[Bababooey]

Hey all, last fall I was smoking my tires trying to impress my girlfriend, wound the car up a bit too much and broke and bent a couple pushrods, and rocker arm studs. Anyways, since then I've thrown new pushrods, rocker arm studs, nuts, threw the engine back together. I didn't inspect the cam with a fine tooth comb but it didn't seem that any of the lobes were wiped out. And to verify I took off the valve covers and cranked the engine after adjusting the valves and all the arms were popping up and down just fine. I did a compression test to make sure I didn't screw up a valve and she was showing 150-160 psi all the way around the car. I don't have a timing light but I've been messing around with positons of the distributor playing it by ear and no significant affect. The cam isn't really known for low end performance unless it's in a bigger engine or with a higher stall convertor, but I used to be able to smoke em' halfway thru second from a roll. Now all I can do is brake torque to get anything.

I guess I just don't understand why it don't have the get up it used to. It's still decent but nothing like it was. Any ideas would be greatly appreciated. I will say that I'm not a carburetor person and it has a Holley 750 that I really don't want to mess with but I feel that may be the problem. I know these aren't great on gas but 20 bucks worth is just enough to last a days drive. I'd appreciate any help.

Thanks

Brandon

69' Firebird, 400 .30 over, 670 heads, RA IV cam clone, Holley 750, HEI recurved, TH 400, 3:55 posi

[Bababooey]

Hey all, last fall I was smoking my tires trying to impress my girlfriend, wound the car up a bit too much and broke and bent a couple pushrods, and rocker arm studs. Anyways, since then I've thrown new pushrods, rocker arm studs, nuts, threw the engine back together. I didn't inspect the cam with a fine tooth comb but it didn't seem that any of the lobes were wiped out. And to verify I took off the valve covers and cranked the engine after adjusting the valves and all the arms were popping up and down just fine. I did a compression test to make sure I didn't screw up a valve and she was showing 150-160 psi all the way around the car. I don't have a timing light but I've been messing around with positons of the distributor playing it by ear and no significant affect. The cam isn't really known for low end performance unless it's in a bigger engine or with a higher stall convertor, but I used to be able to smoke em' halfway thru second from a roll. Now all I can do is brake torque to get anything.

I guess I just don't understand why it don't have the get up it used to. It's still decent but nothing like it was. Any ideas would be greatly appreciated. I will say that I'm not a carburetor person and it has a Holley 750 that I really don't want to mess with but I feel that may be the problem. I know these aren't great on gas but 20 bucks worth is just enough to last a days drive. I'd appreciate any help.

Thanks

Brandon

69' Firebird, 400 .30 over, 670 heads, RA IV cam clone, Holley 750, HEI recurved, TH 400, 3:55 posi

[Junkyard Dog]

Get a timing light. Borrow one if you have to.

[wheelspin]

Brandon,

Welcome to the Forums.

Based on your sequence of events, I suspect ignition timing is the problem, assumming that you repaired the top end damage. Lacking a timing light, "power time" the engine by advancing the the distributor (clockwise) until the engine "pings" under acceleration and then back it off until it stops.

Use premium gas for the test and regular operation unless your engine is low compression or you have reduced the compression.

Les

[bmpmdf]

How tight did you go on your rocker arm adjustments?

[Bababooey]

Yeah, I'll get a hold of a timing light somewhere and check things out. I didn't remove the distributor taking everything off, but I'm thinking she may have gotten bumped somehow.

I adjusted the rocker arm nuts according to the stuff I've read off of this site and others. Spinning the pushrod while tightening the nut, as soon as I felt resistance I stopped and tightened the nut another1/4-1/2 a turn. I think the reason one broke initially was it had the stock bottleneck studs, and with me overrevving it I don't think they could take it. I've upgraded since to 7/16" studs.

Thanks for the help guys

Brandon

[GR8ONE68]

Brandon,

When you adjusted the valves, did you make sure that the lifter was on the flat part of the cam?

[Bababooey]

Yeah, I did it according to the method posted on Bill Boyle's site. Y'know with the #1 at TDC adjust, and at #6 TDC adjust the listed valves. I kinda figured that may be the problem so I re-adjusted a couple times to be sure that I had them in the right positions, and making sure the #1 mark on the balancer was in the right position.

I appreciate the help, I got a local car show coming up soon and I don't want to be all bark and not any bite if you know what I mean. Gonna be alot of chevies there.

Thanks

Brandon