i am planning on installing better heads on my 91 tbi 305.
has a small cam. the comp cam 08-500-8
but i have some questions first.
does anyone know what are the valve specs of the origional heads on this motor?
are there any other things that i should take into concideration before installing new heads other than chip tuning?

and any suggestions on what is a good cumbustion chamber size volume to go with??

are there any junkyard motors that i should look for that might have a good salvagable set?? i would not mind finding and taking a set to get it ported and polished.

thanks in advance for sharing your knowledge.

 

Look for 14022601 heads which use 1.84/1.50" valves and have 58 cc combustion chambers (same across LG4/L69/LB9). Also look for 416 from 1982-1986, and 081 for 1987 LG4's and '87-up LB9's (VIN code "F"). Note that 87 and newer heads have different intake manifold bolts (Gen2).

Stock LO3 heads were paired with cams having 0.350/0.384 lift, while LB9 had 0.413/0.428 lift. The comp cam has 0.480/0.488 lift so the existing drive train is not in a position to handle additional lift. At minimum I would change springs and make sure that spring bind is not an issue.

//RF

 

i agree with that - it was the advice i got and i have been following it one piece at a time.
i got the hooker 2055 headers with 3 inch y pipe for exhaust.
i was told a bigger cam - but i did not radical so i found that the zz4 cams .474/.510 lift. they are about 100.00
i go back and forth on the heads.
the 601 are 53 cc and will give you a compression boost.
the 416 are ok too.
my problem is i dont want the smog people to see a modification so when you use the 601/416 heads they are no longer center bolt heads and they stand right out. if you live in cal it is important. if you do live in cal the 081 heads are the center bolt version of the 416.
also if you have a newer car you have 6 bolts on each side of your intake. the center 2 bolts are at 72 degrees. pre 87 heads are 90 degrees. easy to fix but its just one more problem you should know about.
i also went to tpi from a 91 350 - got all wires and ecm box and all so no problem with mounting. it is a map system so if you get a tpi that maf tpi from pre 87 then you will not have a problem with bolting up to pre 87 heads but you will have a problem with post 87 - that 72 vs 90 degree thing i mentioned above.
that is a start.
and use the wearch key on the red stripe at the top of the page. read everything you can find before you spend one dollar.
good luck.
good luck.

 

so will I need to change the intake or drill into the heads? I have the edelbrock tbi intake right now. And will I need to port the 601s? I have a third gen 83 z28 with the old style heads would these be good ones for my 91 rs

 

no you dont drill the heads, you drill the intake so that the bolt goes in at the correct angle. it took me a while to figure that out too.
i like the edelbrock but it is a tbi and i went to tpi. but you can get a bigger flow out of your tbi if you change to a higher flow tbi. i cant remember the number now but there was one from a truck that added some power. ok i found it - holly 670 CFM - 510-502 and the sub numbers are either 5, 6 or 7 depending on your engine.
i never tried it but i am told it is the way.
the one really good thing about tbi is that you only have to buy 2 matched injectors instead of 8.

 

so what cars came with 416s and 601s? i have an 83 z28 that is junk but has a motor. i have not checked the casting number on them yet. did that year have good ones? oh and does anyone know what size vavles and cc specs on the 91 305 tbi heads?

 

the 601's and 416's were on 305's pre 1987.
91 tbi heads are swirl port - and i think they are 58 cc's.
GM Cast # 14102187
Intake Valve 1.84”
Exhaust Valve 1.50”
Intake Runner
Exhaust Runner
Max. Valve Lift
Combustion Chamber 58cc

there is this read line at the top of the page and the word SEARCH is there. it really works - its a great search engine. it took about 15 seconds to find this for you.

 

im starting get confused. do i want more cc's or less cc's. because 58cc is similar to the other heads. would it be worth to port these? i know that the 601 and 416 have a slightly bigger intake valve. oh and if i do go with older style heads, will i need to get new rocker arms and push rods? sorry i got so many questions. i thank you alot for your help.

 

well if you use the 601's you will have 53 cc's and more compression, that is a good thing.
416 and 081 are 58 cc's and they are what you have now with a 305.
you dont want more than 58 cc's with a 305 or your compression will go down and you will have to blow into the heads with a straw to get the pistons to move. lol
actually you could get away with slightly bigger heads and then change the pistons to flat top to keep the compression up.
if you are going to a turbo or blower you might now want to have too much compression or you will blow the heads off.
read read read and you will learn.