Help with sb combo

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supersean

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m putting a mild 340 back together to hopefully run this coming season. Im torn between what intake and cam I should use. Car will be raced not street driven, only the occasional car show.

340 - .30 around 12 ish comp
TRW pistons
Worked stock 340 rods
318 crank
J-heads milled with a lil work and large valves
904 w/9 in conv stalls around 4500+ on fb
750 Holley

Before anyone says anything about getting new pistons/rods, that isnt an option. Im using what I have unless something ends up being broke. that being said what intake and cam do you all recommend? A few options Im considering

296/ .557 cam
296-298 . 577 int .555 ex cam
or suggestions??

Mopar single plane or Air Gap??
 
I also replied at the other joint , but I'll throw out some generalities.
Heavier car will like the dual plane intake and I'd cam for more grunt than r.p.m.
The 750 c.f.m. carb could be small if you plan on spinning the motor hard too.
Are you thinking big hydraulic or solid ?
I would call Bullet cams and tell them what your combination is.
They will recommend a cam that is going to be very effective for your real world end use.
 
I was planning on a solid, the one cam is a Schneider cam and i told him what I was planning and details on the car. Will probably run around a 4.56 gear and yes the car should be around 31-3200 isn
 
As "tubtar" said, talking with some different cam companies can give you a lot of info. I'm thinking the Victor340 intake and a cam somewhere in this range will get you started.......
http://www.summitracing.com/parts/CCA-20-231-4/

I'm staying a little conservative with the "J" heads and unknown flow numbers. I like the single plane for the fact that with the 750 carb will still have decent mixture velocity.

Until you get some passes under your belt, it's a little hard to narrow down on a exact combination. I would think your gonna be using slicks around 28" tall at the track?
 
supersean said:
I was planning on a solid, the one cam is a Schneider cam and i told him what I was planning and details on the car. Will probably run around a 4.56 gear and yes the car should be around 31-3200 isn
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Open plenum then I think.
You aren't going to be lugging with that gear.
Probably a little less cam than you show.
OldmanRick's pick for the same reasons would be a decent choice.
I might even settle for a hydraulic just for the put it away wet factor.......less maintenance and potentially better reliability.
Something like this
http://www.summitracing.com/parts/LUN-10200705LK/
 
yes i was planning on a 28 in slick. I forgot that I actually have a Racer Brown STX 19M that I picked up the other day cheap, would that be a decent cam? Thanks for the help guys
 
supersean said:
yes i was planning on a 28 in slick. I forgot that I actually have a Racer Brown STX 19M that I picked up the other day cheap, would that be a decent cam? Thanks for the help guys
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That baby is stout in the duration dept...lol. I've found two numbers, [email protected] & [email protected].? You could give it a shot since you already have it, but be prepared to spin it pretty tight. Your gear and converter may be just enough to do alright with it. Power curve would definetely be upstairs in a 340. Surely would like the single plane intake and probably a good size primary tube header. Lets see what some others think? Would be curious to see thoughts on the power range with that cam and the worked J heads too?
 
I wonder what the rpm range is on that cam? been meaning to call but havent had a chance. Wouldnt mind using it being that ive already got it but dont want to have to turn the motor sky high with it either.
 
supersean said:
I wonder what the rpm range is on that cam? been meaning to call but havent had a chance. Wouldnt mind using it being that ive already got it but dont want to have to turn the motor sky high with it either.
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That's a good idea. My thought was that peak torque would probably occur around 5000 rpm's and would the heads/motor be able to pull high enough so the 1-2 shift rpm drop would't be too much and take it out of the sweet spot. A little slow here on the weekend, but i'm sure some more opinions will come in eventually. Gonna watch a little football, have a good afternoon Sean.
 
OldmanRick said:
That's a good idea. My thought was that peak torque would probably occur around 5000 rpm's and would the heads/motor be able to pull high enough so the 1-2 shift rpm drop would't be too much and take it out of the sweet spot. A little slow here on the weekend, but i'm sure some more opinions will come in eventually. Gonna watch a little football, have a good afternoon Sean.
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That's asking a lot of stock rods and heavy pistons I think.
Not what I'd call a " mild " 340.
Sure.......it would work.
But I don't think it would be optimum.
 
tubtar, when i said good idea, just to be clear, i meant good idea to find the range of that Racer Brown cam. I agree with you that the TRW pistons are heavy and the required rpm range is getting a little high. Sean, i don't know the exact specs, but the duration numbers i found were a concern. The Hughes cam sited may lower the torque peak some which i would consider a good thing. I do know that with the 106* LSA that would be one nasty soudin' MF........lol. tubtar and i both started off being a little conservative and i'm still leaning that way. A cam with peak torque around 4500 and a hp peak in the 6500 rpm area would be my choice with the current set up. Should make a little over 400hp and be capable of 11's at 1teens shifting around 6800 and clearing the traps at 65/6800.
 
yea i know that the old trw's are a lil hevy but hate to spend uneeded money when i dont have to. i may try callinga few places this week and geeting a custom ground cam
 
I am thinking that you want a big cam , but don't really have parts to support it.
The heads are strike one.
The carb is too small for making big power at big rpm.
The pistons and rods will work , but you will be working them as hard as they want to be worked.........I like to have a bit of a margin or over build for reliability's sake.
Something in the .550 lift and 240ish @.050 will be a lot easier on parts and need less expensive parts like valve springs and pushrods to keep happy.
And should give you plenty of power to churn out low 7's in the 1/8th.
The more radical the valve train , the more you want better components involved.
This way , you are building more of a motor and less of a grenade.
If it were me and I was doing a similar build , I'd focus on something that will make laps and not give me headaches......in the head or the wallet.
As noted above , you can do what you want on pump gas if you have well matched parts.
 
OldmanRick said:
tubtar, when i said good idea, just to be clear, i meant good idea to find the range of that Racer Brown cam.
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We definitely park our cars in the same garage Sir.
I like the conservative approach here too.
I know there are shelf grinds that will work just fine and the numbers will not be as big as Sean seems to want , but will work a lot better.
More is not always better.
 
tubtar i completely undersand that bigger isnt always better, im not here asking if a huge roller will work with my stock stuff just asking for what people have found to work best. im not going to over cam but nor do i want to undercam either
 
For me, i think i'll go back in the direction that i originally posted.

http://www.summitracing.com/parts/CCA-20-231-4/

Should bleed of enough compression to run pump gas and still run strong. May not produce maximum power, but if you want to bracket race and win some rounds, you want a crisp clean runner that doesn't need alot of work and can make pass after pass. Your carb, converter, gear along with the single plane and a min. 1 3/4" header should be a fine bracket set up and still be able to hit the cruise in and show when the desire hit's.


P.S. I should have qualified my comment on pump gas as i believe with a stock cc chamber, if not heavily milled, and most of the TRW's that were available, i don't think the comp ratio would be as high as 12.0. If it is, i would have to rethink my cam choice. Only proper measurements and head gasket choice would tell the whole story.
 
Seen a similar grind,in a 340.11 to1 ,4.56.s./4200 stall.Peak torque,5000 ish, Peak h.p.,6300,6500 zone.Ran 1160/11.70's consistently.Nice cam choice,on the Comp solid.
 
Which TRW pistons do you have? What is your local definition of pump fuel? What work to the heads?
 
Pistons I have no clue, had them for a long time. Local pump gas is 93. Heads have been ported and polished a lil and has big valves
 
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