First time post engine rebuild advice please

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vgv8

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Hi all

I have been scouring the net for ideas on an engine rebuild, I have the how to hot rod small block mopars by larry sheppard and about 50 bookmarked internet pages.

I currently have a 318 with KB167's, standard stroke, purple shaft 340 muscle repro cam (268/276 duration 429/444 lift) and :angry7: cracked late model heads running 9.1:1 comp with a cast iron 360 four barrel intake and Thermo Quad with headers. The engine has done around 3000miles since a rebuild and has cracked the heads between the valves.

I have a set of 360 J heads on the shelf and a set of stock early 70's 318 heads on the shelf. The car is a cruizer and made around 270 flywheel horsepower. I want to use either the J heads or the 318 heads. I am really confused by all the talk about port velocity etc... when using 360 heads. Which heads should I use? Finally has anybody used hughes engines camshafts like the 1928al?

Appreciate the advice I just find all posts and books saying use the 360 heads and just as many saying dont. I am not after a race car but woul like the car to perform the same with 318 or 360 heads as it did with late model heads.

Thanks in advance
 
welcome to the site:) ask lots of qs and stick around lol. there are a lotta smart ppl on here that will know a lot more then me but i will share a lil lol. i was lookin at 360 heads on a 318 and they are bigger so it sounds like it would be good but you lose all the velocity. so unless its gonna get forced inductior or really high rpms the 318 heads will be better for a 318. that is how i understood it anyways. my 360 got ported and bored and all and has the regular 360 heads and it is a very sexy piece of steel lol. i would suggest that to anyone looking for a good small block just keep it simple
 
hi, the 318 head will have more velocity , install sst intake valves, they flow much better, a 3 angle valve grind, you can blend the sharp edges down in the bowls, carefully, this will increase velocity at this point and help fill cylinder better. this will make for a very responsive motor.
 
Its a bigger cam but I have a Hughes 2832 in my 440 Coronet. It works very well for the size of the cam. I would buy their cams again.
My 66 Coronet has gone 13.02 with 3.23's and street radials.

I would e-mail them or call with your combo, see what Dave recommends.
 
The 360 top end will be a better choice at higher RPM's....the 318 top end will probably give you a bit better low RPM torque. There can be other variables depending on some of your other equipment, rear axle ratio, head castings, port work, etc. Whichever you choose, make sure that everything matches (ie. port sizes) so everything flows good. CC your old heads and compare to whichever replacements you choose to make sure your compression ratio stays where you want it. The bigger question is why the 1st set of heads cracked! Overheat? A/F ratio too lean? Detonation? No (or too little) spark advance? All needs to be checked before you toast another set!
Thanks, Mark
 
perfacar said:
hi, the 318 head will have more velocity , install sst intake valves, they flow much better, a 3 angle valve grind, you can blend the sharp edges down in the bowls, carefully, this will increase velocity at this point and help fill cylinder better. this will make for a very responsive motor.
Click to expand...

Perfacar -this is interesting - i want to do exactly what you said -but is there any chance of a few closeup pictures of what you are talking about, or even a good description re the bowl cleanup, sharp edges etc. What about the casting roughness inside the bowl? Is it better to make the CChamber as smooth as possible? Thanks!


Also, in relation to VGV8's Question. Have you seen the other relevant post about this? 360 heads on a 318? There is a lot of info there that will help you. Most of it is recommending the 360 heads, however most people always say that your CR will drop due to the bigger Comb chamber volume, therefore power may suffer, therefore higher comp pistons or decking/facing is required.
 
I think in your case you have already addressed the biggest down side. You have better pistons in it so you can play a little more. If you are running a milder cam profile, which is what I'd suggest, I think the 360 heads with the 1.88/1.65 valves, a .030 mill, and a performance valve job would be fine over doing any special prep work on the 318 heads. There will be a bunch of other ideas. But that's mine. There is much to be said about over thinking a basic combo and I think with the lower end done you are head and shoulders over someone with a stock piston.
 
Thanks for the replies! cudamark I was around 250 miles from home when I noticed the temperature rising and falling from normal to 3/4 and then the odd miss. I pulled into a shop to get it looked at (I didn't build the engine, I dont have that sort of ability) At first I was told headgasket failure. The guys pulled the heads off and thought the gaskets looked ok and then tested the heads and found one with a crack between the valves through a seat or port(?) anyway the block is ok but I need to use one set of heads that I bought for the original build.

moper 360 heads sound good. As I am not mechanically minded when I read alot of posts and magazine articles it all gets a bit much. I think your right about overthinking the build. Whatever I do it will still run alright by the looks!

70hardtop The original machine shop will know how much to mill the 360 heads to get everything right again?

Thanks all!
 
VGV8 - machine shops only usually do what you tell them to -unless it directly convenes certain basic rules for a rebuild. As said before, i think 0.030 was recommended off the heads, decking the block would also raise the CR a bit as well. Doing these things though might mean you have to get the gasket faces of the inlet manifold machined as well otherwise the bolt holes may not line up any more. Unless you understand about this, you will not know what i am talking about. I would talk to the machine shop about that. Remember, when modifying engines from stock, you cannot usually just change one thing -other related components also usually have to be modified.
 
I'm with Moper on this. Though milling the 360 heads can be a plus, it can be a pain as well.

The Huges cam you listed is much smaller than the OE/Repro 340 cam you have now.

What is your gear ratio?
 
Rumblefish: I am running 3.23:1 rear axle ratio. Would you leave in the 340 cam or go to a larger Hughes cam? I like the sound of the Whiplash series they run, here is a link to a guy with one: http://www.youtube.com/watch?v=3aiKrwGXFOo

Appreciate any suggestions
 
My dually would so smoke that car............

Sound comes with power, I have heard bad *** 340 cam cars, and weak sounding 340 cam cars. I have a 268/276 voodoo here, I would recommend it if you are going hyd lifters. It chops like the cam in your movie, and has another 1K or so over the powerband of the stock 340 cam, and seems to not have any less low end.
 
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