Guys In about 4 hours I am about to pull the plug on my honeymoon on the hotrod power tour. I have built a brand new L98 (gm L31 shortblock) and have a lifter type rattle in the motor. It has been in the motor since I fired it. It runs great, good power, idle, decent mileage, BUT it rattles. It sounds like a badly adjusted solid camshaft. Its a stock L98 roller cam from the first motor with brand new GM roller lifters. New roller rockers, pushrods, tall valve covers etc. I've had the top end apart and everything is mint. I've taken the 1.6 rr's off and installed the stock steel 1.5's...no change. Its got great oil pressure and all sorts of oil at the rockers. I installed a new tpis bigmouth and the four pads that the fuel rails bolt onto are a machined surface. Except for one. Bad casting that is to low. Not alot, but low. Now I cannot remember if the injector body bottoms out on the intake. When I screw the rails down the injectors are pushed right down onto the intake so that the body of the injector is right in the intake. I am wondering if the injector pulse is resonating through the now aluminum heads (were steel before) and thats what I'm hearing. are the injectors on you L98's pushed right up to the body of the injector? Also I installed a holley afpr and I can feel the ticking sound through the body of the afpr. Has anyone else installed one of these and head it tick loudly. I took the car on a 6 hour round trip Saturday and it ran fine. But I am not taking the chance of leaving my new wife on the side of an interstate 1500 miles from home on our honeymoon. Help me out here guys. I've got $7000 and 4 1/2 months of my time in this to go on the power tour and I'm hours from pulling the plug. Please look at your injector locations or let me know about your afpr (mines a holley) Sorry for the long post.

 

i'd suspect preignition. have you checked timing and what octane you run? do you knoew where the base is set and what the total timing is?

 

Nope not that......I've spared no expense....GM cap, rotor, module, msd wires, 91 octane 10.1 motor. Runs very well. Timing is at *8 advanced. I just stuck a screw driver in the afpr and the noise is right there. I can feel it if I rest it on the adjuster ****. If I put the screw driver on the fuel rail pass side its very loud through there. If I put it at the same location on the intake at the injectors, no noise. Thanks though. Anybody elses Holley afpr sound like this?

 

Buy another afpr and take it with you. That way, if it quits you can fix it and be the hero thereby further convincing her that she married the right guy! If you cancel the honeymoon, you'll never hear the end of it.

 

Thanks for the help guys....Heres what I found. After six weeks of chasing this noise (motor apart twice) I have pinpointed it to this. The Big mouth intake, when I pulled it from the box has for mounting points for the fuel rails. Three are machined, one is not. This tells me its a bad casting that is low. As I tighten the rails down it pushes the body of the injectors right up against the intake. I believe these injectors are suppose to float, yes? Therefore if the injectors are solid up against the intake any injector noise, and they are bosch's, would be transfered through the intake into the aluminum heads (new to this motor, steel on the old motor) which is amplifying the injector pulse. Add to that I am now running an afpr (when the old motor was stock) with 45 psi and the old motor had 41 psi. Also being a batch fire injection system it makes matters worse. The old....stock intake, steel heads, these bosch injectors, stock steel 1.5 rockers, 41 psi......the new motor.......tpis intake, aluminum heads, same bosch injectors, afpr w/ 45 psi, 1.6 rr's. So bury the injectors which are louder due to more fuel pressure and then let all the new aluminum amplify the noise and you have a bad lifter noise. I did a search on this last night and found three posts (1 exactly the same problem) with the same issues. I am going to loosen the rails and slide some washers in (easier said then done with the plenum on!) untill the injectors are clear of the intake. Thanks for your suggestions. Power Tour here we come!

 

Were picking it up in VA with the Camaro. See ya there.

 

Blue jag convertable.....have a safe trip

 

Dang, I wish I'd have caught you in time.

Should have cancelled the wedding.

Ya, grunt now, but post back in 15 years