33IMP
Well-Known Member
Uh, that's a 71 chevelle. (Year in question, but it sure ain't no olds.)
318 1/8 time improvement
- Thread starter Slantsix64
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Uh, that's a 71 chevelle. (Year in question, but it sure ain't no olds.)
BVoelzke
Well-Known Member
Just a little FYI ! years ago I broke the 340 in my 68 Dart race car , I bought an original 318 out of a 68 Charger we did a quick valve job , put in a stock type 340 cam and an old LD4B intake, Holley 750 , 1 5/8 headers and the car ran 13.90s with a 3.91 gear. I put on set of 360 heads and the car ran 13.20s . I took out the 10 inch converter and put in an 8 inch Turbo Action converter and the car ran 12.60s . ( I run a 904 )
I too, have always gained when putting 360 heads on a 318. But many here will give a hill of a spill why you will lose performance with that swap
Nice run for the 318 !!Went to the track, went faster than last time and nothing broke. If you had a bunch of fun doing it, awesome day out.
Bummer that the track is going away.
That's interesting it needed a 4600 stall rpm to run 12's with the 360 heads. I saw a 318 headed car at my local track run 12.5's with only a 2500 stall and 3.23 gears.
BVoelzke
Well-Known Member
Probably had more compression and a bigger cam or was spraying it . I just threw it together to race while my 340 was being fixed. It wasn't really my primary race engine I am sure with more work the 318 could have ran quicker. I sold the motor but wish I would have kept it.
No spray. 11-1 comp ported 318 heads with stock valves in a standard looking 4 door valiant
Cam was comps 218/218 hydraulic
BVoelzke
Well-Known Member
There you go !!! 11 to 1 compression and ported heads , my 360 heads were stock and I am lucky if the compression was 8.5 to 1. I went 11.30s with a 9 1/2 to 1 340, 557 lift cam and ported J heads. Now I run 10.80s with a 9 1/2 to 1 compression 410 inch small block , 585/595 lift cam with ancient W2 heads
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Ported 318 heads with stock sizes 1.78 intake valves don't flow a whole lot more than a 360 head stock but the higher comp certainly helps not to mention less gear, converter and carb.
A stock 318 head only flows around 170 cfm peak where as a 360 head will flow around 200 cfm. The port volume is significantly higher too with the 360 head
BVoelzke
Well-Known Member
OK you Win !!! the guy has the best and fastest 318 ever !!
Ported 318 heads will go into the 250+ range with good porting. Even a small valve head will go 230's...
Good choice to stop... LOL quienes mas macho type stuff
Your stuff runs well and you win races... have a good holiday!
He's got a thing about proving the SMALL is just as good or better
BVoelzke
Well-Known Member
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Its not about winning but seeing how different people get things done and learning from it. The real questing is why can it go mid 12's with a small cam, stock gearing and a 2.5K converter with 225 street tyres.
I agree as I have a set flowing 240+ cfm but with an 1.9 11/32 valve and a port volume somewhere in the 140's. I don't think you're gonna get 230's with a mild port job and a stock 1.78 valve. I have seen a set of super stock heads go 224 cfm but they're a work of art.
BVoelzke
Well-Known Member
11 to 1 compression probably on race gas as that compression is too much for pump gas IMO. A S/S head is a whole different ball game . Why waste your time on a 318 head when you can run an Edelbrock, Indy , "J " or W style head. If you want to make real power put a stroker kit in it. Thats another question ? what stroke is the 12 second 318 ? Stock ? how many cubic inches is the 318 ? What intake and carb does it run ? Headers ? 904 or 727 ?
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Its a street car and runs on pump gas and I know people associated with the build.
I'm personally at 10-1 on your equivalent 87 octane pump fuel now with a cam that's 212/220 and I'll bump it up to 11-1 in the not too distant future.
BVoelzke
Well-Known Member
The fact that its a " build " tells me a lot of thought went in to it and there's more to the story. Its not some 60,000 mile half worn out 318 like mine was. Yes 12.50s is fast but imagine how much quicker it would be with gears and a converter , say a 10 inch converter and 3.91s and still be street able.
I understand what you're saying but its not anything exotic nor am I trying to take away what you've managed to accomplish which is impressive to say the least. If you saw the car you would agree it was a nice restoration and look over the engine and say to yourself this will only run 14's because its stock except for an Airgap, Holley carb and an MSD ignition. All else it was stock down to the steel wheels and 225 street tyres.
What is interesting is the acceleration rate with a 2500 stall and 3.23 gears. This thing has to be making a LOT of torque to be able to run those numbers with those 2 limitations. The cylinder fill has to be extremely efficient across the entire rev range to achieve that.
BVoelzke
Well-Known Member
I think its been " stroked " and its not really a 318 but bigger, especially with that much torque.
Unlikely, the guys involved are really sharp. I know the carb builder has run 12.5 to 1 on pump fuel.
BVoelzke
Well-Known Member
Wow !!! the gas must be really good where you are ! I am currently running 9 1/2 to 1 compression and I constantly check the specific gravity of the fuel I buy it usually checks 728-734 where it should be for 92 Octane Super . Lately its been checking at 710 no good ! According to my engine builder I am risking detonation and it has happened on several motors he has seen even with not much timing.
Nope.....same **** like everywhere. What cylinder pressures are you cranking?
There are more factors involved than just octane when it comes to detonation.
BVoelzke
Well-Known Member
I know that but the gas is a big factor and the air / fuel ratios , timing etc. I don't remember the cranking pressure , I would have to look at the build and dyno sheets. I would like to see the bearings after a couple hundred runs at 12.5 to 1 compression on pump gas !!! I just got my carb back from AED maybe I should have sent it to your guy.
Do a cranking compression test and see what you get. There's quantity and then there's quality of fuel delivery and the guy who built that carb for the 318 builds them with quality in mind. That's one of the reasons it performs so well.
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