Question about heads
02-03-2003, 07:00 PM
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Question about heads
I am looking for a cheap head replacement for my LO3 engine. I want it to be as cheap as possible while actually gaining some performance. Any brands to look for? Will some junkyard vortec heads work well? I am switching over to carb if that will help any.
02-03-2003, 07:20 PM
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Car: 1989 IROC-Z
Engine: 5.7L EFI LTR setup
Transmission: T-5 World Class
Watch which Vortecs you get out of a junk yard ..... there are two different kinds ( different casteing #'s) the one is a good one and the other is useless.
do a search you might find this ..........I forgot where I got the info ....but I will post a link if I can remember it
good luck vortecs are the best bang for the buck I am told
do a search you might find this ..........I forgot where I got the info ....but I will post a link if I can remember it
good luck vortecs are the best bang for the buck I am told
02-03-2003, 07:31 PM
#4
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The cheapest performance head swap for a 350 TBI is to get a set of HO or TPI 305 heads rebuilt and upgraded with
performance springs and new larger 1.94 valves along with some
porting. Find a serviceable set, get a die grinder, port them up
yourself and take them into a automotive machine shop for
a rebuild and upgrade. ( springs, pinned studs, bigger valves,
3 angle valve job, New guide linners if nessessary.) You can also have them shaved a bit to raise compression a bit. Do not exeed 10:1 for street gas.
The 305 head castings to look for are 416 or 450 for the older pre 86 style HO heads and 081 for the 87+ 305TPI heads.
Both these heads have 58cc chambers. When you sweep out the chambers to fit the larger valves you'll be at 60/61cc's.
Just have them shaved a bit to return to 58cc.
These heads come alive with the porting and larger valves.
Once this is done your motor will be wanting a little bigger cam
to go with the improved head flow.
How big to go will depend on the rest of your planned mods.
A better exhaust system will help a lot.
You can expect some 30+ horsepower gain.
performance springs and new larger 1.94 valves along with some
porting. Find a serviceable set, get a die grinder, port them up
yourself and take them into a automotive machine shop for
a rebuild and upgrade. ( springs, pinned studs, bigger valves,
3 angle valve job, New guide linners if nessessary.) You can also have them shaved a bit to raise compression a bit. Do not exeed 10:1 for street gas.
The 305 head castings to look for are 416 or 450 for the older pre 86 style HO heads and 081 for the 87+ 305TPI heads.
Both these heads have 58cc chambers. When you sweep out the chambers to fit the larger valves you'll be at 60/61cc's.
Just have them shaved a bit to return to 58cc.
These heads come alive with the porting and larger valves.
Once this is done your motor will be wanting a little bigger cam
to go with the improved head flow.
How big to go will depend on the rest of your planned mods.
A better exhaust system will help a lot.
You can expect some 30+ horsepower gain.
02-03-2003, 11:39 PM
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Car: 1986 Sport Coupé
Engine: 305-4v
Transmission: 700R4 and TransGo2
Originally posted by zerotosixtyV8
could I just use my stock 305 heads and rebuild/port them?
could I just use my stock 305 heads and rebuild/port them?
The LO3 305 uses "swirl-port" head castings and they are too much trouble to straighten out. Do as F-Bird'88 says--he's about the smartest head porter on the site. Follow my instructions linked at the end of my sig.
Good luck
And if you need any help, contact either me or F-Bird'88
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