How can I add compression to a built engine?

GTV · Posted: Thu Nov 13, 2014 8:33 am Post subject:

If you actually do have 58cc in the chambers and only 7.2:1, you have a massive .166" deck. That needs to come down. .050" will give you the 9:1 that you're after. Going to 9:1 will make a massive difference. BTW, 44x37.5 valves are huge for what you're doing.
If swapping the cam isn't in the cards right now I wouldn't worry about it too much. It will wear out the lifter bores, but you can always have them re-bushed when you are ready to split the case. It won't turn your case to junk.

What carbs and exhaust are you using?
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[email protected] · Posted: Thu Nov 13, 2014 8:38 am Post subject:

nobody can give accurate cam recommendations until you tell us what carb(s) and exhaust you have. We are not mind readers.
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jz56oval · Posted: Thu Nov 13, 2014 8:49 am Post subject:

I have Weber redline 40's. and a Vintage speed exhaust. That deck height is huge if you are correct.

Would I need to check each cylinder for deck height or just one?

Dale M. · Posted: Thu Nov 13, 2014 8:53 am Post subject:

jz56oval · Posted: Thu Nov 13, 2014 8:59 am Post subject:

Is measuring cc easy. should I measure it even if the maker shows it on the website?

Thanks

GTV · Posted: Thu Nov 13, 2014 9:09 am Post subject:

Measure everything.

Carbs are too small, heads are too big... Pull the heads off and see if what you think you have is what you really have.
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hooker · Posted: Thu Nov 13, 2014 9:17 am Post subject:

Kfeher2000 · Posted: Thu Nov 13, 2014 10:53 am Post subject:

I had a similar situation with a 1904cc.
It was 7:1 and I took the heads off, reconfigured the barrel spacers to make it 8.7:1 (a weekend project)

Best thing I could have done
It runs stronger, cooler and gets better MPG

Gene Berg's CR recommendation of 7:1 is out dated and no longer relevant with today's fuel

jz56oval · Posted: Thu Nov 13, 2014 11:08 am Post subject:

GTV · Posted: Thu Nov 13, 2014 11:20 am Post subject:

Barrel spacers are placed under the cylinders (barrels) to get the desired deck height. You'll have to pull the motor first to see what you're was built with.
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Max Welton · Posted: Thu Nov 13, 2014 11:33 am Post subject:

Kfeher2000 · Posted: Thu Nov 13, 2014 11:33 am Post subject:

jz56oval · Posted: Thu Nov 13, 2014 11:36 am Post subject:

Thanks for all the info and help guys. Ill get to it when I have time. Would it be wise to make the heads lower cc's or leave at 58cc?

jz56oval · Posted: Thu Nov 13, 2014 11:38 am Post subject:

This will be your new best friend
http://www.cbperformance.com/v/enginecalc.html

I used a combination of barrel shims and copper head gaskets to get the desired deck height.

Pull the motor, use an engine stand...and take your time.
If you never pulled a VW engine down before, do plenty of research first but don't be afraid to tackle it.[/quote]

I have pulled my engine plenty of times. Just havent taken it apart or removed the heads. Shouldn't be hard. Just time.

Just by looking at the calculator with what I think I have, ill need a DH of 4.08 or 4.13

Now I cant wait to pull it out and check

hooker · Posted: Thu Nov 13, 2014 12:42 pm Post subject:

jz56oval · Posted: Thu Nov 13, 2014 3:35 pm Post subject:

So I'm guessing that the shims are between the block side and not head side?

Max Welton · Posted: Thu Nov 13, 2014 3:48 pm Post subject:

Barrel spacers go between the case and the cylinders. This increases deck-height by raising the cylinder, lowering the compression ratio.

MConstable · Posted: Thu Nov 13, 2014 4:05 pm Post subject:

jz56oval · Posted: Thu Nov 13, 2014 4:30 pm Post subject:

Was wondering what is a good gasket sealant? What is on there now is a red/orange color.

MacLeod Willy · Posted: Thu Nov 13, 2014 4:47 pm Post subject: cr

Just pull the engine, pull the heads and see what you have. Speculate all you want. Your gonna end up doing more than you think once your that far into it anyway


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How can I add compression to a built engine?
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