318 garage clear rebuild

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1974scamp

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Hi at all,

I have a 318 sitting around in my garage which came out of my car as it was replaced by a 408.

Now i have some parts laying around which could probably make a nice little budget 318.
What i got:

Full 1969 318 engine (should be 9.2 compression)
4 Barrel Intake
1976 360 j heads with 1.88 valves which are in usable condition
Scat I beam rods from a 408 stroker kit
Comp XE274 cam with lifters
Windage tray
HV oil pump
Double roller timing chain

I would like to put the 360 heads on the 318 and use the XE274 cam. I think i rember that i have measured the 360 heads to about 70cc could that be right??
So i think flat top pistons would be needed for example something like: that:Silvolite Pistons 3234H-STD Silv-O-Lite Hypereutectic Pistons | Summit Racing

The other thing is as i live in Austria and machine work over here is really expensive, i would like to avoid it as much as possible. So maybe there are some pistons which give me a higher compression and i dont have to rebalance the whole rotating assembly??
Or what would be my compression if i just put the 360 heads on the 318 with the stock pistons and the thinnest head gasket i can find? I think the xe274 cam needs 9 to 1 compression, would i get away with that?

Thanks for your ideas!
Laurin
 
First start by measuring what you have. Where are the pistons in the block? Measure the distance from the block surface at TDC on all 4 corners. Then measure the chambers in the 360 heads. Carefully check the 360 heads for cracks between the center chambers between the valves. Unmilled 360 heads were about 72-73 cc.
 
First start by measuring what you have. Where are the pistons in the block? Measure the distance from the block surface at TDC on all 4 corners. Then measure the chambers in the 360 heads. Carefully check the 360 heads for cracks between the center chambers between the valves. Unmilled 360 heads were about 72-73 cc.

Yes of course, till now its all just ideas.. have not even opened the 318 yet hope it needs no bore

Is there no information about how much the original pistons should be in the block? And how much cc do the 1969 318 heads have about?
 
Nothing wrong with using/reusing what you have.I would think that cam might be a tad big for a stockish 318 but run what you brung. Milling the heads a little and advancing the cam might help a bit. The more gear and stall you run will cover up the non existent low end torque.
 
Nothing wrong with using/reusing what you have.I would think that cam might be a tad big for a stockish 318 but run what you brung. Milling the heads a little and advancing the cam might help a bit. The more gear and stall you run will cover up the non existent low end torque.

I got 3.23 and 3.91 gears and a 2500stall hughes converter.

Also one major reason i wanna use the 360 heads is, i just got new tti headers in my car and the previous owner welded extra material in the ports to make them seal 318 heads. I just grinded that all out (and im never putting those damn hooker headers back in my car :BangHead:) so the TTIs will seal the 360 heads
 
A stock 318 short block with 360 heads will end up around 7.5 compression...
 
Its coincidental but I am building my spare 340 for the same reason, been sitting around as parts for years I am like 'time to build this thing "
 
Make sure you measure for compression. May have been "rated" at 9.2, but trust me, it AIN'T. lol
 
I just got an offer to mill the block for 140€ plus tax in Germany

so if the block would be zero deck, and with some flattop pistons i would be just over 9 to 1 compression with 73cc heads and 0.040 head gasket.

So if I could find flattop pistons with about the same weight could i just exchange the stock ones with them?

As said i dont really need this motor because currently the 408 is in my car, so its would be really a budget build for fun as a backup
 
Yes of course, till now its all just ideas.. have not even opened the 318 yet hope it needs no bore

Is there no information about how much the original pistons should be in the block? And how much cc do the 1969 318 heads have about?

If they are 675 heads they should be about 68 cc. You still need to check to be sure. Who knows what they did for exports.
 
That gets you down to 65cc on 360 heads.
I was going to do the 360 heads on a 318 years ago but an older mechanic advised Imshouldnt because of the crowd drop. Good info here guys...I ended up running a 340 so I never sorted out the 318. I ran it stock save for a cam ,edelbrock intake, and 600 Holley.
 
Is there a table somewhere or equation that tells what compression psi is what cr?

Too many variables. You have to check.

360 heads run fine on a 318, but you need compression and a slightly smaller cam. It has to be a total package, similar to a 1972 340.
 
Too many variables. You have to check.

360 heads run fine on a 318, but you need compression and a slightly smaller cam. It has to be a total package, similar to a 1972 340.

What would be the downsides of using the xe274 cam, i thought that could work out fine with the 1.88 intake valves of the 360 heads and make a engine which likes a bit rpm, when the compression is high enough??
 
You are sliding the power band higher in the rpm range. It would depend on what you want and your expectations.
 
What would be the lowest c.r. that you would want in a street performance engine? I'm thinking 10:1 Is still doable on today's gas...A 318 with 360 heads I'd think the lowest I'd want is 8.5:1
 
Isn't the .040 head mill part of the "recipe"?
A .040 can be changed for what ever ratio hour trying to achieve so saying it is part of a recipe is kind of ambiguous. Anybody can put up a recipe with any head mill spec they want.
Is there a table somewhere or equation that tells what compression psi is what cr?
No, the cam can change that easy. The dynamic compression ratio is different than the static compression ratio. The cam changes the dynamic ratio with every cam swap.
I was going to do the 360 heads on a 318 years ago but an older mechanic advised Imshouldnt because of the crowd drop. Good info here guys...I ended up running a 340 so I never sorted out the 318. I ran it stock save for a cam ,edelbrock intake, and 600 Holley.
Crowd drop?
The 318, no matter what year it is or what ratio is listed suffers from low compression. Using a 360 head makes it worse.
What would be the lowest c.r. that you would want in a street performance engine? I'm thinking 10:1 Is still doable on today's gas...A 318 with 360 heads I'd think the lowest I'd want is 8.5:1
It’s not so much the static ratio your worries about but the whole package that makes power. The more power you want, the higher the ratio in order to keep the cam & engine combo as a whole efficient.
 
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