Cam advice for ill advised 318 combo?

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motorpirate

serial mopar owner
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I plan on building an engine from "shop sweepings" I know it's less than ideal but I know someone has been there before me and found something that at least sort of works so here goes.
Parts list:
Stock '73 318 short block 50K miles can still see cross hatch in cyls
Stock '69 J heads W/ 202 intakes. aftermarket stainless valves
Stock rockers or 273 adjustables
Edelbrock Performer intake W/ Thermoquad


Now I know those big valves are going to bleed off a lot of compression and I didn't have enough to start with.

Any cam suggestions for this combo? Fess up I know someone here has done it before!!

Or am I better off with the 2bbl cam in it now?

Headers or stock manifolds?

I know this is less than ideal and I intend to move the top end to a 360 eventually but I would like to drive the car in the meantime..

Am I nuts?? or will it be such a pig I should find a 2bbl top end for it?
I hate to buy a cam I cant reuse but buying heads/intake /carb I wont reuse seems like an even bigger step backwards.

Thanks, and don't hate me...
 
The large valves do not bleed off compression.
Yes to headers and 273 rockers
The Edelbrock Perdormer is equal to the OE 4bbl. I take.
Keep the TQ if it works good.

What is the compression ratio. Calculate it with the head gasket your going to use.
What is your I tended gear ratio a d tire size?
Are you willing to purchase a high stall converter?
What trans?
What is the desired goal?
 
Car is a "74 Duster with 3.25 gear and 235/70/15 tires
Hadn't thought of a converter..Suggestions?
I have no idea on compression. Stock pistons about .040 down the hole and the J's are not milled.
My real goal is to have it perform better than a 2bbl 318 (not be an embarrassment to itself) until I can build a legit 360 bottom for it....
 
MP thin head gaskets, the Summit "small" camshaft, cheapie small tube headers. If you want a little more romp the Comp Magnum 270S would be fun.
 
The open chambered heads may be hurting compression. Why not have them planed and run a thin head gasket to bump the compression up a little and then choose your cam. A reputable machine shop will plane heads for cheap $. I have done this on low compression 340s and achieved huge gains
 
If you get a set of 10.5 pistons, with the J heads on the 318 your final compression ratio will be 9.2:1. Otherwise you'll be below 8:1 with stock pistons.

a stock 340 cam or close (260 - 270) duration will work nice with a set of Rhoades variable duration lifters.

I ran a similiar combo before and got 17.75 MPG with 2.76 axle.
 
MP thin head gaskets, the Summit "small" camshaft, cheapie small tube headers. If you want a little more romp the Comp Magnum 270S would be fun.
Summit shows a 272/272@454 lift. Do you mean this one?
I looked for the Magnum 270S...It comes up a SB Chevy cam??
Camquest gives me 2 at the bottom (most conservative?) 262/270 @462/470 and 268/268 @454 is the split pattern better for my bigger intake valve than I need VS unported exhaust?
 
The open chambered heads may be hurting compression. Why not have them planed and run a thin head gasket to bump the compression up a little and then choose your cam. A reputable machine shop will plane heads for cheap $. I have done this on low compression 340s and achieved huge gains
How much can I plane them before creating valve train geometry problems beyond what the 273 rockers can deal with?
Thanks for all the input guys..Keep it coming!!
 
The stock cam pretty weak any performance cam is a major improvement I'd go with a comp xe262h or similar cam from voodoo or whoever, from what I've read in the forums here the actually 318 chambers come out to about 68cc and 340-360 are about 72cc which if you mill them .020" should even them out with a thin gasket, I wouldn't mill the crap out of them just to gain a little CR.

P.S. if your thinking a 262 cam is too small it's a lot more cam than the stock 340 cam if you look at there .050" specs.
 
The stock cam pretty weak any performance cam is a major improvement I'd go with a comp xe262h or similar cam from voodoo or whoever, from what I've read in the forums here the actually 318 chambers come out to about 68cc and 340-360 are about 72cc which if you mill them .020" should even them out with a thin gasket, I wouldn't mill the crap out of them just to gain a little CR.

P.S. if your thinking a 262 cam is too small it's a lot more cam than the stock 340 cam if you look at there .050" specs.
Thats exactly what I need to Know. At .020 surely no problem for the 273 rockers to accommodate the change and they still would be useful on the 360 later.
It looks like I can be up and running for $500 with cam/lifters/headers/gaskets.
I just want as much cam as I can get without going overboard(don't we all?)

Thanks Guys...
 
Milling heads .020" in your situation is an absolute total waste of money. It takes about .075" to make close to one compression point difference, so .020" is a drop in the bucket. Best thing you can do is sell those heads and buy some 302 castings. That will get your compression close to or possibly over 9:1 with thin head gaskets. The 302 heads will be a much better match for your 318. They will have the correct size ports, smaller, closed chambers to raise compression and the valve sizes will be a better match. Shouldn't be too difficult to sell those 2.02 heads.
 
I have a very similar combo.
Did a re ring on a low mileage 318 block, Put on a set of small valve 360 heads I had on the shelf, 340 spec camshaft, torker 340 intake, eddy 600cfm carb, headers w/ 2 1/2" x pipe exhaust. Then I have a 833 od, 3.23 gears and 275/60/15 tires. It roasts the tires all the way through first gear and gets up and goes pretty decent.

The big thing with a engine with such low compression is timing. You need boatloads of timing! Another thing that helps immensely is lightweight distributor springs. The stock stiff springs that come in the distributor will make this engine seem like a total dog.

Use what you have pick the right camshaft and time it rite and you will have a decent engine for a low budget. :thumblef:
 
Converted suggestion?!?!?!

That comes after the engine is planned out with a known camshaft.

Are you going to reuse those 360 heads? If so, don't mill them.

Go with Mopers suggestion. The 270s cam is also made for every other car manufacturer there is.
 
Maybe do a trade your 2:02 360 heads for some 302 casting heads... Im with RustyRatRod, you would have to mill the crap out of them heads to gain 1 point in compression. I had to mill .080 off of my J heads and run thin gaskets to get compression up to 9.5:1 in a cast crank 340. The closed chambered 302 casting heads will be a much more beneficial to you than 2:02 valves.
 
Unless your gonna port the 302 head the lost of air flow hp ain't gonna be made up by the 302 compression bump and you still have to mill the crap out of 302 to get anything like 9-9.5:1, and the .020" and thin gaskets on the 360 heads will only break even with CR on the 360 head swap, I wouldn't worry about CR just don't go crazy with cam and you'll be fine, it's only a temp engine afterall.
 
MP thin head gaskets, the Summit "small" camshaft, cheapie small tube headers. If you want a little more romp the Comp Magnum 270S would be fun.
I did find the Magnum 270S on Comp's website,A couple questions..
1) do you think this cam is OK with my low compression?
2) why do you recommend a solid lifter cam over a hydraulic?

I'm hip with the solid as I have a 273 in my '66 Cuda and have had too many Slant 6 cars to count, just curious the reason you chose it over the 270H ?

Depending on the response I get to this I will probably go with this cam.

Thanks again
 
I would say it's probably a great little cam to use in a mild engine...not too much overlap, not a great deal of duration, good LSA for a street engine with smaller displacement. I used the hydraulic version in a mild 302 several years ago. It was a nice little street cam. As long as you match the converter and gears to it, it'll probably pleasantly surprise you

From what I read on the description on the 270S grind, it might actually "act" slightly milder than its hydraulic sister cam...but if you have the adjustables, might as well use them :)
 
Yep. I was t going to answer the question posed to Moper but that is about it. I assume you all ready have the pushrods so that would be reused again and save you some bucks. The mechanical pushrods are a different length the the Hyd units.

The cam will also cover a wide rpm and perform well in a stock engine as a excellent upgrade. A wide verity of gear ratios will work fine as well. A stock converter should be acceptable with it as well. Considering the listed parts in your first post, I think this is a good cam to use with those parts and the yet unknown gear ratio or weather or not your willing to change torque converters out.
 
Put the 318 heads back on with a little bigger valves in them and new springs.
Lunati voodoo 10200702 (60402) cam with headers.
This combo will match up with what you have and the stock converter will work.
Degree the cam and tune it.
This should run well till you have the resources for the 360.
 
Yep. I was t going to answer the question posed to Moper but that is about it. I assume you all ready have the pushrods so that would be reused again and save you some bucks. The mechanical pushrods are a different length the the Hyd units.

The cam will also cover a wide rpm and perform well in a stock engine as a excellent upgrade. A wide verity of gear ratios will work fine as well. A stock converter should be acceptable with it as well. Considering the listed parts in your first post, I think this is a good cam to use with those parts and the yet unknown gear ratio or weather or not your willing to change torque converters out.

Yes I am willing to consider changing converters.
My axle is a 3.23 w/235/65/15's
Sounds like the 270S is my cam.
Only other thing I can think to ask is weather the headers will affect the choke operation of the Thermoquad as the heat riser valve will be gone?

Thanks again
 
3.23s shouldn't give you any issues with that size tire. The only departure I would make from rumble's advice would be with the converter. The cam description says a stock converter is acceptable for matching components, but depending on how you want it to accelerate from a dig, I'd (personally) choose something about 2200-2500 RPM because of the lower static compression ratio and the cam suggests power band starting about 1800. You could advance it a few degrees and try to help out the bottom end a little..JMO though-take it with a grain of salt.

Although I can't be too sure regarding the choke, but I'd venture to say it may be a little delayed by comparison to manifolds.
 
It is not my advice to stick with the OE converter though it would work OK. This is why I kept asking the question(s) I did. When the poster posts his question, It is often left out of the question in the description of what they have. Sometimes a converter change is not in the wallet.

I like the converter suggestion you gave. This will help get the car moving out of the hole better. It makes good sense.
 
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