Heads

[mopar3762]

im done posting, but I did work as a propulsion engineer at pratt whitney here in fla on jet engine testing and design for the military. I retired at 40 and just live the easy life now but these forums are a waste of my time, so from here out I wont be posting but the lil dogs will be yapping on my comments after I leave as usual, im just here to try to give a kid a great deal on a 1974 duster from here out.

 

[mopar3762]

sublime, its been a pleasure ,you have the most knowledge here on dans situation, take care

 

[Demon_Dan]

My apologies, all we can go ahead and lock this thread before more people get pissed off.If anyone has anything to add that is constructive to the cause Id be happy to hear you out in a PM.

 

[rumblefish360]

Well, I'm not pissed but confused and WOWed! at some comments and poor pot shots.

I really don't give much of a crap about getting upset on things posted. Just trying to understand a few things here.

I'm out.

 

[BJR Racing]

No problems here. I haven't been nor will I be PO'd everyone has a right to say what they think.
It's just when working with a 318 that they are easily over headed and cammed, putting in a larger cam doesn't help the engine and will hurt low end performance. Which is where you wanted to drive it anyway.

Sorry if anyone had ill feelings as any of my comments weren't said to be taken this way, but to be informative. If theres any disagreement then we'll just have to agree to disagree.

Sublime, I don't think that Blueprint engines are mopar crate engines I believe that they are a seperate company totally.

 

[sublimeswinger]

sublime, its been a pleasure ,you have the most knowledge here on dans situation, take care

Wow Thats a first. lol, I love Teens, and i mean the motor, but ive gotten alot of info from the people right here and have learned alot from them as well as else where.

Sublime, I don't think that Blueprint engines are mopar crate engines I believe that they are a seperate company totally.

Ya didnt look at the link, IIRC they seemed to be underpowered for the money, i think you could build better for cheaper, agree?

Dan, i to am sorry that this has turned in the wrong direction, but your combo is not lost. A few minor tweeks or changes, which wont cost alot of money, and your combo will rock.

 

[sublimeswinger]

I dont think that will see anything close to 400hp. Maybe 300hp.

Adam, i refer to the combos that were created by the mag articles. Since mine is not Dyno'd at this time, its all i have to go on.

http://www.popularhotrodding.com/enginemasters/articles/mopar/0667em_mopar_318_engine/index.html

http://www.hotrod.com/howto/113_0304_318_small_block_build/dyno.html


http://www.moparmusclemagazine.com/techarticles/mopp_0409_318_engine_build/index.html

 

[BJR Racing]

Ya didnt look at the link, IIRC they seemed to be underpowered for the money, i think you could build better for cheaper, agree?



Agree, but 408 engines aren't big power producers but more for Tq. IMO. Piston speeds are too fast to make tons of HP let alone the rod angles, also too with pistons speeds this fast the heads that Dan has now would work better on the 408 and in all reality the 408 engine needs about 205-220 cc intake runner to get the most HP and supply the engine effectively. This hurts these engines more than anything as to get a head this size for a small block mopar will end up costing the end user near $6,000.00 when finished, so it's just not feasiable.

 

[mopar3762]

I can agree to disagree.

 

[Moparmal]

What I DONT understand is this - My specs are listed in bold -

Dans heads flow the same as mine asusming its a bowl blend - (205 / 215 cfm)

Hi compression is almost the same (10.2 / 10.8:1)

His camshaft is smaller (.495 - 231@.50 / .480 230@.50

His gearing is two stages more on the "hwy" side than mine - but not appalling - 3.9- 15" wheel / 3.55 - ? Wheel

His converter is so close to mine it doesnt matter - (3000 / 2800)

SO WHY is everyone saying his heads are the only problem?

Clearly if I can run a flat 13 with my specs in a similar weight car - I still suspect a 'dud" build or a TERRIBLE port job.

 

[BJR Racing]

Mal,
If his heads are or have been milled a bunch then he could be at 10.8:1 but KB lists the 167's at 10.3:1 with a 57 cc head so his heads would have to be 53 cc's and a .038 gasket to achieve this. This would mean that the heads have been milled .085 if the heads were 70 cc's to start with.
I personally don't think that the build is all that bad but the heads are the main contributing factor in how the engine will respond and build Tq. at a low rpm. I agree with you that the heads are a problem and that there are other things that need to be addressed. But I also ran a combo similar to this a few years ago and in a 3290 lbs car it would run low 12's, true I had more gear and more stall but the engine still has to have the potential or the car won't run. I think that his biggest gain is going to be in the smaller runner heads for what he's trying to do. It will give him more Tq. and HP where he wants it, in the lower rpm range and up to 4000-4500 area. The small high velocity ports of the 302s will really wake up the combo that he has. The heads that he has that Aero did are more that likely a very good set of heads but in the wrong application. On this engine it would be like running a high overlap cam without the compression to handle it. High overlap cams will kill the low rpm power like a runner thats way too large for (port volume) the engine.
Along with the 2.02 intake valves that are in his heads this contributes to the loss of velocity, as the bore is only so large and can only pull so much air in for a given stroke of the engine. Once again the air speed is too slow for the 318s bore size. Thus giving him the sluggish low end performance and the lack of Tq. in which he's looking for.

Just last year I had a build very sililar to his and I ran the 360 heads with 1.88 and 1.60 valves, it ran 7.48 1/8 and a 1.62 60 ft. time, then I switched to the 302 heads and the car ran 7.31 and 1.57 60 ft. times. I had a 750 VS carb on the engine with the 360 heads and then because of the high intake vacuum of the 302 heads that it wouldn't open the secondaries so I put a 650 DP on and it and it made a huge difference. The high intake vaccum came from the small high velocity ports and small intake valves being that they were only 1.78 and 1.50 valves on the exh.. Sorry for being so winded.

 

[Moparmal]

BJR - I see where you're coming from - I guess Im jus suprised that such a mild head port would kill his bottom end that much.....live and learn I guess!!

 

[BJR Racing]

Mal,
What everyone forgets is the fact that the 302's are only 118-120 cc's on the intake port volume and the 360's are all around 150-152 from the factory so now your already 30+ cc's larger and then they opened up the bowls even more when installing the 2.02 valves. So I would bet that the heads that he has are in the 154-158 cc range. Which this is very large for a 318's bore and this is the reason that they used these on 340's and 360's. Port volume is determined by rod length and piston speed, slower piston speeds and longer rods generally like less port volume and just as shorter rods and faster piston speeds like larger ports. This is why the BBD had 176cc's in the 906 heads and the 452's have 180 cc ports, then too the BBC has 290 cc's in there sq. port heads and the difference is in the amount of stroke as the BBC has 4.00 stroke and the BBD has 3.75. Then too the BBC has a rod length of 6.138 and the BBD has a rod of 6.768.

This is what you found also when you did the 349 engine. You had the 318 heads but needed the 360 head. The reason is and was because the stroke of the crank was increased so piston speed went up and the heads became the restriction. Then when you changed the heads to the 360 casting the performance came up. The piston speed became faster so the larger port volume became necessary, just as slower piston speeds need smaller ports. A 318 engine reguardless of bore size can only use 138-140 cc's of port volume max. The only thing that will change this is the stroke and rod length but then again you don't have a 318 engine anymore either. So the needs will change. I would use a head in the 124-126 cc range for his engine. This would be a 302 head with bowl porting and gasket matching, useing a stock valve size so port velocity will stay up, I would also narrow the guide up. Doing this should have the flow in the 210 to 220 cfm range even with the small valves.

 

[Moparmal]

Thanks for the explanation - I didnt think valve sizes effected velocity that much - so thats good to know.:read2:

So many guys run milled 360 heads on 318s without Dan's problems - I guess Im just suprised that something like valve size would "cripple" Dan's car so much.disgust....

....although with all due respect to everyone who's posted on here - I still smell a dud port job or dud cam timing.:banghead:

 

[BJR Racing]

And you still maybe correct on this, as you've said he may have other issues also.

Here's some info so you won't be mislead for intake valves X the bore by .52 for the max valve size for the intake and use .72 for the exh. valves but you use the intake valve to get the exh. size. So a 3.91 bore would be 2.03 and the exh would be 1.46. Or it would look like this
3.91 X .52 = 2.033 X .72 = 1.46. Keep in mind that this is the MAX that can be used, but doesn't necessarily mean that it's the best or the right one for the engine. This would be considered an ALL OUT setup RACE ONLY. What I've found to work the best is the 1.78 intake in a 318 head and a 1.88 in a 360 head and a 1.60 in both heads on the exh. side. The 1.60 will flow close to the intake side on the 318 head but will make more Tq. and thats why I use them. I always use the smallest valves that I can on the intake side as this helps the port velocity. Also to from years of experience and many sets of heads that larger valves only increase the high side of the flow chart and looses the flow in the low side of the flow chart. This comes as the loss of port velocity due to a larger opening. For a street or mild race engine I use the 12% rule, which is 2.033 X .12 = 1.79 which is close to what the heads come with from the factory. I use this on the intake side only, then if you want the heads to be more efficent then use 90% of the intake valve to get the exhaust valve size. Or it would look like this 1.79 X .90 = 1.61 so the 1.78 and 1.60 valves are whats used.

 

[rumblefish360]

Moparmal; If your car is set up or simply takes advatage of the track well, the actuall flash of the converter is a small issue and possible advantage. Converters are a lot like socks, they all cover the feet, some better than others.

Your cam could have a slight advatage somewhere in it's grind. Faster ramps? You do have a ever so slight lift advantage over him. .015 might not be jack in some places, but in valve lift, and what exactly the head likes, power can be quickly found or lost. More torque? ....... which leads me to your rear gears. More torque release, faster out of the hole, quicker to top end.

In drag racing.... on a lower street like level, I alllways said, "First one outta the hole and to a 100 MPH should win this."