Thread: Red HOT Headers - Literally

Tweet

Originally posted by ewingr
My cam is a B&M cam that was recommended to use with this blower in teh 1999 timeframe. Specs:

Lift: Intake 488 Exhaust 510
Advertised Duration: Intake 282 Exhaust: 292

I have stock jets in it now, which I estimate to be 85s in front and 74s in the back. I'm estimating that based on a set I have in front of me now, which are 87 and 76. I had tried to jet it up in the past, and I seem to think that I went up 2.

Interesting that you mention no jets in the back. I've never heard of that concept. Of course, I haven't been around a race track for years.

So, I'm going to put in the 87s in the front, and see what happens.

I'm waiting on new aluminum collector gaskets to come into the auto parts this morning. I had one blow out on the right side. As soon as I get that in, I'm going to experiment with advancing the timing more, and the jets.

i hate to be so neg. but why anyone would recommend that cam to go with a 1956 loaded up conv. chevy for the st. ???????????? you could have dropped down 2 notches and
had good power and vac. to. i ran a little above stock cams and had more power than i could hook up, good low end power and good vac. thats a full race cam you got there. JMO

May very well be a full race cam. It's been 5 years since I put it in. I don't recall if even the topic of how teh car and what car was discussed at this point.

I suspect it was the 'only' cam designed to be used with that blower, hence it was recommended, and they nor I brought up discussion of use. Although, I can't imagine that I didn't specify...but at this point, that's what I assume.

Well, at any rate, except for vacuum, it's been OK. I do have to say that the engine sure ran hotter after that build. I don't remember what original cam was in it when I first built the engine. (Did that back in 1985. This cam went in when I refreshed in 1999). I presumed the combination of the different cam, and boreing 30 made it run hotter. Took a bit to get that under control.

thats just it with the blower though, you want to get the valves opened and closed as soon as possible. the blower is gonna blow the gas in, so the valves dont need to stay open no longer than they have to and that would be closer to stock cam. when i started messing with blowers there was no blower cams for the st. and all i could read on it was a stock cam would work fine. i put the big cams in, didnt sound no dif. had to much power, no vac. so i went with 2 steps above stock. did fine.

I remember all that type of discussion when I got this cam. In particular there was another measurment that I don't remember what it was, but it wsa 14 degrees, and this cam supposedly has that. I don't see any reference to that number on teh spec sheet.

At any rate, I've got what I've got for now.

[EDIT]

Just looked at the instructions posted on Holley. It's 114 degrees lobe centerline.

I just looked at Holley's web site. They now recommend

this for a "...streetable cam with reasonable idle, plenty of vacuum..."

Specs are close

i tried them all. i wish i had all the money back that i blew out the bottom of blower motors, and it want because of the blower, because i didnt know whas i was doing. i get it right then they wouldnt pass st. insp.

I increased my timing to 18 advance. Holly said today to have a max timing at 2500 rpm at 34-36, with as mucuh at idle as long as I don't have starting problems when it's warm. They had said a long time ago when I spoke with them, the samd 34-36 max, but 10 at idle. I had it at 10 to start with. This did help, but not fix.

I put in the 76 jets. Helped some more. I put in the 87 jets, and it smells quite rich, but now it just barely glows down at the collector. The plate where they collect, not the tubes.

So, I'm thinking I need to try something larger than 78, but definitelyl less than 87.

Had a follow-up call with Holley, and they said that maybe the combination of my smaller tailpipes (unfortunately, with teh X member and all, I'm at 2 1/2' pipes) and the shortie block hugger headers, that maybe a little glow down there is going to be 'normal'. I'd think I would have noticed that in the past.

I am still wondering why it started after this engine work. However, with new lifters and fresh adjusting of valves, maybe it's just pushing more through. It definitely runs much better.

Originally posted by lt1s10
i wish i had all the money back that i blew out the bottom of blower motors, and it want because of the blower, because i didnt know whas i was doing. i get it right then they wouldnt pass st. insp.

Ain't that the truth.

keep in mind when you think blower, low comp. late timing. lots of gas, and respect.


didnt you say you had 10" vac. thats not good vac. maybe you have a vac. leak.

Originally posted by lt1s10
keep in mind when you think blower, low comp. late timing. lots of gas, and respect.


didnt you say you had 10" vac. thats not good vac. maybe you have a vac. leak.

Too much cam

I agree on cam. I've experience vac leaks, and I'm pretty sure it's not that.

Interestingly the Lunati cam I linked to above has very similar specs, yet even longer duration. Hmmmm....

Anyway, back on topic:

I just took a drive with the way larger jets in the carb. Very rich. Plugs turned black. I drove through downtown Lawrence, which is 5 mph, and red lights every block. I also experienced fairly severe...uh, I guess I'd call it stumbling. Not right off the line, but I'd get going, and at 5mph or so, it would surge: drop, go, drop go...until I'd get up some rpms. I presume it's loading up.

Just put the 76 jets back in,and am about to go for another drive.

Your guys discussion is almost as interesting as working on teh car Every time I come back in teh house, I can't resist checking to see the responses.

Originally posted by techinspector1
Too much cam

"...streetable cam with reasonable idle, plenty of vacuum..."

he said this is the way they was describeing the cam he just put in. but if its over 500 that cant be true. maybe i miss read.

I have the 76 (+2 over stock) jets in, and have set advance to 18 (total advance comes in at ~ 34).

Engine is running good. No hesitations. No RED HOT when I park and leave engine running and check (my latest check).

I'll update again if I decide different.

sounds like youer getting close

Just a note to say all is well. I think that advancing the timing was the thing that really fixed the red hot header problem.

Thanks for all the help, everyone.