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well that's good news for me. that will save me a heck of a lot of work trying to get those things equal.
As a matter of fact, the full headers that I cut apart to get started did not have equal length tubes either. The fronts were a good 12" longer than the rears.
thanks for the info.
Hopefully when I get home tonight I'll have a box from summit on my doorstep to keep me busy for a few days.
Southerner, do you recall what is the effect of the header pipe after the header. My impression is that it is better to have a 2 1/2" collecter diameter rather than a 2 1/4" tubing, but you mention torque enhancement with a smaller collecter and I would like low rpm torque to run in OD at about 1800 rpm.
Don Shillady
Retired Scientist/teen rodder
yep,... what you say is right Don, you run a smaller diameter collector, but it is also longer so that it keeps the exhaust gas velocity up at the lower rpms. This is crucial so that the fast moving gases create a low pressure reading in the cylinder.
Also I might add the most appropriate way to keep exhaust gas velocity up is to get your exhaust as free flowing as possible. This is achievable with the right mufflers, resonator boxes and correct diameter tubing. You would need a muffler that flows 2.2 cfm per horsepower to achieve no or low flow restriction.
This is a thing that surprises me, we all do the high performance mods on our engines, all the large flowing carbs, manifolds, heads, cams and headers. Everything ends at the header flange and either a stock exhaust or a poorly thought out one ends up connected to the collector pipes and we wonder why this thing feels clogged up ?:rolleyes:
i think if you are looking for bottom end you need the small exhaust. big exhaust will hurt you on bottom end i think. big exhaust on top end. JMO:cool:Quote:
Originally posted by southerner
yep,... what you say is right Don, you run a smaller diameter collector, but it is also longer so that it keeps the exhaust gas velocity up at the lower rpms. This is crucial so that the fast moving gases create a low pressure reading in the cylinder.
Also I might add the most appropriate way to keep exhaust gas velocity up is to get your exhaust as free flowing as possible. This is achievable with the right mufflers, resonator boxes and correct diameter tubing. You would need a muffler that flows 2.2 cfm per horsepower to achieve no or low flow restriction.
This is a thing that surprises me, we all do the high performance mods on our engines, all the large flowing carbs, manifolds, heads, cams and headers. Everything ends at the header flange and either a stock exhaust or a poorly thought out one ends up connected to the collector pipes and we wonder why this thing feels clogged up ?:rolleyes:
on the st. 3" will kill you. :cool: :LOL:Quote:
Originally posted by DennyW
:) You mean like this Southerner? :)
well, sort of more like this.
that might work, never seen anything like that. :cool:Quote:
Originally posted by southerner
well, sort of more like this.
hmmm, the collectors on the headers I cut up are 3". So you guys are saying I should get some 2 1/2" collectors?
Quote:
Originally posted by tcodi
hmmm, the collectors on th up anyhowe headers I cut up are 3". So you guys are saying I should get some 2 1/2" collectors?
depend on what you got for intake and cam. if you built yourself a bottom end motor keep the exhaust smaller, if you got a bunch of big stuff in the motor then open the exhaust up. if youve got enough HP it wont make no dif. what you do on the st. and at the strip youll want to open it up because youll be running wide open anyhow. a good rule of thumb ive allways heard is for the st., bottom end, torque, use smaller exhaust. if you build your motor for wide open, HP, high RPMs go with bigger exhaust.what sountherner is showing there is not a open exhaust, looks like to me its got a lot of restrickions in it which is fine if that what your motor needs.he can explane that set up to you. :cool:
I put in a 226 @ .050 cam, single pattern. It had a 255 @ .050 cam in it originally that I took out for streetability reasons.
I suppose I may need to modify my collectors to 2 1/2".
My mandrel bends just arrived today, here's the start I got. Now I have to figure out how to get them all into the same collector.
good luck, you can do it. :cool:Quote:
Originally posted by tcodi
I put in a 226 @ .050 cam, single pattern. It had a 255 @ .050 cam in it originally that I took out for streetability reasons.
I suppose I may need to modify my collectors to 2 1/2".
My mandrel bends just arrived today, here's the start I got. Now I have to figure out how to get them all into the same collector.
Eventually, they have to meet like this:
Ain't it fun figuring out all those angles and curves?
like this....................
Eggzactly
Pro70, I think I know beautiful work when I see it! I just got my shorty tight-fit headers today but you guys making your own are really craftsmen of the top drawer. I am breaking in indirectly to confirm from the discussion above, that although I have a 2 1/2" collecter, I now need to sleeve it down to 2 1/4" for low rpm torque? Well anyway the AHC coating looks great on my headers and I hope I can keep it in the carb/timing range to avoid burning off the coating. The weather has to get better soon, maybe in a week or two because I have now accumulated a few parts which need to be installed, but it's been going down to the low 20s F every night and not getting above freezing until late afternoon and I think I will wait until it really is Spring before I start wrenching. Maybe two weeks will do it, but in the meantime thanks for putting up with my rambling just sitting at the computer hoping my immune system will finally beat the cold that just about everyone I know has had in the last month. Hey maybe Southerner is seeing the end of Summer down under? Well thanks for putting up with me and helping with a lot of tips that I would not have guessed. For instance DennyW says to use double gaskets with the headers (heated in warm water at that), does that not put more soft stuff at the gap and more likely to blow out? Anybody else favor the double gasket idea for headers?
Don Shillady
Retired Scientist/teen rodder
No Don we are definitely are not seeing the end of summer, if anything we are having a late one, temps today are at low 50 deg F and highs of 83 deg F, they predict this will go on to the end of March, so it looks like late seasons all around.:HMMM:
ive had to double gaskets and wet them on some headers don, some people just do it anyway. some headers flanges warp after you change them a few times and thats a way of saving them. some of the flanges will bend when you tighten them. after they get used up some, if you dont double gasket them you throw them away. headers can be a pain in the butt, if you mess with them long enough. i hope you have good luck with yours. after you get them on and let it run and get the motor hot be sure to go back a retighten them or they will leak. some people wet them before they put them on, and there is a reason, because headers have been known to leak. **) **)
DennyW, No offense intended, I just never heard of double gaskets before. I have put headers on the little 1275 cc MG engine and twice on a VW flat four and had no problem with leaks. In the tight MG engine comparment the main problem was getting around the steering; on the VWs there was plenty of clearance and the gaskets seemed to seal OK. This is my first try on the SBC so I appreciate comments from experienced folks. I guess I just have to try it.
Don Shillady
Retired Scientist/teen rodder
Well maybe this thread is winding down so let me just chit chat while I wait for better weather. DennyW, I really appreciate your tips and the avatar you set up for me and lt1s10 is certified by my local machine shop friend at Joe's Machine Shop which is the local hang out for gear heads. Lucky Southerner has some Summer left but Joe's Shop has one of those full blast propane heaters attached to a propane bottle and in the mornings that is really necessary here since that seems to be the main heat for his shop. I still say Pro70 has done a fabulous job on those headers but they look shiny as coated or what? Well I'll try the double gasket trick and tighten them up after first run in so maybe I won't have a problem. I admit this Chevy stuff is all new to me and I have a lot to learn. I can go over to the VW thread and know what they are talking about, but I am really a novice with this Chevy stuff so thanks for helping out. For DennyW's info I also got my Performer-EPS manifold today and found that it needs either Felpro or Edelbrock gaskets so I ordered the Edelbrock gaskets just so I can hope the intake will be sealed up correctly too. Yes, Joe Butler showed me how to use the sealer at the ends of the intake instead of the paper gaskets so I guess I can get that right.
Don Shillady
Retired Scientist/teen rodder
:CRY: I hate to be the bearer of deflating news, but those headers where welded up and ceramic coated @ the factory (Dynatech). I did consider building my own before I bought these but decided by the time I welded them up, then sent them somewhere to get the ceramic coating, I wasn't gonna save too much. Then there's that "How do I weld next to a foam mock up head" thing. I could have borrowed scrap heads and block from an engine builder, but this was one of those ''speed up the build and buy the parts'' situations. :whacked:Quote:
Originally posted by Don Shillady
I still say Pro70 has done a fabulous job on those headers but they look shiny as coated or what?
1 Want to cut a straight line on a tube, just tighten a hose clip around the tube and its a guide for a hacksaw or cutting disc
2 to pull all your primary pipes together into a cloverleaf pattern before connecting up the collector flange, just pull them all together with a big hose clamp and start welding.:D :D
:HMMM: :toocool:Quote:
Originally posted by southerner
1 Want to cut a straight line on a tube, just tighten a hose clip around the tube and its a guide for a hacksaw or cutting disc
2 to pull all your primary pipes together into a cloverleaf pattern before connecting up the collector flange, just pull them all together with a big hose clamp and start welding.:D :D
those tips seem pretty useful, I wish I knew them a couple days ago. I think I got the pass side pipes close enough to pull them into one collector. Of course I didn't buy enough bends and now I have to wait to finish the driver side.