Thread: engine timing

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Hello-I have a 71 chevy pu with a big block 402 / with early model 427 closed chamber heads 101 cc xtreme energy cam 224-230@.50-515 - 520 lift somewhat mild for a BB - Perfomer RPM Air gap 750 Edelbrock carb - 2" full length headers- flowmasters.New Mallory HEI. Problem- I have got the static advance set @ 20' and no pinging 45' total and it seems it could take more - The truck noses down off the line and then goes-- any one have any ideas

45 Degrees is huge. Earlier big blocks tend to like about 14 degrees initial with about 38 total.

What happens when you dial it back?

Originally posted by Greg Peterburs
Hello-I have a 71 chevy pu with a big block 402 / with early model 427 closed chamber heads 101 cc xtreme energy cam 224-230@.50-515 - 520 lift somewhat mild for a BB - Perfomer RPM Air gap 750 Edelbrock carb - 2" full length headers- flowmasters.New Mallory HEI. Problem- I have got the static advance set @ 20' and no pinging 45' total and it seems it could take more - The truck noses down off the line and then goes-- any one have any ideas

You sure your timing marks havent slipped or something, 20 degrees initial timing and its starts ok hot

Couple more degrees initial, and I'll bet you could get that motor to run backwards.

Seriously, nosing over early indicates accelerator pump in the carb to me.

Have you checked your timing mark against #1 TDC to make sure the balancer is indexed properly. I agree with lt1. Something sounds odd here.

Also, do you have vacuum advance? If so, did you set the timing with the vacuum line disconnected and plugged?

Originally posted by Henry Rifle
Couple more degrees initial, and I'll bet you could get that motor to run backwards.

Seriously, nosing over early indicates accelerator pump in the carb to me.

Have you checked your timing mark against #1 TDC to make sure the balancer is indexed properly. I agree with lt1. Something sounds odd here.

Also, do you have vacuum advance? If so, did you set the timing with the vacuum line disconnected and plugged?

its got to be something like that, because hes talking 20 initial and could stand some more. something ant right.

I replaced the accelerator pump -- I called Edelbrock - They said to change the metering rod springs - primary system not com ing on fast enough

Originally posted by Greg Peterburs
I replaced the accelerator pump -- I called Edelbrock - They said to change the metering rod springs - primary system not com ing on fast enough

all of that may be needed but id get my timing fixed before i did anything else. you need to find your TDC and find out what timing you really have. 20 degrees is to high, but the way you talk it could stand some more and if your balance has slipped then that could be your problem. you know you got a problem there so fix that first. did you tell the guy at Edelbrock that you was runing that much tining? something to think about.

Have a new balancer & stock timing cover - pointer - I will ck. tdc

Just a thought from experiance.
Double check the condition of your cap and rotar. Dirty cap and fouled cap can cause all kinds of weird stuff when putting a timing light on the balancer.

My big block likes a ton of timing too, and I know of several others that do as well. You cant just say it's too much timing, every engine is different. I have run a total of 48 degrees on a big block with no problem, that's the way it ran the best. I would think the carb is the problem, and I think you'll find the fix with the route you're taking. You need more fuel when you hit it. I think you'll be OK after that. Check the timing again to be sure, but dont worry about it if it runs good. Just watch for signs of detonation.....little silvery specks on the plugs for example. You cant always hear the pinging, so dont just go by that. John

I went back to this post because I just read LT1S10s comments about this on Why Isn't. First I dont know a lot about Big Blocks.Only owned two in my life. BUT--------- I know 45-46-48degrees of timing is a L_O_T_T_A timing. And Tho ,I dont know much about big blocks I certainly know the people that do.I called the one tonight that I value his opinion on this subject more than anyone else's. Many people just call him "MOORE" He has built somewhere close to 200 big blocks. In the 60's he raced 409 Chevys, Then switched to Pontaics and had a factory Sponsorship.Since the 70's he has been building big blocks for boats. If you have a 35 ft. boat and want to run over a 100mph he's the man people all up and down the East Coast call.
-He tells me that a 468 is now a small motor . Most that he builds are 540, 572 or bigger. Says the most timing he ever runs in any big block is 36 to 38 degrees.He tells me he did race a 454-450hp chevelle way back when that he would run 42 degrees on the holeshot , hit a toggle switch on the dash that dropped him back to 36 degrees.He wondered how anyone would get the car started with as much timing as some say they run,and he also ask if the people recomending all this much timing intended to help pay for the motors that would be distroyed.One more thing , the last big boat race in the area ,Sept 25th ,the top 4 money winners were his motors ,tuned as he directed.