First engine build

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dickey_440

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I'm starting my first engine build and wanted to get some advice. Car is a 73 swinger mini tubed 8 3/4 4.10 gears, 727 2800-3200 stall. I just got the motor tore all the way down and am going to recam it. It's a 30 over 69 340. TRW 12.5 to 1 pistons and it had an Isky 296/555. X heads. I'm wanting a good street/strip car and was trying to get some cam recomendations. I have a Holley strip dominator that I was planning to use with a Holley 750. This is my first build and I am really enjoying it. Any advice would be appreciated!
 
First, let us ask you a few things. Are you going back with all that compression? Nuthin at all wrong with it, just askin. That'll help with the cam choice. Course you KNOW it won't be a pump gas motor. A big cam will help, but with iron heads and true 12.1 it ain't gonna happen.

What kinda limitations we got to work with? Hyd flat tappet? Solid flat tappet? Hyd roller? Solid roller? I guess that's a polite way of askin how deep are your pockets? lol

Lastly, lets us know what bolt ons you plan to run. Intake, ignition, type headers, primary and collector sizes. The Strip Dominator is ok, but again, this is 2013. There are a lot better choices.....but the Holley WILL work.

I believe you'll find there are much better choices than X heads out there today. I mean night and day difference. But if you wanna run um, go for it. Nothin I love more than a sho nuff old school build and that would sure be it.
 
Thanks for the reply. I am planning on staying with the current set up as far as heads/pistons. MSD 6al. I'm going flat tappet and would be ok with solid or hyd. I am going to be getting Tti headers but not sure of the size yet. I currently have a Holley strip dominator and an old edelbrock torker, but I have been looking at dual planes as well. This will be a weekend cruiser/occasional strip car so I have no problem running high octane fuel.
 
Cool. Sounds like my kinda build. I never had problems with race gas either. You sure won't be drivin it everyday, but when you do, it will be fun.

I'm gonna veer off the beaten path with a cam recomendation. You're whoppin up a nice old school build. So, keeping that theme in mind, I think an old school cam company will fit the bill. I like this one.

http://schneidercams.com/292-96FLAsolid.aspx
 
That's what I'm looking for as far as duration and lift but was hoping to get a little more low end, say a range of 1800-6000 or 2000 to 6200. I don't plan on winding the motor up past six grand very often. Is that a realistic expectation or will a cam with that range be to small for this amount of compression?
 
I have been looking at comps 20-227-4. 225/525 and lunati voodoo 273-360 276/284. .513/.533. That is about all I have found that is in the power band I was hoping for
 
Certainly you can go with something smaller, but it wouldn't be a matched combo. I would tune in some bottom end responsiveness through the timing curve and carburetor and valve adjustment. Remember, those RPM ranges are meant only as a guide. You can taylor at least 1K RPM either way through tuning, maybe more. Also don't forget, you can advance the camshaft timing and gain a lot of bottom end that way as well.
 
One more thought would be to get them to grind it on say a 110 or even a 112 LSA. That would jack up bottom end torque and flatten the torque curve out a good bit. It would even smooth out the idle for better streetability and give more vacuum signal.

One more thing. LOL

When you say "12:1" keep in mind that may not be the actual measured compression ratio. I would hold off on any cam choice until I knew for sure what the head chamber volume is, where the pistons sit in the bore at TDC, what head gasket you'll run......all that. Figure your ACTUAL compression ratio first. It may fall well below 12:1 and if it does, that will certainly open the door for some choices that would have the RPM range in the bottom end you're looking for. I think setting a decision in stone before you know all of that will be a mistake.
 
Ya the cam stuff is a bit premature. I'm having the machine shop take a look at the block this week and getting the heads cc'd to get a better idea of where I am at. Thanks for the advice.
 
Ok I am looking for some more advice. The 340 checked out fine at 30 over. I have decided to make this build a little more street friendly and I want a compression range of 9.5-10.0-1 . Problem is I cant seem to find any pistons that will get me there. The X heads checked out at 74cc. I have called several piston companies with no luck. Ross racing said without having the heads milled my only option was getting a set of dome pistons and having them cut. Anybody know of any pistons I haven't found yet? Most companies I have looked into offer very few options in the 340 unless you are going stroker.
 
RustyRatRod said:
First, let us ask you a few things. Are you going back with all that compression? Nuthin at all wrong with it, just askin. That'll help with the cam choice. Course you KNOW it won't be a pump gas motor. A big cam will help, but with iron heads and true 12.1 it ain't gonna happen.

What kinda limitations we got to work with? Hyd flat tappet? Solid flat tappet? Hyd roller? Solid roller? I guess that's a polite way of askin how deep are your pockets? lol

Lastly, lets us know what bolt ons you plan to run. Intake, ignition, type headers, primary and collector sizes. The Strip Dominator is ok, but again, this is 2013. There are a lot better choices.....but the Holley WILL work.

I believe you'll find there are much better choices than X heads out there today. I mean night and day difference. But if you wanna run um, go for it. Nothin I love more than a sho nuff old school build and that would sure be it.
Click to expand...
was looking at a dyno test on various sbm intakes,best single plane only 6 hp better then holley intake...
 
You could order custom Cometic head gaskets.Not cheap,any thickness you want. Food for thought.I like the compression, on this one.And the solid you have. My .02 cents.
 
dickey_440 said:
Ok I am looking for some more advice. The 340 checked out fine at 30 over. I have decided to make this build a little more street friendly and I want a compression range of 9.5-10.0-1 . Problem is I cant seem to find any pistons that will get me there. The X heads checked out at 74cc. I have called several piston companies with no luck. Ross racing said without having the heads milled my only option was getting a set of dome pistons and having them cut. Anybody know of any pistons I haven't found yet? Most companies I have looked into offer very few options in the 340 unless you are going stroker.
Click to expand...

This is interesting as the stock '69 340 head (2531894) shows to have a 63 cc chamber. The only LA head near that size was the 318 Cop Car head (4323345) which had a 75.1 cc chamber. This head had the 1.60 exhaust valves, but the intake valves were 1.88 inches like the 72 & 73 340s. Parenthetical numbers are the casting numbers for the heads.

Assuming that your head cc numbers are correct, I'd be inclined to drop a +.030 stock replacement piston and a thick head gasket into it and call it done. I've heard that Mopar tended to be a bit generous in their published compression ratios.

If you don't think that will work, how about the Keith Black KB243? Sportsman Racing Products also has a piston that looks like it will work, but I haven't, nor do I know anyone who has used their pistons.

With the compression ratios you're talking about, look at cams in the 215-224º duration @ .050". Power band is 200-4800 rpm, torque band is 2,500-4000 rpm. Cams toward the high side of the range may require a reserve vacuum tank. To get the most out of the cam, plan on a 3.55:1-3.73:1 rear gear.

Enjoy the build. Don't stress. When you hear your baby turn over for the first time and not spewing fluids, a lot will be forgiven.
 
ive been reading about your build. one thing i dont like on the street is the use of 12;1 compression pistons. i personnally think that your goal of using a compression ratio around 9.5 to 10.0 to one makes way more sense on pump gas, which is street use . one good old way of doing this is to use trw/ speed pro pistons number l2316. with a .030 cut on your x heads at 74cc ,you will get 68cc and 9.8;1 ,which is around your goal. now for a camshaft to use with this and using the 3000 rpm stall torque converter ,i would use a comp xe275-hl cam (20-227-4) so that your operating range is from 2000-6000 rpm, like you expected. i have never used that particular cam, but have seen good hp numbers in several builds from it, mostly in a street application. as far as intakes ,i think the strip dominator would loose way too much torque in a stock-stroke engine like yours . you would be better off with a good dual plane intake and you probably wouldnt loose any hp with a large gain of torque with this engine. recommended intakes would be; rpm air-gap, ld 340 or performer rpm, in that order. i have used the first two with very good results. switching to a strip dominator was slower at the track in my case.
 
The stock 68-71 340 pistons will get you in your compression range you've chosen. You may need to mill the heads a bit, but those pistons will get you there. They were rated at 10.2 at a 65 CC chamber. 74 CC heads would probably drop exactly 1 full point off that. between some light milling and a thin head gasket, you could easily get to 9.5 to 10.1 with the early 340 piston.
 
Thanks for all the replies and the good info. After a lot of research I decided on the KB243s. Then my dad called this morning (he is helping me put this build together) and offered to buy a stroker kit as a birthday present. What are your thoughts on the below kit with my X heads (which will receive a port job.) I am also going to have the CC's checked again because everyone I have talked to has a hard time believing X heads are coming out at 74.

http://www.hughesengines.com/Index/...el1=MzQwLzQxNiBTdHJva2VyIEtpdHM=&partid=25285
 
Stroking it is the way to go for great power and streetability, only thing is a stroker needs to breath and while X heads are ok for a 340 their barely adequate when you start talking 400+ cubic inches. They'll make good low end torque but run out of air above 5000 rpm real fast even if you use a big cam. Just something to keep in mind. Also keep in mind a solid flat tappet cam will make more power all the way through the rpm range over a hyd. flat tappet. If you have adjustable rockers or can afford to get some a solid is the way to go. And don't believe the crap about needing to adjust them every month. The old stuff made 30-40 yrs. ago may have been that way but with today's tight lash cams once a year is usually sufficient for a street car. I used a solid in my 408 when I built it and in 4000 miles the lash only opened up .001-.002"...

74 cc's from stock X heads is about right. The published figure of 68 cc's from Chrysler were very generous. I had a set of X heads that had been milled .030" and they cc'd at 72 cc's. Most small block 340 and 360 La heads were 70 cc's or more from the factory and every time the valves got ground it dropped the valves farther in the chambers upping the cc's. And the type of valves used in them can also make a big difference. I installed a set or REV stainless valves in those same X heads without doing anything else and it dropped the chambers to 66 cc's.

If you do go the stroker route also keep in mind it takes a lot more cam to spin the same rpm. I'm running what I consider a very small cam for a 408. It's 239 degrees at .050" and .520 lift and runs the best when I shift it at 5600.

Sell both the intakes you have and buy a Eddy. Air-gap. Can't beat it for the street.

Keep in mind one more thing, gears. Those 4.10's are a killer on the street. My Cuda had 4.10's in it when I bought it and I hated them. Only thing they were good for was take off. Could barely run 60 down the highway or it sounded like it was gonna throw a rod I put 3.55's in it and with the stroker it runs like a scalded dog and cruises great at 65-70 mph.

The Hughes stroker kit looks good
 
Understand the budget thing. That cam with those heads will be a stump puller. It's a little smaller than what I've got in my 408 so expect the rpm range to be somewhat lower. Probably peak out at around 5000 with the X heads.
 
dickey_440 said:
Ok I am looking for some more advice. The 340 checked out fine at 30 over. I have decided to make this build a little more street friendly and I want a compression range of 9.5-10.0-1 . Problem is I cant seem to find any pistons that will get me there. The X heads checked out at 74cc. I have called several piston companies with no luck. Ross racing said without having the heads milled my only option was getting a set of dome pistons and having them cut. Anybody know of any pistons I haven't found yet? Most companies I have looked into offer very few options in the 340 unless you are going stroker.
Click to expand...
I'm using Mahle 10.5-1 forged pistons on my .40 over 340 . So far have 10,000 miles on it and it runs great , burns no oil has great compression . They are coated with something , forget what . They are light as well .
 
And the next question is if I had my heads milled and the block decked would that throw off the valve train geometry? I have stock push rods and stock 1.5 adjustable rockers.
 
dickey_440 said:
http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=671&sb=2
Ok how about stepping up to this cam. With the pistons from the Hughes assembly and if my heads cc out to 74 I will be in the 9 to 9.5:1 compression range. I am also assuming that I will need to get the block milled to .000 deck.
Click to expand...

That's a real good cam if you don't mind a pretty choppy idle. The 1st one you mentioned will be a lot milder but still idle with some authority.

dickey_440 said:
And the next question is if I had my heads milled and the block decked would that throw off the valve train geometry? I have stock push rods and stock 1.5 adjustable rockers.
Click to expand...

It won't affect valve train geometry at all because the only way to affect geometry is to raise or lower the rocker shaft. The rocker shaft height is fixed on a Chrysler LA engine. Completely different than a Chevy. You will probably need some shorter pushrods and may have to have the intake side of the heads milled or the intake won't fit right. It's generally good practice to have the intake side of the heads milled .0095" for every.010" you take off the chamber side.
 
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