How much can a 354 Hemi be bored out?

Stock bore on a 1956 354 Chrysler Hemi is 3.94". Can it be safely bored more than 0.060" over stock? If so, how much more?

It'll be a mild street engine in a Model A Tudor hiboy sedan- dual 500 cfm carbs with vacuum secondaries, ~230 degree hydraulic cam, ~9.25:1 CR & stock heads, backed by a T-700R tranny.

 

are you sure about the 230 degree cam? my 58 392 has an Isky 280 hydraulic cam.

 

280 is "advertised" duration.

230 degrees duration @ 0.050" lift roughly translates to ~270 degrees of advertised duration, subject to the cam's ramp angle (how "steeply" it rises).

 

Took my 354 out to 4in no problem blown ant runs on 180c in trafic

 

Do you need to bore it over .030?. if not, I would'nt the power to be gained is so mimimal its not worth it. ya never know you may have to bore it again and it's nice to have a little meat left.
FED

 

If you are having a reputable machine shop doing the bore/hone,they should also be able to sonic test the block and tell you EXACTLY how far you safely bore it. 50.00 where I go for machine work.
It is cheap insurance.
FWIW,I had a late model 3.0 Mitsu V-6 block checked......
We ended up boring it .080 over and still had a LOT of "meat" left in the bores.

 

I wonder if there's enough for a standard 4" bore. 4" pistons seem to be reasonably common, and a 392 is 4".

What is the rule of thumb for min. wall thickness anyway?

-Bugman Jeff

 

Dont know the rule but the machine shop will sonic test the block to see if has enough meat to bore it to 4"

 

I bored my 354 out .060 and used a good set of used 1958 10-1 392 pistons , great if your on a budget

 

Yes you can go to 4" & use 392 pistons but make sure that the piston is not sticking too far out of the bore, so check clearance to your valves before getting too far...
cuz the pin heights might be different. I just went 40 over cuz one was already 20 over....

 

I had a '56 354 that I sold to Fab32 and it has some water damage in a couple cylinders. I will need more than a quick honing to do the job.

I bought tons of parts from Bob Walker at PowerPlay, now owner of Hot Hemi Heads. In talking to Bob about the problem he said that it's no problem to bore it out to a stock 392 bore, that's .060" over. He has done this many many times and sells his kits for the 354 with stock 392 pistons.

I'd give Bob a call and talk to him about it. I think he's probably got some of the best prices around and he's willing to help you out with information.

I tend to support vendors that support me. I know that P.A.W. has their Hemi catalog and has all this stuff but try to get the kind of answer from them that Bob can offer. My money is for the support and accurate knowledge of the genre.

Good luck with your project and hemis rule.



Oh, this little baby set me back just over $14K. It dyno'd at 654 hp and 575 torque. Fab32 was there the day we dyno'd it, he had a great time. Nobody want to get in front of me as I was quite excited and had a little wood action going on. Okay, I was really excited to see my new toy come to life and purr like a kitty on steroids.

You can build a neat hemi for a lot less than this if you do the work yourself. I did build the pan on this baby from a stock pan. The builder said that he wanted about 8 qts in the pan and this one turned out at 9 with the filter. Add the 2 quarts my MasterLube preluber added, an 11 qt oil change with Mobil 1 set me back about $70 each time. The only real on going problem I had with the motor was the rear main seal. They don't make a new style replacement and maybe I should have gone with the original rope style but I knew they would leak a bit now and then and didn't want that. I went with a 440 Mopar urethane seal. They fit the crank great but are too small in the block and main cap. You have to very carefully seal around the seal when installed. If you have to replace them afterwards, you can't seal them as well as when the crank is out and they do leak.

Anyways, good luck and give Bob Walker a call.