Drone358

Hey guys gotta 355 carb motor and have 10:6:1 Compression and wantin to install D-1 Procharger Now my question is they gotta make a lil spacer or shim that sits on the deck of the block under the head right? Its gotta be the simplest way to go jus get longer bolts if needed. Jus wantin ur opinion and advice! Thanks!

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Drone358

And i know they make thicker Headgaskets too but wasn't sure how much a difference it would be

Orr89RocZ

The last thing you want to do is get a thicker head gasket or spacer. That will destroy your quench and increase detonation.

Best bet is to swap pistons or get a head with a much larger CC chamber. Going from a 64cc or so up to a 75-76 cc will bring you down in the mid 9's to 1 which is better with a blower motor. Just make sure your ring gaps arent too tight like a n/a motor usually is and it should be ok. Make sure the tune is dead nuts and you will be much better off as well

__________________

1989 Twin Turbo IROC-Z
"Twin Turbo 401 Buildup Pics "
"FQuick Garage"
9.86 at 141 mph 14psi, street tune

bart91406

I am pretty sure they do not make a spacer like that, but you would be suprised how much difference a thick head gasket makes. I have even seen an article where they stacked head gaskets!

One of the many problems you will have with getting rid of compression this way is your intake seal, raising the heads will alter the angles and could pose problems.

Also the wedge type combustion chamber that is used on sbc is designed to use the tight distance between the piston and the closed side of the head to get complete combustion. Whenever you increase this clearance you are actually making the engine more prone to detonation, even with less compression.

Long story short, buy new pistons or larger chamber heads. Any other way that you go about reducing compression will be half***, and probably not even get you close to the 9 to 1 or less you should be shooting for.

Sonix

Better question - what parts do you have now?

Pistons (part number, size, etc)
heads (chamber size, port size)
deck height
camshaft (part number. not "race cam" or some stupid BS like that)

1983sc

Just to try and help you out,

Right now i run 10 lbs on my 383 with 10.7-1 CR
ported vortec heads
292 Comp cams "NX express" 274/292, Lift .487/.501 on a 113 LSA
850 Demon blowthrough with alot mods
RPM airgap intake
Summit BTM digital ign.
MSD Probillet Dis.
Baster 2
ect ect just to give you the basics

I run water-meth and pull a lot of timing under boost. I know i am leaving alot on the table but i dont have the cash to pull it back down for new pistons. IT CAN BE DONE! But like stated you have to be spot on with the tune. A wideband is a MUST! watch your AFR really close. at WOT i dont like to see my AFR over 11.5-1. read plugs and make sure you have a good fuel system. everyone told me that it could not be done, and so far its worked great. its all in fuel and timing. i am really conservitive on timing, ran about 34* and pulled between 2-4* for every pound of boost. Just make sure your on top of it and you will be fine.