I just purchased a 1970 mailbu i assume with a 307 or maybe a 350 with a 2 bbl. I cannot find any numbers on the engine block, none in the proper locations. but that aside, from what i can find if it is a 307 in stock trim it should produce 200 hp with a 2bbl. it also has a gm hei ignition. my question is would installing a dual plane holley or eldebrock intake with a 500 cfm carb, set of headers with 3" collectors and new 2.5" duals with flowmasters yeild me at least another 50 hp. all of this being said all the upgrades would later be transplanted to a new crate engine 350. i don't want to spend the money twice.

thanks for any input.

I wont guess on a h.p increase but I would go with the parts you mentioned.I'd get a 600cfm carb and forget about the 500 though. Did you look for casting info. in Mortec.com? I'd post the link but this pc is acting like a spaz.

not as yet, i going to scrub the engine down and see what #'s i can find. it's not that bad, pretty clean actually. no leaks that i can find. just road grime. it has chrome valve covers, i am going to pull them and get casting #'s off the heads. this should reveal more also as to what i have.,

thanks, for the reply. got snow?

Mortec tells you were to find #'s also. Sorry I did'nt mention that before,was'nt sure if you already knew.I found a code on the pad behind the alternator that let me know wich block I have.

We had 1 small dusting of snow so far.

just my opinion but if its a 307 I would stay away from 2.5 " exhaust. 2 to 2.25 would probably be better for the little 307 but if you ever decide to build up the 350 or go bigger (stroker) the 2.5 should be ok.

I have a 307 in my coupe right now. according to Desk top Dyno (take it as a rough estimate) after I added a edelbrock performer intake (dual plane) crane 266/266 cam, edelbrock performer 4 bbl carb (600 cfm) and 1 5/8 full length headers and stock heads, I gained 50 Hp. I really dont think it was that much but could be close. The stock heads is the limiting factor for HP gain.

someone has done work or something to it if it has an hei. might have a mid 70's 2bbl 350,
if it is a 307 a 600 cfm is to much unless your heads are a little worked,jmo
shane

When my brother swapped out his stock quadrajet 500cfm(rebuilt) and cast iron intake on his early 80's cutlass with a 305 it helped . He put on a weiand dual plane and a vc sec. holley 600. Did'nt bog or anything , nor was it spectacular . The extra power was noticeable through the ranges , was enough to get the tires to start lighting too :D Thats before headers and true 2 1/2" duals with an h pipe. That also helped. Then he finally seen the light and got a 350.

Nothing wrong with 2-1/2" pipes even on a wheezy 307. You don't NEED any backpressure at all . . . so why would you go with small exhaust pipes? (header primary and collector tube diameter is a different story altogether)

As for the intake / carb combo, I'd get the Performer RPM and maybe a 650 vac secondary speed demon. If the engine doesn't need the extra flow the secondaries won't open. Both carb and intake will be excellent for your future 355.

chevykid,

For your information there are only two real Q-Jets made! A 750cfm and an 800cfm!!

E-brock owns the rights to them now and have since came out with their hi-po 850cfm model too..

It was neat how the 750cfm carb. fit on all the different sized motors b/c it could run great once set up for the size engines use..

pdq67

PS., and the suckers were made stock by both Rochester, hence the name, and by Carter Carb. when they went looking for extra OEM carb. supply work for GM.

Thanks, for all the reply's. I still haven't found any numbers. I've looked in all the right places, but nothing. I believe it to be a 350 because this thing will light the tires. ample punch just as is, but could use a little more. I guess i will find out soon enough. since it does not leak any fluids or smoke i am just clean up the engine change the intake and paint the block. i should find some casting numbers along the way. currently i working on detailing the undercarriage and installing a B&M floor shift for the th350. i am removing the column shift lever and using the location to mount a tach.

i have a bench seat and don't want to install buckets.

i heard somewhere that 307 came with a different size harmonic dampner? can anyone chime in here? if this is true would the dampner identify it as either a 307 or a 305/350/(327?)

Originally posted by pdq67:
chevykid,

For your information there are only two real Q-Jets made! A 750cfm and an 800cfm!!

E-brock owns the rights to them now and have since came out with their hi-po 850cfm model too..

It was neat how the 750cfm carb. fit on all the different sized motors b/c it could run great once set up for the size engines use..

pdq67

PS., and the suckers were made stock by both Rochester, hence the name, and by Carter Carb. when they went looking for extra OEM carb. supply work for GM. I had em' mixed up. It was a carter. It's still here in a heap in our shed. Thanks for the heads up. My dad has one of those older quads on his 73 b.b. I kinda got used to that name.