Rebuild thoughts

[Deleted User]

i pulled the 308 down today (first chance to really get into it in the many months since it arrived) to find the pistons any thing from .004 to about .015" under and the bores around .005 over on average.plus they are mighty ridged around the top where the pistons stop. i managed to get a .016" feeler gauge in between number one. clearly in need of work. the valve seat faces only need a glance to see they are shot. this engine was "rebuilt" before i got it. the rod bearings were new which sort of backs that claim up. anyhow, since i have to get this thing done i might as well go oversize, I am thinking .060 over pistons and 7x valves with 30deg faces. being a 55 block it has factory reliefs. any advice on a better combination would be appreciated. i'd like to drop in a higher lift cam as well but the old budget wont go that far. the head has been shaved as well since it was warped so the compression will be higher already. for now i will be running a WGD 2 barrel and standard manifold.

i know ive been a bit all over the place with ideas lately but this is the #1 priority because without the engine in place there's not much more i can do. thanks all- stuart

[Deleted User]

Can you post a picture of the top of the block so we can see the factory relief on the 55 block? thanks

Unknown

why do you want to jump to .060 overbore? makes it where one has fewer chances to rebore in the future and makes walls thinner thus more chance of heating problems . least from the machinist position one should overbore to the size that removes the wear .

mike

[Deleted User]

mike, heat is why im holding out on going out to .090"

from a speed fan's position why spend the money on going out .010" when for little more i can go a lot bigger.... i know if i hurt it it gives little grace but thats the line you toe, you know.

i've had my eye on both what randy maas and dale cooper offer, there is also a company in adelaide called jp that can do batches of pistons, i have asked for a price on their pistons, hoping by keeping it in oz i can save on some air freight. we'll see.

[Deleted User]

got a quote from JP today, i have to send them a piston to see if they can make them, and they want $140AU per piston, making around $1000 for a set freighted. seems i will be going with ready made pistons then!

but the machine shop up the street from work can make a set of valves for $250 AU which is better than buying ready made and paying to freight them here. 7X spec valves, valve seats machined and bores done for roughly $600AU. thats some good going in my book.

looks like i will be placing an order with dale cooper for some pistons, valve guides and a few assorted extras. too bad i have to save my money to move house this month. aaaargh

[Deleted User]

these 36 chev pistons got a touch of titanium in em! or something like that. im not so hard up for parts that i have to go make my own pistons! i can make some stuff but that i will leave for mr munro

i had a chat with the friendly machinist down the street this afternoon and we discussed the plan. i will be waiting until i have everything here, pistons rings guides and whatever else before he gets it. then he can make his valves match the new guides and the like

hudsonguy

half baked wrote:

these 36 chev pistons got a touch of titanium in em! or something like that. im not so hard up for parts that i have to go make my own pistons! i can make some stuff but that i will leave for mr munro

i had a chat with the friendly machinist down the street this afternoon and we discussed the plan. i will be waiting until i have everything here, pistons rings guides and whatever else before he gets it. then he can make his valves match the new guides and the like

FWIW, when I rebuilt a Hudson engine last year, I first took it to the machinist, who then hot tanked and magnafluxed everything first to determine that they were good, rebuildable parts in the first place. Then he told ME what size bore, etc. based on what Mike says above. That is that it's determined by the amount of wear. At that point I bought pistons, etc. (from Dale Cooper), and once the machinist had pistons, valves, etc. in hand, then he proceeded with the machine work.

Geoff

Hudson308 wrote:

Just remember that you don't want to bore the block until you have the pistons in hand. You can't properly finish hone the holes until you have the exact measurement of the piston O.D. Same goes for the valve guides... the final I.D. of the guides will depend on the exact valve stem diameter. Say... wasn't there a kiwi fella who cast his own pistons down there? Seems to me I've seen him in a movie... a few chunks of Ford... a couple pieces of Chevy... something like that.

Think about that quote - '36 Chev had cast iron pistons!

[Deleted User]

while i'm at it i may as well match the ports and manifolds and clean them up.

hudson guy i'd left out the cleaning and measuring step..... that will happen before i go ordering parts.

51 hornet here is a picture of the '55 valve relief as requested. yeh theres a lot of rust around i blew the water jackets out. a bit of brake cleaner and disassembly took care of that

barrysweet52

I heard of a Jag man in Adelaide that wanted a set of original Jag pistons, instead of the local JP pistons. After a long wait and paying a lot more for tax, freight & insurance, they arrived from England. They had JP stamped on the pistons. JP told me they source pistons & rings from around the world including from India.

[Deleted User]

Thanks for the photo. Good to see a 55 block wanted to know what the factory relief looked like.

[Deleted User]

about 3/16" at the bottom of the slope. after the larger valves are done this will

have to be machined deeper like a 7x. here is a photo i "borrowed" from randy maas' msn 7x tips for a comparison

bob ward

Half baked, I have a set of 60thou pistons in Brisbane that I'm not going to use.



coldesig@gil.com.au

Fred

I think the previous referenced flik is " The fasted Indian in the world". Great movie!

Fred