351W hot and making me crazy.

Jimchil · Oct 19, 2020

Got a 73 Mustang with a crazy 351w someone put in instead of 302. Runs incredibly fast and came with all kinds of goodies. Performer RPM aluminum heads and roller rockers, Holley, MSD dist and 6A box, ceramic headers, tubular front suspension, etc. Runs hot, very hot. I put my hand behind the fan while idling and in seconds my hand cooks. The gauge doesn't show hot until I turn it off. Try to start it again and it turns over agonizingly slowly. Initial timing is 5 degrees advanced. If I back off more it turns over more easily and runs cooler but less power and slight backfires. Feels like it is the timing because it runs cooler by adjusting the dist. Has a huge aluminum radiator. Clutch fan. Any thoughts? Thanks.

wicked93gs · Oct 19, 2020

Probably is the timing...but its worthless to do anything with it until you get an accurate way to measure the temp.....actual temp, no the H or L the stock idiot light shows.

rbohm · Oct 19, 2020

the first thing you want to do is check the timing marks on your car. it sounds like your timing is way off. find TDC but not with the marks on the balancer. once that is done THEN check the balancer and see where the marks line up. and go from there.

7991LXnSHO · Oct 19, 2020

After the timing is set, the starter may work better as it stays cooler. If not, get it bench tested, and replace or voltage drop test the cables.
If the engine is high enough compression, a high torque mini starter and a heat shield might be worth it.

Jimchil · Oct 19, 2020

Thank all of you. For now I will check the timing marks and temperature, though my hand I thought was a pretty good gauge. It has a Ford gauge and it climbs to hot after I turn it off. It also has tape with timing numbers stuck on the balancer. Something seems screwy because on the MSD distributor, a little plastic part of the cap sticks out on both sides and the intake blocks it from turning much more. I would design the plastic part to be safely in the middle. I will check the timing but I will bet either the timing chain or distributor is off a tooth. Probably dist.

wicked93gs · Oct 20, 2020

MSD distributors do not have the best reputation for several reasons....most prefer factory Ford dizzys with an electronic ignition conversion.(Petronix 1, the Petronix 2 unit again doesn't have a good rep).

Adieu · Oct 20, 2020

wicked93gs said:
MSD distributors do not have the best reputation for several reasons....most prefer factory Ford dizzys with an electronic ignition conversion.(Petronix 1, the Petronix 2 unit again doesn't have a good rep).

MSD's distributor is the only reliable part under the hood of my Mustang II with their name on it. Their EFI system, ignition box, and coil have all failed and been replaced over the years, but that billet distributor is the finest thing Mostly Starts Dammit ever made!

But yeah, MSD's products had devolved to garbage by the time Holley saved them from bankruptcy, and I have zero faith in Holley righting that ship.

If OP narrows part or all of his issue down to the distributor, Pro-Comp makes a good, cheap, HEI-style distributor a lot of guys run in budget builds without issue, which adds the convenience of using super-common Chevy tune-up parts on the distributor itself.

Stangninjak · Oct 23, 2020

I run a Proform HEI myself on my 351w no fuss no muss. If you seem to lose power when you adjust the timing, you may want to look at how the carb is setup as well.

hftrud · Oct 29, 2020

Jimchil said:
Thank all of you. For now I will check the timing marks and temperature, though my hand I thought was a pretty good gauge. It has a Ford gauge and it climbs to hot after I turn it off. It also has tape with timing numbers stuck on the balancer. Something seems screwy because on the MSD distributor, a little plastic part of the cap sticks out on both sides and the intake blocks it from turning much more. I would design the plastic part to be safely in the middle. I will check the timing but I will bet either the timing chain or distributor is off a tooth. Probably dist.

Sounds like you may have a large cap MDS dist. Get a small cap MSD dist with magnetic pickup. Then it can be adjusted.

Jimchil · Oct 29, 2020

hftrud said:
Sounds like you may have a large cap MDS dist. Get a small cap MSD dist with magnetic pickup. Then it can be adjusted.

Thank you. I do have a large Adapt-a-cap MSD and the under the cap spacer had worked loose.

rbancy · Nov 8, 2020

what do you have for a thermostat ? don't go by the dash guage, get a mechanical gauge even if you don't put power it in, least you'll know the temperature. Remember with the alluminum radiator they get really hot after you drive it for awhile and car is shut. Usually 180 thermostat is good. Depending on how you drive it, then at least you get an accurate temp. Let me know after you hook up a gauge what the temp is at ? Also when your timing is done right - be a big difference on temp.

WORTH · Dec 5, 2020

I agree you need to get a thermometer on it to see if it is actually running too hot. And like previously stated, pull the #1 piston up to TDC on the compression stroke and see where the timing mark is. Hot starter is another possibility too. You mentioned headers, are they close to the starter? Is there room to make a heat shield for it?

chuck gibson · Dec 5, 2020

This is most likely not your problem but several years ago a friend of mine was having weird problems with his timing and temperature and it ended up being his harmonic balencer. The rubber insert had literally broken loose and it had spun a few degrees. he replaced it and the car ran fine..

351W hot and making me crazy.

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