hey all.........happy new year

Submitted: Tuesday, Jan 29, 2008 at 22:43
ThreadID: 54023 Views:1474 Replies:2 FollowUps:1
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After putting away far too much food and way too many tinnies, I guess it's time to knuckle down and get back to reality.

But while I'm still in DREAM mode, I was wondering......has anyone ever attempted a head job on a 3H petrol motor.
How much can you shave before it hurts??

I know we are all searching for that extra bit of grunt, back back when we were kids , it was common practice to give the old EH a head job to get some more power out of those old steel engines.

Can it be done on an old cruiser???
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Reply By: Member - Lionel A (WA) - Tuesday, Jan 29, 2008 at 22:49

Tuesday, Jan 29, 2008 at 22:49
Careful mate....head job one one of them....probably knock a few teeth out.....lol
AnswerID: 284416

Follow Up By: wyrss - Tuesday, Jan 29, 2008 at 23:05

Tuesday, Jan 29, 2008 at 23:05
thanks Lionel,
I'm truly touched by your concern for my dental security.

see ya mate
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FollowupID: 549179

Reply By: Member - Oldplodder (QLD) - Wednesday, Jan 30, 2008 at 09:03

Wednesday, Jan 30, 2008 at 09:03
Depends what fuel you are willing to use, as to what compression ratio it will take.
Having some older cars (pre 1980), that run a variety of compression rations, we use ULP (91 octane) , PULP (95 octane) and 98 octane.

From memory, the old EH use to just about run on standard , so a head shave to lift compression to 10:1 , and using super (98 octane) gave a performance increase.

What are you using now?

If you go gas and not use petrol, it is 105 octane :o)

Basically, up to about 8 or 8.5:1 for ULP, and up to 10.5 to 1 for 98 octane. Depends what your pocket can afford, and what you can get. 98 octane may not be easy to source out west.

When I modify the head on any car, I check what the standard compression ratio is, and then check the capacity of the combustion chamber, and work it out from there. Balance the combustion chambers while you are at it, and give the ports a clean up, and match the inlet and exhaust manifolds to the head.
AnswerID: 284463

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