Good mild 318 build plan?

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MopaR&D

MopaR&D

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As some of you may know my valves are bent from a slipped timing chain in my '70 318 Duster and I've decided that I'm going to just go semi-all-out (?) and pull the engine for a top-end rebuild. I don't want to set it back to stock because the dismal compression compounded with the 7000 ft. elevation, stock converter, and 2.76 gears made it pretty gutless. At the same time it ran out of breath by 3500 RPM which really annoyed me, especially when I needed the extra power on the highway driving to and from Breckenridge, CO (big hills). Here's what I have in mind:

-- #302 heads cleaned up, ported (suggestions for this?)
-- Lunati Voodoo 256/262 cam + lifters + springs
-- Stock pistons, but new rings (only 120,000 miles on the engine)
-- Stock 360 cast-iron exhaust manifolds (headers too expensive/chore to install in car)
-- Edelbrock Performer intake
-- 800 cfm ThermoQuad carb (don't know if it will work OK, came from an '83 360 with EGR)
-- Pypes 2.5" Race Pro exhaust system (cheapest option for me)
-- New freeze plugs, gaskets, re-paint

I was also wondering if it would be a good idea to change the converter. Would this cause me to lose gas mileage and/or increase cruising RPM with the stock rear end? I've heard that stock 170 /6 converters have a higher stall than 318 ones, where could I get one of these? I'm not searching for a certain HP level or 1/4 mile ET, I just want to actually have some getup and a little more efficiency.
 
I think your selection of parts looks pretty good. I'd get the book How to Rebuild a Small Block Mopar; there is a lot of good information in there. If the taper in the cylinder walls is out of spec the new rings won't seal.
 
Make sure you degree the cam in. When I built my 318 last year I advanced the small cam similar to yours two degrees and this things burns the tires off. If I had installed the cam straight up it would have been retarded 2 degrees which would have killed bottem end torque.
 
Don't forget that a longer duration cam drops cylinder pressure. You may be better off getting a stock cam and installing 1.6 rockers for more lift.
 
I actually just got that book a couple days ago on the off chance I'd end up having to disassemble my engine. I think the pistons seal pretty well right now, before when I did a compression test I got around 90-100 psi on all the cylinders. I just want to put in new rings because this engine has flooded itself countless times (not my fault; shitty gas boiling in carb) and I plan to put many more miles on this engine until I gather the funds to unleash my 360 Magnum/4-speed combo.

I don't think 2* would make that much of a difference in my torque; besides, I want to be able to rev out to 5000 RPM in a light-to-light or during kickdown when going up a big hill.

EDIT: In regards to the last message, the cam I listed is only 213*/220* @.050". It's the second smallest Voodoo cam after the 250/256 which is basically a P/U or light tow rig cam.
 
That cam will be a nice increase across the RPM band over the stock broomstick. The closed chamber heads will bump compression a little as well, which will help you up in the thin air.

Unless you absolutely have your heart set on the ThermoQuad, I'd reconsider. A 600 CFM vacuum secondary Holley or an Edelbrock 1406 may be easier to set up, and a hecuva lot easier to get parts for.
 
Well, I already have the TQ sitting in my garage that just needs to be cleaned a bit; I also have a new rebuild kit for it. If it was out of tune all I'd need would be some metering rods or jets from DemonSizzler. I don't think those other carbs are bad, I just don't see the need to buy one.

Also, what are anybody's recommendations on head work? How should I port them? Is there literature out there that shows the basics of head porting? Or should I just get a valve job and toss them on?
 
that t/q needs a trash can. go with a Holley 600cfm or a Edelbrock 600cfm it will idle better,give you more power. as far as the cam i would use the m/p 280 cam it has been available for many years you can use a stock converter it is good from idle to 6000 rpm .i had one in my Barracuda and it ran great.but for what i am dooing with the car now it will not work. if you want to save some $$$ send me $100.00 + shipping and i will send you the Cam & Lifters. the cam i have now i can shift @7200rpm making power as far as the Exaust goes the system you have chosen will work well for you.when i get my 700dp i can send you my 600 Edelbrock Carb..$75.00 this might help you some.


good luck with your project

Don
813-434-5577
[email protected]
 
kid, the build looks fine from where I sit. In fact, while you can port the heads, I think you'd do better to leave them as is, and have a really good performance valve job done on them. That by itself will do about the same as a stage one porting job. I love teh Thermoquads. I've run a bunch. There is a book on how to race and tune Carter carbs.. one of those HP books. Get it. You will want to rebuild the carb, and make sure the primary throttle shaft is not too loose in the casting. If it is, look for another one, or buy a new carb. Keep asking questions. you're doing fine.
 
Anybody know as far as cost for a valve job? I read the article on BJR's site, lots of great info. If I don't port the heads and just get a valve job done, about how much power would I give up compared to a bowl blend and gasket match (all other things being equal)?
 
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