[71 Ventura II]

WOW, I must be lucky or something! LOL I was going to say degree it at ICL 108 especially for the NA runs but leave it degreed at ICL 110 for the nitrous use. I huess it wouldn't hurt to to with the 108 to start. Keep in mind, when you add the nitrous to those cylinder pressures they will jump big time! Good luck! JD

[meanone]

IN the Jan. 2004 issue of HPP mag. there is a '68 'Bird running this cam, but on a 108lsa and a 104 ic. The combo is very similiar except he has 270 cfm iron heads, 950 carb, and 1.75 headers. At a race weight of 3595lbs, his best says 10.47 @ 128. If you lowered the race weight to 3300lbs., like yours, it would probably run 10.10's @ 131 or so. Then you add your bigger headers, carb, and 80 cfm more of head flow and you're really running well. So advancing the cam probably isn't going to hurt you.

[BruceWilkie]

Originally Posted by meanone

IN the Jan. 2004 issue of HPP mag. there is a '68 'Bird running this cam, but on a 108lsa and a 104 ic. The combo is very similiar except he has 270 cfm iron heads, 950 carb, and 1.75 headers. At a race weight of 3595lbs, his best says 10.47 @ 128. If you lowered the race weight to 3300lbs., like yours, it would probably run 10.10's @ 131 or so. Then you add your bigger headers, carb, and 80 cfm more of head flow and you're really running well. So advancing the cam probably isn't going to hurt you.

His heads flow 90 cfm difference additional. That totally changes the cam requirements. His current cam if advanced even 6 degrees still peaks at the same basic rpm points. Advancing merely decreases the power averagess in that rpm window and increases them slightly at lower rpm points. Ideally the combo would still want a 5000+ stall convertor with that cam. The car will not run 10.10's with a 3500 convertor and his current cam. With the engine below peak tq at launch and at every shift it cant run to its potential.(most average power in the race rpm band) Just plugging in a smaller duration cam at similar lift on one attempt finds 10 more hp and ft-lbs at the same rpm points and I didnt yet try to optimize anything like LSA or ICL.

N2O and pump gas might be the consideration behind the cam pick(kill detonation tendencies) but NA with his convertor its not a great choice.

[79TA455STROKED]

Bruce,the converter is a 4500 stall,not 3500.
I have not tried to put it up on the brake yet to see where it actually stalls but it was built to stall at 4500rpm.

Man,i wish i just had the extra cash to go to a BOP belt drive!LOL!!!
This way i can play with cam timing easily and see what it likes.

[Ron H]

Tell me about it regarding the BOP belt drive.
I was looking to adding one with the front plate and a tube front in my car but monetarily not possible this year. That would be the cats azz.

Have you talked to Butler? It seems they spec'd this whole combo for you. Maybe talk to them and fnd out what they were intending etc. Maybe you could post that info.
I am not sure I agree this cam is too big.
Except that you probably need more compression?
These spec'd you out for a reason. It would be good to hear what the reasons were.

[BruceWilkie]

Agree that Butler likely speced it that way for a reason.(see my speculation above). Based on Gachs 505 Andy Mitchells 505 and PDudes 535 combo being better suited to that cam than a 468.(all three of those motors like that cam spec when I plug it in btw) Those wideports move a lot of air. That cam is killing compression. (160 cranking psi at over 11:1 compression). Big flowing heads on relatively small(compared to flow capacity) engines greatly reduce duration requirements.

If the convertor actually stalls at 4500 it still would not be OPTIMAL for an engine with a 5000 rpm tq peak. Consider the performance issues PDude had with a too tight convertor that did stall against the brake close to same as the new one.

Again IF N2O or pump gas(especially both) were discussed, Butler chose the right cam to keep detonation at bay and really wake up with N2O. If they discussed a 505 or larger in the near future its a very very good pick. Not being in on the conversation I WILL NOT say the Butler pick was wrong or bad in anyway. That is also a good pick for a typical 320ish or less head at 468 cid depending on the intentions and supporting equipment.

I merely picked 12 less degrees duration(260/268) on a 440 lobe and gained 10 more hp at same 6500 peak and a bit more than 10 ft lbs at still 5000 rpm peak first stab at it. Installed straight up. Not uncommon profile for other engines with similar flows at that stroke range.

Ron that particular Butler cam MIGHT be killer with your combo. I dont know your entire combo though so IT COULD be off by a mile.

[79TA455STROKED]

You guys are rite about pump gas and n20.I wanted this thing to run on pump safely and wanted the option to spray later on if i decided.

I took it apart today,waiting for the new timing set.
I found my lash was at .015 cold!
Should of been set at like .020-.022 cold to give me .026-.028 hot.Dont know what happened there but that could have been effecting cyl pressure.

Also,i degreed the cam the way it was for the hell of it before pulling old timing set off.Wanted to see if anything changed.
It came in at 112!
I set it at 110 when i put it together.Dont know what happened there,maybe timing chain stretch or my error.
Anyway,im sure that effected cyl pressure as well.

I can tell you even with this thing being off on both lash and cam timing,it was an ANIMAL throughout the rpm range.
Can wait to see what it feels like when i get it sorted out!