Hopping Up A Straight Six

What if I hold out for a 302 Jimmy? Am I going to have make some serious mods to the radiator core support and/or firewall, or are the GMC and Chevy blocks the same length? Reason I ask is because there isn't much space between the radiator and the fan blades.

 

A GMC is obout 1 1/2 inches longer than a chev. OldWolf

 

I like this idea of opening up the stock intake for more breathing. It seems to be a good way to increase performance without a lot of $$$ I like the simplicity and 'sleeper' affect of one carb hidden under a big ol' air cleaner. 'Trucked' can you explain a little more on details of this mod? Especially opening up the "heat riser area" seems that it would go into the area around the carb?

 

39cent, until Truckedup gets back to you, here is a short youtube video of another truck he built of which I am now the happy owner.

http://www.youtube.com/watch?v=ceOJ0xpcwDc

It's a GMC 302 inline six

 

So have two '53 powerglide blocks that I've had, so go by the casting number instead.

 

I guess if I'm able to get a 302 Jimmy, I can move the radiator in front of the core support and bolt it to the core support with some extra spacers to hold. This way I wouldn't have to mess with the stock location of the core support. Moreover, I wouldn't have to mess with the fender mounts which are located on the radiator core support.
Sound about right?

 

Just to chime in... I swapped out my leaky-*** Rochester 1bbl for a 2bbl Holley Weber awhile back (with the adapter mentioned earlier) and couldn't be happier. My stock 235 gets better gas mileage then it did (and the mpg was already pretty killer!) and it's a bit more "snappy" as well.

That being said, I'm building a another 235 to replace my original and I've already scored a '60s Edelbrock 2x1 and a pair of Carter YFs...

Either set-up is a great upgrade, although the 2x1 is much cooler looking!

-ns

 

how does the linkage on that work? Did you fabricate it or did you buy it?

 

39Cent,on the intake modifications;The exhaust heat riser surrounds the carburetor opening.Think of a Thermos bottle,one cylinder inside of another so to speak.So when the carb opening is modified to an oval shape to match a two barrel,you break into the heat riser area.It's a simple matter to weld up the small areas. The new opening will be slightly tapered on the sides.Just do it,you'll see what I mean.The carb I used was a Holley from an IHC 266 V-8,similar to a Holley 2300 350 CFM two barrel.Hope this helps.
And what some circle track guys used to do,block off the carb opening,flip the intake over, open up the larger bottom former heat riser area for a 2 bbl carb.This has the intake at a funny angle when bolted to the engine however.
To Haney,I've built several inlines with a 3/4 cam,increased compression and more carburation.On my engines and several other guys I know,there was no reduction in torque below about 1200 -1500 rpm.In fact from 1500 rpm on up,the modifided engine strongly out pulled the stocker.
Some guys try to put in too lumpy of a camshaft.These engine aren't rpm spinners,cams over about 206 degrees duration at .050 lift will kill low end with no power increase in the normal driving range of 4500 or so maximum rpm's.
And it's generally necessary to retain some sort of intake manifold heat for good low speed throttle response.That and a faster spark advance curve and keeping the vacuum advance.

 

Trucked' hey good info as i was thinking of something like that, but hadnt heard of anyone actually doing it. Really a good way of getting performance without h***les an expense. I have a 1939 chev 2dr w a 261 and i think i will try that, also a 39' buick Century that i am gonna experiment with, keeps my interest up !