'302 Head Work

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Well I figured I would get the exhaust testing over with as I do not intend to really do much more than add the 5/16" guide, cut down the stock 1.625" Magnum valve to 1.600" throw a decent 3 angle valve job at and take 1 or 2 minutes with a cartridge roll to the major lumps and bumps. Back to the VGS-20 for the guide work and to "rough" in the valve job. I like to use a formed seat cutter when I am enlarging a seat (from 1.50 to 1.600") and then I finish it with the stones. Here are some pics.

I flowed them with and without a 1 5/8" pipe. Here are the numbers:

1.6" Magnum exh 4" bore @ 28" water

.1 50 50
.2 87.2 92.5
.3 116.5 121.5
.4 130.2 138
.5 137 149
.6 139.5 152

I'm glad the port really picked up with a pipe on it as I will be using headers. J.Rob
 

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Here you can see the level of effort I put into this exhaust port --ha! J.Rob
 

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I told you guys I couldn't leave well enough alone so I decided I didn't like the valve job on the intake side so I changed it a bit. Of course that meant flow testing again to document any changes.

Revised valve job------the number to the right is what it flowed backwards

.1 57.3 66.2
.2 107.5 103.5
.3 155.4
.4 193 (194 cfm was recorded @ .420")
.5 191
.6 192

As you can see the valve job revision netted a small but measureable increase. I was also pleasantly surprised that this head does not like to flow backwards at all (think reversion). Also looking at these intake flowrates vs the exhaust flowrates you can see that they jive really closely to that vaunted 75% rule. I'm starting to develop a soft spot for these suckers. J.Rob
 

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What is the chamber size on the 302? What intake are you going to use since there are very few "true" 318 port size intakes.Holley street dominator and the old edelbrock LD4B are the only ones that come to mind.
 
I will measure the chamber and port for those that want to know. As for the intake you raise a good question--I want something with the correct ports as you mention Seth and I want something with the exhaust crossover in it as well. I have used the Ld and really liked it although I may use something extra funky--I have an old Offy dual port that I may try and "fix". J.Rob
 
Ok chambers come in at 62cc's and the port comes in at 126cc's. J.Rob
 

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I have a street dominator with a damaged section where the egr port runs from the crossover to where the egr mounts behind the carb.You are welcome to test with it since you are going to dyno it. Not sure what I would get into shipping it to canada though.

62cc's is about what a magnum head is correct?
 
RAMM said:
Ok chambers come in at 62cc's and the port comes in at 126cc's. J.Rob
Click to expand...
cool.
Is this is after the work you've done?
I get 64cc, heads off of stock steel head gasket 318.
I also get 124cc for the stock valved int ports.

Cool to see what the bigger valves and accompanying valve job nets, it's another way with much porting. As for the amount of work, it's close...that is between say mild porting to a stock valve and just doing bigger valves,guides, and light porting. I wonder the cost diff.



good work
 
1wild&crazyguy said:
cool.
Is this is after the work you've done?
I get 64cc, heads off of stock steel head gasket 318.
I also get 124cc for the stock valved int ports.

Cool to see what the bigger valves and accompanying valve job nets, it's another way with much porting. As for the amount of work, it's close...that is between say mild porting to a stock valve and just doing bigger valves,guides, and light porting. I wonder the cost diff.



good work
Click to expand...

Yes this is the port that I have worked on. The Magnum valves have a generous dish in them and I figure they added maybe 1 or 2 cc's, however I have zero knowledge of the history of these heads--maybe they have been resurfaced in a past life??? If you divide cfm by the total cc of the runner you get 1.53 cfm per cc--which is quite a stout level of efficiency. There is more to it than that obviously, however it is a guage I can use when dealing with a "family" of cylinder heads. J.Rob
 
guys...this is what i'm thinking about for my next project.
you may want to check with HOTROD DAVE over on Moparts.
he built a 318 for a '68 cuda that got over 30 mpg using un ported "302's
......al
 
RAMM, I really respect your input! I would appreciate direction on my build.1968 318 and like I said before...I would love to get at least 350 H.P. I don't care about gas mileage as long as it will perform well on 91 octane! Thanks again.. Craig.
 
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