping the compression ratio due to thicker head gasket as the pistons I used raised it to 8.6.

Using fresh decks on the block and head, apr head studs  and the cometic gasket is a very strong seal. I even torqued the arp studs a bit more than they recommend. I have been running 30psi and had 0 problems with it, it even accidentally saw 40psi last week and didn't complain 😂. The last composite one I had let go after a couple of weeks at 20psi.

Yeah, that was my motivation. I've been forced to have the mating surfaces machined, and I already have the head studs. I also plan on getting Rocket's chip which is going to double the factory boost levels. I might as well spend the money on the nicer head gasket, at this point. Plus, if (god forbid) I ever need to open the block back up, I won't have to deal with scraping the remains of that composite crap off ever again. That was terrible. It was also the reason why I had to get the surfaces machined in the first place.

And Matt, I've managed to lose the stock crank pulley bolt. Well, I'll take the blame, but really I think my machinist lost it. That's why I'm replacing it. As far as the seal diameters, if you click into a few of them for more information, they actually give you some measurements. I left my micrometer at work so I can't go double check myself, but I'm 99% sure I got the right part this time.

Oh actually Matt, I did have a question for you. Have you ever gotten Dyno sheets for a Capri before/after getting a Rocket chip? I kind of want to dyno my car once I get it running, before I drop the chip in. I'm curious what (if any) effect all the hours of porting and polishing the head will make to the factory power levels. If I do end up doing it, I'd be totally down to re-dyno it after I get your chip in there, if that's information you still need.

Getting so close I can taste it.
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EShepherd

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    • 1991 Capri XR2, 1991 Capri XR2 Rusted out Shell
Re: '91 Capri XR-2 Resto-Mod
« Reply #257 on: October 06, 2021, 07:17:39 PM »

So I was watching some videos on YouTube, and heard an interesting tidbit on the topic of head gasket choices. Now, this was about a 4G63, so not the same engine...however I think it'd still apply to our engines. After all, the 4G63 is still a cast iron block with aluminum heads, and a four cylinder to boot. Anyways, the guy stated that he had consistently run multiple engines at over 20psi of boost, with the factory head gasket material (graphite, same as ours), without any problems. That was with ARP head studs. Ever since I heard that, I've been debating just using the head gasket I've already got. I figured I'd pose the question here, see if anyone has any input.

The video in question was by a YouTuber who goes by "Jafromobile", by the way. I STRONGLY encourage anyone remotely interested in building engines to check his stuff out. The guy is a treasure trove of knowledge. I'd say 90% of what I know about building engines, I learned from him. I just wish he was a Miata guy, instead of a DSM guy. It doesn't truly matter though....most of the information is good for our cars, too.
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greywolf27030

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    • 1991 XR2, 1992 XR2, 1993 XR2
Re: '91 Capri XR-2 Resto-Mod
« Reply #258 on: October 07, 2021, 08:06:57 AM »

The number of bolts and the bolt placement could have an effect on the results.
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Jack Byrd

EShepherd

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    • 1991 Capri XR2, 1991 Capri XR2 Rusted out Shell
Re: '91 Capri XR-2 Resto-Mod
« Reply #259 on: October 08, 2021, 05:38:36 AM »

Front main seal arrived last night, and it was in fact the correct part!
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EShepherd

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    • 1991 Capri XR2, 1991 Capri XR2 Rusted out Shell
Re: '91 Capri XR-2 Resto-Mod
« Reply #260 on: October 09, 2021, 05:35:22 PM »

I got the bolt in last night, too. Funnily enough, after Mazda telling me they don't make it anymore and can't get it for me, and ordering it from Flyin' Miata....it showed up in a OEM Mazda bag. Looks to me like said company bought out all of the short nose crank bolts, just so they could sell them themselves for a stupid amount of money. Ah well.

I'm going to rip the cams back out of my head tomorrow, then the plan is to drop it off with the machinist on Wednesday. Then, it's up to that slow dude. Once I've got it back, it's smooth sailing. Just need the free time, but should be able to get the engine back in the car within a few weeks.

UPDATE
---------
So I pulled the head out of storage. The deck surface was not nearly as bad as I had thought it was. So moving forward. I'm going to skip the machine work, and use the graphite head gasket I've already got. I just need to wait for the m11x1.5 tap I just ordered to show up, so I can clean out the threaded holes in the block for the ARP studs. That -SHOULD- be here tomorrow, Tuesday at the latest. Once I have that, it's smooth sailing. But of course I didn't have the correct sized tap...of course. I do need to dig up some pictures of how this one engine mount goes back on the block. I'm pretty sure I need to put it on before I put the head on, but I can't for the life of me remember how it goes.
« Last Edit: October 10, 2021, 06:27:35 PM by EShepherd »
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EShepherd

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    • 1991 Capri XR2, 1991 Capri XR2 Rusted out Shell
Re: '91 Capri XR-2 Resto-Mod
« Reply #261 on: October 17, 2021, 01:21:36 PM »

I've been battling with a stupid problem that has had me stuck. The alignment dowel pins for the cylinder head/block were stuck flush into the head. I needed to get them out, so I could use them to align the head gasket and make sure everything went together smoothly. The damn things were completely recessed into the holes, so there was nothing I could grab onto and try to spin or pull them out.

I eventually (just today) managed to get the things out with a cute little miniature slide hammer and some two-jaw pullers that thread onto the end of it. It wasn't easy, and of course I destroyed the dowels in the process. Does anyone know where I can buy new ones? I can't find them on Rock Auto. I'll call Mazda tomorrow, they may be able to help me. Figured I'd see if anyone on here had any ideas before I go the dealership route.

EDIKT:
Nevermind, found and ordered them. Should be here sometime within the next two weeks, sadly.
« Last Edit: October 17, 2021, 04:32:22 PM by EShepherd »
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EShepherd

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    • 1991 Capri XR2, 1991 Capri XR2 Rusted out Shell
Re: '91 Capri XR-2 Resto-Mod
« Reply #262 on: November 03, 2021, 01:15:19 PM »

Hey guys, I've got some good news, some other good news, and some bad-ish news.

Good news #1. I've given up on the dowel pins I ordered ever showing up, so I'm getting ready as we speak to drive to a Mazda dealership in New Jersey and pick some up. Should be able to put the entire engine together, with manifolds and all, once I've got that missing piece. Good news #2, I have tracked down a transmission. Looks like that's my second major hurdle resolved. That does bring me to the bad-ish news, though. I won't be able to get my hands on the gearbox until sometime in January, or maybe February. So, it'll be a couple months until I can have the car all back together and *fingers crossed* running.

That does give me a couple months to tidy up the engine harness, and grab the last couple bits I know I'll need to have the car street drive-able. Both axles, brakes all the way around, fluids, that kind of stuff.

Stay tuned for updates. I hope to (freaking finally) mate the head to the block later today!
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greywolf27030

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    • 1991 XR2, 1992 XR2, 1993 XR2
Re: '91 Capri XR-2 Resto-Mod
« Reply #263 on: November 04, 2021, 11:07:42 AM »

I've been battling with a stupid problem that has had me stuck. The alignment dowel pins for the cylinder head/block were stuck flush into the head. I needed to get them out, so I could use them to align the head gasket and make sure everything went together smoothly. The damn things were completely recessed into the holes, so there was nothing I could grab onto and try to spin or pull them out.

I eventually (just today) managed to get the things out with a cute little miniature slide hammer and some two-jaw pullers that thread onto the end of it. It wasn't easy, and of course I destroyed the dowels in the process. Does anyone know where I can buy new ones? I can't find them on Rock Auto. I'll call Mazda tomorrow, they may be able to help me. Figured I'd see if anyone on here had any ideas before I go the dealership route.

EDIKT:
Nevermind, found and ordered them. Should be here sometime within the next two weeks, sadly.

I'm not sure how I missed this but there is a company called McMaster-Carr that is an industrial supplier I've been using for 40 years. They have pretty much everything and will have it to you in a couple of days. Not the cheapest, but quick and dependable. The only times I've ever had them make a mistake, they told me to keep what they have shipped and I got the replacement in  a couple of days.
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Jack Byrd

EShepherd

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    • 1991 Capri XR2, 1991 Capri XR2 Rusted out Shell
Re: '91 Capri XR-2 Resto-Mod
« Reply #264 on: November 14, 2021, 04:44:39 PM »

Have some pictures of my progress. Sorry it's been slow going...work has been extremely hectic. Finances have also been kind of tight. I finally outgrew my toolbox at work, and am now being forced into buying something bigger. I don't know if you guys have ever shopped for big tool boxes, but good lord. Prices range from a cheap used car to a decent brand new car. I'm leaning towards a 72" Harbor Freight top/bottom, which will -only- run me $2800 or so, but yeah. Put a bit of a damper on my budget for this thing.

However, here's the part numbers for the parts I did manage to get. Nothing exciting. Cylinder head dowel pins, and a new crank bolt. I strongly recommend anyone doing a rebuild on a short nose crank engine to get the bolt, even if it is a bit of a pain in the ass to track down. Got mine from Flyin' Miata.



Here's the bottom sealing surface of the head. I think it looks good enough to not feel too guilty about not getting it re-surfaced.


Prepping the holes for, and installing the, ARP head studs:



Timing finally set, and a mockup with the valve cover in place. I'm probably going to paint the valve cover to match the block and oil pan, although I may still take a stab at polishing it. I do have a couple months of waiting before my new (to me) tranny comes, so I may actually have the time to polish it.



Bonus pic. I got stickers, yo.

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greywolf27030

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    • 1991 XR2, 1992 XR2, 1993 XR2
Re: '91 Capri XR-2 Resto-Mod
« Reply #265 on: November 15, 2021, 08:16:52 AM »

Pretty work. I noticed when you were cleaning out the treads it looks like you were using a threading tap. On a couple of different shows lately I've heard that you should use a re-threading tap. A threading tap would distort the thread. Really? I've always used a regular tap. What are your views?
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Jack Byrd

EShepherd

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    • 1991 Capri XR2, 1991 Capri XR2 Rusted out Shell
Re: '91 Capri XR-2 Resto-Mod
« Reply #266 on: November 15, 2021, 06:45:33 PM »

Pretty work. I noticed when you were cleaning out the treads it looks like you were using a threading tap. On a couple of different shows lately I've heard that you should use a re-threading tap. A threading tap would distort the thread. Really? I've always used a regular tap. What are your views?

So the old-timer who I apprenticed under explained it to me like this. A new tap is for cutting threads. They can be used to clean threads, but you've got to be very careful. An old tap becomes a thread-chaser. Once it's been used and has lost it's edge, it's perfect for cleaning threads without causing too much damage.

I didn't have any used taps in the size our head bolts are, so I used a new tap. Even with a fresh tap, it was incredibly difficult to clean those threads out. I didn't feel any play in the studs as they were being installed, so I think I managed to not do too much harm to the threads.

I'm too cheap to buy thread chasers. I have used taps in a lot of common sizes, and they do work quite well for cleaning up bolt holes. However, on something as caked up with crap as these head bolt holes were, I'd have used a fresh tap even if I had a used one. They were a serious pain in the butt to clean.
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greywolf27030

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    • 1991 XR2, 1992 XR2, 1993 XR2
Re: '91 Capri XR-2 Resto-Mod
« Reply #267 on: November 16, 2021, 09:07:59 AM »

Pretty work. I noticed when you were cleaning out the treads it looks like you were using a threading tap. On a couple of different shows lately I've heard that you should use a re-threading tap. A threading tap would distort the thread. Really? I've always used a regular tap. What are your views?

So the old-timer who I apprenticed under explained it to me like this. A new tap is for cutting threads. They can be used to clean threads, but you've got to be very careful. An old tap becomes a thread-chaser. Once it's been used and has lost it's edge, it's perfect for cleaning threads without causing too much damage.

I didn't have any used taps in the size our head bolts are, so I used a new tap. Even with a fresh tap, it was incredibly difficult to clean those threads out. I didn't feel any play in the studs as they were being installed, so I think I managed to not do too much harm to the threads.

I'm too cheap to buy thread chasers. I have used taps in a lot of common sizes, and they do work quite well for cleaning up bolt holes. However, on something as caked up with crap as these head bolt holes were, I'd have used a fresh tap even if I had a used one. They were a serious pain in the butt to clean.

Thanks
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Jack Byrd

EShepherd

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    • 1991 Capri XR2, 1991 Capri XR2 Rusted out Shell
Re: '91 Capri XR-2 Resto-Mod
« Reply #268 on: November 21, 2021, 03:59:12 PM »

So, I've gotten the timing cover, water pump pulley, exhaust manifold, and intake manifold all on the engine.




I'm pretty sure I goofed here. I think the exhaust will need to come back off, in order to install the water pump outlet. Unless the pipe that goes into that can be separated and reinstalled. Not sure. I've got it packed up to go to work with me tomorrow to see if I can take it apart, and so I can clean it. Other than that, it's just the harmonic balancer, some hoses, some mounts, and the belt drive system. Basically just silly ancillary stuff. The engine is 98% of the way back together now  ;D
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greywolf27030

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    • 1991 XR2, 1992 XR2, 1993 XR2
Re: '91 Capri XR-2 Resto-Mod
« Reply #269 on: November 22, 2021, 09:47:10 AM »

Excellent
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Jack Byrd
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