The 355 I have built Problem? - NJFBOA - Home of New Jersey's Camaros and Firebirds

r0nin89 · 09-25-2006, 02:06 PM

The 355 I have in my basement is an est 300hp with a hot cam (no specific numbers), edelbrock intake, holley carb, paper weight heads, and stock internals. It was built by Bill Shian (spelling?) in Manasquan. Since the block was a full resto just and everything was in such bad shape he had to bore one cyl over 10 while the rest remained 30. So I now have 7 cylinders 30 over and one at 40. He told me everything is balanced around what he did and it should run find and continued to tell me that at the monitor competition drags they used to bore cylinders 100 over and leave the one the judges measured at 30 over and everything was find.

The question is will this pose any problem with the engine?
Would it pose any problem running the engine hard?
Would it be safer to have everything else bored to 40 over? Worth it?
Any other info would be good.

PS: I dont think I ever posted this on here but if its a repeat I couldnt find the old one with search sorry in advance

V · 09-25-2006, 02:23 PM

first off, i would never run and engine with mismatched bores, but thats just me maybe. It seems your machinist isnt the best place to be going to, thats why hes so cheap. 350 blocks are cheap, i sold a few shortblocks and longblocks for 150-250 bucks and the one could have been honed and ran with std. bore still. I always try to avoid increasing bore just incase i want to rebuild it again down the line. if you run a 40 over engine and it needs a rebuild, next is 60 over and thats getting iffy for higher hp levels IMO.

r0nin89 · 09-25-2006, 06:54 PM

Thats the thing I this is going to be this blocks last build. You say you would never run like that but does that mean you cant? And as far as the machinist goes from what i've heard hes the most credited one around my area.

WildBillyT · 09-25-2006, 07:36 PM

What exactly did he do? The .040 over piston will be heavier than the others.

automotivebreath · 09-25-2006, 07:45 PM

Quote:

Originally Posted by r0nin89

.... So I now have 7 cylinders 30 over and one at 40. He told me everything is balanced around what he did and it should run find ...

Personally, I wouldn’t think twice about running it hard. The 0.010” difference is next to nothing.

r0nin89 · 09-25-2006, 08:13 PM

Basically I have a 355 but one piston is .040 over while the rest are .030

BonzoHansen · 09-25-2006, 08:26 PM

Quote:

Originally Posted by WildBillyT

What exactly did he do? The .040 over piston will be heavier than the others.

That was the first thing I thought. Sounds half-assed. But I am no engine expert.

Screw it, if it is built & ready to go, put it in!

johnjzjz · 09-25-2006, 08:29 PM

After being in the car bizz for as many years as i have and all that i have seen people do it is not as un common as u might think -- if he at least he lightened the .040 over piston as a low performance 350 hp and down u will never have known if he didn't tell u or u seen it --- all u can do is put it in treat it correctly on start up and see what happens -- if it makes u nuts sleave the one cylinder -- but thats another problem hahahahah -- i hope it runs ok u wont know unless u try it or sell it -- jz

r0nin89 · 09-25-2006, 08:44 PM

Well he said everything was balanced and functional perfectly around that piston.

automotivebreath · 09-26-2006, 05:27 PM

Quote:

Originally Posted by johnjzjz

... as a low performance 350 hp and down u will never have known if he didn't tell u or u seen it --- all u can do is put it in treat it correctly on start up and see what happens -- jz

Like he johnjzjz said, if he didn't tell you - you would never know, you won't see the difference in performance. Low HP and low RPM is very forgiving, put it in and forget you even know about it.

r0nin89 · 09-26-2006, 06:26 PM

Ah ok sweet... You say 350hp will that mean I may have a problem should I put different heads on to bring it to 400hp?

IROCdan330 · 09-26-2006, 08:01 PM

i dont think you will have a problem.

many engines are like that...different classes for racing have different rules, and an instructor told me at school (for example purposes) that one tool they have for checking something in some class can only check the number 2 piston, and thats it..so the race team will make that piston to spec while the rest of the engine is breaking the rules.

i believe tim told me that in SCCA its the same thing...on the side of the engine in some vehicles with all of the accessories, they will run all kinds of crazy stuff...but on the other side without accessories it will be totally stock...because the judges will check the easier to get to side.

pretty much as long as the engine is designed for something like that, you should be fine.

r0nin89 · 09-26-2006, 08:03 PM

Alright good deal because thats exactly what my machinist told me.