327 Ready to fire

[scrpirn56]

My original post was "Surprise under the hood" I followed Tech Inspectors advise on the build with Edelbrock Performer RPM alum heads and Howards roller cam. I ended up adding Comp Cam 1.6 roller rockers. When it came time to drop the distributor, I rolled the engine over to find TDC on #1 and had no compression. I had originally set lash at zero per instructions and went 1/2 turn more. I removed the valve cover and started over on setting the valve lash. I could only go 1/8th of a turn more without loosing compression on that cylinder. It feels right on the push rod so my question is, is this normal? Did I have the rockers too tight therefore holding the valves open? Please advise. Thanks in advance.

[rspears]

Sounds like you've got the lifters way too tight. Rather than go into a discussion here, this is a link to a place that TechInspector often references that has the good stuff, linked specifically to adjusting lifters - http://www.crankshaftcoalition.com/w...raulic_lifters

[scrpirn56]

Thank you rspears!

[jerry clayton]

when you were at TDC #1 cyl-------with no compression--was it on the overlap stroke???????????

[scrpirn56]

No and I cranked it thru several revs with no change. I reset lash back to zero and went 1/8th turn on all. I dropped the distributor in, hooked up the carb and she fired right off! I'll go thru the break in now. New question- with roller cam, do I need to run at 2200 RPM for 20 min?

[rspears]

No and I cranked it thru several revs with no change. I reset lash back to zero and went 1/8th turn on all. I dropped the distributor in, hooked up the carb and she fired right off! I'll go thru the break in now. New question- with roller cam, do I need to run at 2200 RPM for 20 min?

Nope, the twenty minute run at 2000 to 2200rpm is a flat tappet cam requirement. With roller lifters there is no special break in requirement, but running a good break in oil, or a break in additive, is still a good idea, IMO.

[scrpirn56]

OK new problem. Rear main is leaking! Its a 68 327 large jrnl 4 bolt. Any way to replace without pulling the engine back out?

[scrpirn56]

OK got the rear main fixed. No way to do it without pulling the tranny or the engine. Engine was easier. Got my 68 Camaro back on the road and lovin it! Now I have an Edelbrock 650 carb and its OK and I mean JUST OK. TI1 had recommended a 750 on my original post when I started the build but did not get specific. So what can you all recommend for my 327? Once again, bored .040 over, flat top pistons, alum heads w/185 runners, roller cam 510/525, 4 sp Muncie. Thanks in advance!!!

[HWORRELL]

I ran a couple of the carb calculators on a 330 C.I. mild build engine @7000 rpm.
They showed a 634 cfm carb. So your carb should be good. Just remember those carbs come out of the box with standard jets and settings, sometimes you get lucky and its all good. But most of the time you gotta change the jets and tuning to suit your engine.

[rspears]

If your Edelbrock was a new buy you got a DVD showing both installation and tuning tips, but if not it's readily available on line plus a PDF manual at the bottom - Carburetor Installation & Tech Videos - Edelbrock, LLC.

[rumrumm]

Edelbrocks are jetted rich so you will want to check your plugs and adjust accordingly. The only way to really dial it in is with a A/F gauge.

[techinspector1]

I don't like 1.6 rockers on a SBC. Any street or street/strip cam you buy will have been designed for 1.5 rockers. 1.6's will add considerably to the effort of the motor to cycle through and if there's one thing the valvetrain does not need, it is additional effort to operate. I have seen only 10 to 12 hp gain from going to 1.6's, a gain that would not be felt in the seat of your pants, one that would only be beneficial if you were in competition and needed an extra 10 hp to drive around your competitor.

I will strongly urge you to learn how to tune the motor by reading the spark plugs. You need to make a full power run, then go to neutral and chop the ignition, coasting to a stop. Any low rpm idling or chugging to another spot before pulling the plugs will mask what's going on in the motor under full power. If you idle the motor after the full power run, you will be reading what the motor is doing at idle, not at full power. Use either a drag strip or a lonely, safe stretch of road where you can coast to a stop at a place where you can pull and read the plugs.

These first 3 videos from youtube are very basic, but are a good introduction to spark plugs.

https://www.youtube.com/watch?v=c-mkbQ7Ner8
https://www.youtube.com/watch?v=siJx2yt1jaw
https://www.youtube.com/watch?v=saCDmyiBmb0
Detonation and Pre-Ignition
Reading spark plugs | Tuning Spark Plugs

You'll want to invest in a good plug loupe (10X) with built-in light, such as this Longacre unit.....
Longacre Racing 50884, Longacre Tools and Pit Accessories | Longacre Racing
so that you can see what's going on with the porcelain all the way up to the end of the porcelain in order to divide the porcelain into three parts and read it correctly.

I don't have this book, but I would highly recommend buying it for the tips on tuning that you may not find anywhere else. I would consider it an excellent value at 20 bucks....Otherwise, it could take you years to learn what this guy can teach you....
Spark plug reading

If you want to go fast with a 4-speed, bolt on a 750 double pumper carb.

.

[jerry clayton]

IF your 650 carb is big enough for 7000 RPM----------consider that it isn't big enough for 3-4500 rpm just driving around----------airscopes and carbs are ONLY big enough at max speed and never big enough at some of the intermediate ranges


put the 750 or an 8000 gouble pumper on it

[camaro_fever68]

Any street or street/strip cam you buy will have been designed for 1.5 rockers. 1.6's will add considerably to the effort of the motor to cycle through and if there's one thing the valvetrain does not need, it is additional effort to operate.

Where did you dream this up? Lobe lift dictates everything. If the lobe is stable, 1.6 rockers are a benefit.

Less lobe for the same lift makes more power. Read up here Why in the he!! do people buy 1.5 rockers? • Speed Talk

[techinspector1]

Where did you dream this up? Lobe lift dictates everything. If the lobe is stable, 1.6 rockers are a benefit.
Less lobe for the same lift makes more power. Read up here Why in the he!! do people buy 1.5 rockers? • Speed Talk

OK Ray, I can see that I'm gonna have trouble with you on most everything I post and that you are either F-BIRD-88 or you are cozy with him. Most of these fellows who ask for help here are building a mild to moderate street motor, they're on a budget and cannot afford to replace parts regularly like a dedicated racer can. Therefore, there is no reason to build a motor for them right up against the wall at the risk of fraggin' something. If you want to use 1.6 rockers on a SBC motor and you're spending your own money, knock yourself out, but I will continue to err on the side of caution for these younguns who ask for our help. 10-12 hp is not something that a fellow would feel in the seat of his pants anyway in a street motor, and there are no time slips to compare. Get a grip.

.