350 heads on a 307?

[RIA69]

I have a 307 that needs heads on it and I have some off of a '71 350 the casting is 3932441 these are the stats for them

76 CC Chambers
Intake flow 152 CFM
Exhaust flow 93.2 CFM

and valves

1.94/1.50

I will be running a 280h comp cam with a weiand intake and a eddy 4bbl 600 cfm carb. my question is will I run into any issues with compression or anything? I know 307s are the "red headed step child and all but I like it.
I will also be running flow tech headers with cherry bomb glass packs straight off the headers.

thanks in advance.

[71 super]

Cam is going to be lumpy and you are not going to be very happy with that combo. If you are running a manual you will be a little better off, but if heads are stock (no port /polish) and an automatic with a 3.07 gear it is going to be a dog. That cam is going to want to run around 2800 or more to begin to make power and your motor in stock form will run out around 4000, never reaching the potential of the cam. You need to match your parts better to get the most out of the setup you are going to run.

[BADPURPLE70CHEVY]

Originally Posted by 71 super

Cam is going to be lumpy and you are not going to be very happy with that combo. If you are running a manual you will be a little better off, but if heads are stock (no port /polish) and an automatic with a 3.07 gear it is going to be a dog. That cam is going to want to run around 2800 or more to begin to make power and your motor in stock form will run out around 4000, never reaching the potential of the cam. You need to match your parts better to get the most out of the setup you are going to run.

Thats what i was thinking.

[RIA69]

ya I can understand that but at this time this is all I have at my disposal. Im in the middle of a divorce and this truck is supposed to be my daily so I have to try to get it running before the future ex takes the good running car. the tranny is a 4 speed manual, still not to sure of what it is though. I know its a granny geared one. I have a 350 that I took the cam and heads off of, but its so nasty inside it will take me months to clean it up, I just dont have to much time this set up im thinking will only be temparary. once taxes hit then Im going to rebuild the 350 and port and polish the heads and do a mild build up but for now this is what Im stuck with. I think the rear end is 4.10's or something its a torq monster. thanks for the input though its helped. would it even be worth messing with? I dont want to run this combo if its going to destroy the parts.

[71 super]

It will not destroy parts, but you mileage will not be the greatest. Sorry to hear about the divorce. I hope that everything works out. If you could find a set of 305 heads and a 265 or 270 cam the truck would like it better. The 305 heads have a smaller combustion chamber and increase the compression quite a bit, and since you have the 280 cam, this will help to bleed off some pressure so it will run on pump gas. The increase in compression will wake up the 307 some. If you have a 4.10 gear you will get away with a little bigger than the normal cam simply due to mechanical advantage created by the gear and trans combo. If it is a 3.73 you will lose some advantage. Summit did have a cam line that had a really good selection that would better match the parts you already have on the cheap. I ran one in a 327 I had a couple of years back and it would flat out roast the tires with a 3.73 gear. Seems like the lift was .465 and .470 dual pattern for less than $80, this was with a performer rpm, hei, headers and 600 holley- nothing special just parts that matched up. Good luck with your project and have fun with it.

[jim zag]

Low compression and a big camshaft. You will not be happy. A better choice would be a set of 305 4 Barrel heads and a cam that is less than 220 degrees @ .050 duration. This will give you more pumping compression and way better driveability.

[special-K]

You just need from a stock to RV-type cam.The heads aren't an issue at all.

[raycow]

It's not the best combination because of the low CR. Please reconsider about the cam unless it is already installed in the engine. The good news is that the manual transmission will somewhat make up for the lack of low-end grunt, so it won't be as bad as it would have been with an automatic.

Ray

[WIDESIDE72]

I think you would be happier with a store brand cam, Speed Pro, or one of the bare bones cams. Too much cam and not enough cubic inches or compression. I know from experience about overcamming an engine. A 280 is too much even for a DD 350 with 10:1+ comp. Go stock if you have to. It will actually run better and give better mileage.

[RIA69]

thats what I would like to do and plan on doing once I have some money to use on it. I have been looking for a set of 305 heads for my 350 I am building up to replace the 307and I am thinking of just going with a 260 cam or something for it. the previous cam that I had in the 307 which i still have is the reason the motor got tore down in the first place has 4 flat lobes which I didnt know until I drove it 1200 mile from utah to kansas. not a fun drive by the way. thanks again guys.

[RUSHNBOBO]

Originally Posted by RIA69

thats what I would like to do and plan on doing once I have some money to use on it. I have been looking for a set of 305 heads for my 350 I am building up to replace the 307and I am thinking of just going with a 260 cam or something for it. the previous cam that I had in the 307 which i still have is the reason the motor got tore down in the first place has 4 flat lobes which I didnt know until I drove it 1200 mile from utah to kansas. not a fun drive by the way. thanks again guys.

When u build a motor all the parts need to match and compliment each other in your desired rpm range ......
The variables are endless ..tens of thousands of combos just for a street SBC.
That being said here's my fav drivable street 350 combo...that i run in my daully......also low buck and makes (around 350-375 H.P.)

A. flatop pistons (I run forged speed pro but cast will work up to 5500 rpm) and 64cc heads camelback ...gives around 9.7:1 to 10:1 compression

B. Cam: Comp XE268...nice lope very driveable and largest cam that will work with a stock converter ...although i run a slightly higher stall in mine.
(more than 1 magazine test calls this the best all around street cam on the market...power to 5800 rpm!!!)

C. 1 5/8 long tube headers ...1 3/4 gives slightly better top end numbers but low end torque is lower

D. Performer rpm manifold ....i prefer the older style without the air gap due to the cut down plenum divider....which affects snappy off idle response due to a poorer signal at low rpm (velocity)....off idle they show nearly identical numbers to 6500 rpm. The benefits of the air gap though do come into play only on fully warmed up engine after heat soak sets in .....how much? probably not enough to justify the much higher price tag. IMO

E. DO NOT USE A CARB LARGER THAN 650 CFM on a street 350 ...every dyno chart ive seen there's no high rpm power gain and often a loss at low rpm.
A mild 350 simply cannot use any more carb


Remember this when build any street motor .......................................

"A little to small always beats a little to big" (except cubic inches of course)

My girlfriend though thinks just the opposite.....ummmmmmm

[ffk]

hey i have a set of heads off a 68 307 motor...there still on the complete motor...just sitting here..love to sell complete or ill sell the heads

[w3lfd]

You are basically spelling out exactly what the PO of my truck did and it runs like a big fat turd, even with a manual transmission.

I am "upgrading" to #416 305 HO heads (got them for 95 bucks shipped) just to get away from this set up.

305 Heads are CHEAPCHEAPCHEAP. If money is an object I would seriously go this route rather than the 350 head.

The 350 / 400 heads actually bring compression way down on the 307. My fuel consumption is through the roof (this may or may not be directly related to feeling the need to floor this POS to make it move). You would probably be better off saving the gas money up by limping on the motor you have and then buying decent upgrade parts.

Seriously. Think 8 MPG. Just think about it.

['72customdeluxe]

305 heads aren't recommended for performance usually these days, but a vortec would have your compression pretty low aswell. You could get some 601 (305 ho) or atleast 416 (305 4-barrel) heads remanufactured off of ebay cheap. Here are some -601's that have been rebuilt and they claim 52cc chambers
http://cgi.ebay.com/ebaymotors/SB-SB...Q5fAccessories Not only will the 305 ho heads keep you from dropping to unacceptably low compression levels, but the chambers are better looking and ports should be better. I would run something like a 204/214 (summit-rebox, lunati, everyone makes them) for a cam