300 vs. 340 heads.

[BACKROAD]

Howdy from warm Arizona and my first post.....

Is there any difference in valve sizes or ports between the 300 and 340 heads? I'm running a nice little (original and not rebuilt & about 50,000 original miles) 300 V8 4bbl in my Willys DJ3A and am looking to upgrade a little. I have a set of headers that I built and running a 650 Holley with adapter. Stock cam currently. Turbo 350 auto with 300 stall convertor. I'm probably going to change cams to one of Crowers with a lopey idle. With the factory 11-1 compression, it should respond nicely to the larger cam change. I'm looking for a better head flow, but not willing to give T/A $3000 for a set of their heads.

[bob k. mando]

there's very little option for these engines. the 300 ( 1964-67 ) and 340 ( only produced in 1966-67 so rare as hen's teeth anyways ) used the same head castings so you have no joy there.

the 215 / Rover v8 engines are all smaller than your 300 ( referred to as a 4.9L in metric, although it's a very large 4.9 ). you might be able to make a model year ~2000 4.6L Rover head work and see some benefit.

on the other hand, i'm not sure that's what you want in a Jeep anyways. a high flowing HP head is for some form of racing, usually in an engine that spends a lot of time north of 5000rpm.

whereas, jeeping and rock crawling tends to be a low rpm endeavor in which intake velocity ( because it creates low rpm torque ) is far, FAR more important than peak HP numbers. narrow intake runners are ... good for low rpm airflow.

so, *i* would look at getting a crank out of a 1968-81 Buick 350 ( or 340, same thing, the Bu350 short block is just a bored out 340 ) and use the Hot Rod mag article to build a short deck, light weight 340 using your 300 block.

http://www.hotrod.com/how-to/engine/...od-any-engine/

doing some basic bowl and valve work is never a bad idea so if you really want to do something with your head, look at Burek's head porting article that i posted.

http://www.teambuick.com/forums/cont...orting-article



note that you CANNOT use a Bu350 head. the 1966-2004 Rover / 1961-1967 Buick heads use a EI, EI, IE, IE valve order while the Bu 350 uses a Chevy style IE, IE, EI, EI valve order. 'Rover style' engines use stepped diameter cam bearings while the 350 cam bearings are all the same size. as well, the pushrod ports in the 350 block are in the wrong place for the 'Rover style' cam lobes. so trying to convert a 350 head is probably just a huge pain in the ***.

assuming you've got the extra room above the heads for the Bu350 taller deck, the cheapest option would be to just put a 1970 'SP' code 350 in place of the 300 ... which should be a drop in swap.

[BACKROAD]

My previous even fire V6's with aftermarket cam would pull to 6000 rpm without too much trouble and they were only 9.5-1 engines. I'm going to run a midrange to upper end cam. With my low axle gears and custom low range gears, i'll have plenty of crawling ability. I guess I'm limited to a mild porting on the heads and intake and upgrading the valves to a tulip performance type with a 3 angle cut. Theres not any room for larger valves. I'm just not capable anymore of spending big bucks on motoe work or changes. If I had the money I'd be running a Ford 351C, as I have a number of the and lots of parts. I'll be a happy camper if I can get in the neighborhood of 300hp, which should be feasable.

If my 300 4bbl didn't have 11-1 compression, I'd think about turbocharging. Thanks for the help.

[BACKROAD]

The 300 is painted Ford blue and with the distributor up front, I'm truly enjoy telling people is a 5.0 Now to decide if I want to find an HEI Distributor out of a 350 or just do an electronic conversion to the existing Delco....

[BACKROAD]

bOB.... I can only imagine how hard it would be to locate an 1970 SP code 350. Do you have one available?

[BACKROAD]

I do have a 350 HP 350 Chevy sitting at the house that just needs a bit of freshening. I really do dislike the Chevy arrogance though and I was actually saving it for a 2wd Willy's ratrod project.

[bob k. mando]

bOB.... I can only imagine how hard it would be to locate an 1970 SP code 350. Do you have one available?


yes, i do have one. no, i'm not selling it.


but that's okay. if you have a little bit of patience, you should have no trouble finding one. Buicks are scarce BUT they are also very low demand.

keep an eye on the Classifieds / for sale ads
here on TeamBuick
v8buick
aaca
craigslist
racingjunk
eBay

and i would be VERY surprised if you didn't find one in less than six months for ~$500-700 . might even be able to get a whole car for ~1000. then you swipe the engine and, worse case, crush out the car.



I'll be a happy camper if I can get in the neighborhood of 300hp, which should be feasable.

the 'SP' code 350 engine was factory rated ( Gross HP numbers in 1970 ) for 315hp.

[bob k. mando]

I do have a 350 HP 350 Chevy


compare weights. the 350 SBC weighs in the high 500s, a 350 SBB weighs ~450. the 300 is lighter yet.


in fact, if weight is a big issue for you, you probably just ought to get a Rover 4.6L, those are all aluminum.