I'm running cj heads on my 460. However the person i bought the boat from said not to run a Exhaust gasket, but to use gasket sealer (high Temp). He say that the gaskets are always blown out? Is there any truth to this? I believe that the cj heads are bigger that the exhaust manifold ports slightly? I have Logs for 460 heads bolted to the cj heads?Any advice is greatly apprieciated. Last year while running this setup I had a slight Exhaust leak.
Thanx to all who can help?
Also looking for headers if anyone has a set that they are not using.THX
It's true that a lot of people will not use gaskets when they are using log manifolds. This is due to the fact that many log manifolds are warped in the gasket surface. Personally, I never had a problem using gaskets on my Oldsmobile engine with logs, but I no longer have that boat and engine. It's a matter of personal preference - there is no harm in just using a high-temp sealer, but if gaskets work for you, I say keep them in.
SteveM.
Remembering back when I was running logs, I think most years the gaskets did blow out. This makes a mess, is noisy and if the engine is enclosed makes an exhaust smell in the boat. If there is no gasket it can't blow out. If the sealant blows at least it is not a big gap. Km
Try the Copperseal exhaust gaskets from Mr. Gasket company. Solid copper gasket with raised edge around all exhaust ports. I've used these gaskets on my 460 for three years now and no blowouts! They can be ordered from Jegs highperformance mail order.
You can go either way! My 460came with no gaskets back in 1976 and just last year I had to mill one only manifold surface to mate the head perfectly.I would use the high temp copper gasket maker . If manifolds,heads surfaces are straight you don't need a gasket.If in doubt use the mentioned copperseal gasket.I've logged over 2000hrs on my original log manifolds and still in good shape.The cobra head ports are no problem with the 460, the SCJ heads are the ones that much bigger.Almost all 460's came with the 429 SCJ intake manifolds for boats back in the seventies and they worked well even with the standard 460 heads.I've tried all kinds of aluminum intakes and none of them gave me better performance on the same engine.There was an article in performance boat [predecessor of hot boat]about an enduro race by a ford engined boat ,called 10-ford, and that boat's performance astonished everyone,and they couldn't beleive it wasn't a race engine.The SCJ intake is much larger than the 429/460 heads and despite the fact it's mismatched, it works well!
Any help with what size carb i should be using it has a 850 mech on it now and seems to be running real rich. 20 ft hawaiian with 460 cj heads roller motor and a ral looping cam not sure of the cam grind but it was made by Clay Smith. Would a 750 vac sec work better. It also has a wieand stealth intake. It runs out to 58 mph (GPS) Seems like it should go faster. At 5100 rpms w/b impellor? Any help is greatly appriciated you are all a great help thanx
JOHN Originally posted by spectras only:
You can go either way! My 460came with no gaskets back in 1976 and just last year I had to mill one only manifold surface to mate the head perfectly.I would use the high temp copper gasket maker . If manifolds,heads surfaces are straight you don't need a gasket.If in doubt use the mentioned copperseal gasket.I've logged over 2000hrs on my original log manifolds and still in good shape.The cobra head ports are no problem with the 460, the SCJ heads are the ones that much bigger.Almost all 460's came with the 429 SCJ intake manifolds for boats back in the seventies and they worked well even with the standard 460 heads.I've tried all kinds of aluminum intakes and none of them gave me better performance on the same engine.There was an article in performance boat [predecessor of hot boat]about an enduro race by a ford engined boat ,called 10-ford, and that boat's performance astonished everyone,and they couldn't beleive it wasn't a race engine.The SCJ intake is much larger than the 429/460 heads and despite the fact it's mismatched, it works well!
Hawaiian , I wouldn't go any smaller than 780, go to a vacuum secondary with jetboats or mechanical with v-drives. 780 run well with 72 primaries, 84 secondaries jets, 850 holley's run good with 84 primeries 94 secondaries.Checking plug colour will tell you the rigth combo.I would stay with the "A" impeller.
[This message has been edited by spectras only (edited March 18, 2002).]
spectras only: On your response, are you suggesting that vacuum secondaries are better for a jet, while mech carbs are better for a v-drive? I am thinking of switching to a mechanical for my jet boat to improve throttle response and I am curious as to which you think would be the better option. Thanks!
.Jetboats have instant RPM for take off ,therefore no need for extra fuel anyway.Engine vacuum would manage the secondary diaghpragm to supply more fuel at high RPM's.Prop boats have less slippage at any speed so they get loaded up rigth away thus could benefit from earlier fuel volume.This is also an issue of fuel economy for jets.My jetboat using more fuel in my 20 footer than the v-drive in my 24 at similar speeds.This is my experience only, others may have different opinion.The only real test is to try the different carbs yourself.Check your power valve in yor carb, it should be 6.5 or lower.
Ps; If I remember well, Joe Mondello's recommendation for 460 Ford was 800 CFM Holley, 45 powervalve 72 primary jet ,86 secondary and going two sizes up incrementally if it's too lean.
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