Been awhile since I have posted here. I have some 882 smog heads off a late 70s 350. Can I run the 882 heads on a late 70s 305? I plan on using a Weiand 177 on the 305 so if the 882 heads won't work, are there any other stock gm heads I can use other than Vortecs?
Smog head question
- Thread starter Sandmann
- Start date
Those heads are a 76cc combustion chamber, the 305 block has a 3.736 bore, same stroke as a stock 350 at 3.48". Those heads will bolt on without any problems. What you can expect though is a DROP in compression. If you have a stock block with stock pistons, the pistons are "dished" and work well with a 60cc head. The 305 heads {probably casting # 462614} from 77-79 have a 60cc combustion chamber, going from 60cc to 76cc you will lose compression, MORE compression will make more power, LESS compression you will lose power!! Go to the link and search out some other factory heads for you combo. Good luck!!
http://www.mortec.com/
http://www.mortec.com/
If your going with a 177 blower, you will want a lower compression engine about 8.5-1. With lower compression for a blower motor you will be able to hit it with more boost and overall make more power.
What do you plan on doing with this motor, the cast pistons will only handle so much boost as with the rest of the stock parts.
this will help you a bit.
http://www.blowerdriveservice.com/faq.php
What do you plan on doing with this motor, the cast pistons will only handle so much boost as with the rest of the stock parts.
this will help you a bit.
http://www.blowerdriveservice.com/faq.php
But since he said it was a late 70's 305 it probably already had 8.5 or less CR. So adding the bigger cc heads will only drop the CR even farther to ~7.25-7.5 CR. and therefor make less power than it would @ 8.5-9.0 CRbowtie81 said:
That's why i stated he would want to have a compression ratio of 8.5-1. even if he had a compression ratio of 7.5-1 he could run 10lbs of boost and still have a final compression of 12.6-1. the higher the intial compression it limits you to how much boost you can go with. As it shows in this chart.alowerlevel said:
http://www.blowerdriveservice.com/techcharts.php
I am running a B&M 162 blower on mine, i'll help you out as much as i can
Obviously I need lower compression for the blower. I was just wanting to know if the 882 heads would work on a 305 block and it sounds like they will. I know they aren't the best heads and block but thats kind of what I have to work with now. Yes I will have to spend some $$$ on some good forged pistons. Any suggestions on forged pistons ie: cc size, brand, price etc?
Find out what your compression is now before you put those 882's on. I'm using a stock set of x-rods with arp bolts, trw forged pistons that were only around $250.00, when you choose a piston you'll need to know the heads you are gonna use the thickness of gasket, your deck height.
The 882 heads will work on your 305 but it may drop the compression to much, if it's already around 8.5-1 stick with that and figure out the pulley size to achieve around 5lbs of boost with the stock bottom end. your not gonna want to put too much timing to it, around 32 total timing all in by 2500.
If you need any help dont hesitate to ask.
The 882 heads will work on your 305 but it may drop the compression to much, if it's already around 8.5-1 stick with that and figure out the pulley size to achieve around 5lbs of boost with the stock bottom end. your not gonna want to put too much timing to it, around 32 total timing all in by 2500.
If you need any help dont hesitate to ask.
these are the pistons i went with: http://www.summitracing.com/parts/TRW-L2256F/Sandmann said:
Now my heads are 72cc chamber with .005 deck height, standard thickness of headgasket and i'm on the high side of still being in the normal range for compression. so my compression is around 9.5-10.0-1, if you use a 76cc head you should be around 9-1 which will be just fine.
