New 318 build, just need some input.

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wolfhammer

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Ok guys what I have is a 1969 318 and I have a plan for a rebuild.
Block needs to be bored at least .030
My plan is to use the stock crank and rods with KB167 pistons for the bottom end.
302 heads with stock valves and a little unshrouding around the valves
Comp Cams Adv. Duration 268/280, Lift .477/.480 I think it's known as the XE268.
Mopar M1 dual plane intake 650 cfm DP carb and Summit headers to 2 1/2" duals
I'm running a 4 speed with an 8 3/4 rear 3.55 gear
With the KB pistons and that comp cam will I still have enough piston to valve clearance? Should I run a lower lift?
I will check clearance but I don't want to buy another cam or cut the piston eyebrows.
Would I be better off with stock replacement pistons?
I think the combination I put together is pretty good and being on a strict budget I'm using the 302's because I already have a fresh pair. The only big expense will be the complete cam kit, pistons and machine work. Strictly a street car but will see a few 1/8 mile runs at the track.
I want to keep it under $2000 so the wife doesn't freak out lol
Thanks for any and all (on subject non argument) input guys.

PS, It's just a "street car" guys and I won't be looking for 12 seconds in the 1/4
 
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After seeing Charles servedio port the mission impossible 302 heads on YouTube. I would go with some other head’s unless you do a full port job. They flow poor stock and wake up somewhat with porting.
 
You cant go wrong with a pair of edelbrock heads and a rpm or rpm airgap intake. I know that is more than what you want to spend but I would not go to the expence of porting the 302’s because of their limitations. And if you do port the 302’s have them done by someone who knows what they are doing cause air flows where it wants to not where you think it should. I learned alot from Charles videos and David vizard as well. I had no idea air flows like that in a head. An inexperienced porter can ruin a pair of heads right quick.
 
ch1ll said:
You cant go wrong with a pair of edelbrock heads and a rpm or rpm airgap intake. I know that is more than what you want to spend but I would not go to the expence of porting the 302’s because of their limitations. And if you do port the 302’s have them done by someone who knows what they are doing cause air flows where it wants to not where you think it should. I learned alot from Charles videos and David vizard as well. I had no idea air flows like that in a head. An inexperienced porter can ruin a pair of heads right quick.
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Thats exactly why I'm only going to polish them. There isn't much to port except that I forgot to mention a gasket match. My thing is that on those ports I don't want to cause any reversion and have them sending the pulse backwards.
 
wolfhammer said:
Thats exactly why I'm only going to polish them. There isn't much to port except that I forgot to mention a gasket match. My thing is that on those ports I don't want to cause any reversion and have them sending the pulse backwards.
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I would rethink your decision to polish the intake ports.
 
Your not going to gain much if anything with a gasket match and may lose some by polishing. Runners like a carbide burr finish but even that may lose some if you cut the wrong areas. After watching the YouTube videos I mentioned, its silly to mess with it unless you know what you are doing. I did not till I watched the videos, I would have been dead wrong.
 
glockr said:
Polishing the intake ports can cause problems with fuel drop out.
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Fuel should be atomized before the runners so I don't know about "drop out" in an atomized state when its already travelling. If we were talking about an old bread box tunnel ram that the fuel would puddle up in and explode that I would understand. When you port it actually takes down the imperfections and any flash or casting lumps while opening up the bore which in turn is a form of polishing I would think.
 
I think polishing will probably just slow it down a little bit. Gives it the effect of larger. flow more? maybe? How much? 2 cfm ,maybe more.. but probably not more than 10cfm.
It would be worth running those heads if your compression didn't end up really high for pump gas and you did the chamber mods and some mild bowl/short turn porting so that they flow as good as other open chamber heads, even better.
Otherwise why use that camshaft for heads that are designed and flow like truck heads? At the same time those heads were out they also had open chamber versions that went in cars... the trucks got the small chamber, the small chamber didn't allow the intake port to flow as well because it shrouds the valve. The open chamber heads allowed the intake port to flow a little better. what do trucks do? low speed torque. what do cars do? go down the highway in the fast lane light loads etc.
Sorry about the run-on sentence I'm using talk to text cuz I'm really really busy.
If you wanted something quick and easy and not aluminum heads...I would sell the 302s and get a fresh set of Magnum heads...then drill them for an LA intake OR simply use a aftermarket magnum 4 brl intake dual pattern knock off.
If you're going to do any work like polishing and stuff like that where you have to disassemble the head and clean it and all that mess.. you may as well put that work or effort into drilling for an LA bolt pattern on some better magnum heads with the same size chamber. You can then take your empty block and Bolt the heads onto it scribe them to the bores and then play with opening them up evenly to get to the chamber volume you need with those 167 Pistons so that you don't end up with two high compression for pump gas with that little idle to 5500 cam.

You asked.. that's just my opinion... if you don't like it..that's fine ...spare us both and don't bother responding to it in that case.
too busy.
Best of luck.
 
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ch1ll said:
Your not going to gain much if anything with a gasket match and may lose some by polishing. Runners like a carbide burr finish but even that may lose some if you cut the wrong areas. After watching the YouTube videos I mentioned, its silly to mess with it unless you know what you are doing. I did not till I watched the videos, I would have been dead wrong.
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Watch out for loaded questions. :elmer:
 
I’m just opining by what I learned from two of the best porters in the world. I have not ported anything. Best left to professionals.
 
MOPAROFFICIAL said:
I think polishing will probably just slow it down a little bit. Gives it the effect of larger. flow more? maybe? How much? 2 cfm ,maybe more.. but probably not more than 10cfm.
It would be worth running those heads if your compression didn't end up really high for pump gas and you did the chamber mods and some mild bowl/short turn porting so that they flow as good as other open chamber heads, even better.
Otherwise why use that camshaft for heads that are designed and flow like truck heads? At the same time those heads were out they also had open chamber versions that went in cars... the trucks got the small chamber, the small chamber didn't allow the intake port to flow as well because it shrouds the valve. The open chamber heads allowed the intake port to flow a little better. what do trucks do? low speed torque. what do cars do? go down the highway in the fast lane light loads etc.
Sorry about the run-on sentence I'm using talk to text cuz I'm really really busy.
If you wanted something quick and easy and not aluminum heads...I would sell the 302s and get a fresh set of Magnum heads...then drill them for an LA intake OR simply use a aftermarket magnum 4 brl intake dual pattern knock off.
If you're going to do any work like polishing and stuff like that where you have to disassemble the head and clean it and all that mess.. you may as well put that work or effort into drilling for an LA bolt pattern on some better magnum heads with the same size chamber. You can then take your empty block and Bolt the heads onto it describe them to the boards and then play with opening them up evenly to get to the chamber volume you need with those 167 Pistons so that you don't end up with two high compression for pump gas with that little idle to 5500 cam.

You asked.. that's just my opinion... if you don't like it..that's fine ...spare us both and don't bother responding to it in that case.
too busy.
Best of luck.
Click to expand...
Thats the type of answer I'm looking to get. I'm not into all the BS on youtube although I do have a youtube channel. There are some that are good but I don't like that some are just putting out BS on automotive issues and it makes me laugh that there are so many who will watch a whole series on a Carter 2bbl carb and how to make it perform. It's all about the money for those people to BS an average Joe and give them hope that they can run a 13 second quarter mile with junk lol
 
wolfhammer said:
Fuel should be atomized before the runners so I don't know about "drop out" in an atomized state when its already travelling. If we were talking about an old bread box tunnel ram that the fuel would puddle up in and explode that I would understand. When you port it actually takes down the imperfections and any flash or casting lumps while opening up the bore which in turn is a form of polishing I would think.
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If only that were true. There are pressure differentials in the manifold that turn atomized fuel back to liquid, plus you have wall flow you have to deal with.

If you haven’t seen the Jon Kasse video with his finger in the tunnel ram go find and watch it.

Don’t grab the grinder until you spend some more time investigating and learning the physics of what’s going on in the intake tract (or what we know about it) as that will shorten up your learning curve a bunch.
 
ch1ll said:
I’m just opining by what I learned from two of the best porters in the world. I have not ported anything. Best left to professionals.
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That's a pretty strong statement! Who are these "2 best" you speak of?
 
wolfhammer said:
Thats the type of answer I'm looking to get. I'm not into all the BS on youtube although I do have a youtube channel. There are some that are good but I don't like that some are just putting out BS on automotive issues and it makes me laugh that there are so many who will watch a whole series on a Carter 2bbl carb and how to make it perform. It's all about the money for those people to BS an average Joe and give them hope that they can run a 13 second quarter mile with junk lol
Click to expand...
The two porters I mentioned are world class and much can be learned from their YouTube videos including porting a two barrel carb that will apply to a four barrel carb as well. I might add 302 heads were 2 barrel heads. Why would you put a 4barrel carb on heads that flow 170 cfm intake stock.
 
  • you can find just as much garbage on forums as on youtube... just say'n
  • I like the build, there are better heads but if you have them and want to use them, do it. Make sure the springs match the cam. It will still run good for you
  • Piston to valve clearance is checked by the builder.
  • going 13's on junk is easy. :)
 
318willrun said:
  • you can find just as much garbage on forums as on youtube... just say'n
  • I like the build, there are better heads but if you have them and want to use them, do it. Make sure the springs match the cam. It will still run good for you
  • Piston to valve clearance is checked by the builder.
  • going 13's on junk is easy. :)
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You got that right brother lol You have some good videos though. I'm going with the complete kit from Comp so everything will work. The heads are what I have on hand as I said and yes I'm sure I will be buying some playdoh lol Thanks for the straight up reply bud
 
i think that cam is perfectly suitable for this build. it's basically a "plus one" from a 340 cam and the lift isn't that outrageous so i don't think you'll have any clearance issues. obviously it should *always* be checked, but you're not over .500 or using increased ratio rockers so you should be fine. i'd pull the trigger but check the return policy...

the heads are a big compromise here. i mean, you're not building something all that aggressive and there's a whole "use what i've got" mentality. that being said anything can benefit from a bowl blend/pocket port/gasket match. and in the case of the small port 302's might revisit consideration of intake (maybe something "small port" ie performer, LD4 or weiand 8007?) and possibly the cam.

the 650 DP is a fine choice. i personally would go a little more mellow with something like an AFB/AVS or a 750 vac 2ndary holley

change the heads and you change the entire nature of this build. that's the limiting factor.
 
Max lift is not what causes valve to piston contact guys. Max lift happens when the piston is no where near TDC.
 
I think you will be alright with piston to valve clearance, the valve releifs are pretty big on the KBs but check it out anyway. (Clay is cheap)
Mine are 0.015" above deck and had heaps of clearance with a 0.574" lift cam.
The 302s aren't the best head but if you have a fresh set already clean the bowls up and any casting flash in the ports and send it.
 
Ted265 said:
I think you will be alright with piston to valve clearance, the valve releifs are pretty big on the KBs but check it out anyway. (Clay is cheap)
Mine are 0.015" above deck and had heaps of clearance with a 0.574" lift cam.
The 302s aren't the best head but if you have a fresh set already clean the bowls up and any casting flash in the ports and send it.
Click to expand...
TT5.9mag said:
Max lift is not what causes valve to piston contact guys. Max lift happens when the piston is no where near TDC.
Click to expand...
Mopar wedge engines are known to have a modest amount of P/V clearance.
Cams in the .520 lft range have clearance with factory flat tops without reliefs.
The overlap period is where the problem can arise.
 
wolfhammer said:
Ok guys what I have is a 1969 318 and I have a plan for a rebuild.
Block needs to be bored at least .030
My plan is to use the stock crank and rods with KB167 pistons for the bottom end.
302 heads with stock valves and a little unshrouding around the valves
Comp Cams Adv. Duration 268/280, Lift .477/.480 I think it's known as the XE268.
Mopar M1 dual plane intake 650 cfm DP carb and Summit headers to 2 1/2" duals
I'm running a 4 speed with an 8 3/4 rear 3.55 gear
With the KB pistons and that comp cam will I still have enough piston to valve clearance? Should I run a lower lift?
I will check clearance but I don't want to buy another cam or cut the piston eyebrows.
Would I be better off with stock replacement pistons?
I think the combination I put together is pretty good and being on a strict budget I'm using the 302's because I already have a fresh pair. The only big expense will be the complete cam kit, pistons and machine work. Strictly a street car but will see a few 1/8 mile runs at the track.
I want to keep it under $2000 so the wife doesn't freak out lol
Thanks for any and all (on subject non argument) input guys.

PS, It's just a "street car" guys and I won't be looking for 12 seconds in the 1/4
Click to expand...
I noticed you edited your post after my reply. If you're going to run those heads and cheap as the goal cheap usually means more work so don't chince out on the more work part or you will really regret it... they are the worst flowing as cast 318 ever made. No lie. The numbers are way behind .100-.400 lift as cast.
I'm not going to tell you which videos to watch cuz I think that's tacky but you can find some on YouShit showing what's necessary and what that along with a good performance valve job can do.
If those two things are done...they will outperform home ported ground to the 45 seat 3 angle valve job stuff that's out there running high 13's. Theres a diff between 13-13.4 and 13.7-13.9..and it's in head prep.
 
fishmens67 said:
Mopar wedge engines are known to have a modest amount of P/V clearance.
Cams in the .520 lft range have clearance with factory flat tops without reliefs.
The overlap period is where the problem can arise.
Click to expand...
ok, I'll admit it, I didn't even check... I'm at about .530 with a factory assembled short block .. LOL.
 
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