im looking to build a 350 and make 400 hp? i need heads r the pro-comp heads any good? some people say junk and had problems what do u think? or the dart iron eagle ?

 

What kind of problems did they claim to have with the ProComp heads?
Was it the head itself or did they buy them complete without matching the spring rates to their camshaft?

 

I'm not a super fan of ProComp heads. The few set I've had hand-on with the machine work was "eh" at best, and it looked to me like the port profile was lousy, especially the floor of the port. Just one guy's opinion.

More information about the build would be helpful - but the first question is why not a 383?

 

Dart has just introduced some inexpensive aluminum heads. They are basically the older style Pro 1 heads made out of 356 aluminum. For the $$$ they look pretty decent. I'd take them over Pro Comp anyday.

Might look at Brodix also.


JIM

 

i want to use the stock parts its an L-82 so i have a steel crank/pink rods need new pistons.i think i can get close to 400 hp? i have an msd ign.need roller hyd cam intake and heads if the crank needs to be cut maybe than 383 what kit scat/eagle looking to build a good streetable car it has 355 rear/2600/2800 11inch stall converter 400 trans no headers ac/ps/power brakes any help thanks

 

Quality of the pro comp heads has been talked about a lot. Everything from valve seats coming loose to very poor machineing. Have seen one set the neighbor bought but has never used. Oval port BBC set. Valve covers won't fit on them without him grinding the outer edges of the head so the valve cover lip won't hit the head when tightened down. If money is the object take the advice of a dart or brodix head that will give you way less chance of your engine build turning into failed parts.

 

I went with the AFR Street Eliminator 195's.

 

X2 good advice Jim

 

Reading carefully, there are a lot of questions here beyond a random cylinder head recommendation

First, do you have a budget for the build? Budget drives more decisions than any other factor...and without a budget, design is impossible as the choices are virtually unlimited.

Next, is originality important? If it is...I'd highly suggest setting aside your original engine and starting from scratch. The cost increment is pretty small in the end, as you'll learn as you start working through the build.

400 HP at the crank is a very reasonable target and very nicely balanced for a C3. It's straightforward for a 355, and almost the minimum power even a mild 383 will make

The details from here are completely dependent on your budget and how you intend to use the engine. You note wanting to reuse parts - but you may find in many cases that the cost of machine work is higher than the cost of new parts, so careful planning is required.

You also note wanting a roller cam - definitely a great choice, but not required at the power level you're seeking, and not an inexpensive choice to retrofit to an older GEN I block.

More information on the budget and usage will help tune the guidance - lots of smart builder here and I'm sure the discussion will get "lively"

 

Do they have a model name or a part number or something?


Scott

 

I think they are referring to the Dart SHP heads.

 

bought a set of these Dart heads. they look good. Have not run them in yet.. Price is very good.

 

Here's what Summir Racing says about them:

"These Dart SHP Special High Performance cylinder heads are designed to provide an affordable option to those looking for the weight savings of aluminum heads for a performance street engine. They are manufactured from A356-T6 aluminum and are designed to work with most off-the-shelf components. These SHP cylinder heads are available with your choice of 64cc or 72cc combustion chambers and come in both 180cc and 200cc intake runner ports that are precision-cast and designed to offer excellent flow and power without the need for CNC-machined porting. They feature optimized chambers for increased combustion efficiency and multi-angle intake seats. The cylinder heads' radiused exhaust seats dramatically increase their performance and the manganese bronze valve guides increase their life."

930 bucks for a set, and they give you some choices, too. I have been planning on using a set of Edelbrock E-street heads, but these look very nice for about 20 bucks more. If I find some flow data, I'll post it.


Scott

 

Found the flow chart in Darts NEW 2012 Catalog.
http://www.dartheads.com/catalog.pdf

200cc Intake Runner: http://www.summitracing.com/parts/DRT-127322/
DART SHP 200, 64 or 72cc
FLOW DATA @ 28” Water
Lift Intake Exhaust
.200” 129 114
.300” 185 145
.400” 229 164
.500” 261 172
.600” 263 174

180cc Intake Runner: http://www.summitracing.com/parts/DRT-127222/
DART SHP 180, 64 or 72cc
FLOW DATA @ 28” Water
Lift Intake Exhaust
.200” 139 114
.300” 190 145
.400” 218 164
.500” 222 172
.600” 218 174

I didn't actually look these up in the DART catalog, I just cut and pasted it from another forum. The 180s look good for my purposes, I plan on running a relatively mild cam (Comp Cams EX250H, maybe EX256H) but for a 400+ HP 350, the 200s might be the way to go. Hopefully, someone who knows what they are talking about will come along and analyze these flow numbers for us. I don't know a whole lot about cylinder heads, but these new DART heads look like they might be a great deal!


Scott

 

Just a bump.


Scott

 

They look like a great deal! US made by a company with a great rep! Glad to see our US manufacturers competing with the chinese.
General rule of thumb is 2 HP per CFM of intake flow is possible on an allout race build. Less on a street build. Intake/exhaust ratio close to 80% is really good and often overlooked when comparing heads. Just recommended these in another thread.

 

Does your neighbor still have the heads? Does he want to sell them?

 

You won't get your money back by melting them down, these heads are made in China, how many chevyl block hotrods do you think are running around a country with over a billion people, maybe 1 or 2.

Don't buy crap buy what was suggested above and no one ever mentions Vic Jr. heads, a quality head but 215cc oooooohhhhh way to big for my little small block 383 or 406ci

 

He now lives around 15 miles from me. He came by while i was not here a week ago borrowed my engine lift. He may have now installed them on his four wheel drive pickup project. I can call him or e-mail him if your really interested. There set up for a hydraulic flat tappit cam.

He took my suggestion on a lunati voodo cam after he had already bought the heads without him knowing anything about pro comp or asking me. After i steared him over to speed talk to help confirm what i was telling him. He then turned a little sick lol. He bought them at a company on line. Sure enough he calls them wanting his money back they wanted to charge him a $250.00 restocking fee. Thats what these scumbags do they sell you some crapola. Then they would love to get back $250.00 for a set of heads that only cost $900.00 complete then turn around sell them again. They could care less if your engine is destroyed only some profit. I know its hard to have to spend $1600.00 to $2000.00 for heads for a rat motor or more. But what does a screwed up engine because of crap parts cost in the end game doing it all over. Even though i don't know you from boo recomend you do something else.

My friend and X neighbor between him and his wife have a $220,000 income. In texas you can live pretty well off that. Maybe you should let them experiment they can afford to take the loss, how about you ?

I sold him my 454 four bolt block and two steel 427 cranks after i got tired of him drooling all over it on the engine stand one day. So now he has a pickup with overkill block for a pickup project and nothing but crap for heads. I just gave him a set of new harland sharp rockers for it i have had for 34 yrs.

Maybe i should drive out there help grind on the heads make the valve covers fit. After we made sure it was the heads not two sets valve covers the problem. Loaned him my first class valve spring compressor so he could pull the junk apart check things. I know this was a waste of my time. Slap that baby on it will work.

He pulled this pickup apart powder coated the frame. Spent $6500.00 for paint, body had no rust problems. Block is now .040, 427 over.

 

The Dart SHP 180 heads are the way to go for a solid street design. They are currently available in a HR valve spring assembly for $465 per piece.

As for making 400 HP, if I were you, I wouldn't be thinking about making HP. I'd be thinking about making torque and as much of it as possible.

The smaller ports are going to work better at lower RPM than larger ports...which will work better at higher RPM. With larger volume, you sacrifice low-RPM performance for higher-RPM performance.

The "sweet" thing to do is to go with a stroker and add the cubic inches. However, since budget is always an issue, if you can make your factory crank and rods work for you (you'll have to rebalance the entire assembly), buy a set of dished (aka reverse dome) pistons and a set of small combustion chamber heads. With the 64cc chambers, you'll be somewhere around 9.5:1 compression ratio, which is a good ratio for pump fuel.

Add a good roller camshaft and you'll enjoy the combination quite a bit.

I am currently building a 383 for my '77 C3. Here are the build parameters:



...and here is an estimate of the output:



From this graph, you should be able to tell that I'm definitely not focused on HP, rather TQ. If this happens to be fairly close to reality when the engine is completed, it will make over 450 foot pounds of torque throughout its entire effective RPM range.

The lines of the graph clearly show how the red (HP) is nothing but a calculation of work over time reflected by the green (TQ).

The power chart tells that story:



At some 480+ FTLB TQ, you're seeing factory big block torque in a small block package.

From idle to 5000+ RPM, this design will bring the old girl back from the dead in terms of its "sports car" moniker.


MxB