BUILD THREAD Sweet Johnny & Gina: A Love "Two Large" To Fail

[Sweet_Johnny]

First thing you do with the 1245 set is get rid of those rubber end strips, aka china rail gaskets. They do not seal well and they will squirm and move on you. The best alternative is a continuous 1/4 inch high bead of RTV in your color of choice. For that get the RTV in the caulking gun version, the long tube, because it is easier to maintain pressure on the trigger as you apply the sealant. Using the smaller tube and hand pressure to get that bead on the back rail can become problematic. The bead should start right at the point where the head meets the block/china rail and continue in a non-stop application to the same point on the other side. Oh yeah, be sure to apply a thin smear of the RTV around the front and back ports where the coolant would be flowing to seal them up. Thing with the RTV is that a little bit can go a long way and it does smush under torque and pressure so will ooze out. ever so little. Once you have your torque sequence done, you can ever so gently wipe off anything that looks unprofessional to get that "polished" look.

Also going to suggest that you consider ARP 12 point intake screws, either black or chrome, as your new fasteners. Not a plug for the product per se, just easier to put a 12 point socket or wrench on them when dealing with tight spaces. As for the tightness, maybe a drop or two of Loctite blue as a bit of insurance.

Just a thought or two here,

Nick

I appreciate the solid advice, thank you. I look forward to any and all input, especially from the more experienced folks here. I often forget things or get in a rush but feel confident that I installed the intake correctly the last 2 times, though it has been a while. I never use the end rail gaskets even if they're cork, my RTV color of choice was the reliable Permatex Ultra Black in a 3 oz. tube, and I can lay a bead with the best blind man in town. Joking aside, my RTV beads look like they came from a caulking gun. Most of the time. In my teens I'd simply slap it together without waiting but now that I'm older I also allow it to get tacky before installation by taking a cigarette break and organizing things for about 15 minutes. I applied a thin film around the water jacket ports, gently set everything in place without any movement or sliding, and utilized 1" long 12 point bolts from Summit the second time I bolted it on. The first time I used a hex/Allen style that were way too short in all honesty. I went with zinc dichromate or gold Cad, whichever it is nowadays, because they'll look similar to my desired look for the brake booster that I still need to purchase. I love ARP and I love chrome/ stainless but I won't use a black phosphate or black oxide fastener without first sealing it with paint, unless its life is spent submerged in oil of course.

I have each color of Loc-Tite on hand but chose Teflon tape to prevent coolant leaks at the four corner bolts as well as the lifter galley, and always re-torque the bolts numerous times after multiple heat cycles as that method has served me well dozens of times in the past. I know a sealer that dries hard is much preferred by some, and that the tape will skew the torque readings but I torqued the bolts to 35 lbs in two stages to compensate, and avoid using extensions or wobbles if possible to minimize losses. I may go with Loc-Tite this time, but also don't want to go changing a procedure that I doubt is the source of any current issues.

What do you recommend I do about adding the metal crossover plates to gaskets that didn't come with holes for them? Can I simply "cut and paste" since I'm running an EGR valve? And can I use them on a gasket that's twice as thick as the one they originally came with? A stock 305 with EGR isn't quite what I'm used to, though in essence it's not terribly different either.

 

[CopperNick]

For myself, I wouldn't add the plates if there is no opening or provision for them in the gasket being used. Typically those small metal restrictor inserts get used when the manifold itself either has no crossover passage casted into it or to limit the amount of heat transferring from the heads to the bottom of the manifold. You'd need an engineer to explain the whole logic but back when cars had clutches and chokes, having the crossover passage under the plenum area in the manifold was a way to heat the air fuel mixture for the purpose of helping it to remain a mixture until it reached the combustion chamber. Something about the heat "exciting" the molecules of fuel and air so they move around more and remain closely packed. So along with the engineer, add a chemist.

If the manifold you plan to run does not have that crossover passage in it, then the plates get used to block the cutouts in the intake gaskets because some kits are made to be more or less universal to accommodate a wide range of years and the plates get used in that case if an older engine, with the air delivery ports casted into its heads, is being fitted with an aftermarket 'fold. that doesn't have that provision.

However, if the gaskets in question don't have the crossover hole in them but are blank, then adding those thin flat plates adds to the thickness of the gasket, maybe only by a thou or two but it still affects the ability of the gasket to generate an absolute seal across the entire gasket surface. Yes, the intake holes on the gasket can be rimmed with a sealing bead of some kind for better sealing but that ring will crush as flat as the gasket itself under torque. The metal plates aren't as forgiving and, being metal, will only compress so much and no more.




Nick

 

[Sweet_Johnny]

For myself, I wouldn't add the plates if there is no opening or provision for them in the gasket being used. Typically those small metal restrictor inserts get used when the manifold itself either has no crossover passage casted into it or to limit the amount of heat transferring from the heads to the bottom of the manifold. You'd need an engineer to explain the whole logic but back when cars had clutches and chokes, having the crossover passage under the plenum area in the manifold was a way to heat the air fuel mixture for the purpose of helping it to remain a mixture until it reached the combustion chamber. Something about the heat "exciting" the molecules of fuel and air so they move around more and remain closely packed. So along with the engineer, add a chemist.

If the manifold you plan to run does not have that crossover passage in it, then the plates get used to block the cutouts in the intake gaskets because some kits are made to be more or less universal to accommodate a wide range of years and the plates get used in that case if an older engine, with the air delivery ports casted into its heads, is being fitted with an aftermarket 'fold. that doesn't have that provision.

However, if the gaskets in question don't have the crossover hole in them but are blank, then adding those thin flat plates adds to the thickness of the gasket, maybe only by a thou or two but it still affects the ability of the gasket to generate an absolute seal across the entire gasket surface. Yes, the intake holes on the gasket can be rimmed with a sealing bead of some kind for better sealing but that ring will crush as flat as the gasket itself under torque. The metal plates aren't as forgiving and, being metal, will only compress so much and no more.




Nick

I was skeptical that a positive seal would be possible but for all I know the metal pieces would sink and/or bite into the gasket if overlapped and the Permatex would fill the voids. I've got solid ones (blockoffs) as well as some that match the pieces that were in the 1256 gaskets. I wondered if I should make it a snug fit into the holes I cut, or if it should fall in place and not disrupt the gasket itself. If the hole is cut slightly oversized then the metal piece can just rest in its hole completely surrounded by red RTV and since it's thinner than the gasket it shouldn't prevent sealing at all. The only benefit would be that the metal would protect the gasket edges and prevent fraying. I figured that the thin sheet metal (20g?) wouldn't get in the way of a gasket that's 1/8" thick but felt I'd ask since that's free.

Sounds like I'll be punching a hole in the gasket, throwing the metal pieces in the garbage, using the Permatex spray and possibly a schmear of high temp RTV. This engine runs great but has blowby and fraying gasket fibers in the crossover after a year or two wouldn't be the end of the world. This endeavor has rejuvenated my dislike for EGR since I would've NEVER used a factory intake if not for wanting to retain it for a change. All of this trouble and I still haven't even got a functional TVS for the thing.

 

[Sweet_Johnny]

This is starting to be a regular sight in my garage:



Alright, I'm a little behind as usual but I did manage to be slightly productive since I last posted. The intake manifold situation seems to finally be handled- after putting on the thicker gaskets Gina no longer seeps coolant and the only vacuum leak is the brake booster. Now, these gaskets didn't go on without a struggle because that just wouldn't be right. Due to the additional height of the thicker gaskets the bolt holes were slightly off and I fought to get over half of them started, and had to remove the rear bolt that holds the cruise control diaphragm bracket to the head to get the back 2 driver side intake bolts in. Until now that bolt had remained just loose enough to swing the bracket out of the way. I cut out openings in the gaskets for the EGR valve/ heat crossover to be functional, and utilized Permatex Copper Spray-A-Gasket to help ensure a good seal. The new bolts that I used are just your average 1.25" long 9/16" headed Grade 5 hardware store units. I considered 12 pts of the same length but they're $50 and I've already spent that much on intake bolts that I can't use. I just wanted this to be done.

Here's the offending manifold which I have not used any power/ air tools on. I did grab a new b*st*rd file just for it though:



The intake and valve covers now have a few small scratches after being removed multiple times but everything seems to be copacetic and functional. I experimented by switching from ported back to manifold vacuum for the distributor but I had to set the idle pretty high (just over 1k rpm) for it to stay alive in gear (400 rpm) with the base timing dropped down to 15° and the vacuum line reattached. It lost 4-5" of vacuum which the converter and current gears just don't like, so I'm back to 25° with 20° of ported advance and the mechanical isn't all in until 4k. This may not be ideal for full power runs but it gets good mileage if I drive conservatively. I still detect no detonation or pre-ignition but may end up going down a heat range on the plugs this summer. Now that I have nearly 0 vacuum leaks I doubt that I could run as much timing as I was able to during initial testing, and the temp creeps just a tad higher than before on the freeway.

The alternator that I was afraid I ruined has also been salvaged. I couldn't get the pulley off earlier, grabbed a hammer, and messed up the threads as well as deformed the end of the threaded shaft. After a little work with the new file, a needle file, and a different nut we're ready for a fresh coat of paint. In fact, it was the old paint on the shaft that was preventing the pulley from coming off. I didn't remember using a pulley remover when I painted it white so many years ago but as I was fighting it I wondered if I'd simply forgotten. Nope, no special tool necessary unless you wedge it on there like I did. At first I thought I could pry it off, but decided that might break the fan. In the end an Allen headed socket provided the necessary protection for me to finish removal. The threads don't look too bad in the pic, which was taken after I used a bronze bristle brush to clean things up a bit.



I forgot to mention that I replaced the lower radiator hose the last time the intake was off, and I had to replace the EGR gasket again as well since I removed it for better access to the intake bolts.

As usual with old cars there's no shortage of things that need attention. I have 2 exhaust leaks (collector defect & ill-fitting pipe junction), 2 transmission leaks (gear selector & speedo), my master cylinder drips, and the booster slowly leaks vacuum. A left front wheel bearing is howling at me too, so a complete front suspension and brake rehab is in order since I've already got some of the parts. I also need to replace the kickdown cable that I melted, the speedometer quit working 2 weeks ago, and I can't always trust the other gauges. There's also a set of spark plugs and wires waiting to be installed alongside a rebuilt carb and spacer.

And we think this is fun.