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Discussion Starter · #1 ·
<COLOR color="darkblue">Hey all,

Looking for some info on the 3400 ... like the title says...

Can anyone tell me the clearances on the 3400 between the pistons and the valves. I'm thinking thinner headgaskets but I'd like to keep the valves away from the pistons :wink:

I've seen 2 different thicknesses given for the stock headgasket thickness (.043 and .060). I'd like to know which one is accurate for the 3400. I should be able to run 10:1 CR with 91 octane and those beautiful heartshapes, yes :D .

If some one knows the 3400 deck height or cylinder head volume I would appreciate it as I've been guessing to get rough CR estimates.

I'm thinking of going N/A first and adding a SC at a later time what's the max boost I can reliably run on the stock 3400 bottom end w/ an 8.35:1 CR. (This will determine if I rebuild or upgrade the bottom end.)

The 3400 crank is exactly the same as the 3.1 so I can use a JBP crank and 3.1 main bearings, right? How about the ARP rod, main, and head bolt sets?

I'm guessing the reground 3400 cam raises the torque curve in the RPM band. If that's right how far up are we talking about.

Thanks for any advise/info.

~neophile_17

PS I have done several searches for this information, but it's either not there, I missed it, or it left some doubt in my mind. Thanks again.
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hmm I'll answer as much as I know. Stock compressed height of the head gaskets for the aluminum head 2.8, 3.1, 3400 and 3100 are 0.060". the measured deck height of my pistons (stock 3100) were 0.022" above the deck. I am pretty sure the 3400's are the same. assuming they are, the 9.6:1 compression would be pretty much 10:1 with the IRon head gasket (compressed thickness of 0.040") cylinder head volume has always been the same, 28-29 cm^3 (depends on who you ask ;) ) the ARp head studs should work, but the 3400 has "4 bolt" mains which the 3.1/2.8 don't. rules using the 3.1 ones out. I know people peaking at 10 psi on stock bottom end. Doesn't mean it's the greatest idea though :D

hope that helps.
 

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you cannot use anything thinner than the stock COMPRESSED thick Gasket....060 or maybe if you find it a compressed thickness .050 gasket.

the reason is due to the Pistons being above the deck by .020 you only now have with stock gasket .040 clearance between the head and the piston.

slip in a .040 gasket :nono: and youve got piston "kissing" the head problems. not good.

cyl head volume IIRC is 28cc's. is the same between the 3100/3400/3.1L/2.8L

the newer 3400's have a larger 1.76 intake valve.

stock 3400 compression is 9.6:1, so with a good resurface of the head you can achieve your 10:1 ratio you desire.

arp rod bolts work.
the arp head bolts dont work that are listed for the 2.8L they are too short.
you will need a custom set pieced together. as daily said.
give arp the specs for your main's and they can get you bolts for that as well.
 

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Discussion Starter · #4 ·
<COLOR color="darkblue">hey 'gain,

Many thanks for those replies. Something is puzzling me about your info though v6h.o. How is taking material off the head (resurfacing) and using a big headgasket different than leaving the head and using a thinner copper gasket. Let me know.

~neophile_17
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Hey Colin,

The ARP head bolts are to short due to the block? or size of the head? I installed them on mine, and I noticed that I didn't screw them into the block, as far as they could go. Still over an inch in the block though.

Now you got me worried.

feavs
www.feavs.com
 

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feavs said:
The ARP head bolts are to short due to the block? or size of the head? I installed them on mine, and I noticed that I didn't screw them into the block, as far as they could go. Still over an inch in the block though
Eric, if you ordered a set of 2.8L IRON head, head studs. your SOL.... the only KIT that ARP sells for the 660 is the 2.8L kit, but its for the IRON heads. the iron heads use different lenth head bolts. the longest Iron head bolt is actually the same lenth as teh shortest Aluminum head bolt.
you'll need a custom Head Bolt kit from ARP. IF you have a Iron head kit... well sounds like youve already installed them... i guess you'll have to eat half the cost of the bolts that dont work and just order up from ARP a set of studs that are the specs for the other bolts that are different lenth.

i ran into this as well... i totally forgot about the different lenths.. Mr. Walker gave me the bad news this summer when i said something about ARP bolts... he said well if you ordered the stock kit its not going to work. sure enough he was right. measured them out... sent them back.
im going to order up a custom kit sometime soon.
 

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Something is puzzling me about your info though v6h.o. How is taking material off the head (resurfacing) and using a big headgasket different than leaving the head and using a thinner copper gasket. Let me know.
like daily driver said...

when you install a thinner head gasket smaller then you are decreasing the distance between the head and the Piston. the head sits closer to the block and piston.
with this way you not only increase the distance between the valve and the piston, but you also increase the distance between teh piston and the head.

now taking material off the head only, you decrease the cyl head combustion chamber(alters the chamber size)
this results in the head staying the same distance away from the piston. but..
yes the valve will be closer to the piston.

i dont think you have to worry about piston to head clearance. i run the thin .040 thick head gaskets (stock 3.1L pistons in the block .00725)
shaved heads
and .469 inch valve lift. ive still got quite a bit of clearance.
i know a guy that runs .496 intake and .510 exhaust lift on a 3100 engine.
 
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