350 engines to avoid for a rebuild

jeff swisher

Veteran Member
Apr 26, 2018
1,957
Yukon Oklahoma
305 heads??? Waste of time

Yea I think that book spoke of 305 heads and stated he did not like them.

I have many choices of cylinder heads I have people trying to sell me old double humps some times but I turn them down.
I have ran dozens of 305 heads and none of them disappointed me.
Very thick chamber walls in the 601 305 HO head and you can shape it to almost anything you want.
Stupid amount of power to be had in a chamber.

I take every book for what it is. An opinion of the person writing it.
There are good things I get from books and sometimes some stuff I do not align with.

That is why there are multiple books and multiple opinions out there.
Educate yourself and get some hands on tweaking and see what works for you.
 

jeff swisher

Veteran Member
Apr 26, 2018
1,957
Yukon Oklahoma
For the 601 heads I have used they are 53cc with 1.84-1.50 and finished ported they are 57cc
while still using the 1.84-1.50 valve and easy 12's in the 1/4.
I have ran the smaller 1.72-1.50 valves in the 1978 year 305 heads and went 12.51 at 111
in a full weight 78 Nova with a 357" engine.
Ported of course.
Do not toss stones at a small valve until you have ran them in ported form.

Yes a larger valve would have made more power but for a great daily driver there is nothing wrong with them.

If I run larger 1.94 valve in the 601 head the chamber needs kicked out more or you will be down on RPM and that chamber ends up at 61.5-62cc.
This is without any milling of the head.
Not much more cfm of air flow with the 1.94 valve vs the 1.84 at least not enough for me to stick a 1.94 in my own personal head and I have free 1.94 valves and can cut the bowls and chambers myself.

The 1.84 gets it done for me just fine with a 350" engine.. the 1.72 will be down on RPM by about 500.
The 1.84 valve will pull hard to 7200 and the 1.72 tags out about 6700 for me.
280H cam [email protected] .050
The 1.94 valve if you do not get the chamber right will be done before 7000 rpm.
with a [email protected] .050 cam and get the chamber kicked out correctly and it will not fall off until past 7500 rpm in a 350"

These are loose built SBC engines .003" or more piston to wall clearance with a cast piston.
Set them up tight like .0015" with an old school long skirt big ring piston and you will be down a lot of RPM.
 

f-body freak

Veteran Member
Nov 22, 2014
547
northern ohio
For the 601 heads I have used they are 53cc with 1.84-1.50 and finished ported they are 57cc
while still using the 1.84-1.50 valve and easy 12's in the 1/4.
I have ran the smaller 1.72-1.50 valves in the 1978 year 305 heads and went 12.51 at 111
in a full weight 78 Nova with a 357" engine.
Ported of course.
Do not toss stones at a small valve until you have ran them in ported form.

Yes a larger valve would have made more power but for a great daily driver there is nothing wrong with them.

If I run larger 1.94 valve in the 601 head the chamber needs kicked out more or you will be down on RPM and that chamber ends up at 61.5-62cc.
This is without any milling of the head.
Not much more cfm of air flow with the 1.94 valve vs the 1.84 at least not enough for me to stick a 1.94 in my own personal head and I have free 1.94 valves and can cut the bowls and chambers myself.

The 1.84 gets it done for me just fine with a 350" engine.. the 1.72 will be down on RPM by about 500.
The 1.84 valve will pull hard to 7200 and the 1.72 tags out about 6700 for me.
280H cam [email protected] .050
The 1.94 valve if you do not get the chamber right will be done before 7000 rpm.
with a [email protected] .050 cam and get the chamber kicked out correctly and it will not fall off until past 7500 rpm in a 350"

These are loose built SBC engines .003" or more piston to wall clearance with a cast piston.
Set them up tight like .0015" with an old school long skirt big ring piston and you will be down a lot of RPM.
Thanks Jeff!!! Always appreciate reading your knowledge & experience on this topic
 

G72Zed

Veteran Member
Sep 8, 2015
4,060
Canada
Do not toss stones at a small valve until you have ran them in ported form.

Yes a larger valve would have made more power but for a great daily driver there is nothing wrong with them.

X 10^^^^ Totally agree with Mr. Swisher on that statement.

The EQ "305" Iron Vortec heads that are not even ported or cleaned up make the power they should, all through a 1.84 valve.

Look at the thread i put on here called -

Project "383 MisFit" Getting the "right" results from the "wrong" parts​

Those stock replacement Iron Vortec's flowed a max of 230 cfm , and supported 473hp on a 383....mmm, 2.057 hp per observed cfm ? that number rings a bell for some reason.
 




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