Exhaust reversion
 

Question on exhaust reversion?
I have a new cam I was about to run and i have been told to be catious of exh reversion.
I dont want to wast a motor.

I was going to run stock the manifolds

Cam spec .544 In .547 ex. durration @50 226 In 236 ex.

I was going to get new edelbrock heads and intake.

If I have to get a new exhaust which would be a good choise?
330 trs drive
Tom

Re: Exhaust reversion
 

I wouldn't run the stock manifolds with that much duration.
I was just recently exhaust shopping and the cheapest NEW manifolds I found were Eddie Marine with a long riser for $1575.00 at www.diamondperformanceparts.com there is a lot of reasonably priced used stuff out there also just make sure you have it leak tested.


Doug

Re: Exhaust reversion
 

i was thinking of going with used exhaust.
can i just use any performance exhaust? just extending the hoses?
Do i have to run a dry tail pipe? Is it that much better? Or necessary?

I found used manifolds can i use any style as long as it has casting around the manifold?
Do some systems last longer? (fresh water Mi.)
thanks

Re: Exhaust reversion
 

i have some used exhaust, cmi uni top's , stellings logs, merc logs, call me 516 799 6029

Re: Exhaust reversion
 

You need to run a longer riser than stock to put the water in the exhaust stream farther away from the engine. Just lengthening the hose would not help this at all.
Completely dry exhaust is very loud.
I would think that almost any aftermarket manifold style exhaust system with a long riser would work good and last a long time in fresh water.


Doug

Re: Exhaust reversion
 

Just curious, anyone ever had a motor fail from rev . probs. If so can you explain in detail what happened to the motor and in what order it happened in. I believe even if you had a bad case of rev. it would take quite a while before you had motor probs.

Re: Exhaust reversion
 

A major factor causing reversion is lobe seperation. What is the lobe seperation on that cam?

Re: Exhaust reversion
 

lobe seperation is 112.0
comp cams 11-236-4 xm 270h-12

Re: Exhaust reversion
 

Can I put risers on and just dump right at the end of the pipe aprox. 6' away from the tail pipe.
Does that make the motor much louder?
Would that solve the reversion?
Do i have a potential problem?

Re: Exhaust reversion
 

I ran a cam close to that with stock center rise exhaust 226/234 on a 111 lobe angle. After starting engines on the shop floor I removed the risers and found water pooling in the manifold. Couldn't afford two sets of exhaust at the time so I bought Imco stainless steel riser and bolted them on my stock manifolds. Moved the water back several inches which seemed to do the trick. They also claim a 10hp improvement due to the sweeping elbow. I since sold those risers to an OSO member and bought headers.

As far as engines failing due to reversion, I had an exhaust valve shatter one time which I concluded was embrittlement due to cold water quenching after a hard run. Never sure.

BT :cool:

Re: Exhaust reversion
 

Have seen many jet and v drive boats with water injected headers running stupid big cams with massive dur. Take the motor apart and see that water is present in the exhaust and they still go all season with no probs. All these guys run good valves and seats. The water is usually injected at the bottom of the header. A lot of guys don't run those style headers anymore but you see my point.

Re: Exhaust reversion
 

112* lobe seperation is on the tight side. I would say that you will have a problem with stock exhaust. You should do something to correct this problem before it costs you a motor. You have to dump the water into the exhaust as far back as possible, by whatever means works for you and your budget.

Re: Exhaust reversion
 

I agree with everyone about having to dump the water as far away from the valve as possible with big camshafts and tight LS. I just think the revision problem gets alot of hype and it actually takes a while for you to have problems with the motor, unless you have a cracked manifold and when you shut the motor off the water drain's into an open valve. I just see people having motor probs and revision is the first thing that gets blamed for the motor failure.

I built a set of 383 small chevys with
510 510 lift
228 228 @ .050
284 284 ad.
108 LS
for a Formula 5 years ago. It had dart 200cc heads with Inconel exaust valves. I told him he would have to get headers or different manifolds for the rev. probs. and he said he couldn't afford that at the time. I told him I would not warr. the motors if they dropped a valve, but would warr. the lower end. Like I said that was 5 seasons ago. Winterize the motors every year with no probs yet. (stock manifolds) This is the only motors I have built that didn't have headers.

Been around boat motors all my life am still waiting to see a motor failure from rev.

Re: Exhaust reversion
 

I have a pair of Merc/Gil manifolds that would probably work for your motor.They are dry exhaust so you probably wouldnt have to worry about reversion.I would let the whole system go for $ 1300.00. That would include the manifolds, ss risers, Gil mufflers,air pump,actuators,lines.E-mail me at [email protected] if your interested.Chris

Re: Exhaust reversion
 

:p :p those gills will du the trick ,, iam running hyd cam 646 lift -264duration-- 1.8 rockers, then cut the weild at the riser , cut the inner and outerpipe, added 14in. driled3 half in holes at the bottem 1 in from the end of pipe works grate :D

Re: Exhaust reversion
 

Hey thanks for all of the knowledge.
I think this site is great.
I will look into buying a new set of risers and dumping the water at the rear part of the tail pipe.
I am wondering if i can get away for a few months with just using the newer riser?
Or should i find the new manifolds also?
Do all risers have the same flange and bolt pattern?

Tom

Re: Exhaust reversion
 

I've seen exhaust valves with cracks from reversion. That was years ago before some of the newer alloy valves came onto the market.

Re: Exhaust reversion
 

Tom,
Did you get my email along with the photos. If not, let me know and I'll resend them over. Chris