7.3 cylinder heads.......????

[Nrliftedranger]

well taking my heads to the local machine shop Saturday to get them decked and checked out, seats and valves cut

what valve springs is everyone running?? where are you getting them from

any mods for them besides a minor port (gasket match)??

Thanks guys

Nick

 

[icanfixall]

Make sure the shop does not resurface the heads. For whatever reasons these heads have a min thickness measured from the deck to the top of the valve cover gasket machined surface. The min is 4.795 to 4.805. The intake valves MUST be recessed into the heads 0.042 to 0.054 deep and the exhaust valves MUST be recessed into the heads 0.051 to 0.063. Now the precups can be recessed by -0.0025 or +0.0025. Thats above or below the heads by 2 1/2 thousands. They are made from inconel material so they are very hard to machine. It takes a special cutter to clean them up with the heads being a softer cast iron. Some shops remove them because they can't afford the expensive fly cutters. Be careful when you talk stuff with the shop know it alls. Make them prove what they are going to do. Many shops will cut the heads because it looks good and they get paid to do it wether it needs to be done or not. They are in it to make money anyway they can off you.. The customer. You have rights. Many members are running the 910 valve springs. BTW we run the same spring for the intake and exhaust. The both have the same open or closed pressure. Make sure the exhaust valve seals are pressed up under the valve spring keeper. Not done on the valve guide like the intake is. Head surface flattenss is 0.003 in any 6 inches overall.. Never allow any shop to knurl the valve guides. Thats a temp fix and all it does is crushes the cast iron into the valve area. It mostly just chips off but some does swell in that area. Then they ream it to fit. It wears out quickly too.

 

[idipwr]

Great info Gary. What machine shop are you using Nick?

 

[Nrliftedranger]

Terry hawk ant hawk engine and machine in north Royalton. He's been there for 40 years really a great guy. Not the cheapest by any means but great work

 

[freebird01]

i will be parting out two complete motors if you need any internal parts.

 

[OLDBULL8]

This head machineing info Gary submitted, should be put in a sticky.
Just in case your machine shop doesn't have this info for the 7.3 IDI.

Intake valve seat angle. 30 degrees.
Exhaust valve seat angle. 37.5 degrees.

Intake valve seat width. 0.065 to 0.095
Exhaust valve seat width. 0.065 to 0.095

Minimum valve margine width, 94 and earlier,except DIT.
Intake. 0.112
Exhaust. 0.053

 

[gingrass179]

Make sure the shop does not resurface the heads. For whatever reasons these heads have a min thickness measured from the deck to the top of the valve cover gasket machined surface. The min is 4.795 to 4.805. The intake valves MUST be recessed into the heads 0.042 to 0.054 deep and the exhaust valves MUST be recessed into the heads 0.051 to 0.063. Now the precups can be recessed by -0.0025 or +0.0025. Thats above or below the heads by 2 1/2 thousands. They are made from inconel material so they are very hard to machine. It takes a special cutter to clean them up with the heads being a softer cast iron. Some shops remove them because they can't afford the expensive fly cutters. Be careful when you talk stuff with the shop know it alls. Make them prove what they are going to do. Many shops will cut the heads because it looks good and they get paid to do it wether it needs to be done or not. They are in it to make money anyway they can off you.. The customer. You have rights. Many members are running the 910 valve springs. BTW we run the same spring for the intake and exhaust. The both have the same open or closed pressure. Make sure the exhaust valve seals are pressed up under the valve spring keeper. Not done on the valve guide like the intake is. Head surface flattenss is 0.003 in any 6 inches overall.. Never allow any shop to knurl the valve guides. Thats a temp fix and all it does is crushes the cast iron into the valve area. It mostly just chips off but some does swell in that area. Then they ream it to fit. It wears out quickly too.

this is awesome info gary...ive heard about different valve guides for these engines too...do you know which ones have had the least problems...and sorry but im doing a partial hijack but the block im getting the pistons have been cut .080 would I be safe to deck the block some to bump my compression some...thanks again

 

[jaluhn83]

0.080"????!!!! Are you sure on that number? That's about 0.060" more than anyone I've heard and enough that I'd be seriously worried about the top ring groove strength, thermal issues, piston crown thickness, etc.

I'd say you *can* deck the block, but I wouldn't unless absolutely necessary, and only the minimum needed. You'd need to do both sides equally and shave the intake a small amount too. The key factor is going to be piston height above the deck.

 

[freebird01]

i have a 6.9L that had the pistons shaved .060 appx.. now it has 2 burnt pistons due to other reasons but the crowns look good after 7-10k... i plan on shaving the pistons im putting back in but not near that much. ill probably only go .040" to help with cold starting.

 

[jaluhn83]

Well maybe, but I'd be worried about the top ring land. The more you cut off the less metal there is holding it on, and the closer that top ring get to the combustion gasses - ie heat.

 

[jaluhn83]

This head machineing info Gary submitted, should be put in a sticky.
Just in case your machine shop doesn't have this info for the 7.3 IDI.

Intake valve seat angle. 30 degrees.
Exhaust valve seat angle. 37.5 degrees.

Intake valve seat width. 0.065 to 0.095
Exhaust valve seat width. 0.065 to 0.095

Minimum valve margine width, 94 and earlier,except DIT.
Intake. 0.112
Exhaust. 0.053

Personally I'd say if the shop doesn't already have the specs then they probably shouldn't be working on your motor cause they've obviously never done one before.

 

[gingrass179]

0.080"????!!!! Are you sure on that number? That's about 0.060" more than anyone I've heard and enough that I'd be seriously worried about the top ring groove strength, thermal issues, piston crown thickness, etc.

I'd say you *can* deck the block, but I wouldn't unless absolutely necessary, and only the minimum needed. You'd need to do both sides equally and shave the intake a small amount too. The key factor is going to be piston height above the deck.

positive...r and d currently milled his .050 and my pistons are ceramic coated to help

 

[riotwarrior]

Decking block and heads can mean NEW pushrods among other thngs....

the shorter you make the deck the pushrods are affected and press down on valves sooner than they should. I'd really be researching a lot before doing any machine work on yer deck. These type of changes can have major effects on the entire build; sometimes good ones...sometimes catastrophic....building without knowing is like well..jumping in the lake to go swimming without knowing how to swim and wearing cement shoes!


JM2CW

Al

 

[gingrass179]

Decking block and heads can mean NEW pushrods among other thngs....

the shorter you make the deck the pushrods are affected and press down on valves sooner than they should. I'd really be researching a lot before doing any machine work on yer deck. These type of changes can have major effects on the entire build; sometimes good ones...sometimes catastrophic....building without knowing is like well..jumping in the lake to go swimming without knowing how to swim and wearing cement shoes!


JM2CW

Al

yes i totally understand...but decking the block gets done...right???...so do we even offer different pushrods? Im trying to gather all my info first...lol trying....the pistons are cut .080 and they are ceramic coated so that should help with heat dispurtion...im trying to mend what has already been done by pistons being cut .080 and if i can deck the block even some it will benefit me greatly...this is definitely where different ratio rockers would help....

 

[Nrliftedranger]

where are you getting the valve springs from.. I will also be adding a banks sidewinder if that makes and difference in reccomendations

Nick
thanks