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Author Topic:   dart 215 heads
nw15x
Dirt Maniac

Total posts: 129
posted December 20, 2004 09:53 AM  
using them on a 355 motor with flat tappet cam. Are they good righ out of the box or is there anything that should be done to the before install like pocket porting/blending

Larry Lundin
Dirt Full Roller

Total posts: 45
posted December 21, 2004 08:25 AM  
I purchased a set of 49cc for my flat top 406. I cleaned them up with a quick wash and bolted them on right out of the box. They sure woke that engine up!!

Flyinbison
Dirt Roller

Total posts: 12
posted January 05, 2005 07:24 PM  
We also have a set of 49 cc's on a flat top 406 and I agree that they sure woke it up. I bought them mid season and the machine shop guy said if he had time he would have done some cleanup work on them. We took them apart this winter and they did need some cleanup but not so much that I think it will be a major difference.

RACEINMUD
Dirt Freak

Total posts: 323
posted January 06, 2005 07:50 AM  
Hi, Did you guys with the 406's drill the steam holes in the heads? I'm thinking about getting a set for my 406. Did you have to do anything special on the 49cc heads or just bolt them on? Thanks, Race

wayoutfront
Dirt Maniac

Total posts: 149
posted January 06, 2005 12:28 PM  
i think they would be to big with a 355 stay with a 200cc runners

Flyinbison
Dirt Roller

Total posts: 12
posted January 08, 2005 01:54 PM  
We just bolted ours on. We didn't have the steam holes drilled because my mechanic said we wouldn't need to and we haven't had any problems with them. We had them on a 377 first and then went to the 406. We haven't had them checked for compression but using the math calculations the 406 figures at 13.68 to 1. with the flattops in it. I can't remember ever coming off the track hotter than 210.

nw15
Dirt Full Roller

Total posts: 28
posted January 14, 2005 02:58 PM  
I put mine on and at first I had a push rod to intake port problem. I had to loosen up every guide plate and shift it so it would clear. The intake valve had been move over .030 so it won't line up perfectly but it will work. Now I have valve to piston problems. I took some duration out of the cam and now its closer but still need to flycut the pistons. Has anyone ran accross this as well.

stockcar5
Dirt Forum Champ
Total posts: 578
posted January 14, 2005 03:34 PM  
the valves are .100 closer to the piston on the 49cc heads and if you run a big cam you'll need to flycut.

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www.geocities.com/dirtstockcar5

racin78p
Dirt Freak

Total posts: 333
posted January 16, 2005 04:15 AM  
I agree with wayoutfront, 215cc heads can be too big for a 355. 406 yes. nw15x, can you get a hold of a set of 200cc heads? You could end up with those bigger heads causing back flow problems (intake flow reversing). Not trying to scare you or anything here, just an opinion! Either way, good luck.

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racin78p
if it ain't fun, then don't run

dirtracer14
Dirt Forum Champ
Total posts: 1261
posted January 16, 2005 09:01 AM  
Intake flow reversing? What is that....i have a set of 235 cc runners on my 355?

goinrcn44h
Dirt Freak

Total posts: 205
posted January 16, 2005 10:58 AM  
It depends on the combination as a whole. if the intake, carb/injection, and cam can utilize the larger cfm then its a good thing, but if they can't, then its useless and a waste, thats where a flow bench comes in handy......
44H

racin78p
Dirt Freak

Total posts: 333
posted January 17, 2005 12:12 AM  
To try and answer dirtracer14 without making a huge post: it is VERY possible to have too big of intake runners (cc's). When the pistons are sucking down the air/fuel mixture, if it is too much (the mixture) because of the size of the runners, the excess has to go somewhere. Like back up into the intake runners! A reverse flow effect, if you will. This is especially more true with small cc chambered heads. The best way to know for sure, is to flow the heads, as goinrcn44h stated. On an average, 200cc heads will flow (optimum) better on a 355/358 than anything bigger. 215cc heads are the MOST I would consider using, but that is because of what I have in my engine right now. 383 or 406 or bigger and yes the larger cc intake runners (especially alcohol) are the ticket. Hope this clears up what I posted before!

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racin78p
if it ain't fun, then don't run

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