[silver68]

One more thing, I can explain why you must "degree" the cam. On both of my personal engine builds each cam was off 2 or more degrees. Never trust a timing chain set with multiple keyways. That is especially true of cloyes true rollers.

["Puddles the Pontiac"]

thanks for all your help and i do plan to check out the mentioned web sites.

as for tuning, the plugs look good on all three levels of the porcelain. as well, the electrode is showing that i do have the correct range plug. after rechecking, i had found some of the gaps to be off. all are reset to .045.

an issue i am having is that i am only getting about 10* of mechanical advance (there are no provisions for vacuum adv.) i am looking for a weight set to get me more, i do physically have more room for more advance (via the slots), but the weights are stopping early. i am looking around for stock weights now.

i know i cannot compete with a wide band. but my idle, off idle is great. not a stumble or pop to be found. the engine will "bark" with a quick stab at the pedal. not to mention the thing will start like a new, fuel injected car. i do have serious traction issues and this car is quick.

but the miss is still there. and it is a light miss (not a surge) which leads me to believe it is in the ignition. i can best feel it during "cruise" situations. i plan to change the coil and module. i can see nothing physically wrong inside the distributor.

fyi, i do have the new cam in (290b-6). the cams lobes all survived break in. at a 106 lsa there is no issue with a lack of dynamic compression (thanks screamingchief for the cam lesson last year). these are 93cc 6x-4 heads on a .030 over 455, zero deck. you are right to say i am guessing the static compression ratio when i guess 9.75 to 10-1. and i am going to use a friends inductive light when setting timing. i will get back to all with any new results. again thanks to all.

p.s. does it make anyone else nervous to see their oil pressure drop to 10lbs at idle? i have never gotten over that.

[MikeB'70Tempest]

5-7 cross fire maybe?? Are the wires running next to each other??

[silver68]

Try gapping the plugs at .035, I may be mistaken but I have heard wider plug gaps cause more problems than performance gains. Also use wires with a low ohm per foot rating. Parts store brand wires are notoriusly problematic and have very high resistance, even when new. Make sure you have 12 volts going to the hei, use a volt meter not a test light. The power wire to the coil was a resistor wire from the factory and does not supply 12 volts. Be sure your alternator is producing between 12 and 14 volts and that you have proper grounds fromthe engine to the frame to the battery.

["Puddles the Pontiac"]

well, here is an update.

i tested the pickup and ignition coil. all are good. replaced the module, no improvement. tested all my wires, they are about 5000ohm/ft. (stock wires). plugs themselves all look the same.

now my misfire has increased to a "popping" out the exhaust pipe. sometimes even a full backfire. and it seems as if i have a spark plug wire unplugged.

now i am going to recheck everything mechanical. i will do a compression check and check my cam lobes and springs.

i have NEVER had a miss this hard to find. this is INSANE.

[Old Man Taylor]

I have had bad spark plug wires that check out just fine.

["Puddles the Pontiac"]

i forgot to add that while i was going back through my distributor i noticed the shaft had alot of end play, as well, the thrust washer above the gear looks worn. is this an issue for a pontiac since it does spin opposite of what a chevy spins?

this thing fires off like a champ, its just everything after that, it has issues.

[screamingchief]

Any time a problem persists even after attempts to correct it,it's time to drop back on basic engine diagnostics.

Compression test,leak-down test,vacuum gauge readings,that sorta stuff.

Along with close inspections of stuff like the valvetrain and valvesprings and such.

At the very minimum you would be establishing a "baseline" for this combo,that way you can always track the engines "health" based on how it was when it was "fresh".

And you may just find something that needs attention before it gets really nasty.

Timing & ignition really should'nt be all that complicated,mostly nail down the basic set-up and forget it for the most part.

Also agree that degreeing the cam should not have been considered "optional".

And you can throw rocker arm geometry and pushrod length into that "mandatory" catagory as well.



BP.

["Puddles the Pontiac"]

well, here is another update. i did a comp. check of all my cylinders and everyone of them, except for #6, checked out at 150lbs. #6 was at 148. i did not round any of them up or down. guess i am off to the next check.

[screamingchief]

Well,the numbers are nice & even across the board,so that's very reassuring that it's not hurt in any major way.

If nothing else,you now have a baseline no. for this combo as it sits,record those numbers and keep them in a tuning log or such for future reference.

Though to me the numbers seem just a bit low for the 290b6 with 9.75:1 CR,but I could be a bit "off" on that impression.

I for sure would wanna degree it now,just to know exactly where the ICL is.

And if it was @ 106° or greater ICL,I'd advance it some to get it down to 102° ICL or thereabouts.

But I doubt that CL stuff has anything to do with the issue your chasing right now.

Also,what is the lash set @ on this?

If you got the lash set really tight,that might help explain the lower than expected cranking compression numbers some as well.

Just a few thoughts...

HTH

BP.

["Puddles the Pontiac"]

well i expected the psi to be close to that since the cam is straight up. i was closer to 215 with this cam advaced 4 degrees in a previous engine. i am afraid to advance this cam back to 4 degrees because of the issue i had with pump gas when i used this cam before.

i will be tearing down the carb and making sure it isnt clogged anywhere.

again, is there any issue with having alot of endplay on my distributor?

this weekend i will probably throw a pertronics module (to match the coil) decent plug wires and some plugs at this.

any suggestions on a set of good plug wires at a decent price?

p.s. the lash was set as per the card.

[screamingchief]

Originally Posted by Puddles the Pontiac

well i expected the psi to be close to that since the cam is straight up. i was closer to 215 with this cam advaced 4 degrees in a previous engine. i am afraid to advance this cam back to 4 degrees because of the issue i had with pump gas when i used this cam before.

No way it would go from 150 psi to 215 psi from only 4° of advance with the same cam in the same combo,something there does'nt sound right at all.

Was that before or after the switch to the 1.65 rockers?

What ratio rockers are on this right now??

If your currently using the 1.65's,were the pushrod slots properly clearanced for the 1.65 rockers?

Were there any other changes in there???

Originally Posted by Puddles the Pontiac

again, is there any issue with having alot of endplay on my distributor?

Please define how much is "alot"...

When it comes to distributor endplay,normally a bit of extra endplay wont cause huge troubles,but it wont hurt tightening it up some either.

Usually I've run into more problems with timing when someone did'nt get the eccentric assembled properly,how was yours assembled?

Did you use the fuel pump eccentric,or an eccentric eliminator spacer when assembling the timing chain set?

If not,then one is definitely needed,the cam snout needs to be pulled past the face of the cam gear to establish proper cam endplay.

As for the plugs,exactly what plugs are you running,what gaps?

I agree with what someone said earlier,you dont need a bunch of gap,I mostly stay between .035" to .045" gap unless using nitrous,boost,or really high compression,and those applications get even less gap,not more.

What plug wires are on there now??

I use either MSD 8.5mm super conductors or the Taylor "thundervolt" 50 10.5mm wires.

Plug wires are one place I dont shop on price.

Also,are you using the low resistance bushing for the coil in the cap?

That item has been known to cause issues for some with high output ignitions.

Just some more idea to ponder,sooner or later there's gonna be one of those "AHA" moments...

Bret P.

["Puddles the Pontiac"]

well, the combo was slightly different when i ran this cam last. different pistons, it was a 469 and this one is a 463. different ring package as well.

the endplay seems a little excessive. its allowing the reluctor to raise a little high but not beyond the pickups teeth. there's about a 50/50 overlap if that makes any sense.

plugs are r42ts gapped at .035

i have a fuel pump eccentric eliminator from butler on the cam.

the wires are 8mm supressor "premium" stock replacements. if i could afford it i would have a set of moroso ultra 40's and call it a day. i am looking for a set of good wires in the $50 price range.

and it is a stock replacement bushing.

i cant wait for that "aha" moment. it will be better then christmas morning.

[screamingchief]

Originally Posted by Puddles the Pontiac

plugs are r42ts gapped at .035

Those plugs sound kinda cool for a fairly basic NA street/strip combo,any particular reason you are using them?

I know you said you were reading the plugs,and felt that they were in the ballpark heat range wise,but honestly I feel that may be a waste of time if your using pump gas in this.

Also,some feel the engine has to be shut off immeditately after a WOT blast to get an accurate read on the plugs.

So I gotta an easy enough suggestion,try the next step warmer plug and see what happens.

And get the MSD low resistance bushing for the coil the cap!!!

Could also try venting the cap too,but that's a long-shot fix there.

If none of that stuff helps,I gotta say I'd begin to start looking into areas other than the ignition.

HTH

Bret P.

[sixt8bird]

Did you elongate the pushrod hole?

[screamingchief]

Originally Posted by sixt8bird

Did you elongate the pushrod hole?

Good question,asked it myself earlier,hope he'll tell us.

[sixt8bird]

Originally Posted by screamingchief

Good question,asked it myself earlier,hope he'll tell us.

Sorry, I didn't see that. The next question is if you adjusted the pushrods right? Are you using Poly-locs? Are heads milled?

["Puddles the Pontiac"]

Originally Posted by sixt8bird

Sorry, I didn't see that. The next question is if you adjusted the pushrods right? Are you using Poly-locs? Are heads milled?

yes on all accounts. valve train geometry is right. i went back and checked all my plugs after i realized what i just wrote. some how i managed to mix up the plugs i had bought for the nitrous engine, anyway, they are all r45 now. no change. odd though, every plug looked the same.