trying to plan my winter build. I"m running about 10-12 psi.

I found a set of 350 tpi heads for $40 so i bought them. I got one disassembled tonight and sand blasted.

How do you think the 350 heads with bigger valves and chambers will react on the stock 305 bottom end? I believe the 305 was 9.3/1 with a 58cc. the 350 heads are around 65cc and the intake valves are 1.94 compared to the stock 1.84(?).

My plan is to get the heads cleaned, new springs/seals/keepers and lap the valves. When i pull the heads off i'll make sure the cylinder walls look good and there aren't any chunks of piston missing then put her together with the 350 heads. I hope to have this done in then next 3 weeks before the snow falls. If it works well i'll run it next year with a bigger cam (Peanut cam .311).

Just wondering what you guys think.

thanks

 

I'm running a 1.94" intake valve as well. Can you flip the head over, place the head gasket you'll be using onto it, take a picture and post it up...?

 

I am going to do something like this with the L05 heads just to see what happens. The chamber will actually be bigger than the gasket surface based on what I saw.

 

I'll bring the head into work next week and size it up to the gaskets and post pics.

 

Cool from my understanding you should use 350 HGs with this swap. Someone was saying if you have 76cc heads you can fit 2.02/1.6 valves. Don't know how that will work out for sure but would love to see someone try it.

 

In most cases the chamber ends up bigger than the bore, but the valves clear... what you absolutely don't want is unsupported head gasket exposed to the chamber. 2 possibilities with the head gaskets:
- the best way: get one cut with the 305 bore diameter and notches where the valves are (I've had some custom cut by cometic, have drawings of them somewhere)
- use 350 head gaskets (with a 4.0x" diameter), they will increase the dead crevice volume between the block/head making the combination slightly less efficient and "dirtier" but for the setups that you guys are talking about (especially with the fairly low performance stock type heads) you'll never know the difference (and it will be the difference between a $30 and $200 set of head gaskets)

 

I agree 100%. I'm planning on using the 350 gaskets and see how they run. I'm worried the dead crevis will increase load on the headgasket, a giant flame front with nowhere to go.

IF it works i'll get some good cometics. I'm going cheap for now to see how it works and will decide if i want to run the setup next year.

 

I got one head cleaned and painted tonight and valves polished.

Im getting valve seals but what do u guys think about valve spring for this preliminary run? Ill definetly do them this winter.

 

AAAAHHHHH! ok this is why i am not a JY Builder!

went inspecting the valves and found crack in exhaust valve seat. goes from slightly inside runner across valve seat and into combustion chamber face a little. Fixable or NO? time to get the big heads from dad and put those on.

76 cc chamber and large runners 2.02 valves. need a much bigger turbo to see any boost but at 8:1 i could run alot of boost!

any thoughts?

 

unless you're talking aluminum or aftermarket heads junk em or craigslist em accurately described as-is. Not many production iron heads worth fixing you may as well go dig another set up.