307 head swap

[a7x]

Yes I know... better of dropping in a 350 or 403... only problem is I haven't been able to find one. Now that that's out of the way, I'll get to the question. Has anybody swapped 5a heads onto a roller motor? If so will they work with the roller cam and lifters? I don't care about emissions, and already got rid of the computer. going to change to edelbrock intake and carb, big cam and headders. also already have a good gear posi. :?: :?: :?: :?:

 

[STL84Calais]

No they will not, you will have to swap the cam and lifters to the hydraulic set up. While you have it apart, do a little head work, porting and polishing never hurt anyone, and MAYBE larger valves. You could also shave the heads a little to bump compression. Don't go with a huge cam, that little 307 won't handle it. Nothing crazy, but still a huge improvement over stock would be something like this; http://www.summitracing.com/parts/EDL-3712/ it should do nicely. (stock 307 cam was .370/.390 lift!) Not to mention any performance parts you use will swap to another SBO down the line.

 

[joe_padavano]

No they will not, you will have to swap the cam and lifters to the hydraulic set up. ...

Why? Lifters, pushrods, valves, and rocker arms are all in exactly the same place. The roller cam works fine with the 5A heads. Note that the roller lifters are 0.921" in diameter vs. 0.842 for the non-roller lifters, so you can't just swap them.

 

[442Jayp]

are 5a heads the stock heads or are they a upgrade..becaue my cutlass 307 has 5a heads and i thought they where stock

 

[442Jayp]

hopefully this helps cause it helped me

"The 5A heads were used on the '80-'84 "conventional" (non roller) 307s. The 6A and 7A heads fit the later ('85-'90) roller lifter 307s. The last year for Vin "Y" code 307s with the conventional valvetrain was '84. (The Vin "9" code continued to use the conventional valvetrain for another year or so along with the 5A heads) from that point they all went to the roller valvetrain. Just look on the driver's side of the engine on the heads by the number one spark plug for a casting either 5A, 6A or 7A, you might have to clean some junk off the heads to see if it is a dirty engine. The 5A head 307s have larger ports about the same size as the 350 and will share and interchange the same intakes as the 350 or 430, the 5A head 307s will spin to 5000 RPMs easy."

 

[High Roller]

On the "5A" head swap, install 1.875" Intake and 1.562" exhaust valves, and polish the ports and combustion chambers and shave the heads 0.030", for a true 8.7:1 compression ratio. Also change out the factory intake for the Edelbrock Performer 3711.

Then upgrade the exhaust: Direct bolt on Magnaflow Cat Converter #23427 $101, along with Hooker Cat Back system #16810HKR $376.

 

[a7x]

thanks guys i appriciate the feed back, let you know how it turns out, i am still looking for a 350-403 so if anybody near northwest ohio southeast michigan having one for sale just hit me up thanks a bunch. or i guess i have no problem with dropping a big block in there either preferably buick olds or pontiac, but will go chevy if it's cheap enough

 

[olds307 and 403]

The .030" milling is a good idea. The heads will swap right one. I believe you need your existing push rods. Rocker arms are the same. Also you will need either a performer or the factory A4 intake. Your intake has tiny ports. If you can only find a factory iron normal port intake, use it. They are good, just heavy as hell. Headers and duals should be done at the same time. With the heads off, headers should fit in easier. The Sanderson 1 5/8" Shorty headers are an easy fit. The Hedman 1 3/4" full length fit but make starter removal harder and need the oil filter adapter removed before install. Flowtech headers suck.