My Headers Don't Fit
- Thread starter Bill D
- Start date
can someone please help me out with the problem you are having with the headers? if ALL of the exhaust ports are raised by the same amount - why would that affect the tube fit into the COLLECTORS??? I can understand interference problems with other parts of the chassis, valve covers or whatever - but not into the collectors (by the way - i have victor jr heads on my 289 and the standard bundle of snakes from DRB fit the exact same way that they did on the stock cast iron 289 heads that i used for "dryfit" - two of the tubes required a small amout of "persuasion" to get into the collectors, but once in with a simple wratchet strap, and a little heat cycling - they fit fine.
so, what am i missing in this issue??
dummy dave - just asking - -
so, what am i missing in this issue??
dummy dave - just asking - -
Dave H,
It only really affects the 180° crossover design Headers, this is due to the ex port face of the cyl head being splayed outwards at the top slightly- so when the port or more correctly the threaded holes that the headers attach to are raised it causes the headers to move outboard slightly at the same time, this shows up in the 180° setup where each group of 4 pipes no longer have a 'square' pattern to fit the collector.
Jac Mac
It only really affects the 180° crossover design Headers, this is due to the ex port face of the cyl head being splayed outwards at the top slightly- so when the port or more correctly the threaded holes that the headers attach to are raised it causes the headers to move outboard slightly at the same time, this shows up in the 180° setup where each group of 4 pipes no longer have a 'square' pattern to fit the collector.
Jac Mac
Hi Jac,
thanks for the explaination! - I wonder why mine seemed to fit on the victor jr heads so easily? there was only two tubes that were slightly off and they "relaxed" into place with very little pressure from a simple web strap! then a couple of heat cycles and now there's no issue at all. would a slightly larger header flange area make this issue worse at the top of the head where it splay's out? (e.g. if you have the larger tube headers?)
thanks
dave
thanks for the explaination! - I wonder why mine seemed to fit on the victor jr heads so easily? there was only two tubes that were slightly off and they "relaxed" into place with very little pressure from a simple web strap! then a couple of heat cycles and now there's no issue at all. would a slightly larger header flange area make this issue worse at the top of the head where it splay's out? (e.g. if you have the larger tube headers?)
thanks
dave
Dave,
The raised ports etc are not the only thing that can affect the fit up. Head gaskets of differing thickness, Decking the Block/Head surfaces, Angle milling etc all contribute to cause misalignment on the 180° crossover design when the 90°V factor is considered [Think of it as a right angle triangle to work out the dimensional change].
The only way to be absolutely sure of a good fit [ 180° design ] is to fabricate them on the car in question, Heat cycle them a couple of times, then send them out to be coated etc. I built a set for a 59 T- Bird [ 430MEL ] a couple of years ago which we were unable to heat cycle[stress relieve] and there was no way we could get them to fit after coating, still got em , hanging on the wall to remind me, never do that again!
Moral of the story, if you are buying ready mades, ensure that the builder is using at least the same head /block combo on his jig/mock-up that you intend to use in your car. Tell him that you have angle mill etc if this is the case, save both of you a lot of grief later.
Jac Mac
The raised ports etc are not the only thing that can affect the fit up. Head gaskets of differing thickness, Decking the Block/Head surfaces, Angle milling etc all contribute to cause misalignment on the 180° crossover design when the 90°V factor is considered [Think of it as a right angle triangle to work out the dimensional change].
The only way to be absolutely sure of a good fit [ 180° design ] is to fabricate them on the car in question, Heat cycle them a couple of times, then send them out to be coated etc. I built a set for a 59 T- Bird [ 430MEL ] a couple of years ago which we were unable to heat cycle[stress relieve] and there was no way we could get them to fit after coating, still got em , hanging on the wall to remind me, never do that again!
Moral of the story, if you are buying ready mades, ensure that the builder is using at least the same head /block combo on his jig/mock-up that you intend to use in your car. Tell him that you have angle mill etc if this is the case, save both of you a lot of grief later.
Jac Mac
Some very good points for the problems encountered. I would suggest that the exhaust maker have the car there when he makes them(if possible). That way you can fix any problems that arise in the making. Not too high, not too wide, and it will fit the shape of the hardware around it, like the cross bar and the trans mounts.
These things are not cheap, and you want them right. If you are having them made far away, then give them all the particulars of your build. If they are good, they should take those things into account. The fitting may be off a bit, but as mentioned earlier, heat cycling should take care of it.
Bill
These things are not cheap, and you want them right. If you are having them made far away, then give them all the particulars of your build. If they are good, they should take those things into account. The fitting may be off a bit, but as mentioned earlier, heat cycling should take care of it.
Bill
A set of 351 exhaust might work but if you can get the mess to fit in the collectors and get the engine started and run it at 2000 rpm for a while the metal will relax and improve the fit, but the better fix is either 351 exhaust or different heads, AFR 185's are a good choice, they will make the power and the exhaust ports are close to where Henry intended them to be.
