1970 chevelle 307 base - change course? - Chevelle Tech
Engine General Engine Discussion.

 11Likes
Reply
 
LinkBack Thread Tools Search this Thread Display Modes
post #1 of 21 (permalink) Old Feb 12th, 20, 2:20 PM Thread Starter
Tech Team
 
Join Date: Nov 2019
Posts: 197
1970 chevelle 307 base - change course?

Okay Guys

Here is the deal. I have bought MOST my rebuild parts for my 350 4bolt main that I got on marketplace from Jegs and Summit. I can return many of these parts and only have a few left over that I would have to resell.

Here is how I feel. I went out to my 70 chevelle the other day, it is a 4 door, but man I love it. Anways, I looked under the hood and the space is MASSIVE lol. Am I am considering a big block, 454 to go into it. Now, I have never rebuilt an engine before, hence the appeal of the 350.

My question is this - should I continue on with my 350 build and forget the 454 dream - or should I backtrack? What are the big pros and cons here? Here is how my 350 will be built:

Summit full tube Headers 2466HKR
I have a good 4 bolt main block
350 CHEVY CYLINDER HEADS #041 casting NEW GUIDES .500 SPRINGS
new stainless 2.02 swirl polished intake valves
new stainless 1.60 swirl polished exhaust valves
Heads are assembled with new .500 Z-28 lift valve springs
Xtreme Energy 256H Hydraulic Flat Tappet Camshaft Complete Kit Lift: .447"/.454" Duration: 256/268 RPM Range: 1000-5200
Rebuild/overhaul master kit with moly rings
Edelbrock Single-Quad Performer Manifold and Carburetor Kit for Small Block Chevy 1955-1986 - Performer EPS Intake Manifold, 600cfm Performer Series Carburetor

The heads would probably be hard to sell for what I got in them, but everything else can go back...with the exception of the manifold. I don't want to keep dumping money in it, but I want to be happy with the power. I have a posi rebuild kit for the stock rear, I know its not a big boy rearend but it should hold up with the new Yukon parts.

I would have to source a 454, get the parts, and all that. I am not sure if the gains would be worth the extra expense. Plus I am new to all of this. What do you all think?
s1nemesis1s is offline  
Sponsored Links
Advertisement
 
post #2 of 21 (permalink) Old Feb 12th, 20, 2:27 PM
Senior Tech Team
Bart
 
Join Date: Mar 2014
Location: Illinois
Posts: 1,107
Garage
Re: 1970 chevelle 307 base - change course?

I would stay with the course you are on. I have a 454 in my chevelle and a 283 in my C10. the 454 has the cool factor but the 283 has the reliable more fuel efficient factor. Nothing wrong with a good reliable small block.
Kirk's67SS and LeoP like this.

There's nothing wrong with being stupid as long as you know you're stupid, it's when you're stupid and don't know it that you become dangerous.
Bart_Swisher is offline  
post #3 of 21 (permalink) Old Feb 12th, 20, 4:13 PM
Team Member
Bill
 
Join Date: Jan 2018
Location: Boston Area
Posts: 1,174
Garage
Re: 1970 chevelle 307 base - change course?

I agree if you like to drive gas mileage will certainly be better with a 350. I built, ran and raced many 350 LT1 engines and got beat by some big blocks and I also beat big blocks. One of my worst engines was a 70 454 390 vette engine. Factory machining was horrible. With that said one of my favorite engines was my 70 Buick GS Stage 1 455. The cam you have is very mild and would stay the course but go with a hotter cam. Something with a duration in the 220'[email protected] single or dual pattern. Just keep the lift below .500
Billdini is offline  
 
post #4 of 21 (permalink) Old Feb 12th, 20, 4:16 PM Thread Starter
Tech Team
 
Join Date: Nov 2019
Posts: 197
Re: 1970 chevelle 307 base - change course?

Quote:
Originally Posted by Billdini View Post
I agree if you like to drive gas mileage will certainly be better with a 350. I built, ran and raced many 350 LT1 engines and got beat by some big blocks and I also beat big blocks. One of my worst engines was a 70 454 390 vette engine. Factory machining was horrible. With that said one of my favorite engines was my 70 Buick GS Stage 1 455. The cam you have is very mild and would stay the course but go with a hotter came. Something with a duration in the 220'[email protected] single or dual pattern. Just keep the lift below .500
Okay - I am a dumb dumb. I posted the old specs! Jeez, I changed cams - how does this one sound: COMP Cams Xtreme Energy Cam and Lifter Kits K12-238-2 Duration at 050 inch Lift:218 int./224 exh.
https://www.summitracing.com/parts/cca-k12-238-2

I am still trying to understand Cams. I am reading about them as much as I can.
s1nemesis1s is offline  
post #5 of 21 (permalink) Old Feb 12th, 20, 4:35 PM
Team Member
Bill
 
Join Date: Jan 2018
Location: Boston Area
Posts: 1,174
Garage
Re: 1970 chevelle 307 base - change course?

Quote:
Originally Posted by s1nemesis1s View Post
Any suggestions on the cam? I want to try and squeeze as much power out as possible, but would hate to lose all vacuum.
For hydraulic I had good luck with a Lunati 290 duration cam. Based on the 327/350 hp L79 Cam which I love but a little hotter. Are you going auto or stick. If auto are you going to run an auto how about the torque converter? Parts need to work together, Heads are great, which pistons and CC did you go with, I like a 650DP Holley personally with an Airgap intake but you can make due with a 600cfm. SBC's must breath so don't restrict the intake or the exhaust. I am forced to stay with cast iron intake and exhaust and it kills me not to run the 650DP, nice intake with 1 5/8 ceramic headers and a mandrel bent 2.5 exhaust. Stay with a flow through muffler to avoid the dreadful drone. And a H pipe is nice too to help low end a bit. 3400-3600 pound cars with a 350 like 3.42 or 3.55 if highway rpm's is not a concern, I have a 3.31 with a low 2.20 first gear M21 with my L79 and its a bit sluggish until 15 MPH.. and ignition, well tuned HO distributor, no points. I run about 17 inches of vacuum @ 750 rpm with my Elgin L79 retro cam /223/[email protected] 50 .447/.447 lift
s1nemesis1s likes this.
Billdini is offline  
post #6 of 21 (permalink) Old Feb 12th, 20, 4:41 PM Thread Starter
Tech Team
 
Join Date: Nov 2019
Posts: 197
Re: 1970 chevelle 307 base - change course?

Quote:
Originally Posted by Billdini View Post
For hydraulic I had good luck with a Lunati 290 duration cam. Based on the 327/350 hp L79 Cam which I love but a little hotter. Are you going auto or stick. If auto are you going to run an auto how about the torque converter? Parts need to work together, Heads are great, which pistons and CC did you go with, I like a 650DP Holley personally with an Airgap intake but you can make due with a 600cfm. SBC's must breath so don't restrict the intake or the exhaust. I am forced to stay with cast iron intake and exhaust and it kills me not to run the 650DP, nice intake with 1 5/8 ceramic headers and a mandrel bent 2.5 exhaust. Stay with a flow through muffler to avoid the dreadful drone. And a H pipe is nice too to help low end a bit. 3400-3600 pound cars with a 350 like 3.42 or 3.55 if highway rpm's is not a concern, I have a 3.31 with a low 2.20 first gear M21 with my L79 and its a bit sluggish until 15 MPH.. and ignition, well tuned HO distributor, no points
Here are my more updated specs:


Summit Racing Headers SUM-G9001-SS Full-length Primary Tube Outside Diameter (in):1 5/8 in.
I have a good 4 bolt main block
350 CHEVY CYLINDER HEADS #041 casting NEW GUIDES .500 SPRINGS
new stainless 2.02 swirl polished intake valves
new stainless 1.60 swirl polished exhaust valves
Heads are assembled with new .500 Z-28 lift valve springs
New cam: COMP Cams 12-238-2 Xtreme Energy 218/224 Hydraulic Flat Cam -218/224 Duration at .050". 110 Degree Lobe Separation Angle 462"/.469" Valve Lift 1,300-5,600 RPM Operating Range
Rebuild/overhaul master kit with moly rings
Edelbrock Single-Quad Performer Manifold and Carburetor Kit for Small Block Chevy 1955-1986 - Performer EPS Intake Manifold, 600cfm Performer Series Carburetor


The rear end kit I got was 3.42 posi. If you think that the 600CFM is going to hold me back, I can always sell mine and upgrade - I didn't want to over carb the engine. What size would you all recommend?

I have stock bottom end right now Auto transmission TH350 - What converter would you all recommend?
s1nemesis1s is offline  
post #7 of 21 (permalink) Old Feb 12th, 20, 4:56 PM
Lifetime Premium Member
 
Join Date: Jul 2000
Location: Northeast New Jersey
Posts: 8,389
Garage
Re: 1970 chevelle 307 base - change course?

IF you're just planning on getting them 350 parts then changing them now is OK to do but I thought you already have the 350 and the heads ? if that is the case then stick with the 350,just drive the car around while getting used to your Chevelle's HP,then....
save your nickels and save your dimes then,giddy up giddy up Vortecpro and don't look back.
s1nemesis1s and shovelrick like this.

John
71 El Camino SS
406 SBC M21 3.31 12 bolt
"Quality is always remembered,long after the price is forgotten"
"I would rather have questions I can't answer than have answers I can't question" :R.Feynman
71350SS is offline  
post #8 of 21 (permalink) Old Feb 12th, 20, 6:39 PM
Lifetime Premium Member
 
Join Date: Jul 2000
Location: Northeast New Jersey
Posts: 8,389
Garage
Re: 1970 chevelle 307 base - change course?

^^^ S1nemesis1s said "Auto transmission TH350 - What converter would you all recommend? "
I think whatever converter you choose should be between you and whatever company's converter you choose.So you need to call some conv. company's as the correct converter is so much dependent on what your combination is.I think you need to find out who's converter would fit your combo the best and hopefully someone with a similar combo can tell you what they're running and maybe that may help you with a baseline.
s1nemesis1s likes this.

John
71 El Camino SS
406 SBC M21 3.31 12 bolt
"Quality is always remembered,long after the price is forgotten"
"I would rather have questions I can't answer than have answers I can't question" :R.Feynman
71350SS is offline  
post #9 of 21 (permalink) Old Feb 12th, 20, 8:49 PM
Team Member
Bill
 
Join Date: Jan 2018
Location: Boston Area
Posts: 1,174
Garage
Re: 1970 chevelle 307 base - change course?

Quote:
Originally Posted by s1nemesis1s View Post
Okay - I am a dumb dumb. I posted the old specs! Jeez, I changed cams - how does this one sound: COMP Cams Xtreme Energy Cam and Lifter Kits K12-238-2 Duration at 050 inch Lift:218 int./224 exh.
https://www.summitracing.com/parts/cca-k12-238-2

I am still trying to understand Cams. I am reading about them as much as I can.
I haven't personally run that cam but it is a popular camshaft. The specs look pretty good for a strong street cam. Maybe someone can chime in but you should be good to go. I assume your compression is gonna be in the 9-10 range with flat tops pistons and 64 cc head chambers but you never confirmed that. As far as the carb I like the Rochester Quadrajet for the street and its 750 cfm. However its design only uses as much air/gas as the engine needs. The 600 you mention is a remake of the old Carter. Never been a big fan. I could never rebuild them on boats successfully because the metal became porous and leaked internally. Not sure if the Edelbrock has that issue. Just remember the 69/70 302 and 350 Z28 engines used Holley 780 CFM vacuum secondary carbs. Never a big fan of that one either. The 650 Double pumper was always my go to but they can be finicky which makes the Quadrajet the best street engine carb IMO. I agree with others about talking to torque convertor experts. Just don't go too much of a slip or your mileage will suffer but it certainly can make the car perform much better. Maybe a 2000-2400 stall speed but I am only guessing. Sounds like you should have a nice running car. Enjoy!
s1nemesis1s likes this.
Billdini is offline  
post #10 of 21 (permalink) Old Feb 13th, 20, 8:16 AM
Gold Founding Member
 
Join Date: Aug 1998
Location: 30.1298228, -97.9771166
Posts: 6,827
Garage
Re: 1970 chevelle 307 base - change course?

Going to a big block is kind of a passion pursuit. You dont need it but want it. If you want it that bad just figure roughly its going to double your budget...Between what you recoup from your small block effort and what it will take to convert. Then theres the upgrades transmission, cooling system, rear end, springs, etc. If your passion is strong enough, go for it.
s1nemesis1s likes this.

Protesting should not be a license for anarchy.
Alan F is offline  
post #11 of 21 (permalink) Old Feb 13th, 20, 9:42 AM
Lifetime Premium Member
Tom
 
Join Date: Oct 2017
Location: Traverse City, MI
Posts: 173
Re: 1970 chevelle 307 base - change course?

What you have would make for a fun driving 350 and would put a smile on your face. I would be one of the first ones to say "go big block", but as mentioned, it really increases your budget! Nothing wrong with a good mild no frills 350.
1975TypeS-3 is offline  
post #12 of 21 (permalink) Old Feb 13th, 20, 9:46 AM
Senior Tech Team
 
Join Date: Dec 2005
Location: Lancaster, PA
Posts: 11,206
Re: 1970 chevelle 307 base - change course?

Stick with your plan. Learn how to put the engine together and get it running. Most times a big block swap into a small block car will require accessory upgrades on top of the engine cost. Right now you have a small block platform car that works. So if for any reason the engine has an issue such as overheating, you can pretty much bet its not the car. Have fun with the 350. I have an 80 Malibu project that I am STILL on the fence with what engine to put in it. It has a chevy V6 in it, so all the accessories are there for a small block. So a direct bolt in almost no brainer. But I have a running 454 out of my Chevelle. As much as I want to put the big block in, I keep thinking is it worth the hassle to adapt it, or just go with the small block.

Ray

Best pass 8.87 at 150.98 1.212 60'. Sold 3/2018

1970 SS 396 project in progress. Bought 5/2018
bracketchev1221 is offline  
post #13 of 21 (permalink) Old Feb 13th, 20, 9:51 AM
Tech Team
John
 
Join Date: Aug 2015
Location: Nebraska
Posts: 248
Garage
Re: 1970 chevelle 307 base - change course?

I've been here...not too long ago either...Had a decent 406 that was kinda hot street, spent about $500 on new pistons, rebalance, and hone job at shop. Bought gaskets and everything to get it together. Then changed direction and wanted a 496. 3 years later, I still do not have the bbc done. The cost was my main thing. Since I've never done a BBC, I had nothing, so I needed to buy everything. Marketplace, craigslist and ebay have helped me save some, but you will still end up spending more than you expect. I've told VortecPro, I wish I'd just saved my money and bought one from him, all done. And like mentioned above, more power means other parts will need upgraded, which means more time to accomplish, and more money.

So, if I was you, I would get that 350 together, nothing else, gets you some learning, get it in the car and get the car moving. Enjoy it for a while. Then if you decide you want more, start on a BBC, or plan to buy a complete from Mark, either way. But get ur car going so you can enjoy it and have some fun with it. Life changes quickly, so get it moving while you can. Too many times I've changed directions on my plans, and all it does is make my car sit in the shop longer instead of being on the road where I can enjoy it.
68post likes this.
Rosinbluth is offline  
post #14 of 21 (permalink) Old Feb 20th, 20, 10:35 PM
 
Join Date: Feb 2020
Posts: 6
Re: 1970 chevelle 307 base - change course?

Dollar for dollar...the white knuckle grip cannot be achieved with a small block vs a big block...it is never going to happen. To that point however it is very possible building up marginal big block will grenade that tranny with ease..Think torque...and then there is your differential...
s1nemesis1s likes this.
EyesOpen is offline  
post #15 of 21 (permalink) Old Feb 21st, 20, 12:09 AM
Tech Team
Tim
 
Join Date: Jan 2005
Location: INDY
Posts: 86
Re: 1970 chevelle 307 base - change course?

Quote:
Originally Posted by s1nemesis1s View Post
The rear end kit I got was 3.42 posi. If you think that the 600CFM is going to hold me back, I can always sell mine and upgrade - I didn't want to over carb the engine. What size would you all recommend?
It's actually impossible to over carb a V8 with a vacuum secondary carb.
s1nemesis1s likes this.

T K
68post is offline  
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Chevelle Tech forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address. Note, you will be sent a confirmation request to this address.

Email Address:
OR

Log-in










Thread Tools Search this Thread
Show Printable Version Show Printable Version
Email this Page Email this Page
Search this Thread:

Advanced Search
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome