Build The Clustertruck Rides Again - Refurbishing a 1975 Chevota

[RWBeringer4x4]

I’m long overdue for what has unfortunately become an annual update on the Clustertruck. I finally got back to CLCC’s Fall Crawl this year.

The good news - I had an incredible time, as always, at this event. The CLCC crew and my counterparts in Keystone are a great group of people and they collectively brought about 100 very cool, capable rigs. The trails are challenging, especially for those of us whose trucks are not “well endowed” in the tire department. I also have still done nothing to address the stock gearing which would have helped a lot.

The bad news - carnage always results.

I’m always blown away by how capable this truck is, especially given the circumstances this year… more to follow.

 

[RWBeringer4x4]

The circumstances…

The truck had been running with a touch of a miss for the last year or so that I couldn’t seem to tune out through timing adjustments and idle mixture screws.

Last February at the Keystone Cruiser breakfast meeting, it started backfiring under load and trying to stall up hills. @Pacer took the truck for a spin, quickly diagnosed a lean condition, and helped me find an intake manifold leak right at the exhaust crossover.

So I did what any good cruiserhead would do, I thanked him for his time and then drove it that way for 7 months. The backfiring went away with warmer weather in summer and I didn’t feel like taking my grocery getter out of service.

When I decided to attend Fall Crawl, I figured it was time to catch up on deferred maintenance.

So, the old SP2P manifold came off, leak confirmed, and an Edelbrock 2101 got put on.

This required a little re-routing and am
Emergency order of a new hose barb since it was missing a few ports the SP2P had (like the one for my brake booster).

I bolted the whole thing up with fresh Fel-Pro Printoseal gaskets, installed with a bead of RTV on the China walls and a skim coat around the water jackets, and slapped the whole thing together, and tuned the carb to the new intake with a couple days to spare before the Crawl.

Much to my dismay, the FelPro gaskets started weeping coolant at the water passages onto the top of the head almost immediately.

For anyone counting, this is the third set of intake gaskets I have somehow managed to screw up… I am really not sure what kind of sorcery is required to get these things to seal but it seems like “Fiber” gaskets (with or without the printed rubber rings around the ports) seem to absorb and wick instead of seal… that, or I’m just doing it wrong…

Regardless, I drove it around town a bit, noted I still had a bit of a miss at idle, and some fresh driveline vibrations at highway speed…

So I checked the rear dif, did find some metal “glitter” on the drain plug magnet but nothing alarming. Then I dropped, greased the driveshafts, steering joints, knuckles, etc.

In the end, I changed the oil didn’t see any INTERNAL contamination from a coolant leak, and decided to drive it to Fall Crawl and figure it all out later.

As icing on the cake, when I went to leave for the Crawl at 5am in the dark, I discovered my headlight relay had failed overnight. Clearly, the Cruiser gods were telling me I was not to go on this trip. So I swapped high/low relays, got in the pseudo-functional Clustertruck, drove it 160 miles to Gore, VA, wheeled it all weekend, and drove it home, at this point obviously running on 7 cylinders.

Managed to get about 10.5mpg on average for the road portion of the trip, a solid decrease from the previous 12ish mpg, so I knew something still wasn’t right… it also vibrated/struggled badly up hills at highway speed or anytime there was a load. I suspect missing a cylinder had a lot to do with it. I also did nothing to adjust the vacuum secondaries to the new intake, so it may be going lean/rich (depending on how much more or less vacuum the new intake pulls).

 

[RWBeringer4x4]

That brings us to yesterday. I pulled the plugs to try and diagnose the miss at idle, and it became clear pretty quickly. I only broke 2 plug wires and one spark plug getting them out… so I’m just going to run fresh ignition wires and plugs.

Disregard Cylinder 6, that was me, getting the plug socket wedged in a bad way against the charcoal canister…

Instead, I draw your attention to cylinder 3 (completely, sludge-cake oil fouled) and Cylinder 4… which, while probably not fouled, definitely looked different… Not sure how best to interpret the ashy/black look on Cyl 4…

I’m HOPING this is a carry-through of the previous intake manifold leak. Clearly, blocking the exhaust crossovers had been a bad call, and when the crossovers burned through, I suspect it created the vacuum leak/leak condition, and possibly pulled oil from the lifter valley into the cylinder. Otherwise, I will have much bigger fish to fry.

Fresh plugs, wires, and a compression test will tell me more…

 

[pb4ugo]

I wouldnt use that type of intake manifold gasket. I've been using felpro ms903143
type gaskets for decades. I thinkbits impregnated with sealant. I'll put a bead of sealant on the China wall and that's it, except for 1 time. I install the heat riser restrictions supplied with the gasket kit on both sides. I think you'll find it to be a more robust gasket.

The 1 time I used sealant on the water jacket ports was when I had to redo the intake manifold gasket because of a slight coolant leak from when I replaced the camshaft in my "street" 40. I determined the po's mechanic put 305 heads on the 350 block and then decked the heads mating surface to the max to increase compression. What a fn idiot. I found no freeplay in the distributor shaft and the intake manifold sat to low in the lifter valley which caused the leak. I think i used permatex aviation sealant which is thin and very tacky. You need to let it setup a bit. Since then it's been perfectly sealed.

 

[RWBeringer4x4]

I wouldnt use that type of intake manifold gasket. I've been using felpro ms903143
type gaskets for decades. I thinkbits impregnated with sealant. I'll put a bead of sealant on the China wall and that's it, except for 1 time. I install the heat riser restrictions supplied with the gasket kit on both sides. I think you'll find it to be a more robust gasket.

The 1 time I used sealant on the water jacket ports was when I had to redo the intake manifold gasket because of a slight coolant leak from when I replaced the camshaft in my "street" 40. I determined the po's mechanic put 305 heads on the 350 block and then decked the heads mating surface to the max to increase compression. What a fn idiot. I found no freeplay in the distributor shaft and the intake manifold sat to low in the lifter valley which caused the leak. I think i used permatex aviation sealant which is thin and very tacky. You need to let it setup a bit. Since then it's been perfectly sealed.

View attachment 4020389

I have not tried this style yet, I don’t think. Out of curiosity, are you running aluminum intakes or cast iron? I had been pointed toward the composite “printo seal” gaskets because apparently a lot of the other gasket styles (steel core, raised section, etc). Require more clamping force than you’re allowed to apply to the aluminium intake bolts, or they don’t like the differing thermal expansion rates between aluminum and cast iron. Have you had success with aluminum intakes/cast iron heads?

Do you have a strong opinion about blocking the center exhaust crossover or not?

I had used sealant with the “Mr. Gasket” gasket that successfully sealed the first time around the water jackets. When I pulled them, I had some staining/discoloration (maybe pitting) on the head around the water ports so I figured I’d lay down a skim coat of RTV around them again.

In hindsight, I MAY have just put a skim of RTV on the head and stuck the gasket to it (no RTV on the gasket itself). Maybe without more RTV to stick too, it didn’t fully adhere to the gasket side. Not 100% sure I did that but it’s possible. Next time I may try to dry fit them and just RTV the China wall to see what happens.

 

[brian]

Considering a 2F yet?

 

[RWBeringer4x4]

Considering a 2F yet?

I don’t have the time, or strength of will, to start over.

 

[brian]

Don't think of it as starting over. It would be more like resolving an on going issue with a positive outcome. Life with one of these makes the journey the destination.

 

[pb4ugo]

I used this style of gasket on many different applications. I usually run aluminum intakes and cast heads. I currently have an old edelbrock performer on one 40, a GM performance aluminum intake from a new ZZ4 sbc on another 40. The boat has a cast iron intake. I've used the same style on a 454 BBC with a performer, and have done several AMC V8 engines with performer intakes. I think it's probably an aluminum gasket. I seem to recall the blue coating is from permatex or something like that. I torque them to spec. in 3 stages in the proper sequence when I can. I try to avoid any sealant because we're mating 2 machined surfaces, but a skim coat around the water jackets is fine but nothing too thick. I've used the rubber seals or a bead of sealant on the China walls and corners. I block the crossover with the supplied restriction plates you can see in the pic. They have holes in the center. I can't recall any failures until recently, and I can't blame that one on the gasket. I pretty much use felpro gaskets on most of my rebuilds or repairs.

 

[RWBeringer4x4]

Don't think of it as starting over. It would be more like resolving an on going issue with a positive outcome. Life with one of these makes the journey the destination.

If I had the same amount of free time I had when I did all the driveline work the first time, it would be a consideration, but it would mean new engine, Bellhousing, driveshafts, clutch components, welding new engine mounts, most likely rebuilding the engine, etc. etc. etc.

It’s hard to scrape together 2 hours to dedicate to working on the 40 these days, so a swap back to a 2F would take years…and I’d rather drive it.

 

[RWBeringer4x4]

I used this style of gasket on many different applications. I usually run aluminum intakes and cast heads. I currently have an old edelbrock performer on one 40, a GM performance aluminum intake from a new ZZ4 sbc on another 40. The boat has a cast iron intake. I've used the same style on a 454 BBC with a performer, and have done several AMC V8 engines with performer intakes. I think it's probably an aluminum gasket. I seem to recall the blue coating is from permatex or something like that. I torque them to spec. in 3 stages in the proper sequence when I can. I try to avoid any sealant because we're mating 2 machined surfaces, but a skim coat around the water jackets is fine but nothing too thick. I've used the rubber seals or a bead of sealant on the China walls and corners. I block the crossover with the supplied restriction plates you can see in the pic. They have holes in the center. I can't recall any failures until recently, and I can't blame that one on the gasket. I pretty much use felpro gaskets on most of my rebuilds or repairs.

Alright, well I’m certainly game to give them a shot as I have not tried that style yet. It still begs the question, WHY the style I’m currently using (FelPro 1256) isn’t working, as it tends to be the ones that get recommended most often for aluminum-to-iron mounts.

I’m pretty sure the very first gasket I tried on this motor was some kind of a steel core laminate, and it leaked badly, very shortly after install. Most posts I can find on the subject typically recommend staying away from the steel core laminate intake gaskets because the aluminum can’t compress them enough, but if it works across all those applications, it’s probably worth a shot….

I’m not against chalking this up to installer error, though…

 

[pb4ugo]

Idk, I never took that deep of a dive into the subject. You might be right. Back in 70's or 80's or so, felpro started putting this style gasket in their rebuild gasket sets. Their head gaskets got the blue coating too. It seemed like a quality part, so I never deviated from them. I dont recall ever having a problem. Use what you're comfortable with.

 

[RWBeringer4x4]

Idk, I never took that deep of a dive into the subject. You might be right. Back in 70's or 80's or so, felpro started putting this style gasket in their rebuild gasket sets. Their head gaskets got the blue coating too. It seemed like a quality part, so I never deviated from them. I dont recall ever having a problem. Use what you're comfortable with.

So far, I’m not comfortable with any of them, apparently, but real-world experience trumps the internet so I’ll give those ones a try and report back. I’m also going to take a much closer look at the angles where the heads and intake meet and make sure somethings not way off.

 

[charliemeyer007]

Any gasket I install that has fiber gets soaked in warm water for like 1/2 an hour - it softens them up to allow the high spots to dig in. Torqued in proper sequence by 1/3. Fire it up and let it get up to temp for like 20 minutes. Let it cool out then retorqued at 100 %. After a few good heat cycles torque them again in sequence at 100%. After that I don't worry about it.

I planned my intake and header on a big piece of glass with sand paper. I made custom stepped brass washers so it would apply equal pressure to the 1/4" aluminium intake and the 1/2" steel header. I also used longer studs because of the washers and the 2 Man-a-fre header gaskets. Stainless nuts with high temp anti seize compound. I also cut a notch in the air filter bracket to make it easier the get the socket on the manifold nut underneath.

 

[RWBeringer4x4]

Any gasket I install that has fiber gets soaked in warm water for like 1/2 an hour - it softens them up to allow the high spots to dig in. Torqued in proper sequence by 1/3. Fire it up and let it get up to temp for like 20 minutes. Let it cool out then retorqued at 100 %. After a few good heat cycles torque them again in sequence at 100%. After that I don't worry about it.

I planned my intake and header on a big piece of glass with sand paper. I made custom stepped brass washers so it would apply equal pressure to the 1/4" aluminium intake and the 1/2" steel header. I also used longer studs because of the washers and the 2 Man-a-fre header gaskets. Stainless nuts with high temp anti seize compound. I also cut a notch in the air filter bracket to make it easier the get the socket on the manifold nut underneath.

Interesting, about soaking the fiber gaskets, I’ve never heard that done! Otherwise, I apply about the same logic…

1. Clean the old gasket surface (and avoid using abrasives that would get things out of flat).

2. Small amounts of RTV around water jackets, stick gasket to RTV (if I do this again, I should be sure to p it RTV on the gasket surface too).

3. Thick bead of RTV across the front and rear china walls instead of the China wall gaskets. Usually I let the RTV (Ultra Gray) set up for about 10 minutes.

4. Drop the intake as straight down as I can to avoid things moving.

5. All bolts get a coat of liquid Teflon paste to avoid coolant and oil wicking up the threads.

6. Start the bolts - Tighten bolts to finger tight. Then, torque in sequence to 25 ftlbs in 2 steps (maybe I’ll do 3). Also - very tough to accurate “torque” 350 intake bolts as the carb riser blocks torque wrench access to the center 4 bolts.

6. Usually, I wait 24 hours to let the RTV cure. Then, stab the distributor, refill the coolant, close up all the heater hoses,

7. Fire the engine, get to temperature/heat soak. Dial in timing, tune, etc. Then, shut it down, and retorque when cool.

^^^ Usually at this point, everything is dry. It’s not until I actually take it out on the road and put 15-20 miles on it that I’ll start to see things seeping.

One other thing I’ve noticed is that my Thermostat very occasionally seems to stick - the engine might hit 200 degrees before it opens, then cool back down. This seems to coincide with usually, my radiator hose burping some coolant past the hose clamp and onto the intake. I’m not sure why this happens but I assume this creates a water pressure spike (heat expansion) that might push something past the seals… the engine never overheats though, just gets a little hotter than usual for about 20-30 seconds.

Seems like if that blows coolant out the seals, as well as the coolant hoses, they weren’t sealed all that great in the first place…

 

[charliemeyer007]

Soaking the gasket is an old aviation trick I learned from my dad. My header gaskets have been on 2 different engines for a total of 3 times - they have never leaked.

 

[archie73]

Considering a 2F yet?

Too much work. LS for the win.

 

[SuperBuickGuy]

1) yes, use the blue gaskets - without any evidence other then been-there, the block may have been decked. That brings the heads ever so slightly farther apart, the thicker, more resilient gasket gets better sealing and lets the aluminum expand at a different rate then the steel.
2) yes, remove the EGR cross over, block them.

 

[RWBeringer4x4]

1) yes, use the blue gaskets - without any evidence other then been-there, the block may have been decked. That brings the heads ever so slightly farther apart, the thicker, more resilient gasket gets better sealing and lets the aluminum expand at a different rate then the steel.
2) yes, remove the EGR cross over, block them.

This was a brand new engine from Chevy (one of those drop-in 195 horsepower basic engines, now discontinued). I have not decked the blocks, so I don’t think they’ve been decked…

Out of curiosity, why block the EGR crossover? The last set of gaskets were just fiber, but didn’t have the EGR ports open. The exhaust burned through the gasket pretty quickly… I know the metal block offs would last longer in that case, and I’m not running an EGR or hot hair choke that requires the crossover. There just seems to be a lot of differing opinions out there about whether or not to block them. The only reason I left them open this time was to allow hot gas under the carb. Probably helps start in cold weather, might promote percolating fuel in warm weather…

 

[pb4ugo]

When I've pulled an intake that's been there for many yrs, the supplied block offs were still intact. I'd prefer the crossovers weren't there and the restrictors didnt have a hole, but they're there. Overall I want my carb, fuel and air as cool as possible. I dont care about cold weather starts. I dont run a choke or egr. A cooler air/fuel mix will build more power.

Years ago, my tstat housing would seep on cool down. It was an aftermarket chrome tstat housing with an O ring seal. Eventually I just use a gasket and ruffed up the mating surface. I dont have an overflow bottle, so when I top off the rad it will puke antifreeze out the overflow until it gets to it's happy place. One sbc has a 160 tstat and I have know idea what tstat is in the ZZ4 intake. I've never pulled the factory installed stk housing. I'd guess it's around 160 or most likely a 180. I only use the stk 40 cluster gauges. Its operating temp goes the 1st line.