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Pontiac - Boost Turbo, supercharged, Nitrous, EFI & other Power Adders discussed here. |
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#1
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MLS HEADGASKETS ON A BOOSTED COMBO
Anyone using an MLS head gasket on a turbo/blower combo up to around 30psi?
Have they worked out for you? Please state your block and head material. I'm thinking of trying some on my small 4.090" bore turbo combo rather than getting the heads and block cut for o rings and copper gaskets. They seem to work ok on the SBF with the small bore and 4 head bolts per cylinder. |
#2
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I use them with no problems at all, with a 4.090 bore . I use a 4.160 gasket bore . Ive been as high as 44psi but normally im between 30-36 psi. Aluminum E-head with a stock 1961 block...
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My Half AN Injun..... |
#3
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Thanks Charlie,that's what I was hoping to hear, I have a few questions if you have time.....
Are you running water through the decks or are you dry decked? What thickness gasket? Did you have the decks skimmed to the very fine finish they recommend or not? Are you spraying them with copper coat? (I've always used this on the couple of stock MLS head gaskets I've fitted) Are you using Cometic or another manufacturer? Looking at Cometics site, the smallest bore size is 4.160", I've emailed them to see if they can make me a pair of the 4.160" bore gaskets but without the coolant holes, as I'm dry decked and would like the maximum gasket strength. I'm on iron heads and a '59 block with ARP studs/.250" thick hardened steel washers, so if you're good with your ali head then I 'should' be fine. |
#4
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No problem man
Yes i am running water through them. I would like to go dry deck but im not sure how to do it. I do not have a good enough understanding of what needs to be done to feel comfortable with going that route.. I think its a great idea for sure.. Thickness i use : 0.040 in. Deck finish im not sure . I just drop off my block and tell the machinist im using MLS gasket. To me it looks normal . But i could be wrong . Sorry just being honest . Ill have to ask him the next time im there.. Copper spray is a funny subject. There is a mixed opinion about this one . Cometic says NO and NEVER . Ive used it and not used it. I dont use it anymore . I feel it is not needed. The problem is usually because (at least with a aluminum head) The bolt hole towers start to anneal to the point of no return . The nut/head of the fastener starts to sink and sink into the tower hole heat cycle after heat cycle. I have found that it will not stop until you stop it with a steel sleeve . I use Cometics.. If it was me id just use the ones that they offer, No sense spending more money on a special order on something that you dont need . I dont see the water holes being there making one bit of a difference then there not being there. And yes, your iorn heads should be way better then the aluminum no doubt.. And i have zero issues .. So as you must know by now my motor is a 4 cylinder. So needless to say i need alot of boost to hang with the 8 cylinder guys. Its also a street car . So 30 psi and up is the only choice i got if i want to hang .. I use my car all summer and even into the cold up until it starts to snow. So there are hundreds of miles put on this engine in a season beating the crap out of it. At the end of this summer i raced a z06 with mods done to it making 755 rwhp . So i turned it up to 38 psi . We ran 6 times in a row . All times were full runs . So no time to cool down just one after the other at 38 psi with not 1 problem with the head gasket.. I think you will be fine using a MLS with a iorn head .. Hope this helps...
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My Half AN Injun..... Last edited by charlie66; 12-16-2019 at 09:00 AM. |
#5
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make sure you follow the gasket manufacturers recommendation for surface finish. they will fail prematurely.
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1969 carousel red firebird 455, richmond 5 speed 1964 540 gto 1971 lemans sport convertible 1972 Maverick under slow construction |
#6
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I use the same machine shop as Charlie. RA 50 is what they use, it is a smooth surface.
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#7
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Quote:
I’m impressed! FWIW......doing a dry deck is pretty simple. GTO George |
#8
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Quote:
Maybe one day you could explain it to me...
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My Half AN Injun..... |
#9
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I also saw on other Pontiac web site about someone drilling out the head bolt/studs holes in the heads and installing/pressing in metal sleeves where the bolts/studs go in.
Dry decking is pretty simple....when you get time! GTO George |
#10
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Quote:
Nope, This is not always true. And this is mostly the case with the higher boost levels . The low boost levels it barely happens but can.. But the head starts to give in from all the heat cycles with boost in and boost out .. When im at 35 psi the EGT's go north of 1700*f in seconds and down to 400*f in 1 second on lifting off the throttle . Do that all weekend and check all your exhaust head bolts the next day when the engine is fully cooled off and i will bet there less then what you torqued them at . Then if you dont check them the next day out you do it all over again because in your head you already torqued them 3 times and you feel its ok to make more passes and problem just gets worse and worse .. And thats when to gasket usually goes bad. So now you blame it on the gasket but in reality the head cant keep the clamp that is needed.. So thats where the sleeve came into play .. And believe me , that sleeve solves that problem for sure...
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My Half AN Injun..... |
#11
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Thanks for the info Charlie. I'll see what Cometic say about the gaskets without coolant holes, if it's no go, then I'll try them as they are. My block will need boring/honing to 4.090" - so I can get the decks and heads lightly skimmed to the correct finish at the same time. (After I've welded/brazed up the valley, 3/4 filled the block and fabbed the new mains girdle.)
I dry decked my previous /59 block turbo combo ,and as George said,it's pretty easy, if a bit time consuming. I bought a few boxes of Pioneer steel Allen head NPT pipe plugs from Summit and then drilled out and tapped the coolant holes in the heads faces and block decks to suit the plugs, then screwed them in with Red Loctite on the threads. If you tap deep enough on each hole ,the plug will sit just below the deck and no machining is needed, if they sit above the deck then you would need to get the decks skimmed. I reverse cooled mine at the same time so that the heads get the cooled water first (helps with detonation and probably the hot spots in the heads where the ali goes soft around the centre exhaust ports). I put the water in from my electric pump to the intake crossover using AN10 fittings and braided hose, then took the water out at the rear heater/core plugs, through AN10 hose into the rear side of the block just below the heads (drill and tap a hole each side for 1/2" NPT fittings) . A hole is then drilled at the front of each bank of the block and tapped for 1/2" NPT fittings again, these hoses are routed to a Moroso water filler neck with a radiator pressure cap, and then on to the radiator top hose. It's called a 2 pass system. Hope this info helps. On my 'new' '59 block I will be putting the water into the heads on the exhaust side where the core plugs are at the front of the heads, and out the back of the heads ,again on the exhaust side where the core plugs are, before routing back into the block. I'm trying to encourage the majority of the water to flow through the passages along the exhaust side of the heads . |
#12
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Quote:
No Problem anytime... Yeah what you wrote just confused me more ..lol. Sounds like alot of things need to be done . One of these days ill try to attempt it ..
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My Half AN Injun..... |
#13
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My previous combo is still stripped down, I can take pics of each part of the process if that would help you visualise it. It's pretty easy to do .
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#14
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taff2 I run Cometics with no water holes. They can make them up no problem. When you order them just tell them no water holes. Thanks Rusty
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Blown 4cyl's to the front |
#15
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That would work for me.. Thanks alot..
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My Half AN Injun..... |
#16
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Thanks Rusty.
The MLS solid gasket combo is looking promising,with at least 3 Pontiacs running fairly high HP reliably with them, 2 on the same bore size as me, it will save me the time and cost of getting the heads and block cut for o rings (I cut them myself last time, but I'm not a machinist and they took me forever. How accurate they were compared to a machine shop I don't know). Charlie I'll take pics ASAP and post up. |
#17
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Quote:
Id luv to hear how you did it.. And thanks those pictures would help me out in a good way ..
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My Half AN Injun..... |
#18
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To cut the block o ring grooves I had to turn up a stepped top hat shaped fixture from a piece of 6" steel bar, the lower section was turned to 4.090" to fit the bores and I then drilled a hole in the top flange to take a cobalt steel cutting tool-with the tip ground to 0.030" (the width of the groove). The cobalt tool is adjustable for depth by moving it up or down in the hole and locking with an allen grub screw.
The tool is then just placed in the bore and rotated by hand,the top flange sits on the deck and bottoms out when the groove is cut. It's a similar tool to the old Isky o ring tool or the BHJ tool. I'll take a pic of it this week. That was the easy part...... Cutting the receiver grooves in the heads had to be done on my small mini mill and took forever as the bed is small - I had to clamp down the head, cut groove, and then unclamp and move it for the next groove. I basically made a fly cutter out of a piece of cobalt steel ground to a .040" tip and set to the diameter of the block o ring grooves . To locate where on the head faces I needed to cut the receiver grooves to exactly match the block grooves - I tapped the .8mm steel MIG wire into the block grooves,marked the wires with black marker pen and torqued the head down onto the block, this left a black witness ring on the heads so I knew where to cut. It took me the better part of a month working on weekends and some evenings-as I said,I'm not a machinist! |
#19
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To me what you did is more impressive then a machinist doing it with the right tools. Hats off to you man. Im impressed.. I deffinitely would like to see those pictures..
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My Half AN Injun..... |
#20
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On my E-heads, I ran cometic MLS for years, both with and without water holes. Boost was in the range of 24-30lbs. I would torque them down to 115lbs. and re-torque them after a heat cycle. I would get 15-20 passes out of a new set. Do another re-torque and get another 5 passes out of them...then throw them in the trash. At that point, the leak down was usually 40% or more and the gasket was beat up.
On my CVWHAT's, I could go 20 or so passes before I re-torqued, ran them another 5 or so passes, and then they were trash. Running low boost (anything under 22lbs.), I could go 40 passes on a set of head gaskets.
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East Coast Mafia TTFMF Making CVWHAT's great again. I guess it took a deplorable ECM member to do it! Quote:
Fastest Blow-thru Pontiac powered car in the Country 8.440@166.97 (3465lbs) Fastest Pontiac CV-1 car on the planet with only 6 passes on the combo: 4.80@147.65/ 7.49@180.12MPH (3365lbs) |
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