Hey ya'll new to the site, got a few questions. First off, how big of a difference would porting and polishing my head, plus over size valves make over stock, performance and gas mileage wise? What about shaving the head as well?

Ok and subject two, just replaced the factory junk carb with a weber 38, its awesome, it really woke my truck up, but when first accelerating it cuts out like a miss, but the rest of the rpm range it is just fine, any ideas on the cause?

 

These are just my own thoughts on the subject and will probably differ from others, porting and polishing will probably not gain much of anything on a stock engine, if done by someone who knows what their doing maybe a couple HP on a dyno, if just getting the dremel out and grinding away maybe more harm than good, and fuel mileage may suffer.
Oversize valves, if there just the cheapies that several outlets sell as a drop in with minimal work, whats the gain, the seat and port is still the same size, it just moves the contact area out on the valve face, like putting a bigger lid on the same size hole, true oversize valves that they cut out the seats, replace with bigger ones is better but more money, but if done along with porting, polishing on an engine that has more carb, compression, exhaust, its worth HP.
Shaving the head??? it'll gain a tiny bit of compression, but at the same time retards the cam timing,, so its hard to say, if a person had a dyno and time they could play with advancing and retarding the cam to see what gains could be had.
The 38 on a stock engine, the hesitation could be either lean or over rich, my guess would be on the rich side in the idle circuit until, the engine gets up to RPM and can digest the excess fuel

 

The reason i was considering getting a shop to do some head work is because i'm about to drop in a mild cam, a aftermarket intake,and add some headers. But my old carb finally gave up and kept on flooding so i went ahead and got the weber carb first, instead of all together, because i still drive the truck regularly. I probably sound like an idiot, just tryin to do a mild top end makeover, lookin for some tips and suggestions.

 

I never gave any thought to anyone sounding like an idiot, thats how we learn is by asking Theres a lot of potential in head work but I just feel that for a daily driven street engine the money could be well spent somewhere else, gasket matching the ports, cleaning up the casting flash in the ports, polishing the exhaust ports will slow down carbon buildup, but getting a mirror finish will be short lived, and on the intake side does more harm than good, the roughness of the intake ports helps to break up the fuel to better atomize it for better combustion.
If I were building a strictly race engine then big valves, porting, polishing, ect. would be worth the time to get all I could, but on a street engine the big valves, porting, ect. really helps more on the top end to make them breathe and takes away from off idle throttle response.
Your engine mods you have planned will definately wake the engine up, what intake do you plan on using? Personally I,m not a big fan of the 38, don't get me wrong their a good carb, but not so user friendly as a daily as their pretty aggressive and fuel hungry with the geared throttle plates opening both holes at the same time, but each to their own on carb selection.
Good luck on your build.

 

Thanks! Yeah, i'm starting to think i should have went with the 36/36 or 34 but i'll make do, it had to have a carb. But i think after getting a few more upgrades done it'll work out better tho. I'm considering the Offenhauser intake, i've heard a few great things about them, any suggestions on the intake? And yeah, i think i'll just settle with gasket matching the ports, I'm not really interested in a all out race engine, just a little better perfomance. So far I've deleted the a/c and power steering for a little less drag on the engine, its helped with power, and the gas mileage went up a tad too. Since what all i've done so far it already performs like a different truck.

 

i have read a few places that a stock ported intake is as good as the aftermarket ones. i found a very noticable gain by gasket matching, porting and other mods to a stock intake for my 20r. i also have a good ignition, a header, a new head that had 1mm oversize valves, plus a 32/36. i cut out the bar on the carb mount area, and did alot to the intake.

id say get an extra used at the junkyard, and port it with a kit with a die grinder or a drill. you can get the kits at harbor frieght. and like nook said, dont get it too smooth. i think i finished with 80 grit on the intake.

here are some photos as i did it.

 

That would be a good way to save some cash and put elsewhere, like in my ignition, because lord knows it's due a upgrade. there's a pull a part close to here, and there are plenty stock intakes lying around i can pick one up for around 15-30 bucks. I'm glad you suggested that, i'm used to working with small block v8's so i'm used to just replacing the stock intake with a aftermarket.

 

yeah for downdraft carbs, thats about the best you can do. i dont see the design of the offy intakes being much different than this, so not worth my money. i also saw minor gains by taking the choke butterflys out of the carb. i ended up cutting the whole choke horn off but i wouldnt suggest that unless you have a second upper weber body. lol. start with an intake. you can always switch it back.

i did use a carbide tip to help get the bulk cut for gasket matching. and taking the flash and ribs down. but did the rest with the paper sanders. its by no means perfect or totally even from port to port, but i got them pretty close by my standards. and its worked well. plugs read pretty consistant from cyl to cyl.

 

Yeah, i think i'll leave the butterflies on it for now ha, its a bit cold natured. Well looks like i'm gonna be picking up a old intake and get to work on it within the next week. Thanks for the info, i would have never thought about it

 

no problem. i tell people to do it because of the great gains ive seen. not many listen. lol.

 

lol alot of ppl are stubborn, maybe i can polish up the factory one on the outside and make it more attractive, and remove all un needed vacumn lines while i'm at it.

 

use a few pipe plugs for the vacuum trees. and have fun polishing it. i thought about it, but all the nooks and crannies would suck big. decided my new intake im making will get ground flatish and sandblasted back to a matte finish. lol.

 

i'm known to be creative, so i'll figure somethin out, i'll post pictures whenever i do go though with it tho.

 

ok, i did a tune up and most of the hesitation is gone, i figure after modding the intake itll go totally away.