340 Street Build

[1badfish67]

Getting ready to tear down the 340 in the 67 Barracuda and looking for a few pointers. This car most likely won't be run on the track just looking to build a strong street engine. Car is a 4pd setup with 3.23 Sure Grip/489 case. Before I pulled the engine I ran a cold cranking compression test on all cylinders. Numbers ranged from 168 to 172psi. It has been bored 0.030 as I can see stamp on pistons using bore scope but nothing else. Engine looks very clean, at least under the valve covers as there is absolutely no sign of sludge in that part. Clean as a whistle. It is a Nov 71 block with 72 4bl intake and manifolds. Heads appear to be 72 J heads. I don't know the current cam, piston, crank (Cast/Steel) or head specs but the heads, intake/exhaust manifolds are going to be swapped out along with rocker system.

I don't mind needing to run say 91 octane fuel as it's pretty common around here where I live in Oklahoma. Want to avoid abnormal detonation. Had a SBC 350 when I was a teenager that gave me fits in the summer time. Sometimes had to put it in 4th and drop the clutch to shut it off. It's CC psi was about 205. It does get a might warm in the summer here. We hit 106F ambient here last week. This won't be a daily driver and shouldn't be spun a lot unless we get a challenge and then guessing maybe ~ 6200.

Here is what I have in parts at this time.


235/60/14's on rear
Holley 770cfm Street Avenger Ultra
ProMaxx 171 Heads (65cc) 2.02/1.60
Edlebrock RPM Airgap Intake
PRW roller tip rocker system

Been looking at the COMP XE274H
230/236 @ 0.050"
Lift Int: 0.325
Lift Exh: 0327
Using 1.5 ratio rockers
LSA: 110
ICL: 106
IVC: 63

Nothing definite on the cam until I can get into the engine and check piston location at TDC, see if flat, dish or dome and get some info off the end of the cam. Hopefully grind # may be there?

All that being said, any of you folks have any good SCR/DCR numbers to shoot for on a strong street build to avoid ping/knock with 91oct without need to fiddle -/+ timing? Also good cylinder pressure to shoot for? My thoughts on HP and TQ were in the neighborhood of 425 or so HP and 400 lb-ft TQ out of it. Is that doable and not be a pain to drive on the street in a 340 or out of the question?

Sure I have probably left out some important information but will supply if I have it.

 

[1badfish67]

Sorry, forgot to ask about good quench distance for the application.

 

[junkyardhero]

that'll be a little lopey for a 340 street car, but you've got a 4spd to back it up and with those current SCR numbers i'd say the compression as well.

personally, i'd tear it down and see what cam it has and make a determination from there. if you have a stock cam, that's a big jump. if you have say, a 268 then not so much.

anyway, once you've got it apart you can see where the pistons are at in the hole, then CC your heads and determine the direction you want to go.

 

[Mopar69gts]

The parts you have so far look good to me.
Very similar to my 340 that runs on 91
Since you have adjustable rockers I would go with a Solid Flat tappet Cam.
Just too many issues with Hydraulic lifters these days.
Solids will almost always make more power and rarely need adjustment.
Really no down side IMO
keep in mind when comparing Solid to Hydraulic cams, a Solid will have about 8-10 degrees more duration @.050
(To account for lash)
So around 238-240 to be close to that Comp. 230 your looking at.
Talk with a Cam company like Bullet or Howard's for their recommendation.
Have Fun with your project!!

 

[1badfish67]

that'll be a little lopey for a 340 street car, but you've got a 4spd to back it up and with those current SCR numbers i'd say the compression as well.

personally, i'd tear it down and see what cam it has and make a determination from there. if you have a stock cam, that's a big jump. if you have say, a 268 then not so much.

anyway, once you've got it apart you can see where the pistons are at in the hole, then CC your heads and determine the direction you want to go.

The car was running when I bought it. If it's a stock cam it may be something like maybe a 262 or 268 adv duration cam. It did have some lope to it but nothing like the 280H Comp Cam I had in the SBC 350. Didn't think about CCing the new ProMaxx heads. Hopefully will find some cam info and possibly piston manufacturer and number on the pistons when I get in there.

 

[1badfish67]

The parts you have so far look good to me.
Very similar to my 340 that runs on 91
Since you have adjustable rockers I would go with a Solid Flat tappet Cam.
Just too many issues with Hydraulic lifters these days.
Solids will almost always make more power and rarely need adjustment.
Really no down side IMO
keep in mind when comparing Solid to Hydraulic cams, a Solid will have about 8-10 degrees more duration @.050
(To account for lash)
So around 238-240 to be close to that Comp. 230 your looking at.
Talk with a Cam company like Bullet or Howard's for their recommendation.
Have Fun with your project!!

Thanks. I was planning on calling Howards and Hughes Engines when I get more information after tear down. Also considering Jones Cams. Hughes claims to have a better lobe/ramp speed setup for the Chrysler engines designed around the 904 lifter. Hughes also mentioned having some "Stiffer" than stock lifters in the 904. Any experience with Hughes in this aspect? I may also consider the solid flat tappet. I wasn't sure about using a solid for street application and I don't have much experience with the solid lifters (Except for setting lash on an old VW bug) my wife had 30 years ago.

I ran Sealed Power hydraulics lifters in that SBC. Put a lot of hard miles 100k ++ on that old 73 Nova. It was my daily driver as well. Hard, I mean drag racing folks with several 1/4mi runs every other weekend but I was only about 18 or 19. I'm sure it was nothing like folks on here do but to a kid it was a big deal. Oh what memories!

 

[Mopar69gts]

Thanks. I was planning on calling Howards and Hughes Engines when I get more information after tear down. Also considering Jones Cams. Hughes claims to have a better lobe/ramp speed setup for the Chrysler engines designed around the 904 lifter. Hughes also mentioned having some "Stiffer" than stock lifters in the 904. Any experience with Hughes in this aspect? I may also consider the solid flat tappet. I wasn't sure about using a solid for street application and I don't have much experience with the solid lifters (Except for setting lash on an old VW bug) my wife had 30 years ago.

I ran Sealed Power hydraulics lifters in that SBC. Put a lot of hard miles 100k ++ on that old 73 Nova. It was my daily driver as well. Hard, I mean drag racing folks with several 1/4mi runs every other weekend but I was only about 18 or 19. I'm sure it was nothing like folks on here do but to a kid it was a big deal. Oh what memories!

Sounds good!
Yes definitely get a Mopar 904 specific Cam.
Might as well take advantage of the larger lifter diameter that's a good thing!
When buying a new cam there's no reason not too.
All the companies you mentioned offer them.
B.t.w. Howard's makes Hughes Cams.
Adjusting Solids is an easy job.

 

[RustyRatRod]

"They say" .035" is about optimum quench distance. Although on my current slant six build, it's likely to set up somewhere around .025" or so. I've heard people have run as tight as .018".

 

[1badfish67]

Sounds good!
Yes definitely get a Mopar 904 specific Cam.
Might as well take advantage of the larger lifter diameter that's a good thing!
When buying a new cam there's no reason not too.
All the companies you mentioned offer them.
B.t.w. Howard's makes Hughes Cams.
Adjusting Solids is an easy job.

Would solid tappet produce more consistent valve opening at the upper end of that 6200ish rpm range? I had valve float on that SBC once after missing 3rd gear. Exhaust valve hit piston and bent valve. Luckily had TRW forged flat tops in it. It only put a faint scratch on the piston. That was only a few weeks after my dad and I had put it together. Cut in new valve, junked the old HURST shifter and put in a Mr. Gasket Pro shifter with extra small pattern. Not saying anything bad about the HURST, it just had too long of a pattern and handle. My knuckles hit the radio knob is how I missed 3rd gear that night. It was the shifter that was on the Muncie when I bought it.

Had no idea Howard's made the Hughes camshafts. Crane and Comp hydraulic cams are all I have ever dealt with to date. What about the SCR, DCR, Cylinder pressure and quench numbers. I mentioned the existing psi was between 168-172 psi. I was thinking of bumping to around 190-195 with those new aluminum heads, if the 91oct could handle it.

 

[fishmens67]

"They say" .035" is about optimum quench distance. Although on my current slant six build, it's likely to set up somewhere around .025" or so. I've heard people have run as tight as .018".

I've seen it close enough to take the carbon off. lol

 

[1badfish67]

"They say" .035" is about optimum quench distance. Although on my current slant six build, it's likely to set up somewhere around .025" or so. I've heard people have run as tight as .018".

Sorry RustyRatRod. I didn't see your response earlier. Thanks for the information.

 

[Mopar69gts]

Would solid tappet produce more consistent valve opening at the upper end of that 6200ish rpm range? I had valve float on that SBC once after missing 3rd gear. Exhaust valve hit piston and bent valve. Luckily had TRW forged flat tops in it. It only put a faint scratch on the piston. That was only a few weeks after my dad and I had put it together. Cut in new valve, junked the old HURST shifter and put in a Mr. Gasket Pro shifter with extra small pattern. Not saying anything bad about the HURST, it just had too long of a pattern and handle. My knuckles hit the radio knob is how I missed 3rd gear that night. It was the shifter that was on the Muncie when I bought it.

Had no idea Howard's made the Hughes camshafts. Crane and Comp hydraulic cams are all I have ever dealt with to date. What about the SCR, DCR, Cylinder pressure and quench numbers. I mentioned the existing psi was between 168-172 psi. I was thinking of bumping to around 190-195 with those new aluminum heads, if the 91oct could handle it.

Yes Solids are more consistent
Nothing to pump up or bleed down.
The lifters are lighter so that will also help higher rpms. Usually adds about 500 rpms to a similar Hydraulic cam.
Quench is also a good thing when you can .030 to .045 is common
My 340 has 195 lbs Cranking Compression, runs on 91.
Timing is a bit sensitive about 30 total.
But with aluminum small chamber modern heads and flat top pistons that's actually not a bad thing.
Keeping Engine temperature down is key as well.
Good as large as you can fit radiator, Shroud and Fan/fans
Is a huge deal.
Especially where I live in Phx.

 

[1badfish67]

I've seen it close enough to take the carbon off. lol

Yes sir. That's pretty close.

 

[RustyRatRod]

I would like the Comp 270S for this build, there's just one problem. I wouldn't put a Comp cam or lifters in anything at this point. I bet Oregon Cams could grind you one.

 

[1badfish67]

I would like the Comp 270S for this build, there's just one problem. I wouldn't put a Comp cam or lifters in anything at this point. I bet Oregon Cams could grind you one.

Bad experience with the Comp stuff? That old Nova ended up with over 200k on it in the end. I used micrometer on the lobe bases and peaks to check it for wear and typically saw only a couple thou down from original measurements prior to install but that was quality back in the mid 80's. Can you share details of issues?

WRT the cam grind, not sure I have enough cam knowledge at this point to spec a custom grind but I ain't afraid to research, listen and learn.

 

[RustyRatRod]

Comp has been having cam and lifter issues now for a long time.

 

[1badfish67]

Comp has been having cam and lifter issues now for a long time.

Good to know.

Engine is on the stand right now. Soon as I get some A/C working in my shop I plan to start the tear down. Hopefully get a start of weather cool down around here in a few weeks as well. I'm ready!

 

[1badfish67]

Looking at a few cam options on Bullets website (HC275/333; HC276/334; HC280/335). Anyone know if they publish estimated rpm ranges somewhere on their cams? It looks like these cams are single vs dual profile cams as I didn't see separate lift/dur numbers for Int & Exh?

I read somewhere or maybe saw a video where someone was referencing chamber pumping volume to head flow volume numbers to determine if a dual profile cam was recommended but it's been a while and don't remember exactly where the information originated.

Also, the ProMaxx flow charts indicates that the 171 mopar heads get very close to peak flow at 0.500" lift (251 @ 0.500" vs 254 @0.600" lift). Is there any reason to go much above 0.500" with these heads, assuming valve to piston clearances are in check at 0.500".

 

[AJ/FormS]

build a strong street engine. Car is a 4pd setup with 3.23 Sure

With 3.23s and a 2.66 low gear, yur gonna need a stout bottom end, and the ability to be able to idle along in first gear.
If yur engine won't idle down to less than 750 rpm, then, with your 235/60-14s at say 25.5 diameter, the slowest you will be able to drive, without slipping the clutch, will be ~6.2 mph. Therefore, parading is out.
Furthermore:
if you cam it for peak power at 5200, then the torque peak will come in at around 3700. Which, with 3.23s in First gear will be, ~33 mph. In other words, 33mph is where the torque peaks and the power begins ...... so below that, if the tires are not spinning, you better have a back-up plan, or you will be slipping the clutch to get there.
in my 367, I have a cam pretty much like you have. Except I run it at 10.9 Scr and close to 180 psi. My first gear is equivalent to 4.10s, and I wouldn't want to go much lower. But My engine will idle down to 550 in gear which is 4.0 mph. If I retard the timing, it will go to 500rpm/3.5 mph, and has just enough power to pull itself on flat/level/hard ground, but nothing extra to, say, climb over a dime, lol.
point being, consider how and where your combo will be driven.

 

[273]

Looking at a few cam options on Bullets website (HC275/333; HC276/334; HC280/335). Anyone know if they publish estimated rpm ranges somewhere on their cams? It looks like these cams are single vs dual profile cams as I didn't see separate lift/dur numbers for Int & Exh?

I read somewhere or maybe saw a video where someone was referencing chamber pumping volume to head flow volume numbers to determine if a dual profile cam was recommended but it's been a while and don't remember exactly where the information originated.

A dual pattern probably make more in most applications.

Also, the ProMaxx flow charts indicates that the 171 mopar heads get very close to peak flow at 0.500" lift (251 @ 0.500" vs 254 @0.600" lift). Is there any reason to go much above 0.500" with these heads, assuming valve to piston clearances are in check at 0.500".

A cam say with .550 lift will spend more time in the cylinder heads peak cfms than a .500, do you need to though ?

 

[RustyRatRod]

I ain't sure I go along with the dual pattern thing. Usually with headers, the single pattern shines brighter.

 

[1badfish67]

With 3.23s and a 2.66 low gear, yur gonna need a stout bottom end, and the ability to be able to idle along in first gear.
If yur engine won't idle down to less than 750 rpm, then, with your 235/60-14s at say 25.5 diameter, the slowest you will be able to drive, without slipping the clutch, will be ~6.2 mph. Therefore, parading is out.
Furthermore:
if you cam it for peak power at 5200, then the torque peak will come in at around 3700. Which, with 3.23s in First gear will be, ~33 mph. In other words, 33mph is where the torque peaks and the power begins ...... so below that, if the tires are not spinning, you better have a back-up plan, or you will be slipping the clutch to get there.
in my 367, I have a cam pretty much like you have. Except I run it at 10.9 Scr and close to 180 psi. My first gear is equivalent to 4.10s, and I wouldn't want to go much lower. But My engine will idle down to 550 in gear which is 4.0 mph. If I retard the timing, it will go to 500rpm/3.5 mph, and has just enough power to pull itself on flat/level/hard ground, but nothing extra to, say, climb over a dime, lol.
point being, consider how and where your combo will be driven.

I see what you mean. Now that I think about it I had that slipping the clutch issue with the Nova and the 280H cam setup. I think it was around 11.25 SCR and 205psi. Didn't want to play nice parading down the street. Also needed a rear gearing upgrade.

Just built a spreadsheet for tire ht, 1, 2, 3 and 4th gear tranny ratios along with rear gear ratios. Looks like the 235/60/14's would be ~ 25.1" tall. 750 rpm puts it at about 6.52 mph at 2.66:1 1st gear with 3.23 rear gears. 2812 rpm to get 65mph 4th gear. Thought about a 3.09 first gear kit for the tranny but would big a larger jump to the 1.91 2nd gear or switch to a set of 3.55 gears. 3.55's show about 3050 rpm at 65mph. Not a lot of mph difference at 750 rpm (5.93 mph) 1st gear with 3.55.

Think going with a little less duration on the cam might help lower the peak torque/HP band some and lower the idle rpm capability? What do you think your DCR is in that engine about 8.5ish?

 

[rumblefish360]

I've seen it close enough to take the carbon off. lol

BTDT

A dual pattern probably make more in most applications.


A cam say with .550 lift will spend more time in the cylinder heads peak cfms than a .500, do you need to though ?

Depends on where flow stalls. For a street engine, I’ll lift the valve to stall or slightly higher but not a lot.

I ain't sure I go along with the dual pattern thing. Usually with headers, the single pattern shines brighter.

Depends on the timing events of any cam installed.

 

[1badfish67]

BTDT

Depends on where flow stalls. For a street engine, I’ll lift the valve to stall or slightly higher but not a lot.

Depends on the timing events of any cam installed.

I ain't sure I go along with the dual pattern thing. Usually with headers, the single pattern shines brighter.

Thought I had mentioned someone talking about dual vs single pattern selection in a paper or video. It was in a video I saw several months ago. The guy is talking about the selection based on on Exh/Int flow ratio of the heads. His breaking point was 75%. Anything above go single pattern, below go with dual pattern profile. Think it may be his personal rule of thumb. Don't know anything about the guy, just ran across his 2 part video on cam selection. He does mostly talk about Fords and Chevys but I would think the basis of air flow would apply across the board. He did say cam lift should be determined by head flow but I think that was in part 1 of the series.

Folks here may have already seen this guys videos. Here is the link to video part 2. He talks about the profiles at ~ t=16:53. At 0.500" lift the ProMaxx 171 flow chart from the manufacturer puts it at about 73.7%. 0.600" lift puts the ratio at about 76%. I was thinking of between 0.491-0.502 or in that ball park based on ProMaxx flow chart. Again, I am learning about more of the finer details matching parts of engine building, so I'm not taking everything I find on YouTube as gold. Parts ain't cheap these days but I guess "cheap" is all relative to the size of your bank account! Lol.

Links, if anyone interested.
Part 1:
Part 2:

 

[mopowers]

Getting ready to tear down the 340 in the 67 Barracuda and looking for a few pointers. This car most likely won't be run on the track just looking to build a strong street engine. Car is a 4pd setup with 3.23 Sure Grip/489 case. Before I pulled the engine I ran a cold cranking compression test on all cylinders. Numbers ranged from 168 to 172psi. It has been bored 0.030 as I can see stamp on pistons using bore scope but nothing else. Engine looks very clean, at least under the valve covers as there is absolutely no sign of sludge in that part. Clean as a whistle. It is a Nov 71 block with 72 4bl intake and manifolds. Heads appear to be 72 J heads. I don't know the current cam, piston, crank (Cast/Steel) or head specs but the heads, intake/exhaust manifolds are going to be swapped out along with rocker system.

I don't mind needing to run say 91 octane fuel as it's pretty common around here where I live in Oklahoma. Want to avoid abnormal detonation. Had a SBC 350 when I was a teenager that gave me fits in the summer time. Sometimes had to put it in 4th and drop the clutch to shut it off. It's CC psi was about 205. It does get a might warm in the summer here. We hit 106F ambient here last week. This won't be a daily driver and shouldn't be spun a lot unless we get a challenge and then guessing maybe ~ 6200.

Here is what I have in parts at this time.


235/60/14's on rear
Holley 770cfm Street Avenger Ultra
ProMaxx 171 Heads (65cc) 2.02/1.60
Edlebrock RPM Airgap Intake
PRW roller tip rocker system

Been looking at the COMP XE274H
230/236 @ 0.050"
Lift Int: 0.325
Lift Exh: 0327
Using 1.5 ratio rockers
LSA: 110
ICL: 106
IVC: 63

Nothing definite on the cam until I can get into the engine and check piston location at TDC, see if flat, dish or dome and get some info off the end of the cam. Hopefully grind # may be there?

All that being said, any of you folks have any good SCR/DCR numbers to shoot for on a strong street build to avoid ping/knock with 91oct without need to fiddle -/+ timing? Also good cylinder pressure to shoot for? My thoughts on HP and TQ were in the neighborhood of 425 or so HP and 400 lb-ft TQ out of it. Is that doable and not be a pain to drive on the street in a 340 or out of the question?

Sure I have probably left out some important information but will supply if I have it.

Your 340 build is pretty similar to the 340 in my '68 Dart. Mine has 9.6:1 SCR, RHS heads, hydraulic flat tappet 231 @ .050" .561" w/ 1.6's 108 LSA. It cranks 165psi and runs great on 91 octane gas. It likes quite a bit of initial timing - I run about 26* initial. At 26*, it fires right up and never bucks the starter. For reference, here's the cam card for the camshaft I've got: