Head work... need help from the pros!!!!
Post Fiend
Joined: Dec 2007
Posts: 8,521
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From: Lost
One big difference between a carb and EFI head, is the number of bolt holes for the manifolds. The EFI head has a few more, to ease the install of the 3 manifolds seperately. Carbed versions were designed to install the intake and exhuast manifolds as a mated pair.
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Postmaster
Joined: Mar 2008
Posts: 2,703
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From: Des Moines, Iowa
but I am guessing since I am bolting the EFI manifolds to the older 86 head I am guessing this isn't a problem I need to worry about.
I was more wondering about the CR differences and maybe smog equipment. My 88 doesn't have cats so no air hook up to be done. I'll probably end up taking the whole air injection system off some time.
I was more wondering about the CR differences and maybe smog equipment. My 88 doesn't have cats so no air hook up to be done. I'll probably end up taking the whole air injection system off some time.
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Postmaster
Joined: Mar 2008
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From: Des Moines, Iowa
what the heck...LOL... I just saw this has run on for 5 pages now I haven't even gotten to my head work pics and P&P job.
The 86 head is at the shop and I hope to have it home this week for the P&P work. Sorry for the delay guys. Also sorry for getting of track with this post several times.
More to come soon!
Another question for those that do head work... Is there a good cheap valve spring tool out there? I was looking at the Lisle 16750?
http://www.google.com/products/catal...=0CIABEPMCMAI#
It looked like I'd be able to operate it quicker to disassemble and assemble heads quicker than with the lisle 2300 or the KD 2078. All the screwing in and out seems like it would take forever to do!?!?!?
The 86 head is at the shop and I hope to have it home this week for the P&P work. Sorry for the delay guys. Also sorry for getting of track with this post several times.
More to come soon!
Another question for those that do head work... Is there a good cheap valve spring tool out there? I was looking at the Lisle 16750?
http://www.google.com/products/catal...=0CIABEPMCMAI#
It looked like I'd be able to operate it quicker to disassemble and assemble heads quicker than with the lisle 2300 or the KD 2078. All the screwing in and out seems like it would take forever to do!?!?!?
Senior User
Joined: Nov 2005
Posts: 457
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From: Lathrop, MO
Nathan there is another big difference between the carb and efi heads you need to consider, combustion chamber volume. Stock the carb head should be 76cc while the efi is 65.9cc. There are also differences in the chamber shape, intake valve shrouding. etc that effect burn characteristics.
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Back near the beginning of your thread (and there's nothing at all wrong with a long thread) you asked about increasing compression and the possibility of pinging on the cheap gas most of use would rather use. Later you referred to upgradiing the intake and exhaust systems. Well, the one affects the other. If you get better cylinder filling for a given throttle setting and therefore more dynamic compression (with the more efficient intake and exhaust) then you have to be more conservative about increasing static compression.
Beyond a resurfacing clean-up cut on the head, the best way to raise compression is to start by decking the block until you get to a safe minimum squish height, say .038-.042". This will boost compression a bit, but the main gain is that proper squish makes an engine much more tolerant of increased compression and/or low octane, or a tank of bad gas, or the timing being a little too advanced, etc.. Google squish or quench (Brit.) and Speedomotive for a good explanation. Aside from the fact that you can't make this happen without a complete engine teardown, everything about optimizing squish is a positive.
Beyond a resurfacing clean-up cut on the head, the best way to raise compression is to start by decking the block until you get to a safe minimum squish height, say .038-.042". This will boost compression a bit, but the main gain is that proper squish makes an engine much more tolerant of increased compression and/or low octane, or a tank of bad gas, or the timing being a little too advanced, etc.. Google squish or quench (Brit.) and Speedomotive for a good explanation. Aside from the fact that you can't make this happen without a complete engine teardown, everything about optimizing squish is a positive.
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