will longer rods give me comp?

[96SEN8R]

As the title says, Will slightly longer rods give me more compression. As i made the mistake of putting a larger cam on a low comp engine, im now chancing higher comp. My Senator has to go in for a rear main seal and i was thinking, If my mechanic was going to replace my bearings, will there be a rise in comp if i get a rod a few thou longer? If not then ill just have to spend the extra cash to get the heads taken off while it is on the engine stand and get about 60thou shaved off.

 

[ScoHar]

can you even get a rod slightly bigger? All the rods I have are about 0.300" longer or shorter, then you'll more than likely need new pistons, then well may aswell have full rebuild, its not as easy as rods just a little bit longer.

 

[96SEN8R]

Im fairly saw that the factory holden rod is 5.625" and i was just thinking about replacing them with a set of 5.7" chev rods. Im not 100% that the rods will fit to the piston the same. The only reason that im no going for the full rebuild is my crank will have to be taken out to do the rear main anyway but to replace pisons etc ill have to take everything off. or do you think i should spend the extra cash while it is on the stand to have the full rebuild. That sounds like a fair few extra dollars

 

[383 hatch]

So, let me get this straight....You are pulling the crank out to do the rear main seal, but obviously arent pulling the heads off? Hate to tell you, even if you could (which you wont be able to, a chev rod as you mentioned is 75 thou longer which will have the piston sitting out of the top of the block) get a rod the right size you still have to pull the heads to get the rods out as the piston pin is pressed into the rod. Then, you will have to have the rotating assembly balanced anyway. Mate, just put a set of flat top pistons in it, there is no real cheap way to raise comp, unless you shave a heap off the heads, which isnt really the right way of doing it....

 

[greenfoam]

60 thou of the heads is what you want to do and you want a packet of these

HOLDEN 253 308 304 5.0L CRANE CAMS ROCKER ARM ADJ SHIMS - eBay Engine Parts, Engines, Components, Car Parts, Accessories, Cars, Bikes, Boats. (end time 17-Feb-09 16:32:32 AEDST)

I know it says they are 20 and 40 but on cranes website it says they are 30 and 60 which I believe is the truth either way they will work with 60 and 80/90 off. You will probably have to get the manifold cut too, so it still fits right. 60 thou off is somewhere around 9.5-9.7:1

 

[96SEN8R]

Thanks heaps for the feed back. I was kinda doing backflips thinking about it. I have 8.8 comp standard, If i shave 60thou and do get to 9.7ish, do you think this will be enough comp for a 355 with a crane 286?

 

[sir355]

9 - 9.5 is fine for a 286.

 

[383 hatch]

Edit: Just read your other thread and realised its a factory 350 stroker.....