Dart vs RHS
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Staging Lane
Joined: Oct 2004
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Dart vs RHS I am throwing on a set of aftermarket iron heads for my 454. I am between Dart Iron eagle 308 cc runners and Racing Head service brand 320 cc iron heads. Anyone has experience with either. As far a flow numbers i understand the RHS heads flow more. Wondering if there is something the flow numbers are not not saying. Let me know
6 & 8 Second Club
Joined: Aug 2006
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From: Illinois, RT 66 dragway area
It's all in the combination. Intake runners can make a huge issue if too big for the combo. Milder motors need less intake volume. Cam size, compression, carb size, intake ect ect. 308 & 320 are pretty close, if it was just a mild street motor, I would probably go by price.
Thread Starter
Staging Lane
Joined: Oct 2004
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Stock bottom forged pistons 10:1 a cam similar to xe28 whatever it is and an air gap. I am talking to a guy about a set of used dart iron eagles that's been upgraded to 2.3 inch valves and is polished. My concern is if the work done to the heads is not great how bad can the heads be messed up?
and its a th400 and 3.55 12 bolt
and its a th400 and 3.55 12 bolt
Originally Posted by jarediocamaro
Stock bottom forged pistons 10:1 a cam similar to xe28 whatever it is and an air gap. I am talking to a guy about a set of used dart iron eagles that's been upgraded to 2.3 inch valves and is polished. My concern is if the work done to the heads is not great how bad can the heads be messed up?
and its a th400 and 3.55 12 bolt
and its a th400 and 3.55 12 bolt
Compression is too low, cam is too small, and an air gap will run out before you can utilize the bigger ports.
In a heavy car, small BBC, its hard to beat the Merlins. There are some other aftermarket ovals out there, but my personal exp has been with the merlins.
the merlin oval port heads are not so great. they flow bad. i personally have a friend that had some on his car and on a 454 and swapped to some factory rectangle port heads with the same parts and same compression, both with victor jr. intakes and it went from running 7.00s in the 1/8 to 6.80s with just a head swap. it also had 10.5:1 compression. for the money the merlins cost i would use factory oval port heads. but seriously either of the heads you are talking about will work fine. you probably couldn't tell much difference between the two
Originally Posted by 1badnova496
the merlin oval port heads are not so great. they flow bad. i personally have a friend that had some on his car and on a 454 and swapped to some factory rectangle port heads with the same parts and same compression, both with victor jr. intakes and it went from running 7.00s in the 1/8 to 6.80s with just a head swap. it also had 10.5:1 compression. for the money the merlins cost i would use factory oval port heads. but seriously either of the heads you are talking about will work fine. you probably couldn't tell much difference between the two
If your friend picked up 2 tenths in the 1/8, his combo needed the bigger heads.
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I would check into seeing if AFR is still making the 265cc oval port heads. They out flow the Merlin's hands down and are a lot lighter. They used to be right about the same price as the Merlin's as well. The only reason they may have ended these heads had to do with non-advertisement by wholesellers. They were still available in the 2006 AFR catolog, I do not have a 2007 catolog yet to be able to check it for you. PM Tony Mamo@ AFR to find out if they still are casting them.
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Originally Posted by 1997bird
I would check into seeing if AFR is still making the 265cc oval port heads. They out flow the Merlin's hands down and are a lot lighter. They used to be right about the same price as the Merlin's as well. The only reason they may have ended these heads had to do with non-advertisement by wholesellers. They were still available in the 2006 AFR catolog, I do not have a 2007 catolog yet to be able to check it for you. PM Tony Mamo@ AFR to find out if they still are casting them.
Originally Posted by edcmat-l1
Those would be a damn good choice. Didnt know they were that cheap (inexpensive)...
Lift------Int--------Exh
.200----165--------135
.300----244--------169
.400----297--------219
.500----324--------249
.550----330--------261
.600----332--------272
*flowed on a 4.310" bore fixture and 2 1/8" pipe
These number's are as cast with 0% ported Combution Chambers, 20% ported Exhaust ports (bowl blend), and 20% ported Intake ports (bowl blend).
The part number for these heads is #3610.
Last edited by 1997bird; Jan 13, 2007 at 02:20 AM.
the newer Gm oval port aluminum heads are a great head also and are very reasonably priced. just depends on what kind of money you would like to spend cause the AFRs are top of the line. i have a set of the protopline 320 heads which are the same as the RHS head and they are a great looking head and i hope to get to try them out on my 496 soon
I think that some of you are missing the point of the cylinder head recomendation. He only has a 10.1 454 BBC, with his supporting mods he would have a ineffiecent combo that would really hurt his performance. A good oval port head would compliment the rest of his parts and make him more average HP & TQ. Of the two choices that he is giving us, the lessor of the two evil's is the 308cc Darts. I would save my money and pick up a set of GOOD oval port heads.
Originally Posted by 1997bird
I think that some of you are missing the point of the cylinder head recomendation. He only has a 10.1 454 BBC, with his supporting mods he would have a ineffiecent combo that would really hurt his performance. A good oval port head would compliment the rest of his parts and make him more average HP & TQ. Of the two choices that he is giving us, the lessor of the two evil's is the 308cc Darts. I would save my money and pick up a set of GOOD oval port heads.
Dart 345s are GREAT heads. but they'd kill that thing. It'd be a turd til 5000, and just when the heads start comin on strong, the air gap would peter out.
GM aluminum ovals are a real nice suggestion too.
Thread Starter
Staging Lane
Joined: Oct 2004
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well instead throwing on a set of heads maybe i'll just keep my 049s and have them ported and put head money to a stroker and have a 496 049 oval port. What would be a better street motor merlin 454 or stock ported 496? At least that way If i want to upgrade in the future some rectangular port heads would be a good upgrade for a 496.
oh and by the way i am not necesarily limited to an air gap. I would still have to buy the intake since i have oval port right now. What if I had the above combo and a vic jr? Im just not sure a victor jr would fit under a stock cowl.
oh and by the way i am not necesarily limited to an air gap. I would still have to buy the intake since i have oval port right now. What if I had the above combo and a vic jr? Im just not sure a victor jr would fit under a stock cowl.
6 & 8 Second Club
Joined: Aug 2006
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From: Illinois, RT 66 dragway area
TQ monster, 1/4 stroke with the oval's, wear your hans device when you take off.
Then you can use your oval intake also. If you can afford it, get a decent 1/4 stroke, so if & when you do go up in power, you will be all set. They have some cheap 4340's out there now.
I hope vanilla was joking, those heads are way too big for anything less than a race type motor. Good luck.
Then you can use your oval intake also. If you can afford it, get a decent 1/4 stroke, so if & when you do go up in power, you will be all set. They have some cheap 4340's out there now.
I hope vanilla was joking, those heads are way too big for anything less than a race type motor. Good luck.
Thread Starter
Staging Lane
Joined: Oct 2004
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ok i have decided i definitely am going to stroke that SOB. My original plan for the build was to port my 049s. My builder did say he loves porting oval port heads.
Ok now what are the benefits of going forged steel over cast steel crank because i saw a cast steel Scat kit for really cheap. But i really do prefer to do my bottom end the right way the first time. And i do intend to run at least a 150 shot of nitrous down the road. What would be a kit with good value?
Ok now what are the benefits of going forged steel over cast steel crank because i saw a cast steel Scat kit for really cheap. But i really do prefer to do my bottom end the right way the first time. And i do intend to run at least a 150 shot of nitrous down the road. What would be a kit with good value?
i am putting my 496 together with a set of 049 heads that i ported.nothing like driving to the track having a 1.49 60ft time on motor and driving back home. i bought a nitrous express kit that goes up to 200hp for around $350. before i had a 505 with 8.5:1 compression with these heads on it and i bought a CAT brand cast steel crank. i never had any problems out of but it needed a lot of heavy metal put in it to balance it. by the time i had 5 pieces of heavy metal put in it i could have spent the money to buy a better crank. i sold that crank and now have a eagle 4130 crank. it cost $400 including shipping of ebay and it was very easy to balance. i say good choice of a set of heads for the money.
6 & 8 Second Club
Joined: Aug 2006
Posts: 2,284
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From: Illinois, RT 66 dragway area
Cast cranks flex, especially with spray. I've seen them last for a long time, and I've seen them crack for no reason under load. We had a 8 second 496" with a cheap 4340 1/4 stroke. I would buy that 4130 in a second before even thinking about a cast anything. Like I said, if you ever plan to go up in power, think about a 4340, but at least go 5140 or 4130 steel crank for a mild street motor that u plan to spray. Just my opinion.
Good luck,
Good luck,