fett
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Ive put some on my 4.4 which has the same 88mm bore as a 3.5 so I have a few questions and also wonder if it helped performance much?
whos put p3810 bolt heads on a 3.5 before
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wangie46
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10 bolt heads have a smaller cc than the 14 bolt so if using composite gasket compression ratio should be the same if using tin you will up the compression but don't think it will increase performance that much, think the valves are the same but don't quote me on that also 10 bolt heads have better valve stem seals on inlet and outlet
fett
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i thought the valves were bigger?
what about hitting pistons?
what about hitting pistons?
marccleave
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From here...
As far as I am aware I think the valve sizes only changed in 1976. The size of the ports was increased with the HRC 2479 heads.
Yes you can put the HRC 2479 heads on. I have never heard of the valves hitting the pistons from fitting HRC 2479 heads. Only from putting in a wild camshaft and no cut outs in the piston! Uh oh! There are even people online who have HRC 2479 heads fitted to 3.5s.
As wangie46 said, the cc of the HRC 2479 heads are smaller, 36cc -> 28cc so you will up the compression ratio a tiny bit if you use tin gaskets, but it probably be only slightly noticeable. Whats the cc of the dishes of your pistons? You can work out what the compression ratio will be with 36cc and 28cc heads.
As far as I am aware I think the valve sizes only changed in 1976. The size of the ports was increased with the HRC 2479 heads.
Yes you can put the HRC 2479 heads on. I have never heard of the valves hitting the pistons from fitting HRC 2479 heads. Only from putting in a wild camshaft and no cut outs in the piston! Uh oh! There are even people online who have HRC 2479 heads fitted to 3.5s.
As wangie46 said, the cc of the HRC 2479 heads are smaller, 36cc -> 28cc so you will up the compression ratio a tiny bit if you use tin gaskets, but it probably be only slightly noticeable. Whats the cc of the dishes of your pistons? You can work out what the compression ratio will be with 36cc and 28cc heads.
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fett
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in my case the issue may be fitting it to my 4.4 motor rather than a 3.5, particuarly as the heads been skimmed and I already had 9:1 + compression with comp gaskets and its a performance cam.
I dummy built it using the old comp gaskets torqued to 60ftlbs and turned it over with plastercene in, sadly none of the plastercene stayed on the valves but on the edges of rim of the piston crown i had abut 1.6 mm.
correct me if i am wrong but if it all turns over by hand will it be ok at speed?
I dummy built it using the old comp gaskets torqued to 60ftlbs and turned it over with plastercene in, sadly none of the plastercene stayed on the valves but on the edges of rim of the piston crown i had abut 1.6 mm.
correct me if i am wrong but if it all turns over by hand will it be ok at speed?
marccleave
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Whats the CR of a standard 4.4 fett?
You can get Rover V8s out of P6s with 10.5:1 CR... So you shouldn't have a problem with your setup. How much did the heads get skimmed? So with your skim and comp gaskets, I guess it would be like having a non-skimmed head and tin gaskets, so you'll get an extra 0.6/7 as zen said. So you might end up close to 10:1? You'll just get a bit more poke that's all!
Are you weary of preignition? I wouldn't have thought it will be that much of a problem until you go past 10.5:1. But then again not an expert so don't quote me on it!
(PS more pictures? Your build thread is looking a bit bare recently.)
You can get Rover V8s out of P6s with 10.5:1 CR... So you shouldn't have a problem with your setup. How much did the heads get skimmed? So with your skim and comp gaskets, I guess it would be like having a non-skimmed head and tin gaskets, so you'll get an extra 0.6/7 as zen said. So you might end up close to 10:1? You'll just get a bit more poke that's all!
Are you weary of preignition? I wouldn't have thought it will be that much of a problem until you go past 10.5:1. But then again not an expert so don't quote me on it!
(PS more pictures? Your build thread is looking a bit bare recently.)
fett
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no pics as im nearly half way thru an 8 week recovery from surgery on my arm so not allowed to do owt.
well the block i had would only be 8:1 as stock, bt it already had lr 3.5 8.13:1 pistons in which in this engine is supposed to give 9.5:1 with comp gaskets and the aussie heads, with p38 skimmed heads im lost lol
james martin shud know how much they were skimmed by as he kindly supplies them
well the block i had would only be 8:1 as stock, bt it already had lr 3.5 8.13:1 pistons in which in this engine is supposed to give 9.5:1 with comp gaskets and the aussie heads, with p38 skimmed heads im lost lol
james martin shud know how much they were skimmed by as he kindly supplies them
marccleave
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Ah right, cancel the request and take it easy then!
Just looking up the 4.4 and wow, interesting... Square engine with 3.5" bore & stroke, block height extended and longer conrods.
You picked one hell of an engine to rebuild.
A nice one! I'm jealous!
If you knew some more numbers, you could use this: Engine Compression Ratio (CR) Calculator
Bore: 3.5"
Stroke: 3.5"
Compressed Head Gasket Thickness: 40 thou "
You just need to know, Head Gasket Bore Diameter, Piston Dish(-ve Dome!) Volume, Piston Deck Clearance & the new Combustion Chamber Volume for your motor.
Just looking up the 4.4 and wow, interesting... Square engine with 3.5" bore & stroke, block height extended and longer conrods.
You picked one hell of an engine to rebuild.
A nice one! I'm jealous!
If you knew some more numbers, you could use this: Engine Compression Ratio (CR) Calculator
Bore: 3.5"
Stroke: 3.5"
Compressed Head Gasket Thickness: 40 thou "
You just need to know, Head Gasket Bore Diameter, Piston Dish(-ve Dome!) Volume, Piston Deck Clearance & the new Combustion Chamber Volume for your motor.
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marccleave
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For the P38 10 bolt heads fett wants to put on, they're 28cc. But hes told us they've been skimmed, so they'll be slightly less depending how much was taken off the heads.
fett
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marc, its just got 3.5 comp gakets,Piston Dome/dish volume is low comp one on a 3.5 ie 8.13:1 , Piston Deck Clearance erm no idea-may have written it down? maybe & the new Combustion Chamber Volume for your motor. its 10 bolt head skimmed by james
zen, no idea, same as urs prob lol
zen, no idea, same as urs prob lol
fett
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dunno, not usin em,sold 1 set lol
discomark10
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keep looking into doing this, whats the plan atm fett?
fett
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p38 heads are on
lets see if blows up
lets see if blows up
marccleave
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It won't blow up... but it would be nice to know the exact CR.
fett
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well its a long stroke 4.4 aussie motor with landy pistons and 4.6 skimmed heads so it might!
fett
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if the block survies I will re builder her
u can buy it all for 3k now if u like
u can buy it all for 3k now if u like
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